Ammonium Paratungstate Preparing Cerium-Doped Zirconium Tungstate Ceramic Powder

Recently, zirconium tungstate is the best isotropic negative thermal expansion compound, and also the typical compound which have attracted great interest from the crystal structure to heat-shrinkable properties in new negative thermal expansion compound. Studies have pointed out that dope the other elements into basal body of can change its properties, and it will have a very broad application prospect. A method that use ammonium paratungstate as raw material to prepare cerium-doped zirconium tungstate negative thermal expansion ceramic powder, steps as follows:

1. Take materials: weight eight water zirconium oxychloride, ammonium paratungstate and cerium ammonium nitrate according to a certain stoichiometry, mix the zirconium oxychloride and cerium ammonium nitrate and dissolved in deionized water; at the same time, ammonium paratungstate also dissolved in deionized water, and make sure the concentration of W equals to the summation of concentration of Ce and Zr;
2. Mix the deionized water and concentrated hydrochloric acid at a certain volume ratio to get the hydrochloric acid solution at a concentration of 6-10mol/L;
3. Dropping the mixed solution of zirconium oxychloride and cerium ammonium nitrate, ammonium paratungstate into deionized water by the double-dropping-method with stirring, and control the temperature between 60-80℃, continually stirring for 4-8 hours;
4. Raising the temperature to 80-90°C, dropping the hydrochloric acid solution into the mixture under constant stirring conditions, until the H + concentration in the final solution is 1.5-3mol/L, and then stirring was continued for 16 to 24 hours ;
5. Translating the mixture obtained in step 3 into a teflon-lined autoclave, and heated for 12-72 hours at temperature of 165-220℃, then suction, dried at 60-85℃, so the precursor generated;
6. Placed the precursor in a muffle furnace and heated to 600-700℃, and incubated for 6-12 hours to give a final product--zirconium tungstate cerium-doped ceramic powder.

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