Synthesis and crystal structure of (Sr1-xLa1+x)Zn1-xO3.5-x/2 (0.01 <= x <=0.03)

(Sr1-xLa1+x) Zn1-xO3.5-x/2 (0.01 less than or equal to x < 0.03), was prepa red at 1373 K in the SrO-La2O3-ZnO system, The X-ray and neutron powder dif fraction peaks were indexed with a body-centered tetragonal unit cell (a = 3.75 and c 13.57 Angstrom for the sample x = 0.01), Weak diffuse superstruc ture reflections having periods of similar to 2xa and similar to 2xc were o bserved in electron diffraction patterns. The basic statistical structure o f the superstructure was refined by Rietveld analysis for X-ray and neutron powder diffraction patterns of the sample x = 0.01 with a model related to an oxygen-deficient K2NiF4-type structure, space group 14/mmm, Z = 2, R-wp = 0.1317, R-p = 0.1052, R-1 = 0.0566, and R-F = 0.0371 for X-ray data and R-wp = 0.0796, R-p = 0.0615, R-I = 0.0395, and R-F = 0.0252 for neutron dat a. In a local structure model, the Zn atom is coordinated by four oxygen at oms. Sr and La atoms art? in the eightfold coordination of oxygen atoms. (C ) 2001 Academic Press.