Nb5+ doped monoclinic phase VO2 metal-insulator transition ceramic and preparation method thereof

Abstract

The invention relates to an Nb5+ doped monoclinic phase VO2 metal-insulator transition ceramic and a preparation method thereof. V2O5 is reduced through citric acid by a hydrothermal method, high-temperature heat treatment is performed to obtain monoclinic phase VO2 raw powder, Nb5+ is doped according to different doping ratios and grinded in a mixed manner, and tableting and high-temperature multiple sintering are performed to obtain a VO2 monolithic ceramic material with metal-insulator transition temperature greatly reduced to room temperature and even lower temperature. The prepared ceramic is simple in process, high in preparation efficiency, low in sintering temperature, less in energy consumption, low in cost, environmentally friendly, non-toxic, pollution-free, good in transition performance and stable and uniform in structure, and has huge use values in practical production, and the transition temperature of the VO2 monolithic ceramic is greatly reduced to be around the room temperature of 25 DEG C.

Description

technical field

[0001] The invention relates to the technical field of phase change ceramic materials, in particular to a Nb 5+ Doped monoclinic VO 2 A metal-insulator phase change ceramic and a preparation method thereof. Background technique

[0002] The energy band structure of conductors and non-conductors is different. The conductance of conductors is mainly determined by the situation near the Fermi surface. If the energy band structure or Fermi level can be affected by changing the external conditions, it can cause the transition between metal conductors and insulators. . Vanadium dioxide (VO 2 ) is a smart thermochromic material with metal-insulator phase transition (MIT) properties. VO around 68°C 2 From a low-temperature monoclinic semiconductor phase to a high-temperature tetragonal metal phase, its photoelectric and magnetic properties have undergone great reversible changes, making it a photoelectric conversion material with broad application prospects, opt...

Examples

preparation example Construction

[0030] Nb proposed by the present invention 5+ doped monoclinic VO 2 A method for preparing a metal-insulator phase-change ceramic, comprising the following steps:

[0031] (1) at room temperature, at first, the citric acid that has weighed is put into beaker, adds deionized water, dissolves under magnetic stirring, forms transparent solution; Then weigh analytically pure vanadium pentoxide and put into beaker, Magnetic stirring together to form a homogeneous solution; wherein the molar ratio of vanadium pentoxide to citric acid is 1:1.5-2.5, and the concentration of citric acid-vanadium pentoxide in the mixed solution is 0.025±5% g / mL;

[0032] (2) Pour the uniformly stirred mixed solution into a closed high-temperature and high-pressure container, and then put the container into an oven and heat it at 170°C to 190°C to ensure the high-temperature and high-pressure hydrothermal reaction inside the container; the reaction time is 5-10 hours;

[0033] (3) After the reaction i...

Embodiment 1

[0039] 1. Using Citric Acid-V 2 o 5 Preparation of Monoclinic VO by Hydrothermal Reaction 2 Powder raw material:

[0040] (1) Measure 0.00375mol of citric acid into a 50mL beaker, add 20mL of deionized water, dissolve under magnetic stirring to form a transparent solution, and then weigh 0.0025molV 2 o 5 Add the solid powder to the above citric acid solution, and magnetically stir together for about 30 minutes to form a uniform yellow solution. The concentration of citric acid-vanadium pentoxide in the mixed solution is 0.025±5% g / mL;

[0041] (2) Pour the above yellow solution into a 50mL stainless steel hydrothermal synthesis reaction kettle, and measure 10mL of deionized water several times to rinse the residual drug in step (1), and add it to the reaction kettle together, and the final reaction solution is about 50mL , then put the reactor into an oven, heat to 180°C, and continue the reaction for 5 hours;

[0042] (3) After the above reaction time is over, the solid-...

Embodiment 2

[0050] 1. Using Citric Acid-V 2 o 5 Preparation of Monoclinic VO by Hydrothermal Reaction 2 Powder raw material:

[0051] Prepared by the method in Example 1.

[0052] 2. Preparation of Nb by high temperature sintering 5+ Doping 1% VO 2 The metal-insulator phase change ceramic bulk, that is, the atomic number ratio of vanadium and niobium in the phase change ceramic is 99%:1%, including the following process:

[0053] (1) Calculate and weigh the monoclinic phase VO obtained by the above operation according to the atomic number ratio of vanadium and niobium 99%:1%. 2 Powder 0.5747g, and measured 0.0050g Nb 2 o 5 The powders are mixed, fully ground for 2 hours, and then pressed into tablets;

[0054] (2) Doping Nb obtained by the above operation 2 o 5 Flake VO 2 Put it into a clean quartz ark, and then put it into a tube furnace; wash the gas environment in the tube furnace quartz tube with 400 sccm of ordinary pure argon for 10 minutes, and pump the tube furnace with...

technical field

[0001] The invention relates to the technical field of phase change ceramic materials, in particular to a Nb 5+ Doped monoclinic VO 2 A metal-insulator phase change ceramic and a preparation method thereof. Background technique

[0002] The energy band structure of conductors and non-conductors is different. The conductance of conductors is mainly determined by the situation near the Fermi surface. If the energy band structure or Fermi level can be affected by changing the external conditions, it can cause the transition between metal conductors and insulators. . Vanadium dioxide (VO 2 ) is a smart thermochromic material with metal-insulator phase transition (MIT) properties. VO around 68°C 2 From a low-temperature monoclinic semiconductor phase to a high-temperature tetragonal metal phase, its photoelectric and magnetic properties have undergone great reversible changes, making it a photoelectric conversion material with broad application prospects, opt...

Examples

preparation example Construction

[0030] Nb proposed by the present invention 5+ doped monoclinic VO 2 A method for preparing a metal-insulator phase-change ceramic, comprising the following steps:

[0031] (1) at room temperature, at first, the citric acid that has weighed is put into beaker, adds deionized water, dissolves under magnetic stirring, forms transparent solution; Then weigh analytically pure vanadium pentoxide and put into beaker, Magnetic stirring together to form a homogeneous solution; wherein the molar ratio of vanadium pentoxide to citric acid is 1:1.5-2.5, and the concentration of citric acid-vanadium pentoxide in the mixed solution is 0.025±5% g / mL;

[0032] (2) Pour the uniformly stirred mixed solution into a closed high-temperature and high-pressure container, and then put the container into an oven and heat it at 170°C to 190°C to ensure the high-temperature and high-pressure hydrothermal reaction inside the container; the reaction time is 5-10 hours;

[0033] (3) After the reaction i...

Embodiment 1

[0039] 1. Using Citric Acid-V 2 o 5 Preparation of Monoclinic VO by Hydrothermal Reaction 2 Powder raw material:

[0040] (1) Measure 0.00375mol of citric acid into a 50mL beaker, add 20mL of deionized water, dissolve under magnetic stirring to form a transparent solution, and then weigh 0.0025molV 2 o 5 Add the solid powder to the above citric acid solution, and magnetically stir together for about 30 minutes to form a uniform yellow solution. The concentration of citric acid-vanadium pentoxide in the mixed solution is 0.025±5% g / mL;

[0041] (2) Pour the above yellow solution into a 50mL stainless steel hydrothermal synthesis reaction kettle, and measure 10mL of deionized water several times to rinse the residual drug in step (1), and add it to the reaction kettle together, and the final reaction solution is about 50mL , then put the reactor into an oven, heat to 180°C, and continue the reaction for 5 hours;

[0042] (3) After the above reaction time is over, the solid-...

Embodiment 2

[0050] 1. Using Citric Acid-V 2 o 5 Preparation of Monoclinic VO by Hydrothermal Reaction 2 Powder raw material:

[0051] Prepared by the method in Example 1.

[0052] 2. Preparation of Nb by high temperature sintering 5+ Doping 1% VO 2 The metal-insulator phase change ceramic bulk, that is, the atomic number ratio of vanadium and niobium in the phase change ceramic is 99%:1%, including the following process:

[0053] (1) Calculate and weigh the monoclinic phase VO obtained by the above operation according to the atomic number ratio of vanadium and niobium 99%:1%. 2 Powder 0.5747g, and measured 0.0050g Nb 2 o 5 The powders are mixed, fully ground for 2 hours, and then pressed into tablets;

[0054] (2) Doping Nb obtained by the above operation 2 o 5 Flake VO 2 Put it into a clean quartz ark, and then put it into a tube furnace; wash the gas environment in the tube furnace quartz tube with 400 sccm of ordinary pure argon for 10 minutes, and pump the tube furnace with...

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