ELIMINATION OF COMPOSITIONAL FLUCTUATION IN PEROVSKITE SOLID-SOLUTIONOF SR(CUXZN1-X)(1 2)W1/2O3/

A method was developed for the synthesis of the complex perovskite sol id solution of Sr(CuxZn1-x)(1/2) W1/2O3 (SCZW)having no compositional fluctuation. The method was a combination of wet and dry processes. A very homogeneous powder mixture of CuO and ZnO (CZ-powder) was prepare d by a decomposition of coprecipitate of CU2+ and Zn2+ (wet process). Then CZ-powder and the other raw powders were mixed with an agate mort ar and pestle (dry process). From this mixture, SCZW was synthesized w ith firing conditions of 1200 degrees C and 1 h. A compositional fluct uation in SCZW was studied through a measurement of angle dependence o f width of X-ray powder diffraction peak. SCZW synthesized by this met hod had no compositional fluctuation. SCZW synthesized by the conventi onal dry method (mixed-oxide method) had the compositional fluctuation . The compositional fluctuation decreased with an increase of the firi ng period. However, the fluctuation remained even when the sample was fired at 1200 degrees C for 4 h. This revealed that the compositional fluctuation cannot be easily eliminated by the dry method. It was reve aled that the compositional fluctuation in SCZW results from the inhom ogeneity of Cu2+ and Zn2+ in the raw powder mixture before firing. The fluctuation can be effectively eliminated by the application oi wet p rocess for a part of B-site cations, Cu2+ and Zn2+. This wet-dry combi nation method can be applied for many other solid solution of the type A(a+)(BIxb+BII1-xb+)(d)BIII1-dc+O3 (a + bd + c(1-d) = 6, b not equal c), because the number of cations to which the wet process is applied can be reduced.