Synthesis and crystal structure of (Sr_1-xLa_1+x)Zn_1-xO_3.5-x/2(0.01 ≤ × < 0.03)

(Sr_1-xLa_1+x)Zn_1-xO_3.5-x/2(0.01 ≤ × < 0.03), was prepared at 1373 K in the SrO-La₂O₃-ZnO system. The X-ray and neutron powder diffraction peaks were indexed with a body-centered tetragonal unit cell (a = 3.75 and c = 13.57 Å for the sample x = 0.01). Weak diffuse superstructure reflections having periods of ∼ 2×a and ∼ 2×c were observed in electron diffraction patterns. The basic statistical structure of 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 I4/mmm, Z = 2, R_wp = 0.1317, R_p = 0.1052, R_I = 0.0566, and R_F = 0.0371 for X-ray data and R_wp = 0.0796, R_p = 0.0615, R₁ = 0.0395, and R_F = 0.0252 for neutron data. In a local structure model, the Zn atom is coordinated by four oxygen atoms. Sr and La atoms are in the eightfold coordination of oxygen atoms.