Title:
PHONON SPECTRA NEAR METAL-INSULATOR PHASE TRANSITION IN
LI$_{1+X}$TI$_{2-X}$O$_{4}$ SYSTEM
Authors:
E.P.Buletsa, O.F.Ivanyas, V.J.Kindrat, I.I.Nebola, I.M.Shkirta,
A.J.Shtejfan
(Uzhgorod National University, 46 Pidhirna Str.,
Uzhgorod, 88000 Ukraine)
The phonons of two end members of Li$_{1+x}$Ti$_{2-x}$O$_{4}$ spinel system, i.e., the metallic LiTi$_{2}$O$_{4}$ and the insulating Li$[$Li$_{1/3}$Ti$_{5/3}]$O$_{4}$, are calculated in superspace symmetry approach using a short-range force constant model. The composition dependence of zone-centre optical phonons in Li$_{1+x}$Ti$_{2-x}$O$_{4}$ near phase transition and Li$_{1-x}$Mg$_{x}$Ti$_{2}$O$_{4}$ has been investigated using different models of substitution. One- and two-mode behavior is therefore predicted for F$_{\textrm{1u}}$ and F$_{\textrm{2u}}$ modes in case of tetrahedral and octahedral substitution, respectively.
Key words:
superspace symmetry, phonon spectra, spinel, Li$_{1+x}$Ti$_{2-x}$O$_{4}$
PACS:
61.50.Ah, 63.
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