Synthesis, structure, magnetic susceptibility and Mossbauer and Raman spectroscopies of the new oxyphosphate Fe0.50TiO(PO4)

A new iron titanyl oxyphosphate Fe0.50TiO(PO4) was synthesized by both solid-state reaction and Cu2+-Fe2+ ion exchange method. The material was then characterized by X-ray diffraction, Mossbauer spectroscopy, magnetic susceptibility measurements and Raman spectroscopy. The crystal structure of the compound was refined, using X-ray powder diffraction data, by Rietveld profile method; it crytallizes in the monoclinic system, space group P2(1)/c (No. 14), with a = 7.4039(3) angstrom, b = 7.3838(3) angstrom, c = 7.4083(3) angstrom, beta = 120.36 degrees(1) V = 349.44(2) angstrom(3) and Z = 4. The volume of the title compound is comparable to those of the (M0.50TiO)-Ti-II(PO4) series, where M-II = Mg, Co, Ni and Zn. The framework is built up from [TiO6] octahedra and [PO4] tetrahedra. [TiO6] octahedra are linked together by corners and form infinite chains along the c-axis. Ti atoms are displaced from the center of octahedral units showing an alternating short distance (1.73 angstrom) and a long one (2.22 angstrom). These chains are linked together by [PO4] tetrahedra. Fe2+ cations occupy a triangle-based antiprism sharing two faces with two [TiO6] octahedra. Mossbauer and magnetic measurements show the existence of iron only in divalent state, (t(2g)(4)e(g)(2)). Raman study confirms the existence of Ti-O-Ti chains. located exclusively in octahedral sites with high spin configuration 29 g (c) 2006 Elsevier Inc. All rights reserved.