The crystal structure of Li3SbO4

Abstract

The crystal structure of Li3Sb04 has been determined by analogy with Na,BiO,, and refined by the RiFtveld method using X-ray powder diffraction data. It is monoclinic, space group P2/c, a = 5.1579(2), b= 6.0922(3), c=5.1397(2) A, B= 108.839(4)". The structure is an ordered rocksalt type, with distorted M 0 6 octahedra.The crystal structure of Li,SbO, was first examined by Blasse using X-ray powder diffraction (XRD) d?ta.' The unit cell was given as tetragonal, a = 6.12, c = 8.50 A; the structure was suggested to be an ordered rocksalt structure, where a = $4 and c = 2aR (aR =unit cell of rocksalt). The Sb atoms were estimated to be located in positions ($ 3 0), (+ $), (a + 3) and (3 1 $) within a cubic close-packed (ccp) oxide array, giving a cation order related to that of spinel. Based on the Sb-0 framework, the agreement between observed and calculated intensities was reasonably good, with an R factor of 12%.The powder pattern of Li,SbO, given in the powder diffraction file (card no. 17-824)2 was found to match that of Li2Te04 (card no. 26-8$1),, which has a similar unit cell with a=6.045 and c = 8.290 A. The structure of Li2Te04 was determined in the space group P4,22, and was found to be a distorted inverse spinel with Te in octahedral sites and Li in both tetrahedral and octahedral sites., In spite of the similarity between the XRD patterns of Li,SbO, and Li2Te04, it seemed unlikely, from its stoichiometry, that Li3Sb0, could have a spinel structure. Since, however, the XRD patterns of both Li3Sb04 and Li2Te0, would be dominated by the scattering powers of Sb and Te, respectively, the similarity between the two patterns may confirm Blase's observation of a spinel-like cation arrangement .Other Li,MO, structures with similar-sized M atoms to Sb are Li,NbO, and Li,TaO,; these belong to the rocksalt family, with ordered Na,Ta04 and Na,Nb04 also have rocksalt-related structures and can exhibit both order and disorder of the cations, in different polymorphs. lO,ll The XRD pattern of Li,SbO, was examined as part of an investigation into rocksalt-related phases in the system Li,SbO,-CuO. Although the XRD data were collected on a high-resolution instrument, the pattern could not be indexed adequately on the previously described tetragonal unit cell. The structure of Li3Sb04 has therefore been reinvestigated, and we report the results here.

Crystal Structure of Li3CuSbO5

“…Li SbO presents a crystal structure determined in the space group P2/c by Rietveld re"nement. This structure is an ordered rock salt type, with distorted octahedra of oxide ions (1). The crystal structure of S was already characterized and determined by X-ray powder di!raction.…”

Synthesis of Li3Cu2SbO6, a New Partially Ordered Rock Salt Structure

“…All compositions on this join have the requisite 1 : 1 stoichiometry for the rock salt structure and indeed, we have recently confirmed Li SbO to have an ordered, rock salt structure [5]. Starting materials were Analar grade Li CO , Sb O , and CuO.…”

“…Lattice refinement using the Stoe program LATREF resulted in a unit cell of a"5.4644 (5), b"8.7215 (8), c"9.7760(9) A s , "95.095(8)°; the fully indexed powder pattern is given in Note. Average (2 )"0.011; maximum (2 )"0.020.…”

Synthesis-Controlled Polymorphism, Magnetic and Electrochemical Properties of Li3Co2SbO6

“…5 g samples of Li3SbO4 precursor were prepared based on methods previously described in the literature. 31,32 Li3CO3 and Sb2O3 (99%, BDH Chemicals) were mixed in the relevant stochiometric ratios and ground with acetone using an agate mortar and pestle. The ground paste was dried before being pressed into a 20 mm pellet at ~35 Mpa.…”

“…8 An alternative synthesis route was developed where the precursor Li3SbO4 was reacted with freshly prepared CoO. 31,32 The presence of fully oxidised Sb 5+ in Li3SbO4 (vs. Sb 3+ in the conventional reagent Sb2O3) allowed us to carry out the reaction under Ar flow, preventing further oxidation of Co 2+ .…”