A method for synthesizing a doped niobium dioxide electronic phase change material

Abstract

The application relates to a flux synthesis method of doped niobium dioxide sensitive resistance material, belonging to the field of thermosensitive electronic phase change. Specifically, the application relates to a method for reducing reaction temperature by using a flux, and the doped niobium dioxide electronic phase change material is batch-synthesized through high and low valence state niobium precursor batching and flux reaction in an inert or vacuum atmosphere to prepare powder, ceramic or thin film material. The application provides a non-uniform nucleation condition for new phase growth by introducing an alkali metal halide flux with similar lattice parameters of the synthesized material, reduces the free energy of the nucleation and growth of the new phase, greatly reduces the required reaction temperature and reaction time of the material synthesis, and can realize the batch preparation of high-purity and high-uniformity material in a controllable atmosphere. The reaction speed is fast, energy consumption is reduced, and the prepared doped niobium dioxide electronic phase change material has a chemical formula of Nb 1‑x M x O2: M is a rare earth element or a transition group metal element, and has considerable application value in the fields of high-temperature thermosensitive resistance, critical temperature coefficient thermosensitive resistance, nonvolatile storage, sensors and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of functional materials and electronic phase change materials, and particularly relates to a technical method for effectively preparing a wide range of doped niobium dioxide electronic phase change powder, ceramic and thin film material under a controllable atmosphere by taking an alkali metal halide as a fluxing agent and a non-uniform nucleation trigger, which has application value in the fields of high-temperature negative temperature coefficient thermistors, critical temperature coefficient thermistors and sensors. TECHNICAL BACKGROUND

[0002] Niobium dioxide has a metal-insulator phase transition characteristic at a high temperature near the phase transition temperature of 1070 K 【1】. That is, it is converted from a low-temperature insulator phase to a high-temperature metal phase, and the resistivity is reduced by 1-2 orders of magnitude. The chemical formula of niobium dioxide is NbO2, in which the valence of Nb is +4. Doping niobium dioxide with ions of transition group elements having similar ionic radii can achieve substitutional doping of Nb sites, thereby realizing continuous regulation of the phase transition temperature in the range of 965-1070 K 【2】 and regulation of the degree of resistivity jump. Therefore, the material has considerable application value in non-volatile storage, sensors and memristors 【3-5】.

[0003] At present, the commonly used method for synthesizing niobium dioxide is solid phase reaction. The main process is to seal NbO and Nb2O5 into a vacuum quartz tube, and they exchange oxygen without contact. Oxygen partial pressure balance is achieved by reacting at a high temperature of 1100 ℃ for several days, and finally niobium dioxide is synthesized 【6】. The reaction temperature is relatively high, and it is difficult to synthesize pure phase materials. In addition to synthesizing NbO2 in vacuum, the material can also be synthesized by using H2 as a reducing gas at 1350 K. The synthesized powder material needs to be hot-pressed to form a bulk material under a high pressure of 25 MPa in an Ar atmosphere 【7】. However, this method has a high experimental safety risk at high temperatures and a relatively complicated process. Since the existing methods for synthesizing niobium dioxide bulk materials have a high temperature of 1100 ℃ or above, and usually need a long time of solid phase reaction to obtain pure phase materials of the system, the process is time-consuming and energy-consuming, which increases the application cost of the system materials.

[0004] In summary, at present, there is still a lack of an effective method for synthesizing doped niobium dioxide materials in a large amount by one reaction at a relatively low reaction temperature. The potential application of doped niobium dioxide also needs to be explored.

[0005] [1] Sakata K., Electrical and Magnetic Properties of NbO2[J], Journal of the Physical Society of Japan 1969, 26(3): 867-867.

[0006] [2] Rao C.N.R., Rao G.R., Rao G.V.S., Semiconductor-metal transitions in NbO2 and Nb 1−x V x O2[J], Journal of Solid State Chemistry 1973, 6(3): 340-343.

[0007] [3] Páez Fajardo G.J., Howard S.A., Evlyukhin E., et al., Structural Phase Transitions of NbO2: Bulk versus Surface[J], Chemistry of Materials 2021, 33(4): 1416-1425.

[0008] [4] Kumar S., Wang Z., Davila N., et al., Physical origins of current and temperature controlled negative differential resistances in NbO2[J], Nature Communications 2017, 8(1).

[0009] [5] Stoever J., Boschker J.E., Bin Anooz S., et al., Approaching the high intrinsic electrical resistivity of NbO2 in epitaxially grown films[J], Applied Physics Letters 2020, 116(18).

[0010] 【6】Janninck R.F., Whitmore D.H., Electrical conductivity and thermoelectric power of niobium dioxide[J], Journal of Physics and Chemistry of Solids 1966, 27(6): 1183-1187.

[0011] 【7】Sakai Y., Tsuda N., Sakata T., Electrical Properties of Semiconducting NbO2 [J], Journal of the Physical Society of Japan 1985, 54(4): 1514-1518. SUMMARY

[0012] The purpose of the present application is to provide a synthesis method of doped niobium dioxide electronic phase change material; the main idea is that Nb in NbO2 is 4+ is intermediate valence state, using Nb2O5 higher than its valence state and Nb elemental lower than its valence state, to prepare the required +4 valence NbO2. The molten alkali halide flux is used to fully dissolve the oxide and metal elemental precursor required for the synthesis of the system material, and in the cooling process, based on the lattice matching relationship between niobium dioxide and the gradually precipitated alkali halide flux crystals, the niobium dioxide is nucleated and grown on the surface of the flux precipitated crystals in a non-uniform nucleation manner. Compared with the traditional solid phase reaction method of the system material, the technology provided by the present application can greatly reduce the synthesis temperature and reaction time of the material, and improve the purity and uniformity of the prepared material. The system material can be prepared in a large amount at a set atmosphere, lower reaction temperature and shorter reaction time. By further doping transition elements with different proportions at the Nb site, the metal-insulator phase transition characteristics and electrical transport relationship of the prepared niobium dioxide can be widely regulated, and the prepared material has application value in the fields of high-temperature negative temperature coefficient thermistors, critical temperature coefficient thermistors, non-volatile storage, sensors, etc.

[0013] A synthesis method of doped niobium dioxide electronic phase change material, the method comprising the following steps:

[0014] 1) Preparation of raw materials: The components of doped niobium dioxide material and the selection of niobium oxide or elemental precursor are designed according to the metal insulator electronic phase transition characteristics and high temperature negative temperature coefficient to be achieved. The precursors of niobium oxide or elemental, rare earth elements, third period transition group metal elements, III-V main group elements, etc. are weighed according to the stoichiometric ratio of the synthesized doped niobium dioxide material components and mixed thoroughly. The target material chemical formula is Nb 1-x M x O2, wherein M is a doping element, 0≤x≤0.5. According to the crystal structure of the doped niobium dioxide to be synthesized, an alkali halide is selected as a fluxing agent, and the selected fluxing agent is added to the above-mentioned precursor mixed powder in a certain proportion, and then mixed thoroughly and cold-pressed into a block.

[0015] 2) Heating reaction: The precursor mixed powder with the added fluxing agent is heated to a temperature above the melting point of the fluxing agent in an inert gas or vacuum atmosphere, so that the molten fluxing agent fully dissolves the precursor, and after a certain period of heat preservation, it is cooled to room temperature. In this process, the doped niobium dioxide is co-precipitated with the gradually solidified alkali halide flux through a non-uniform nucleation process.

[0016] 3) Preparation of powder, ceramic or thin film material: The obtained block product is re-ground into powder, and the obtained powder product is washed with deionized water to remove the alkali halide fluxing agent therein, thereby obtaining doped niobium dioxide powder; the obtained powder is further cold-pressed and annealed to obtain doped niobium dioxide ceramic; a substrate with a certain matching relationship with the doped niobium dioxide lattice is additionally added in step 1), and doped niobium dioxide thin film can also be prepared under the reaction conditions described in step 2).

[0017] Further, the niobium oxide or elemental precursor in step 1) is Nb2O5, Nb. The stoichiometric ratio (molar ratio) of the required reactant precursors is Nb:Nb2O5=1:2.

[0018] Further, the chemical components of the doped niobium dioxide synthesized in step 1) are Nb 1-x M xO2, wherein M is a rare earth element, a third period transition group metal element, a III-V main group element, including lanthanide rare earth elements, Ti, V, Cr, Mn, Fe, Co, Ni, Ga, Ge; the precursor of the doping element includes lanthanide rare earth oxides, TiO2, VO2, Cr2O3, MnO2, Fe2O3, Co2O3, NiO, Ga2O3, Ge2O3. By changing the type and proportion of the doping element M, the metal-insulator phase transition temperature, the degree of resistivity mutation, the size of the resistivity, and the high-temperature negative temperature coefficient of the prepared doped niobium dioxide can be controlled; the controllable phase transition temperature range is 600-1080 K, and the controllable negative temperature coefficient range of 300-600 K is -0.1 to -15 %K -1 . In a preferred example, the component is Nb 0.95 V 0.05 O2 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1000 K, and the low-temperature insulating phase has a negative temperature coefficient of -1 to -3 %K at 300-600 K -1 ; in another preferred example, the component is Nb 0.95 Sc 0.05 O2 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1048 K, and the low-temperature insulating phase has a negative temperature coefficient of -0.8 to -1.2 %K at 300-600 K -1 ; in another preferred example, the component is Nb 0.95 Fe 0.05 O2 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1050 K, and the low-temperature insulating phase has a negative temperature coefficient of -2 to -4 %K at 300-600 K -1 .

[0019] Further, the fluxing agent in step 1) has a melting point lower than that of the doped niobium dioxide to be synthesized, and can dissolve the precursor powder in a high-temperature molten state, so that the precursor powder is uniformly dispersed in the fluxing agent at high temperature, which is conducive to improving the reaction rate and uniformity; the alkali metal halide fluxing agent used can regulate the lattice matching degree and reaction temperature of the doped niobium dioxide to be synthesized. The molar ratio of the fluxing agent to the reactant precursor is 0.1-100, and the alkali metal halide fluxing agent includes NaCl, KCl, NaF, and KF. A single fluxing agent can be used to assist the growth of a new phase, or multiple fluxing agents can be mixed to assist the growth of a new phase. The type and proportion of the fluxing agent can be used to regulate the surface morphology and surface crystal orientation of the doped niobium dioxide powder to be synthesized, and further regulate the metal-insulator phase transition temperature and the degree of resistivity mutation. In a preferred example, the reactant precursor used is Nb, NbO2, Fe2O3, the fluxing agent used is KCl, the melting point of KCl is 776 ℃, and the material obtained at a reaction temperature of 900 ℃ has a composition of Nb 0.95 Fe 0.05 O2, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition at a phase transition temperature of about 1050 K; in another preferred example, the reactant precursor used is Nb, NbO2, Fe2O3, the fluxing agent used is NaCl, the melting point of NaCl is 801 ℃, and the material obtained at a reaction temperature of 950 ℃ has a composition of Nb 0.9 Fe 0.1 O2, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition at a phase transition temperature of about 1020 K; in another preferred example, the reactant precursor used is Nb, NbO2, Fe2O3, the fluxing agent used is NaF, the melting point of NaF is 993 ℃, and the material obtained at a reaction temperature of 1100 ℃ has a composition of Nb 0.8 Fe 0.2 O2, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition at a phase transition temperature of about 1000 K.

[0020] Further, the reaction temperature in step 2) is 800 ℃-1100 ℃; the inert gas or vacuum atmosphere includes argon, helium, nitrogen, and vacuum, wherein the vacuum atmosphere has a pressure of less than 10 -2 Pa; and the holding time is 24 h-72 h. The above different atmosphere conditions, reaction temperatures, and holding times jointly affect the micro-morphology and particle size of the doped niobium dioxide, and further regulate the metal-insulator phase transition temperature and the degree of resistivity mutation. In a preferred example, the powder material with a composition of Nb 0.95 Ti 0.05 O2 is prepared at a vacuum degree of 8.5×10 -3The NbO2 powder material is prepared in a sealed quartz tube at 900 DEG C for 24 hours, and the ceramic material after annealing has a low-temperature insulating phase to high-temperature metal phase transition at a phase transition temperature of 920 K; in another preferred example, the component is Nb 0.6 Sc 0.4 The NbO2 powder material is prepared in a sealed quartz tube at 900 DEG C for 24 hours, and the ceramic material after annealing has a low-temperature insulating phase to high-temperature metal phase transition at a phase transition temperature of 920 K; in another preferred example, the component is Nb -4 The NbO2 powder material is prepared in a sealed quartz tube at 900 DEG C for 24 hours, and the ceramic material after annealing has a low-temperature insulating phase to high-temperature metal phase transition at a phase transition temperature of 920 K; in another preferred example, the component is Nb 0.95 Y 0.05 The NbO2 powder material is prepared in a sealed quartz tube at 900 DEG C for 24 hours, and the ceramic material after annealing has a low-temperature insulating phase to high-temperature metal phase transition at a phase transition temperature of 920 K; in another preferred example, the component is Nb

[0021] Further, the substrate with a certain lattice matching relationship with the doped niobium dioxide in step 3) includes Si, (La, Sr)2(Al, Ta)2O6, SrTiO3, Al2O3, MgF2, LaAlO3, SiO2, SrLaAlO4, YAlO3, NdCaAlO3, NdCaO3, MgO, Gd3Ga5O 12 The metal-insulator phase transition temperature, the order of magnitude of the resistivity and the degree of resistivity mutation of the doped niobium dioxide thin film can be controlled by substrate selection, orientation selection and thin film growth thickness.

[0022] The present application provides a large-scale preparation method of doped niobium dioxide electronic phase change material, and the method has the advantages that, compared with other methods, by introducing an alkali halide fluxing agent with a similar lattice parameter of the synthesized material, a non-uniform nucleation condition is provided for new phase growth, the free energy of the new phase nucleation and growth is reduced, the reaction temperature and reaction time required for material synthesis are greatly reduced, and large-scale preparation of high-purity and high-uniformity material in a controllable atmosphere can be realized. By further adjusting the types and proportions of the doping elements, the wide-range control of the negative temperature coefficient, the order of magnitude of the resistivity, the metal-insulator phase transition temperature and the degree of resistivity mutation of the material can be realized. The insulator phase of the doped niobium dioxide resistive phase change material can be applied to high-temperature NTC thermistors, and the metal-insulator phase transition characteristics thereof can be applied to critical temperature coefficient thermistors, temperature alarms, thermal switches and the like. On the other hand, the doped niobium dioxide material has certain application prospects in the fields of non-volatile storage and memristor. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The X-ray diffraction pattern of the NbO2 powder synthesized by the fluxing agent method provided by the present application can show that the prepared powder is a pure phase powder.

[0024] Figure 2 The resistivity of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 4. It can be seen that the synthesized powder undergoes a low-temperature insulator phase to high-temperature metal phase transition near 1070 K. 0.95 V 0.05 The X-ray diffraction pattern of the NbO2 powder doped with V can be seen to have its main peak shifted to the right compared to the undoped NbO2.

[0025] Figure 3 The resistivity of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 4. It can be seen that the synthesized powder undergoes a low-temperature insulator phase to high-temperature metal phase transition near 1070 K. 0.95 Ti 0.05 The X-ray diffraction pattern of the NbO2 powder doped with V can be seen to have its main peak shifted to the right compared to the undoped NbO2.

[0026] Figure 4 The resistivity of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 4. It can be seen that the synthesized powder undergoes a low-temperature insulator phase to high-temperature metal phase transition near 1070 K.

[0027] Figure 5 The temperature coefficient of resistance of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 5. It can be seen that the temperature coefficient of resistance of the synthesized powder is -8.66 %K near the metal-insulator phase transition temperature of 1070 K. -1 .

[0028] Figure 6 The resistivity of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 4. It can be seen that the synthesized powder undergoes a low-temperature insulator phase to high-temperature metal phase transition near 1070 K. 0.95 Fe 0.05 The resistivity of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 4. It can be seen that the synthesized powder undergoes a low-temperature insulator phase to high-temperature metal phase transition near 1070 K.

[0029] Figure 7 The temperature coefficient of resistance of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 5. It can be seen that the temperature coefficient of resistance of the synthesized powder is -8.66 %K near the metal-insulator phase transition temperature of 1070 K. 0.95 Fe 0.05 The temperature coefficient of resistance of the NbO2 powder synthesized by the flux method according to the present application as a function of temperature is shown in FIG. 5. It can be seen that the temperature coefficient of resistance of the synthesized powder is -8.66 %K near the metal-insulator phase transition temperature of 1070 K. -1 . DETAILED DESCRIPTION

[0030] Unless otherwise defined, all terms used in disclosing the application, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Methods and materials similar or equivalent to those described herein can be used in the practice of the application. It is intended that the definition of the terms in this specification be understood as consistent with the definitions in the art. It is intended that the description of the application contained herein adequately describes the subject matter of the application to enable a person of ordinary skill in the art to make and use the application. The present application is not intended to be limited to the embodiments shown, but is to be accorded the full scope consistent with the language of the claims.

[0031] Other aspects of the application will be apparent to those skilled in the art from consideration of the disclosure herein.

[0032] The application is further described below with reference to specific examples. It is to be understood that these examples are merely illustrative of the application and do not limit the scope of the application. Unless otherwise indicated, the experimental methods in the following examples were carried out according to conventional procedures or as recommended by the manufacturer.

[0033] Example 1: Nb, Nb2O5, KCl were weighed according to the molar ratio of Nb:Nb2O5:KCl = 1:2:5, the weighed medicines were placed in an agate mortar and ground uniformly, and a 5 mm x 5 mm x 0.5 mm Al2O3(0001) substrate was embedded therein, then a tablet press was used to cold-press into a cylindrical block with a diameter of 10 mm, and the block was further placed in a vacuumed quartz glass tube with a vacuum degree of 8.5 x 10 -3 Pa. The quartz glass tube containing the cold-pressed block mixture was placed in a muffle furnace, the muffle furnace was heated at a rate of 8 ℃ / min from room temperature to 900 ℃, and kept at 900 ℃ for 72 hours, and then cooled to room temperature at a rate of 8 ℃ / min. The reacted block sample was re-ground into powder, the powder sample was repeatedly washed with deionized water and dried in an oven for 24 hours to obtain polycrystalline pure phase NbO2 powder and a pure phase NbO2 thin film. The obtained powder was cold-pressed and placed in a vacuumed quartz glass tube with a vacuum degree of 8.5 x 10 -3 Pa, and annealed at 700 ℃ for 24 hours to obtain a NbO2 ceramic material, which has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1070 K, and the degree of resistance mutation is 9 times; the pure phase NbO2 thin film has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 900 K, and the degree of resistance mutation is 2 orders of magnitude.

[0034] Example 2: Nb, Nb2O5, Sc2O3, KCl were weighed according to the molar ratio of Nb:Nb2O5:Sc2O3:KCl = 0.19:0.38:0.025:0.95, the weighed medicines were placed in an agate mortar and ground uniformly, and a 5 mm x 5 mm x 0.5 mm Al2O3(0001) substrate was embedded therein, then a tablet press was used to cold-press into a cylindrical block with a diameter of 10 mm, and the block was further placed in a vacuumed quartz glass tube with a vacuum degree of 8.5 x 10 -3Pa, the quartz glass tube containing the bulk mixture was put into a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, and kept at 900 °C for 72 hours, and then cooled to room temperature. The reacted bulk sample was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb 0.95 Sc 0.05 O2powder and Nb 0.95 Sc 0.05 O2thin film, the obtained powder was cold-pressed and then placed in a sealed quartz glass tube under vacuum, the vacuum degree was 8.5x10 -3 Pa, 700 °C for 24 hours to obtain Nb 0.95 Sc 0.05 O2ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1048 K, and the negative temperature coefficient of the low-temperature insulating phase is -0.8 to -1.2 %K in the temperature range of 300 to 600 K -1 ; Nb 0.95 Sc 0.05 O2thin film has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1020 K.

[0035] Example 3: Nb, Nb2O5, TiO2, and KCl were weighed according to the molar ratio of Nb:Nb2O5:TiO2:KCl=0.19:0.38:0.05:0.95, and then placed in an agate mortar for grinding, and a 5 mm x 5 mm x 0.5 mm SiO2(100) substrate was embedded therein, and then a tablet press was used to cold-press into a cylindrical bulk with a diameter of 10 mm, and the bulk was further placed in a sealed quartz glass tube under vacuum, the vacuum degree was 8.5x10 -3 Pa, the quartz glass tube containing the bulk mixture was put into a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, and kept at 900 °C for 72 hours, and then cooled to room temperature. The reacted bulk sample was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb 0.95 Ti 0.05 O2powder and Nb 0.95 Ti 0.05 O2thin film, the obtained powder was cold-pressed and then placed in a sealed quartz glass tube under vacuum, the vacuum degree was 8.5x10 -3 Pa, 700 °C for 24 hours to obtain Nb 0.95 Ti 0.05 O2ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 990 K, and the negative temperature coefficient of the low-temperature insulating phase is -1.2 to -2.8 %K in the temperature range of 300 to 600 K -1 ; Nb 0.95 Ti0.05 The O2 thin film transforms from a low-temperature insulating phase to a high-temperature metallic phase near the phase transition temperature of 955 K.

[0036] Example 4: Take Nb, Nb2O5, VO2, KCl according to the molar ratio of Nb:Nb2O5:VO2:KCl = 0.19:0.38:0.05:0.95, put the above weighed medicines into an agate mortar and grind them uniformly, embed a 5 mm x 5 mm x 0.5 mm PMN-PT (100) substrate into the agate mortar, then use a tablet press to cold-press into a cylindrical bulk with a diameter of 10 mm, further put the bulk into a sealed quartz glass tube which is evacuated to a vacuum degree of 8.5 x 10-4Pa, and then anneal the bulk at 700 ℃ for 24 hours to obtain a Nb 12 (111) substrate, then use a tablet press to cold-press into a cylindrical bulk with a diameter of 10 mm, further put the bulk into a sealed quartz glass tube which is evacuated to a vacuum degree of 8.5 x 10-4Pa, and then anneal the bulk at 700 ℃ for 24 hours to obtain a Nb -3 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.95 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.05 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.95 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.05 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb -3 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.95 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.05 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb -1 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.95 V2O5 powder, and KCl powder, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted bulk sample into powder, rinse the powder sample with deionized water and dry it to obtain a Nb 0.05 The O2 thin film transforms from a low-temperature insulating phase to a high-temperature metallic phase near the phase transition temperature of 970 K.

[0037] Example 5: Take Nb, Nb2O5, Cr2O3, KCl according to the molar ratio of Nb:Nb2O5:Cr2O3:KCl = 0.19:0.38:0.025:0.95, put the above weighed medicines into an agate mortar and grind them uniformly, embed a 5 mm x 5 mm x 0.5 mm PMN-PT (100) substrate into the agate mortar, then use a tablet press to cold-press into a cylindrical bulk with a diameter of 10 mm, further put the bulk into a sealed quartz glass tube which is evacuated to a vacuum degree of 8.5 x 10-4Pa, and then anneal the bulk at 700 ℃ for 24 hours to obtain a Nb -3Pa, the quartz glass tube containing the bulk mixture was put into a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, and kept at 900 °C for 72 hours, and then the furnace was cooled to room temperature. The bulk sample after reaction was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb 0.95 Cr 0.05 O2powder and Nb 0.95 Cr 0.05 O2thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube which was evacuated, the vacuum degree was 8.5 x 10 -3 Pa, and annealed at 700 °C for 24 hours to obtain Nb 0.95 Cr 0.05 O2ceramic material, which has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1030 K, and the negative temperature coefficient of the low-temperature insulating phase is -0.8 to -2 %K in the temperature range of 300 to 600 K -1 ; Nb 0.95 Cr 0.05 O2thin film, which has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1000 K.

[0038] Example 6: Nb, Nb2O5, MnO2, and KCl were weighed according to the molar ratio of Nb:Nb2O5:MnO2:KCl = 0.19:0.38:0.05:0.95, and the weighed materials were placed in an agate mortar and ground uniformly, and then a Si (100) substrate with a size of 5 mm x 5 mm x 0.5 mm was embedded in the mortar, and then a tablet press was used to cold-press the mixture into a cylindrical bulk with a diameter of 10 mm, and the bulk was further put into a sealed quartz glass tube which was evacuated, the vacuum degree was 8.5 x 10 -3 Pa, the quartz glass tube containing the bulk mixture was put into a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, and kept at 900 °C for 72 hours, and then the furnace was cooled to room temperature. The bulk sample after reaction was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb 0.95 Mn 0.05 O2powder and Nb 0.95 Mn 0.05 O2thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube which was evacuated, the vacuum degree was 8.5 x 10 -3 Pa, and annealed at 700 °C for 24 hours to obtain Nb 0.95 Mn 0.05 O2ceramic material, which has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1010 K, and the negative temperature coefficient of the low-temperature insulating phase is -0.5 to -1.5 %K in the temperature range of 300 to 600 K -1 ; Nb0.95 Mn 0.05 The O2 thin film undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 997 K.

[0039] Example 7: Take Nb, Nb2O5, Fe2O3, KCl according to the molar ratio of Nb:Nb2O5:Fe2O3:KCl = 0.19:0.38:0.025:0.95, put the above weighed medicines into an agate mortar and grind them uniformly, embed a 5 mm x 5 mm x 0.5 mm Al2O3(0001) substrate in the mortar, then use a tablet press to cold-press into a cylindrical block with a diameter of 10 mm, further put the block into a vacuumized quartz glass tube, the vacuum degree is 8.5 x 10-4Pa, and put the quartz glass tube containing the block mixture into a muffle furnace, the muffle furnace is heated from room temperature to 900 ℃ at a rate of 8 ℃ / min, and kept at 900 ℃ for 72 hours, and then cooled to room temperature. Re-grind the reacted block sample into powder, wash the powder sample with deionized water and dry to obtain Nb -3 Fe 0.95 O2 powder and Nb 0.05 Fe 0.95 O2 thin film, the obtained powder is cold-pressed and annealed at 700 ℃ for 24 hours under vacuum with a vacuum degree of 8.5 x 10-4Pa to obtain a Nb 0.05 Fe -3 O2 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1050 K, and the negative temperature coefficient of the low-temperature insulating phase is -2 to -4 %K in the temperature range of 300-600 K. 0.95 Fe 0.05 O2 thin film, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1025 K. -1 ;Nb 0.95 Fe 0.05 O2 thin film, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1025 K.

[0040] Example 8: Take Nb, Nb2O5, Co2O3, KCl according to the molar ratio of Nb:Nb2O5:Co2O3:KCl = 0.19:0.38:0.025:0.95, put the above weighed medicines into an agate mortar and grind them uniformly, embed a 5 mm x 5 mm x 0.5 mm Al2O3(0001) substrate in the mortar, then use a tablet press to cold-press into a cylindrical block with a diameter of 10 mm, further put the block into a vacuumized quartz glass tube, the vacuum degree is 8.5 x 10-4Pa, and put the quartz glass tube containing the block mixture into a muffle furnace, the muffle furnace is heated from room temperature to 900 ℃ at a rate of 8 ℃ / min, and kept at 900 ℃ for 72 hours, and then cooled to room temperature. Re-grind the reacted block sample into powder, wash the powder sample with deionized water and dry to obtain Nb -3Pa, the quartz glass tube containing the bulk mixture was put into a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, and kept at 900 °C for 72 hours, and then the furnace was cooled to room temperature. The bulk sample after reaction was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb 0.95 Co 0.05 O2powder and Nb 0.95 Co 0.05 O2thin film, the obtained powder was cold-pressed under vacuum at a vacuum degree of 8.5 x 10 -3 Pa, 700 °C for 24 hours to obtain Nb 0.95 Co 0.05 O2ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1021 K, and the negative temperature coefficient of the low-temperature insulating phase is -1 to -2.5 %K at 300-600 K -1 ; Nb 0.95 Co 0.05 O2thin film, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1003 K.

[0041] Example 9: Nb, Nb2O5, NiO and KCl were weighed according to the molar ratio Nb:Nb2O5:NiO:KCl = 0.19:0.38:0.05:0.95, the above weighed medicines were placed in an agate mortar and ground uniformly, and a 5 mm x 5 mm x 0.5 mm Al2O3(0001) substrate was embedded therein, and then a tablet press was used to cold-press into a cylindrical bulk with a diameter of 10 mm, and the bulk was further placed into a vacuum quartz glass tube with a vacuum degree of 8.5 x 10 -3 Pa, the quartz glass tube containing the bulk mixture was put into a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, and kept at 900 °C for 72 hours, and then the furnace was cooled to room temperature. The bulk sample after reaction was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb 0.95 Ni 0.05 O2powder and Nb 0.95 Ni 0.05 O2thin film, the obtained powder was cold-pressed under vacuum at a vacuum degree of 8.5 x 10 -3 Pa, 700 °C for 24 hours to obtain Nb 0.95 Ni 0.05 O2ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1015 K, and the negative temperature coefficient of the low-temperature insulating phase is -0.4 to -2.2 %K at 300-600 K -1 ; Nb 0.95 Ni 0.05The O2 thin film undergoes a low-temperature insulating phase to a high-temperature metallic phase transformation near the phase transition temperature of 986 K.

[0042] Example 10: Weigh Nb, Nb2O5, Fe2O3, and NaCl in a molar ratio of Nb:Nb2O5:Fe2O3:NaCl = 0.18:0.36:0.05:0.9. Grind the weighed substances thoroughly in an agate mortar until uniform, and embed a 5 mm × 5 mm × 0.5 mm MgF2(001) substrate into it. Then, use a tablet press to cold-press it into a cylindrical block with a diameter of 10 mm. Further, place the block into a vacuum-sealed quartz glass tube with a vacuum degree of 7.5 × 10⁻⁶. -3 Pa, a quartz glass tube containing the bulk mixture was placed in a muffle furnace, which was heated from room temperature to 950 °C at a rate of 8 °C / min, held at 950 °C for 72 hours, and then cooled to room temperature. The reacted bulk sample was reground into powder, washed with deionized water, and dried to obtain Nb. 0.9 Fe 0.1 O2 powder and Nb 0.9 Fe 0.1 O2 thin film, the obtained powder was cold-pressed and then subjected to vacuum at a vacuum degree of 7.5 × 10⁻⁶. -3 Nb was obtained by annealing at 700 ℃ for 24 hours. 0.9 Fe 0.1 O2 ceramic materials undergo a phase transition from a low-temperature insulating phase to a high-temperature metallic phase near the phase transition temperature of 1020 K. The negative temperature coefficient of the low-temperature insulating phase in the 300–600 K range is -1.5 to -3.6 %K. -1 ;Nb 0.9 Fe 0.1 O2 thin films undergo a low-temperature insulating phase to a high-temperature metallic phase transformation near the phase transition temperature of 950 K.

[0043] Example 11: Weigh Nb, Nb2O5, Fe2O3, and NaF according to the molar ratio Nb:Nb2O5:Fe2O3:NaF = 0.16:0.32:0.1:0.8. Grind the weighed substances thoroughly in an agate mortar until uniform, and embed a 5 mm × 5 mm × 0.5 mm (La,Sr)2(Al,Ta)2O6 (111) substrate into it. Then, use a tablet press to cold press it into a cylindrical block with a diameter of 10 mm. Further, place the block into a vacuum-sealed quartz glass tube with a vacuum degree of 7 × 10⁻⁶. -3 Pa, a quartz glass tube containing the bulk mixture was placed in a muffle furnace, which was heated from room temperature to 1100 °C at a rate of 8 °C / min, held at 1100 °C for 72 hours, and then cooled to room temperature. The reacted bulk sample was re-ground into powder, washed with deionized water, and dried to obtain Nb.0.8 Fe 0.2 O2 powder and Nb 0.8 Fe 0.2 O2 film, the obtained powder was cold-pressed and annealed at 700 °C for 24 hours under vacuum at a vacuum degree of 7 x 10 -3 Pa to obtain Nb 0.8 Fe 0.2 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1000 K, and the low-temperature insulating phase has a negative temperature coefficient of -1.2 to -3 %K at 300-600 K -1 ; Nb 0.8 Fe 0.2 O2 film has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 943 K.

[0044] Example 12: Nb, Nb2O5, Fe2O3 and KF were weighed according to the molar ratio Nb:Nb2O5:Fe2O3:KF = 0.14:0.28:0.15:0.7, and the weighed materials were placed in an agate mortar and ground uniformly, and a 5 mm x 5 mm x 0.5 mm SrTiO3 (111) substrate was embedded therein, and then a tablet press was used to cold-press into a cylindrical block with a diameter of 10 mm, and the block was further placed in a vacuum quartz glass tube with a vacuum degree of 6.5 x 10 -3 Pa, and the quartz glass tube containing the block mixture was placed in a muffle furnace, and the muffle furnace was heated at a rate of 8 °C / min from room temperature to 1100 °C, and kept at 1100 °C for 72 hours, and then cooled to room temperature. The reacted block sample was re-ground into powder, and the powder sample was washed with deionized water and dried to obtain Nb 0.7 Fe 0.3 O2 powder and Nb 0.7 Fe 0.3 O2 film, the obtained powder was cold-pressed and annealed at 700 °C for 24 hours under vacuum at a vacuum degree of 6.5 x 10 -3 Pa to obtain Nb 0.7 Fe 0.3 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 900 K, and the low-temperature insulating phase has a negative temperature coefficient of -1 to -2.8 %K at 300-600 K -1 ; Nb 0.7 Fe 0.3 O2 film has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 875 K.

[0045] Example 13: Take Nb, Nb2O5, Fe2O3, KCl according to the molar ratio of Nb:Nb2O5:Fe2O3:KCl = 0.12:0.24:0.2:0.6, put the above weighed medicines into an agate mortar and grind them uniformly, then embed a 5 mm x 5 mm x 0.5 mm Al2O3 (001) substrate into the mixture, and then use a tablet press to cold-press into a cylindrical body with a diameter of 10 mm. Further, put the body into a vacuum quartz glass tube, and the vacuum degree is 6 x 10-4Pa. Put the quartz glass tube containing the body mixture into a muffle furnace, and the muffle furnace is heated from room temperature to 1100 °C at a rate of 8 °C / min, and then kept at 1100 °C for 72 hours. Then, the furnace is cooled to room temperature. After the reaction, the body sample is re-ground into powder, and the powder sample is washed with deionized water and dried to obtain Nb -3 Fe 0.6 O2 powder and Nb 0.4 Fe 0.6 O2 thin film. After cold-pressing the obtained powder, the Nb 0.4 Fe -3 O2 ceramic material is obtained by annealing at 700 °C for 24 hours under vacuum, and the vacuum degree is 6 x 10-4Pa. The Nb 0.6 Fe 0.4 O2 ceramic material has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature of 900 K, and the negative temperature coefficient of the low-temperature insulating phase is -0.7 to -1.5 %K in the temperature range of 300 to 600 K. -1 ; the Nb 0.6 Fe 0.4 O2 thin film has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature of 860 K.

[0046] Example 14: Take Nb, Nb2O5, Fe2O3, KCl according to the molar ratio of Nb:Nb2O5:Fe2O3:KCl = 0.1:0.2:0.25:0.5, put the above weighed medicines into an agate mortar and grind them uniformly, then embed a 5 mm x 5 mm x 0.5 mm Al2O3 (001) substrate into the mixture, and then use a tablet press to cold-press into a cylindrical body with a diameter of 10 mm. Further, put the body into a vacuum quartz glass tube, and the vacuum degree is 5 x 10-4Pa. Put the quartz glass tube containing the body mixture into a muffle furnace, and the muffle furnace is heated from room temperature to 800 °C at a rate of 8 °C / min, and then kept at 800 °C for 72 hours. Then, the furnace is cooled to room temperature. After the reaction, the body sample is re-ground into powder, and the powder sample is washed with deionized water and dried to obtain Nb -3 Fe 0.5 O2 powder and Nb 0.5 Fe 0.5 O2 thin film. After cold-pressing the obtained powder, the Nb 0.5O2 thin film, the obtained powder was cold-pressed and annealed at 700 ℃ for 24 hours under vacuum at a vacuum degree of 2 x 10 -3 Pa, 700 ℃ for 24 hours to obtain Nb 0.5 Fe 0.5 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 900 K, and the low-temperature insulating phase has a negative temperature coefficient of -0.2 to -1 %K at 300-600 K -1 ; Nb 0.5 Fe 0.5 O2 thin film, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 860 K.

[0047] Example 15: Nb, Nb2O5, Sc2O3 and KCl were weighed according to the molar ratio Nb:Nb2O5:Sc2O3:KCl = 0.18:0.36:0.05:0.9, and the weighed materials were placed in an agate mortar and ground uniformly, and then a 5 mm x 5 mm x 0.5 mm MgO2 (001) substrate was embedded therein, and then a tablet press was used to cold-press the mixture into a cylindrical block with a diameter of 10 mm, and the block was further placed in a vacuumed quartz glass tube, and the vacuum degree was 2 x 10 -3 Pa, the quartz glass tube containing the block mixture was placed in a muffle furnace, and the muffle furnace was heated from room temperature to 900 ℃ at a rate of 8 ℃ / min, and was kept at 900 ℃ for 60 hours, and then was cooled to room temperature. The reacted block sample was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb 0.9 Sc 0.1 O2 powder and Nb 0.9 Sc 0.1 O2 thin film, the obtained powder was cold-pressed and annealed at 700 ℃ for 24 hours under vacuum at a vacuum degree of 2 x 10 -3 Pa, 700 ℃ for 24 hours to obtain Nb 0.9 Sc 0.1 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1022 K, and the low-temperature insulating phase has a negative temperature coefficient of -0.6 to -1 %K at 300-600 K -1 ; Nb 0.9 Sc 0.1 O2 thin film, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1005 K.

[0048] Example 16: Weigh Nb, Nb2O5, Sc2O3, and KCl in a molar ratio of Nb:Nb2O5:Sc2O3:KCl = 0.16:0.32:0.1:0.8. Grind the weighed substances thoroughly in an agate mortar until uniform, and embed a 5 mm × 5 mm × 0.5 mm LaAlO3(001) substrate into it. Then, use a tablet press to cold-press it into a cylindrical block with a diameter of 10 mm. Further, place the block into a vacuum-sealed quartz glass tube with a vacuum degree of 5.5 × 10⁻⁶. -3 Pa, a quartz glass tube containing the bulk mixture was placed in a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, held at 900 °C for 48 hours, and then cooled to room temperature. The reacted bulk sample was reground into powder, washed with deionized water, and dried to obtain Nb. 0.8 Sc 0.2 O2 powder and Nb 0.8 Sc 0.2 O2 thin film, the obtained powder was cold-pressed and then subjected to vacuum at a vacuum degree of 5.5 × 10⁻⁶. -3 Nb was obtained by annealing at 700℃ for 24 hours. 0.8 Sc 0.2 O2 ceramic materials undergo a phase transition from a low-temperature insulating phase to a high-temperature metallic phase near the phase transition temperature of 1003 K. The negative temperature coefficient of the low-temperature insulating phase in the 300–600 K range is -0.5 to -0.8% K. -1 ;Nb 0.8 Sc 0.2 O2 thin films undergo a low-temperature insulating phase to a high-temperature metallic phase transformation near a phase transition temperature of 930 K.

[0049] Example 17: Nb, Nb₂O₅, Sc₂O₃, and KCl were weighed in a molar ratio of Nb:Nb₂O₅:Sc₂O₃:KCl = 0.14:0.28:0.15:0.7. The weighed reagents were placed in an agate mortar and ground thoroughly until homogeneous. A 5 mm × 5 mm × 0.5 mm SrTiO₃(111) substrate was then embedded in the mortar. The substrate was then cold-pressed into a cylindrical block with a diameter of 10 mm using a tablet press. This block was further placed in a vacuum-sealed quartz glass tube with a vacuum degree of 3.2 × 10⁻⁶. -3 Pa, a quartz glass tube containing the bulk mixture was placed in a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min, held at 900 °C for 36 hours, and then cooled to room temperature. The reacted bulk sample was reground into powder, washed with deionized water, and dried to obtain Nb. 0.7 Sc 0.3 O2 powder and Nb 0.7 Sc 0.3O2 thin film, the obtained powder was cold-pressed and then annealed at 700 °C for 24 hours under vacuum at a vacuum degree of 1.0 x 10 -3 Pa to obtain Nb 0.7 Sc 0.3 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 950 K, and the low-temperature insulating phase has a negative temperature coefficient of -0.1 to -0.5 %K in the temperature range of 300 to 600 K -1 ; Nb 0.7 Sc 0.3 O2 thin film, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 880 K.

[0050] Example 18: Nb, Nb2O5, Sc2O3 and KCl were weighed according to the molar ratio of Nb:Nb2O5:Sc2O3:KCl = 0.12:0.24:0.20:0.6, and then put into an agate mortar for grinding. A 5 mm x 5 mm x 0.5 mm (La,Sr)2(Al,Ta)2O6(111) substrate was embedded in the mixture, and then cold-pressed into a cylindrical block with a diameter of 10 mm using a tablet machine. The block was further put into a vacuum quartz glass tube, and the vacuum degree was 1.0 x 10 -4 Pa. The quartz glass tube containing the block mixture was put into a muffle furnace, and the muffle furnace was heated from room temperature to 900 °C at a rate of 8 °C / min, and then kept at 900 °C for 24 hours. Subsequently, the furnace was cooled to room temperature. The reacted block sample was re-ground into powder, and the powder sample was washed with deionized water and dried to obtain Nb 0.6 Sc 0.4 O2 powder and Nb 0.6 Sc 0.4 O2 thin film, the obtained powder was cold-pressed and then put into a vacuum quartz glass tube, and the vacuum degree was 1.0 x 10 -4 Pa, and then annealed at 700 °C for 24 hours to obtain Nb 0.6 Sc 0.4 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 920 K, and the low-temperature insulating phase has a negative temperature coefficient of -0.03 to -0.1 %K in the temperature range of 300 to 600 K -1 ; Nb 0.6 Sc 0.4 O2 thin film, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 860 K.

[0051] Example 19: Weigh Nb, Nb2O5, Sc2O3, and KCl in a molar ratio of Nb:Nb2O5:Sc2O3:KCl = 0.1:0.2:0.25:0.5. Grind the weighed reagents thoroughly in an agate mortar until uniform, and embed a 5 mm × 5 mm × 0.5 mm Al2O3 (0001) substrate into it. Then, use a tablet press to cold-press it into a cylindrical block with a diameter of 10 mm. Further, place the block into a vacuum-sealed quartz glass tube with a vacuum degree of 2.0 × 10⁻⁶. -4 Pa, a quartz glass tube containing the bulk mixture was placed in a muffle furnace, which was heated from room temperature to 900°C at a rate of 8°C / min, held at 900°C for 72 hours, and then cooled to room temperature. The reacted bulk sample was reground into powder, washed with deionized water, and dried to obtain Nb. 0.5 Sc 0.5 O2 powder and Nb 0.5 Sc 0.5 O2 thin film, the obtained powder was cold-pressed and then subjected to vacuum at a vacuum degree of 2.0 × 10⁻⁶. -4 Nb was obtained by annealing at 700 ℃ for 24 hours. 0.5 Sc 0.5 O2 ceramic materials undergo a phase transition from a low-temperature insulating phase to a high-temperature metallic phase near the phase transition temperature of 890 K. The negative temperature coefficient of the low-temperature insulating phase in the 300–600 K range is -0.01 to -0.05 %K. -1 ;Nb 0.5 Sc 0.5 O2 thin films undergo a low-temperature insulating phase to a high-temperature metallic phase transformation near the phase transition temperature of 780 K.

[0052] Example 20: Nb, Nb₂O₅, Y₂O₃, and KCl were weighed in a molar ratio of Nb:Nb₂O₅:Y₂O₃:KCl = 0.19:0.38:0.025:0.95. The weighed reagents were placed in an agate mortar and ground thoroughly until homogeneous. A 5 mm × 5 mm × 0.5 mm Al₂O₃ (0001) substrate was embedded in the mortar. The mixture was then cold-pressed into cylindrical blocks with a diameter of 10 mm using a tablet press. The blocks were further placed in a sealed quartz glass tube filled with argon gas. The quartz glass tube containing the block mixture was placed in a muffle furnace, which was heated from room temperature to 900 °C at a rate of 8 °C / min and held at 900 °C for 72 hours. The furnace was then cooled to room temperature. The reacted block sample was reground into powder, washed with deionized water, and dried to obtain Nb. 0.95 Y 0.05 O2 powder and Nb 0.95 Y 0.05O2 thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube filled with argon, annealed at 700 ℃ for 24 hours to obtain Nb 0.95 Y 0.05 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 1010 K, and the low-temperature insulating phase has a negative temperature coefficient of -3 to -5 %K in the temperature range of 300-600 K -1 ; Nb 0.95 Y 0.05 O2 thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube filled with argon, annealed at 700 ℃ for 24 hours to obtain Nb

[0053] Example 21: Nb, Nb2O5, Y2O3 and KCl were weighed according to the molar ratio of Nb:Nb2O5:Y2O3:KCl = 0.18:0.36:0.05:0.9, and then put into an agate mortar for grinding, and a MgO (001) substrate with a size of 5 mm x 5 mm x 0.5 mm was embedded in the mortar, and then a tablet press was used to cold-press the mixture into a cylindrical block with a diameter of 10 mm. The block was further put into a sealed quartz glass tube filled with nitrogen, and the quartz glass tube containing the block mixture was put into a muffle furnace, and the muffle furnace was heated from room temperature to 900 ℃ at a rate of 8 ℃ / min, and then kept at 900 ℃ for 72 hours, and then cooled to room temperature. The reacted block sample was re-ground into powder, and the powder sample was washed with deionized water and dried to obtain Nb 0.9 Y 0.1 O2 powder and Nb 0.9 Y 0.1 O2 thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube filled with nitrogen, annealed at 700 ℃ for 24 hours to obtain Nb 0.9 Y 0.1 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 980 K, and the low-temperature insulating phase has a negative temperature coefficient of -2.4 to -3.5 %K in the temperature range of 300-600 K -1 ; Nb 0.9 Y 0.1 O2 thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube filled with nitrogen, annealed at 700 ℃ for 24 hours to obtain Nb

[0054] Example 22: Take Nb, Nb2O5, Y2O3, KCl according to the molar ratio of Nb:Nb2O5:Y2O3:KCl = 0.16:0.32:0.1:0.8, put the above weighed medicines into an agate mortar and grind them thoroughly and uniformly, embed a MgF2(001) substrate with a size of 5 mm x 5 mm x 0.5 mm into the mixture, then use a tablet press to cold-press into a cylindrical bulk with a diameter of 10 mm, further put the bulk into a sealed quartz glass tube filled with helium, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the bulk sample after reaction into powder, rinse the powder sample with deionized water and dry it to obtain Nb 0.8 Y 0.2 O2 powder and Nb 0.8 Y 0.2 O2 thin film, cold-press the obtained powder, and then put it into a sealed quartz glass tube filled with helium, anneal at 700 ℃ for 24 hours to obtain Nb 0.8 Y 0.2 O2 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 955 K, and the negative temperature coefficient of the low-temperature insulating phase is -2.4 to -3.5 %K at 300-600 K. -1 ; Nb 0.8 Y 0.2 O2 thin film, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 760 K.

[0055] Example 23: Take Nb, Nb2O5, Y2O3, KCl according to the molar ratio of Nb:Nb2O5:Y2O3:KCl = 0.14:0.28:0.15:0.7, put the above weighed medicines into an agate mortar and grind them thoroughly and uniformly, embed a SrTiO3(111) substrate with a size of 5 mm x 5 mm x 0.5 mm into the mixture, then use a tablet press to cold-press into a cylindrical bulk with a diameter of 10 mm, further put the bulk into a sealed quartz glass tube which is vacuumized to a vacuum degree of 8.5 x 10 -3 Pa, put the quartz glass tube containing the bulk mixture into a muffle furnace, heat the muffle furnace at a rate of 8 ℃ / min from room temperature to 900 ℃, keep the temperature at 900 ℃ for 72 hours, and then cool the furnace to room temperature. Re-grind the bulk sample after reaction into powder, rinse the powder sample with deionized water and dry it to obtain Nb 0.7 Y 0.3 O2 powder and Nb 0.7 Y 0.3 O2 thin film, cold-press the obtained powder, and then put it into a sealed quartz glass tube which is vacuumized to a vacuum degree of 8.5 x 10 -3Nb 0.7 Y 0.3 O2 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 895 K, has a negative temperature coefficient of -1.0 to -1.5 %K in the temperature range of 300 to 600 K in its low-temperature insulating phase -1 ; Nb 0.7 Y 0.3 O2 thin film, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 700 K.

[0056] Example 24: Take Nb, Nb2O5, Y2O3, and KCl according to the molar ratio of Nb:Nb2O5:Y2O3:KCl = 0.12:0.24:0.2:0.6, put the above-mentioned medicines into an agate mortar and grind them uniformly, embed a 5 mm x 5 mm x 0.5 mm Al2O3(0001) substrate in the mortar, and then use a tablet press to cold-press into a cylindrical block with a diameter of 10 mm. Further, put the block into a sealed quartz glass tube which is evacuated to a vacuum degree of 1.0 x 10 -3 Pa, put the quartz glass tube containing the block mixture into a muffle furnace, and heat the muffle furnace at a rate of 8 °C / min from room temperature to 900 °C, keep the temperature at 900 °C for 72 hours, and then cool the furnace to room temperature. Re-grind the reacted block sample into a powder, wash the powder sample with deionized water and dry it to obtain Nb 0.6 Y 0.4 O2 powder and Nb 0.6 Y 0.4 O2 thin film, put the obtained powder into a sealed quartz glass tube which is evacuated to a vacuum degree of 1.0 x 10 -3 Pa, anneal at 700 °C for 24 hours to obtain Nb 0.6 Y 0.4 O2 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 860 K, has a negative temperature coefficient of -0.3 to -0.8 %K in the temperature range of 300 to 600 K in its low-temperature insulating phase -1 ; Nb 0.6 Y 0.4 O2 thin film, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature 690 K.

[0057] Example 25: Take Nb, Nb2O5, Y2O3, KCl according to the molar ratio of Nb:Nb2O5:Y2O3:KCl = 0.10:0.20:0.25:0.5, put the above weighed medicines into an agate mortar and grind them thoroughly, embed a 5 mm x 5 mm x 0.5 mm Al2O3(0001) substrate into the mixture, then use a tablet press to cold-press into a cylindrical body with a diameter of 10 mm, further put the body into a sealed quartz glass tube which is evacuated to a vacuum degree of 1.0 x 10-4Pa, and anneal at 700 ℃ for 24 hours to obtain a Nb -4 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. -4 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. -1 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K. 0.5 Y2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 800 K, and has a negative temperature coefficient of -0.2 to -0.5 %K in the low-temperature insulating phase at 300-600 K.

[0058] Example 26: Take Nb, Nb2O5, Ga2O3, KCl according to the molar ratio of Nb:Nb2O5:Ga2O3:KCl = 0.19:0.38:0.025:0.95, put the above weighed medicines into an agate mortar and grind them thoroughly, embed a 5 mm x 5 mm x 0.5 mm NdGaO3(111) substrate into the mixture, then use a tablet press to cold-press into a cylindrical body with a diameter of 10 mm, further put the body into a sealed quartz glass tube which is evacuated to a vacuum degree of 8.5 x 10-4Pa, and anneal at 700 ℃ for 24 hours to obtain a Nb -3 Ga2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 680 K. 0.95 Ga2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 680 K. 0.05 Ga2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 680 K. 0.95 Ga2O3 ceramic material, which undergoes a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 680 K.0.05 O2 thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube which was evacuated to a vacuum degree of 8.5 x 10 -3 Pa, and annealed at 700 ℃ for 24 hours to obtain Nb 0.95 Ga 0.05 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 995 K, and has a negative temperature coefficient of -1.2 to -3.5 %K in the low-temperature insulating phase at 300-600 K -1 ; Nb 0.95 Ga 0.05 O2 thin film, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 900 K.

[0059] Example 27: Nb, Nb2O5, Ge2O3 and KCl were weighed according to the molar ratio of Nb:Nb2O5:Ge2O3:KCl = 0.19:0.38:0.025:0.95, and then put into an agate mortar to be ground uniformly, and a 5 mm x 5 mm x 0.5 mm NdGaAlO3 (100) substrate was embedded in the mixture, and then a tablet press was used to cold-press the mixture into a cylindrical block with a diameter of 10 mm, and the block was further put into a sealed quartz glass tube which was evacuated to a vacuum degree of 8.5 x 10 -3 Pa, and the quartz glass tube containing the block mixture was put into a muffle furnace, and the muffle furnace was heated at a rate of 8 ℃ / min from room temperature to 900 ℃, and kept at 900 ℃ for 72 hours, and then cooled to room temperature. The reacted block sample was re-ground into powder, and the powder sample was washed with deionized water and dried to obtain Nb 0.95 Ge 0.05 O2 powder and Nb 0.95 Ge 0.05 O2 thin film, the obtained powder was cold-pressed and then put into a sealed quartz glass tube which was evacuated to a vacuum degree of 8.5 x 10 -3 Pa, and annealed at 700 ℃ for 24 hours to obtain Nb 0.95 Ge 0.05 O2 ceramic material, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 990 K, and has a negative temperature coefficient of -0.8 to -2.5 %K in the low-temperature insulating phase at 300-600 K -1 ; Nb 0.95 Ge 0.05 O2 thin film, which has a low-temperature insulating phase to high-temperature metallic phase transition near the phase transition temperature of 890 K.

[0060] Example 28: Nb, Nb2O5, La2O3, KCl were weighed according to the molar ratio of Nb:Nb2O5:La2O3:KCl = 0.19:0.38:0.025:0.95, the weighed materials were put into an agate mortar and ground thoroughly, a 5 mm x 5 mm x 0.5 mm SrLaAlO4(100) substrate was embedded in the mixture, and then the mixture was cold-pressed into a cylindrical body with a diameter of 10 mm using a tablet machine. The body was further put into a sealed quartz glass tube which was evacuated to a vacuum degree of 8.5 x 10-3Pa, and then the quartz glass tube was put into a muffle furnace which was heated from room temperature to 900 °C at a rate of 8 °C / min, and kept at 900 °C for 72 hours. After that, the furnace was cooled to room temperature. The reacted body sample was re-ground into powder, the powder sample was washed with deionized water and dried to obtain Nb -3 La 0.95 O2 powder and Nb 0.05 La 0.95 O2 film. The obtained powder was cold-pressed and put into a sealed quartz glass tube which was evacuated to a vacuum degree of 8.5 x 10-3Pa, and then annealed at 700 °C for 24 hours to obtain Nb 0.05 La -3 O2 ceramic material. The low-temperature insulating phase of the Nb 0.95 La 0.05 O2 ceramic material transforms into a high-temperature metal phase near the phase transition temperature of 1020 K, and the negative temperature coefficient of the low-temperature insulating phase is -1 to -3.4 %K at 300-600 K. -1 ; the Nb 0.95 La 0.05 O2 film transforms from a low-temperature insulating phase to a high-temperature metal phase near the phase transition temperature of 1000 K.

[0061] The above description is merely preferred embodiments of the present application, but not to confine the scope of the application. The essential technical content of the present application is defined in the scope of the claims, and any technical entity or method which is the same as or equivalent to the defined scope of the claims is also covered in the scope of the claims.

Claims

1. A method of synthesizing a doped niobium dioxide sensitive resistive material, characterized by The method comprises the following steps: 1) ingredients: according to the metal insulator electronic phase transition characteristics and high temperature negative temperature coefficient to be achieved, the component design of doped niobium dioxide material and the selection of niobium oxide and elemental precursor; the precursors of niobium oxide and elemental, rare earth elements, third period transition group metal elements, III-V main group elements are weighed according to the stoichiometric ratio of the synthesized doped niobium dioxide material component and fully mixed, and the target material chemical formula is Nb 1-x M x O2, wherein M is a doping element, 0≤x≤0.5; according to the crystal structure of the doped niobium dioxide to be synthesized, an alkali halide is selected as a flux, the selected flux is added to the mixed powder of the reactant precursor in a certain proportion, and then cold pressed into a block after fully mixed; 2) heating reaction: the precursor mixed powder with flux is heated to a temperature above the melting point of the flux in an inert gas or vacuum atmosphere, so that the molten flux fully dissolves the precursor, and after a certain time of heat preservation, it is cooled to room temperature. In this process, the doped niobium dioxide is co-precipitated with the gradually solidified alkali halide flux through a non-uniform nucleation process; 3) preparation of powder, ceramic or thin film material: the obtained bulk product is re-ground into powder, and the obtained powder product is washed with deionized water to remove the alkali halide flux therein, so as to obtain a doped niobium dioxide powder; the obtained powder is further cold-pressed and annealed to obtain a doped niobium dioxide ceramic; a substrate with a certain matching relationship with the doped niobium dioxide lattice is additionally added in step 1), and a doped niobium dioxide thin film is prepared under the reaction conditions of step 2).

2. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, The niobium oxide and elemental precursor in step 1) is Nb2O5 and Nb; the molar ratio of the reactant precursor is Nb:Nb2O5 = 1:

2.

3. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, The chemical component of the synthesized doped niobium dioxide is Nb 1-x M x O2, wherein M is a rare earth element, a third period transition group metal element, and a III-V main group element; by changing the type and proportion of the doping element M, the metal-insulator phase transition temperature, the resistance mutation degree, the resistance, and the high-temperature negative temperature coefficient of the prepared doped niobium dioxide are regulated; the controllable phase transition temperature range is 600-1080K, and the controllable negative temperature coefficient range of 300-600K is -0.1--15%K -1 .

4. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, The melting point of the flux in step 1) is lower than that of the synthesized doped niobium dioxide, and the flux can dissolve the precursor powder in a high-temperature molten state, so that the precursor powder is uniformly dispersed in the flux at high temperature, which is beneficial to improve the reaction rate and uniformity; the alkali halide flux used can control the lattice matching degree and reaction temperature of the synthesized doped niobium dioxide; the molar ratio of the flux to the reactant precursor is 0.1-100, and the alkali halide flux includes NaCl, KCl, NaF, KF, a single flux is used to assist the growth of a new phase, and multiple fluxes are mixed to assist the growth of a new phase; the type and proportion of the flux can be used to control the surface morphology and surface crystal orientation of the synthesized doped niobium dioxide powder, and further adjust the metal-insulator phase transition temperature and the degree of resistance mutation.

5. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, Step 2) the temperature above the flux melting point is 800-1100℃; the inert gas or vacuum atmosphere includes argon, helium, nitrogen, vacuum, wherein the vacuum atmosphere pressure is less than 10 -2 Pa; the holding time is 24-72h; the above atmosphere conditions, reaction temperature and holding time will jointly affect the micro-morphology and particle size of the doped niobium dioxide, and further realize the regulation of the metal-insulator phase transition temperature and the abrupt change degree of the resistivity.

6. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, The reactant precursor used was Nb, the flux used was KCl with a melting point of 776 °C, and the material component produced was Nb at a reaction temperature of 900 °C 0.95 Fe 0.05 O2, and a low-temperature insulating phase to high-temperature metallic phase transition occurs near the phase transition temperature of 1050 K.

7. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, The reactant precursor used was Nb, the flux used was NaF with a melting point of 993 °C, and the material component produced was Nb at a reaction temperature of 1100 °C 0.8 Fe 0.2 O2, and a low-temperature insulating phase to high-temperature metallic phase transition occurs near the phase transition temperature of 1000 K.

8. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, The component is Nb 0.95 Ti 0.05 The powder material of O2 is prepared in a sealed quartz tube with a vacuum degree of 8.5*10 -3 Pa at 900℃ for 72 hours, and the ceramic material after annealing has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 990K. The component is Nb 0.6 Sc 0.4 The powder material of O2 is prepared by annealing at 900℃ for 24 hours in a sealed quartz tube with a vacuum degree of 1.0×10 -4 Pa, and the ceramic material after annealing has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature of 920K. The component is Nb 0.95 Y 0.05 The powder material of O2 was prepared in a sealed quartz tube filled with argon at 900 ℃ for 72 hours. The ceramic material after annealing has a low-temperature insulating phase to high-temperature metal phase transition near the phase transition temperature 1010 K.

9. The method for synthesizing a niobium dioxide-doped sensitive resistor material as described in claim 1, characterized in that, The substrate with certain lattice matching relationship with the doped niobium dioxide in step 3) includes Si, (La, Sr) 2 (Al, Ta) 2 O 6, SrTiO 3, Al 2 O 3, MgF 2, LaAlO 3, SiO 2, SrLaAlO 4, YAlO 3, NdCaAlO 3, NdCaO 3, MgO, Gd 3 Ga 5 O 12 The metal-insulator phase transition temperature and the order of magnitude of the resistivity and the degree of resistivity mutation of the doped niobium dioxide film are regulated by substrate selection, orientation selection and film growth thickness.

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