Structural changes upon lithium insertion in Ni0.5TiOPO4

Nickel titanium oxyphosphate Ni0.5TiOPO4 (NTP), was prepared by co-precipitation route. Its structure was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system, S.G: P2(1)/c [a = 7.333(1) angstrom, b = 7.316(2) angstrom, c = 7.339(2) angstrom, beta = 119.62(3)degrees, Z = 4, R-1 = 0.0142, wR(2) = 0.0429]. The structure might be described as a {TiOPO4} framework made of corner-sharing [TiO6] octahedra chains running parallel to [0 0 1] and cross linked by phosphate [PO4] tetrahedral, where half of octahedral cavities created are occupied by Ni atoms, and the other half of octahedral sites are vacant. During the first discharge, the NTP electrode delivered a capacity of 530 mAh/g, upon cycling within 0.5-4 V. To understand the electrochemical reaction mechanism using different characterization techniques viz. in situ synchrotron diffraction. Reciprocal magnetic susceptibility (chi(-1)) of NTP, between 4 and 300 K, shows an almost linear behavior and can be fitted by the simple Curie-Weiss law. (C) 2012 Elsevier B. V. All rights reserved.