This article is cited in 1 paper

International Conference ''Mechanisms and Nonlinear Problems of Nucleation, Growth of Crystals and Thin Films'' dedicated to the memory of the outstanding theoretical physicist Professor V.V. Slezov (Proceedings) St. Petersburg, July 1-5, 2019
Phase transitions

The origin of phase transition and the usual evolutions of the unit-cell constants of the NASICON structures of the solid solution LiTi$_{2-x}$Ge$_{x}$(PO$_{4}$)$_{3}$

N. Bounar

LIME Laboratory, University of Jijel, Algeria

Abstract: Ge-doped LiTi$_{2}$(PO$_{4}$)$_{3}$ has been synthesized by a conventional solid-state reaction. Compounds LiM$_{2}^{\mathrm{(IV)}}$(PO$_{4}$)$_{3}$ with LTP-type structure present a different behaviour depending on nature of M$^{\mathrm{(IV)}}$. For M$^{\mathrm{(IV)}}$ = Ti and Ge, the structure shows the space group R3c, whereas for M$^{\mathrm{(IV)}}$ = Ge the space group is R3. Differences in behaviour of LiTi$_{2}$(PO$_{4}$)$_{3}$-LiGe$_{2}$(PO$_{4}$)$_{3}$ solid solutions are discussed in relation to the composition. Their structures LiTi$_{2-x}$Ge$_{x}$(PO$_{4}$)$_{3}$ (0 $\le x<$ 2) were determined from X-ray powder diffraction method (XRD) using Rietveld analysis. A sharp change in the lattice parameter $a$ is observed between the compositions with $x$ = 1. The lattice parameter c increases as the Ge content increases in the whole range of composition. The space group R3c becomes R3 for the composition with $x>$ 1. The SEM micrographs of the samples show relative porous microstructures due to the effect of the substitution.

Keywords: NASICON, origin of unusual evolutions of lattice parameters, phase transition, scanning electron microscopy SEM, X-ray diffraction DRX, Rietveld refinements.

Received: 30.06.2019
Revised: 30.06.2019
Accepted: 01.07.2019

Language: English

 English version: Physics of the Solid State, 2019, 61:12, 2446–2450

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