Preparation of single-crystal of thermal negative expanding material ZrW2O8

A negative thermal expansion material, negative thermal expansion technology, applied in the direction of single crystal growth, single crystal growth, polycrystalline material growth, etc., to achieve the effect of simple procedure, easy operation and industrialization

Inactive Publication Date: 2005-10-12
UNIV OF SCI & TECH BEIJING
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So far, no hydrothermal growth...

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[0010] Successful Synthesis of Negative Thermal Expansion Compound ZrW by Hydrothermal Method 2 o 8 . The raw material is: ZrOCl 2 ·8H 2 O (analytical pure), N 5 h 37 W 6 o 24 ·H 2 O (chemically pure), HCl (analytical pure). First, zirconium oxychloride and ammonium tungstate are made into solutions of the same molar concentration (Zr and W), and the two solutions of zirconium oxychloride and ammonium tungstate are mixed at a volume ratio of 1:2, and the Add 6mol / L hydrochloric acid solution to the mixed solution, the volume of the hydrochloric acid solution is 1 / 3 of the mixed solution volume, and stir at 80°C for 12h. Then, the mixture was transferred into a reaction kettle with a polytetrafluoroethylene liner, and sealed and heated at a temperature of 180 °C for 8 h. After the reaction, filter with suction and dry at 60°C. The precursor ZrW 2 o 7 (OH) 2 (H 2 O) 2 The final product ZrW was obtained after heating at 550 °C in a muffle furnace 2 o 8 .

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Abstract

A process of preparing ZrW2O8 unit crystal, a kind of negative heating expanding material. Materials are ZrOCl2.8H2O(AR), N5H35W6O24.H2O(BR), HCl(AR). Prepare basic zirconium chloride and ammonia tungstate solution to equal molZr and molW. Then mix them. Volume ratio of basic zirconium chloride and ammonia tungstate solution is 1to 2. add HCl(6-12mol/L) to the mixture at 70-90deg.C. Volume of HCl is 1/3 of that of the mixture. Then put the mixture solution into reactor with polytetrafluoroethylene inside. Heat hermetically at 180deg.C , filter and dry at 60deg.C after reaction, ZrW2O8 is obtained after heating at 500-700deg.C in muffle wall.

Description

technical field [0001] The invention belongs to the technical field of functional ceramic materials, in particular to a negative thermal expansion material ZrW 2 o 8 single crystal preparation method. Background technique [0002] wxya 2 o 8 It is an excellent negative thermal expansion compound with a strong isotropic negative thermal expansion effect, and its negative thermal expansion coefficient is as high as -9×10 -6 K -1 , and the negative thermal expansion (NTE) response temperature ranges from 0.3K until its decomposition temperature of 1050K. Materials with this excellent negative thermal expansion performance can be used alone or used to prepare composite materials, so as to precisely control the volume expansion coefficient of materials. The conventional solid-phase synthesis method has a high sintering temperature and takes a long time, and because WO 3 The volatility is strong, and a single ZrW is synthesized 2 o 8 phase is difficult. The Sleight resea...

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Application Information

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IPC IPC(8): C30B7/10C30B29/32
Inventor 邢献然邢奇凤于然波刘桂荣
Owner UNIV OF SCI & TECH BEIJING
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