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Indian Journal of Pure & Applied Physics (IJPAP) >
IJPAP Vol.44 [2006] >
IJPAP Vol.44(05) [May 2006] >
| Title: | Lattice dynamical calculations of spinel structure compounds |
| Authors: | Kushwaha, A K
Shankar, Girija
Kushwaha, S S |
| Keywords: | Spinel structure
Lattice dynamics
Octahedral
Zone center
Phonons |
| Issue Date: | May-2006 |
| Publisher: | CSIR |
| IPC Code: | C30B |
| Abstract: |
Lattice dynamical
calculations have been performed for normal spinel structure compounds using
the proposed theoretical model. In this model, the dynamical matrix is split
into two parts: (i) the short range part is evaluated by using Taylor’s expansion of the crystal potential
energy in the harmonic approximation and (ii) the long range part is evaluated
on the basis of screened Coulomb potential. This model is applied to study the
zone centre ( =0) phonon frequencies of sulphide
spinels MCr2S4 (M= Mn, Fe, Cd). The significant outcome
of the present work is that (i) the tetrahedral M-S force constants are smaller
than the respective octahedral (Cr-S) ones, (ii) the bending force constants
are negligible, and (iii) the effective dynamical charges of the bivalent metal
ions are nearly zero. The zone-center phonon frequencies, thus calculated using
these parameters are found to be in very good agreement with the observed
results.
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| Page(s): | 385-390 |
| ISSN: | 0975-1041 (Online); 0019-5596 (Print) |
| Source: | IJPAP Vol.44(05) [May 2006]
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