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K 2NiF 4 type compounds Sm 2-xSr xCuO 4 (0≤x≤1.2) were prepared. Rietveld refinement of powder diffraction data shows that the crystal system of these compounds belongs to T′ type tetragonal structure of space group I4/mmm, and the addition of Sr causes a dramatic shift of the O(I) ions along the c axis from Sm (Sr) toward Cu while scarcely affecting the Cu-O(II) bond in basal CuO 4 plane. From XRD data, it can be seen that when 0.0≤x≤0.6, Sm 2-xSr xCuO 4 belongs to a single-phase K 2NiF 4 type structure, while at x≥0.7, both the free SrO phase and the CuO phase exist in these compounds. From the results of XPS and Rietveld refinement, it can be seen that after replacing Sm 3+ with Sr 2+ of lower valence, the valence of Cu and Sm does not change apparently, and thus some defect must be formed at the oxygen ion positions and/or position A on A 2BO 4 to keep charge balance and to stabilize the structure.
Rietveld refinement of powder diffraction data shows that the crystal system of these compounds belongs to T ’type tetragonal structure of space group I4 / mmm, and The addition of Sr causes a dramatic shift of the O (I) ions along the c axis from Sm (Sr) toward Cu while scarcely affecting the Cu-O (II) bond in basal CuO 4 plane. From XRD data, it can be seen that when 0.0≤x≤0.6, Sm 2-xSr xCuO 4 belongs to a single-phase K 2NiF 4 type structure, while at x≥0.7, both of the free SrO phase and the CuO phase exist in these compounds. From the results of XPS and Rietveld refinement, it can be seen that after replacing Sm 3+ with Sr 2+ of lower valence, the valence of Cu and Sm does not change apparently, and some of the defects must be formed at the oxygen ion positions and / or position A on A 2BO 4 to keep charge balance and to stabilize the structure.