A negative thermal expansion material Sm 0.85 Zn 0.15 MnO 3-δ Instantaneous synthesis method

Abstract

The application provides application of a metal electric heating method in synthesis of Sm 0.85 Zn 0.15 MnO 3‑δ . The application also provides a synthesis method of a negative thermal expansion material Sm 0.85 Zn 0.15 MnO 3‑δ , which is a transient synthesis method of Sm 0.85 Zn 0.15 MnO 3‑δ . In the application, current is directly applied to a heating belt, the heating belt is rapidly heated, the temperature around the heating belt is rapidly increased through heat radiation, the ceramic material is in a high-temperature environment, and the transient synthesis of the ceramic powder is realized; and by adjusting the size of the current, the sintering parameters of the ceramic powder are optimized, and the application can be applied to preparation of the negative thermal expansion material. In the transient synthesis method, a large current is applied to the conductive heating belt to generate a heat radiation effect, so that the Sm 0.85 Zn 0.15 MnO 3‑δ material is rapidly synthesized and reaction sintered, and volatilization of Zn and Mn elements is avoided.

Description

Technical Field

[0001] This invention belongs to Sm 0.85 Zn 0.15 MnO 3-δ In the field of synthetic technology, it relates to a Sm 0.85 Zn 0.15 MnO 3-δ The synthesis method and application of Sm are discussed, particularly a negative thermal expansion material. 0.85 Zn 0.15 MnO 3-δ The instantaneous synthesis method. Background Technology

[0002] Most materials in nature exhibit the property of "thermal expansion and contraction," meaning their volume or length increases with rising temperature. When applied in precision instruments or aerospace and other cutting-edge technology fields, the thermal stress caused by increased temperature can degrade the material's mechanical properties and even cause irreversible damage. Negative thermal expansion materials, however, possess the property of "thermal contraction and thermal expansion." Based on this property, negative thermal expansion materials can be combined with positive expansion materials in different proportions to obtain materials with zero expansion characteristics within a specific temperature range, thus mitigating the adverse effects of temperature changes on materials. Materials with negative thermal expansion properties have been discovered to include AM3O. 12 Compounds of the oxide series, fluorides such as ScF3, and perovskite structure series such as AMO3.

[0003] Exploring novel negative thermal expansion materials and their efficient synthesis methods has become a continuous research direction for inorganic materials scientists. Currently, the traditional synthesis method for negative thermal expansion materials is high-temperature solid-state synthesis, which is simple and easy to operate. However, the synthesis process involves several steps, including heating, holding, and cooling, and the preparation and sintering of the material often takes several hours or even tens of hours to complete. The long sintering time can easily lead to element volatilization, changes in stoichiometry, and alterations in material composition. Furthermore, solid-state synthesis results in uneven particle size distribution, high energy consumption, and low synthesis efficiency. Although sintering processes such as microwave sintering, spark plasma sintering, and flash sintering have been applied to the sintering of negative thermal expansion materials... Microwave sintering converts microwave energy into internal energy by absorbing microwaves into the material, but different materials absorb microwaves of different wavelengths differently, making microwave sintering unsuitable and limiting its range. Spark plasma sintering requires the use of special molds for compression during sintering and is difficult to mass-produce. Flash sintering is an electric current-assisted sintering technique that typically uses platinum as an electrode, which is expensive, and the flash point is difficult to control. Although flash sintering samples are mostly long strips or rods, the uniformity of sintering is still poor.

[0004] Therefore, finding a more suitable method for synthesizing negative thermal expansion materials, solving the aforementioned problems of existing sintering methods, and meeting the needs of preparation and research and development of negative thermal expansion materials has become one of the urgent problems to be solved by many forward-thinking researchers in the industry. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a Sm 0.85 Zn 0.15 MnO 3-δ Synthesis methods and applications, especially Sm, a negative thermal expansion material 0.85 Zn 0.15 MnO 3-δ The present invention provides a method for instantaneous synthesis. The instantaneous synthesis process directly applies current to a heating element, causing the heating element to heat up rapidly. Through thermal radiation, the surrounding temperature rises rapidly, placing the ceramic material in a high-temperature environment, thus achieving instantaneous synthesis of ceramic powder. Furthermore, the preparation process is simple, exhibiting excellent stability, repeatability, and controllability, particularly in the case of negative thermal expansion materials such as Sm. 0.85 Zn 0.15 MnO 3-δ It has good prospects for industrial application in the fields of mass production and sintering.

[0006] This invention provides a metal electrothermal heating method for the synthesis of Sm 0.85 Zn 0.15 MnO 3-δ Applications in [the context of the text].

[0007] Preferably, the metal electric heating method specifically comprises a metal electric heating process and a metal electric heat preservation process;

[0008] The synthesized Sm 0.85 Zn 0.15 MnO 3-δ Specifically, Sm is synthesized by mixing samarium, zinc, and manganese sources, pressing them into a compact, and then heating the compact by electrothermal heating. 0.85 Zn 0.15 MnO 3-δ .

[0009] Preferably, the pressed blank is placed between two pieces of metal;

[0010] The specific application is to reduce Sm 0.85 Zn 0.15 MnO 3-δ Applications related to material synthesis time;

[0011] The specific application is to reduce Sm 0.85 Zn 0.15 MnO 3-δ Applications related to material synthesis costs.

[0012] The present invention also provides a Sm 0.85 Zn 0.15 MnO 3-δ The synthesis method includes the following steps:

[0013] 1) The samarium source, zinc source and manganese source are mixed to obtain a mixed powder;

[0014] 2) The mixed powder obtained in the above steps is molded to obtain powder tablets;

[0015] 3) Under a protective atmosphere, the powder tablets obtained in the above steps are placed between metal heating plates. After heating the metal heating plates with electricity and maintaining the temperature, Sm is obtained. 0.85 Zn 0.15 MnO 3-δ Material.

[0016] Preferably, the samarium source includes samarium oxide and / or samarium carbonate;

[0017] The zinc source includes zinc oxide and / or zinc carbonate;

[0018] The manganese source includes manganese oxide and / or manganese carbonate;

[0019] The mixing process also includes a drying step.

[0020] Preferably, the mixing method includes ball milling;

[0021] A solvent is also added during the ball milling process;

[0022] The solvent includes one or more of ethanol, acetone, butanone, and xylene;

[0023] The ball-to-material ratio of the ball mill is (5-15):1.

[0024] Preferably, the mixing speed is 200–800 rpm;

[0025] The mixing time is 1 to 6 hours;

[0026] The diameter of the powder tablet is 5-15 mm;

[0027] The thickness of the powder tablet is 0.5 to 3 mm.

[0028] Preferably, the metal heating element comprises a high-temperature resistant metal heating element;

[0029] The metal heating element is made of tungsten and / or molybdenum;

[0030] The metal heating element is provided with tabs, which are connected to an external power source.

[0031] Preferably, the voltage for the electric heating is 1 to 40V;

[0032] The current for the electric heating is 100-300A;

[0033] The heating time is 0.5 to 60 seconds;

[0034] The temperature after being heated by electricity is 800-1500℃.

[0035] Preferably, the voltage for heat preservation is 1–40V;

[0036] The current for heat preservation is 100-300A;

[0037] The heat preservation time is 10–60 seconds;

[0038] The insulation temperature is 800–1500℃.

[0039] This invention provides a metal electrothermal heating method for the synthesis of Sm 0.85 Zn 0.15 MnO 3-δ Applications in [the field]. Compared with existing technologies, this invention targets traditional Sm [technology / technology]. 0.85 Zn 0.15 MnO 3-δ Traditional sintering methods result in the volatilization of Zn and Mn elements, and also suffer from long synthesis times, high power consumption, low efficiency, and high costs. This invention creatively applies the electrothermal heating method to Sm... 0.85 Zn 0.15 MnO 3-δ During the synthesis process, a negative thermal expansion material Sm was also provided. 0.85 Zn 0.15 MnO 3-δ The synthesis method of this Sm 0.85 Zn 0.15 MnO 3-δ This invention provides an instantaneous synthesis method that directly applies current to a heating element, causing it to heat up rapidly. This heat radiation then rapidly raises the surrounding temperature, placing the ceramic material in a high-temperature environment and achieving instantaneous synthesis of the ceramic powder. Furthermore, by adjusting the current magnitude and optimizing the sintering parameters of the ceramic powder, it can be applied to the preparation of materials with negative thermal expansion.

[0040] The negative thermal expansion material Sm provided by this invention 0.85 Zn 0.15 MnO 3-δ The instantaneous synthesis method utilizes a large current applied to a conductive heating band to generate a thermal radiation effect, thereby rapidly synthesizing and reactive sintering Sm. 0.85 Zn 0.15 MnO 3-δThe material thus avoids the volatilization of Zn and Mn elements. Attached Figure Description

[0041] Figure 1 The instantaneous synthetic negative thermal expansion material Sm provided by this invention 0.85 Zn 0.15 MnO 3-δ A simplified schematic diagram of the reaction apparatus;

[0042] Figure 2 These are images of rapid reaction heating during Embodiment 1 of the present invention;

[0043] Figure 3 This is the surface temperature monitoring curve during the sample synthesis process in Example 1 of the present invention;

[0044] Figure 4 Sm prepared in Example 1 of this invention 0.85 Zn 0.15 MnO 3-δ XRD pattern of powder;

[0045] Figure 5 This is a test diagram of the thermal expansion behavior of the sample prepared in Example 1 of the present invention;

[0046] Figure 6 Sm prepared in Example 2 of this invention 0.85 Zn 0.15 MnO 3-δ XRD pattern of powder;

[0047] Figure 7 Sm prepared in Example 3 of this invention 0.85 Zn 0.15 MnO 3-δ XRD pattern of powder;

[0048] Figure 8 This is a photograph of the appearance of the sample in Comparative Example 1 of the present invention;

[0049] Figure 9 The XRD pattern of the sintered material prepared in Comparative Example 2 of this invention is shown. Detailed Implementation

[0050] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.

[0051] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0052] The purity of the raw materials used in this invention is not particularly limited, but analytical grade or Sm is preferred. 0.85 Zn 0.15 MnO 3-δ The standard purity level required in the preparation process is sufficient.

[0053] All materials of this invention are conventional in the field, and each designation and abbreviation is clear and distinct in its relevant application. Those skilled in the art can purchase them from the market or prepare them by conventional methods based on the designation, abbreviation, and corresponding application.

[0054] All processes in this invention are referred to by abbreviations that are common abbreviations in the field. Each abbreviation is clear and specific in its relevant application area, and those skilled in the art can understand the conventional process steps based on the abbreviation.

[0055] This invention provides a metal electrothermal heating method for the synthesis of Sm 0.85 Zn 0.15 MnO 3-δ Applications in [the context of the text].

[0056] In this invention, the metal electric heating method is preferably a metal electric heating process and a metal electric heat preservation process.

[0057] In this invention, the synthesis of Sm 0.85 Zn 0.15 MnO 3-δ The preferred method is to synthesize Sm by mixing samarium, zinc, and manganese sources, pressing them into a compact, and then heating the compact with an electric current through a metal. 0.85 Zn 0.15 MnO 3-δ .

[0058] In this invention, the pressed blank is preferably placed between two pieces of metal.

[0059] In this invention, the application is preferably to reduce Sm 0.85 Zn 0.15 MnO 3-δ Applications related to material synthesis time.

[0060] In this invention, the application is preferably to reduce Sm 0.85 Zn 0.15 MnO 3-δ Applications related to material synthesis costs.

[0061] This invention provides a Sm 0.85 Zn 0.15 MnO 3-δ The synthesis method of [the substance] is characterized by comprising the following steps:

[0062] 1) The samarium source, zinc source and manganese source are mixed to obtain a mixed powder;

[0063] 2) The mixed powder obtained in the above steps is molded to obtain powder tablets;

[0064] 3) Under a protective atmosphere, the powder tablets obtained in the above steps are placed between metal heating plates. After heating the metal heating plates with electricity and maintaining the temperature, Sm is obtained. 0.85 Zn 0.15 MnO 3-δ Material.

[0065] The present invention first mixes samarium source, zinc source and manganese source to obtain mixed powder.

[0066] In this invention, the samarium source preferably includes samarium oxide and / or samarium carbonate, more preferably samarium oxide or samarium carbonate.

[0067] In this invention, the zinc source preferably includes zinc oxide and / or zinc carbonate, more preferably zinc oxide or zinc carbonate.

[0068] In this invention, the manganese source preferably includes manganese oxide and / or manganese carbonate, more preferably manganese oxide or manganese carbonate.

[0069] In this invention, the mixing process preferably also includes a drying step.

[0070] In this invention, the mixing method preferably includes ball milling.

[0071] In this invention, a solvent is preferably added during the ball milling process.

[0072] In this invention, the solvent preferably includes one or more of ethanol, acetone, butanone, and xylene, and more preferably ethanol, acetone, butanone, or xylene.

[0073] In this invention, the ball-to-material ratio of the ball mill is preferably (5-15):1, more preferably (7-13):1, and even more preferably (9-11):1.

[0074] In this invention, the mixing speed is preferably 200-800 rpm, more preferably 300-700 rpm, and even more preferably 400-600 rpm.

[0075] In this invention, the mixing time is preferably 1 to 6 hours, more preferably 2 to 5 hours, and even more preferably 3 to 4 hours.

[0076] The present invention further processes the mixed powder obtained in the above steps into a powder tablet by molding.

[0077] In this invention, the diameter of the powder tablet is preferably 5-15 mm, more preferably 7-13 mm, and even more preferably 9-11 mm.

[0078] In this invention, the thickness of the powder tablet is preferably 0.5-3 mm, more preferably 1-2.5 mm, and even more preferably 1.5-2.0 mm.

[0079] Finally, under a protective atmosphere, the powder tablets obtained in the above steps are placed between metal heating plates. After heating the metal heating plates with electricity and maintaining the temperature, Sm is obtained. 0.85 Zn 0.15 MnO 3-δ Material.

[0080] In this invention, the metal heating element preferably comprises a high-temperature resistant metal heating element.

[0081] In this invention, the material of the metal heating element preferably includes tungsten and / or molybdenum, more preferably tungsten or molybdenum.

[0082] In this invention, the metal heating element is preferably provided with tabs, which are preferably connected to an external power source.

[0083] In this invention, the voltage for the electric heating is preferably 1 to 40V, more preferably 6 to 35V, more preferably 11 to 30V, more preferably 16 to 30V, and more preferably 21 to 25V.

[0084] In this invention, the current for heating is preferably 100-300A, more preferably 150-280A, even more preferably 200-280A, and most preferably 280A.

[0085] In this invention, the heating time is preferably 0.5 to 60 seconds, more preferably 5 to 55 seconds, and even more preferably 10 to 50 seconds.

[0086] In this invention, the temperature after electric heating is preferably 800-1500℃, more preferably 950-1350℃, and most preferably 1100-1200℃.

[0087] In this invention, the voltage for heat preservation is preferably 1-40V, more preferably 6-35V, more preferably 11-30V, more preferably 16-30V, and more preferably 21-25V.

[0088] In this invention, the current for heat preservation is preferably 100-300A, more preferably 150-280A, even more preferably 200-280A, and most preferably 280A.

[0089] In this invention, the heat preservation time is preferably 10-60s, more preferably 25-50s, even more preferably 40-50s, and most preferably 50s.

[0090] In this invention, the insulation temperature is preferably 800-1500℃, more preferably 950-1350℃, and most preferably 1100-1200℃.

[0091] This invention provides a complete and detailed overall technical solution to better guarantee Sm 0.85 Zn 0.15 MnO 3-δ The stable and controllable synthesis further improves Sm 0.85 Zn 0.15 MnO 3-δ The properties and parameters of the aforementioned negative thermal expansion material Sm 0.85 Zn 0.15 MnO 3-δ The instantaneous synthesis method can be specifically described by the following steps:

[0092] A method for preparing a negative thermal expansion material, with the molecular formula Sm 0.85 Zn 0.15 MnO 3-δ ;

[0093] The raw material oxide powder is mixed using physical methods;

[0094] Weigh a small amount of solid powder and use a powder press and mold to press it into a cylindrical blank;

[0095] The billet material is transferred into an inert atmosphere glove box, placed inside the metal heating element of the reactor, and the clamps and electrodes are fixed to ensure contact between the clamps and electrodes.

[0096] When a constant current is applied by an external power source, the material heats up rapidly, and its surface turns red. After adjusting the applied current and time and maintaining the high temperature for several seconds, the material returns to its normal color, yielding Sm. 0.85 Zn 0.15 MnO 3-δ .

[0097] Samples were taken out and tested using XRD, thermal expansion curves, and inductively coupled plasma mass spectrometry to characterize the phase composition, thermal expansion coefficient, and proportion of each element in the material.

[0098] See Figure 1 , Figure 1 The instantaneous synthetic negative thermal expansion material Sm provided by this invention 0.85 Zn 0.15 MnO 3-δ A simplified schematic diagram of the reaction apparatus.

[0099] Among them, 1. Gas cylinder, 2. Metal heating belt, 3. Ceramic green body, 4. Temperature and humidity sensor, 5. Power supply, 6. Current and voltage sensor, 7. Fixture, 8. Electrode, 9. Vacuum pump, 10. Program control device, 11. Atmosphere chamber.

[0100] The present invention provides a negative thermal expansion material Sm 0.85 Zn 0.15 MnO 3-δ Instantaneous synthesis methods and metal electrothermal heating methods in the synthesis of Sm 0.85 Zn 0.15 MnO 3-δ Applications in Sm. This invention specifically applies the metal electrothermal heating method to Sm. 0.85 Zn 0.15 MnO 3-δ During the synthesis process, a negative thermal expansion material Sm was also provided. 0.85 Zn 0.15 MnO 3-δ The synthesis method of this Sm 0.85 Zn 0.15 MnO 3-δ This invention provides an instantaneous synthesis method that directly applies current to a heating element, causing it to heat up rapidly. This heat radiation then rapidly raises the surrounding temperature, placing the ceramic material in a high-temperature environment and achieving instantaneous synthesis of the ceramic powder. Furthermore, by adjusting the current magnitude and optimizing the sintering parameters of the ceramic powder, it can be applied to the preparation of materials with negative thermal expansion.

[0101] The negative thermal expansion material Sm provided by this invention 0.85 Zn 0.15 MnO 3-δ The instantaneous synthesis method utilizes a large current applied to a conductive heating band to generate a thermal radiation effect, thereby rapidly synthesizing and reactive sintering Sm. 0.85 Zn 0.15 MnO 3-δ The material thus avoids the volatilization of Zn and Mn elements.

[0102] To further illustrate the present invention, the following describes an embodiment of the Sm provided by the present invention. 0.85 Zn 0.15 MnO 3-δ Synthesis methods and the metal electrothermal method in the synthesis of Sm 0.85 Zn 0.15 MnO 3-δThe applications described in this paper are described in detail. However, it should be understood that these embodiments are implemented under the premise of the technical solution of this invention. Detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of this invention, and are not intended to limit the scope of the claims of this invention. The protection scope of this invention is not limited to the following embodiments.

[0103] Example 1

[0104] 1) Negative thermal expansion material Sm 0.85 Zn 0.15 MnO 3-δ The instantaneous synthesis method has the following steps:

[0105] Weigh out Sm2O3, ZnO, and Mn2O3 powders according to the stoichiometric ratio of the metal elements, place them in a planetary ball mill jar, add grinding balls at a ball-to-powder ratio of 10:1, add anhydrous ethanol (just enough to wet the powder), set the ball mill speed (400 rpm) and time (4 h), and grind the raw material powder thoroughly. After grinding, remove the powder, place it in a petri dish, and dry it in a 60℃ oven for 12 hours until it is ready for use.

[0106] 2) Take out the dried powder, pass it through a 140-mesh sieve, and use a powder tablet press to press the evenly mixed powder into batches with a diameter of 10mm and a thickness of 2mm.

[0107] 3) Place the stamped green blank in the heating belt of the molybdenum boat or graphite boat, transfer it to the atmosphere box, connect the wires, and ensure that the heating belt is in contact with the electrode;

[0108] 4) Replace the air in the atmosphere chamber with an inert gas (argon or nitrogen), adjust the applied current to 280A and the time to 50s, and the holding current to 280A and the time to 50s to complete the sintering of the material.

[0109] See Figure 2 , Figure 2 This is an image of rapid reaction heating during Embodiment 1 of the present invention.

[0110] See Figure 3 , Figure 3 This is a surface temperature monitoring curve during the sample synthesis process in Example 1 of the present invention.

[0111] The sample is heated rapidly (e.g.) Figure 3 As shown, the pressed green body undergoes an "avalanche," with the sample surface turning red due to the high temperature. After cooling, the material transforms into black powder.

[0112] The negative thermal expansion material Sm prepared in Example 1 of this invention 0.85 Zn 0.15 MnO 3-δ Characterize it.

[0113] See Figure 4 , Figure 4 Sm prepared in Example 1 of this invention 0.85 Zn 0.15 MnO 3-δ XRD pattern of powder.

[0114] XRD testing of materials ( Figure 4 ), prove Sm 0.85 Zn 0.15 MnO 3-δ The synthesis was successful, and the crystallinity was good.

[0115] Inductively coupled plasma mass spectrometry (ICP-MS) analysis showed that the molar ratio of Sm, Zn, and Mn was consistent with the feed composition (0.0735:0.0131:0.0857), and no element volatilization occurred. In contrast, the prolonged high-temperature sintering, compared to traditional solid-state methods, led to the volatilization of Zn and Mn elements; the molar ratios are listed in Table 1.

[0116] See Table 1, which shows the stoichiometric ratios of each element in different sintering methods.

[0117] Table 1

[0118] Example 1 0.0735 0.0131 0.0857 Traditional high-temperature sintering 0.0729 0.0115 0.0793

[0119] Thermal expansion tests were performed on the samples prepared in Example 1 of the present invention.

[0120] See Figure 5 , Figure 5 This is a test diagram of the thermal expansion behavior of the sample prepared in Example 1 of the present invention.

[0121] like Figure 5 As shown, its average coefficient of thermal expansion is -3.6226 × 10⁻⁶ in the temperature range of 370–800℃. -6 It has negative thermal expansion capacity.

[0122] Example 2

[0123] The difference from Experimental Scheme 1 is that in step 4), the applied current was changed to 240A, and the holding time was changed to 50s. The corresponding XRD pattern is shown below. Figure 6 .

[0124] See Figure 6 , Figure 6 Sm prepared in Example 2 of this invention 0.85 Zn 0.15 MnO 3-δ XRD pattern of powder.

[0125] Figure 6 The absence of starting material peaks or intermediate product peaks in the XRD pattern indicates that Sm0.85 Zn 0.15 MnO 3-δ The synthesis was successful, but the intensity of the diffraction peaks was low.

[0126] Example 3

[0127] The difference from Experimental Scheme 1 is that in step 4), the applied current was changed to 200A and the holding time was changed to 50s. The corresponding XRD pattern is shown below. Figure 7 .

[0128] See Figure 7 , Figure 7 Sm prepared in Example 3 of this invention 0.85 Zn 0.15 MnO 3-δ XRD pattern of powder.

[0129] Figure 7 The target product Sm appeared in the XRD pattern. 0.85 Zn 0.15 MnO 3-δ While it exhibits characteristic peaks, there are also raw material peaks or intermediate products, making it impossible to obtain the pure phase target product.

[0130] Comparative Example 1

[0131] The difference from Experimental Scheme 1 is that in step 4), the applied current was changed to 320A and the holding time was 50s. The heating belt generated an excessively high temperature, and the blank powder melted and bonded to the metal heating belt.

[0132] See Figure 8 , Figure 8 This is a photograph of the appearance of the sample in Comparative Example 1 of the present invention.

[0133] Comparative Example 2

[0134] 1) La was prepared using the same method as in Example 1. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ According to the stoichiometric ratio of the metal elements, a certain mass of La2O3, SrO, CoO and Fe2O3 powders were weighed and placed in a planetary ball mill jar. Grinding balls were added at a ball-to-powder ratio of 10:1. Anhydrous ethanol was added (just enough to wet the powder). The ball mill speed (400 rpm) and time (4 h) were set to grind the raw material powder thoroughly. After grinding, the powder was taken out, placed in a petri dish, and dried in a 60℃ oven for 12 hours. It was then ready for use.

[0135] 2) Take out the dried powder, pass it through a 140-mesh sieve, and use a powder tablet press to press the evenly mixed powder into batches with a diameter of 10mm and a thickness of 2mm.

[0136] 3) Place the stamped green blank in the heating belt of the molybdenum boat or graphite boat, transfer it to the atmosphere box, connect the wires, and ensure that the heating belt is in contact with the electrode;

[0137] 4) Replace the air in the atmosphere chamber with an inert gas (argon or nitrogen), adjust the applied current to 280A and the time to 50s, and the holding current to 280A and the time to 50s to complete the sintering of the material.

[0138] See Figure 9 , Figure 9 The XRD pattern of the sintered material prepared in Comparative Example 2 of this invention is shown.

[0139] XRD testing of materials ( Figure 9 Analysis of the XRD images shows that the La synthesized using this method... 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ Materials and Standards La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ The XRD patterns of the materials do not match, resulting in La 0.8 Sr 0.2 The three diffraction peaks (FeO3, SrLaFeO4, and La2CoO4) did not produce the target peak, therefore this method cannot be used to synthesize La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ Material.

[0140] The above describes the negative thermal expansion material Sm provided by this invention. 0.85 Zn 0.15 MnO 3-δ Instantaneous synthesis methods and metal electrothermal heating methods in the synthesis of Sm 0.85 Zn 0.15 MnO 3-δThe application of this invention is described in detail. Specific examples are used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention, including the best mode, and also to enable any person skilled in the art to practice this invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the wording of the claims, or if they include equivalent structural elements that are not substantially different from the wording of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A type of Sm 0.85 Zn 0.15 MnO 3-δ The synthesis method is characterized by, Includes the following steps: 1) The samarium source, zinc source and manganese source are mixed to obtain a mixed powder; The samarium source includes samarium oxide and / or samarium carbonate; The zinc source includes zinc oxide and / or zinc carbonate; The manganese source includes manganese oxide and / or manganese carbonate; 2) The mixed powder obtained in the above steps is molded to obtain powder tablets; 3) Under a protective atmosphere, the powder tablets obtained in the above steps are placed between metal heating plates. After heating the metal heating plates with electricity and maintaining the temperature, Sm is obtained. 0.85 Zn 0.15 MnO 3-δ Material; The metal heating element includes a high-temperature resistant metal heating element; The metal heating element is made of tungsten and / or molybdenum; The voltage for the electric heating is 21~40V; The current for the electric heating is 240~300A; The heating time is 0.5~60s; The temperature after being heated by electricity is 1100~1500℃; The voltage for heat preservation is 21~40V; The current for heat preservation is 240~300A; The heat preservation time is 40-50 seconds; The insulation temperature is 1100~1500℃.

2. The synthesis method according to claim 1, characterized in that, The mixing process also includes a drying step.

3. The synthesis method according to claim 1, characterized in that, The mixing method includes ball milling.

4. The synthesis method according to claim 3, characterized in that, A solvent is also added during the ball milling process.

5. The synthesis method according to claim 4, characterized in that, The solvent includes one or more of ethanol, acetone, butanone, and xylene.

6. The synthesis method according to claim 3, characterized in that, The ball-to-material ratio of the ball mill is (5~15):

1.

7. The synthesis method according to claim 3, characterized in that, The mixing speed is 200~800 rpm.

8. The synthesis method according to claim 3, characterized in that, The mixing time is 1 to 6 hours.

9. The synthesis method according to claim 1, characterized in that, The diameter of the powder tablet is 5~15mm; The thickness of the powder tablet is 0.5~3mm.

10. The synthesis method according to claim 1, characterized in that, The metal heating element is provided with tabs, which are connected to an external power source.

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