Structure, infrared and Raman spectroscopic studies of newly synthetic AII(SbV0.50FeIII0.50)(PO4)2 (ABa, Sr, Pb) phosphates with yavapaiite structure

Abstract

a b s t r a c tThe synthesis and structural study of three new A II (Sb V 0.5 Fe III 0.5 )(PO 4 ) 2 (A]Ba, Sr, Pb) phosphates belonging to the AeSbeFeePeO system were reported here for the first time. Structures of [Ba], [Sr] and [Pb] compounds, obtained by solid state reaction in air atmosphere, were determined at room temperature from X-ray powder diffraction using the Rietveld method. Ba II (Sb V 0.5 Fe III 0.5 )(PO 4 ) 2 features the yavapaiite-type structure, with space group C2/m, Z ¼ 2 and a ¼ 8.1568 (4) Å; b ¼ 5.1996(3) Å c ¼ 7.8290(4) Å; b ¼ 94.53(1) . A II (Sb V 0.5 Fe III 0.5 )(PO 4 ) 2 (A]Sr, Pb) compounds have a distorted yavapaiite structure with space group C2/c, Z ¼ 4 and a ¼ 16.5215(2) Å; b ¼ 5.1891(1) Å c ¼ 8.0489(1) Å; b ¼ 115.70(1) for [Sr]; a ¼ 16.6925(2) Å; b ¼ 5.1832(1) Å c ¼ 8.1215(1) Å; b ¼ 115.03(1) for [Pb]. Raman and Infrared spectroscopic study was used to obtain further structural information about the nature of bonding in selected compositions.