Inelastic neutron scattering from and lattice dynamics of α-KNO3

Rao, K. R. ; Chaplot, S. L. ; Iyengar, P. K. ; Venkatesh, A. H. ; Vijayaraghavan, P. R. (1978) Inelastic neutron scattering from and lattice dynamics of α-KNO3 Pramana - Journal of Physics, 11 (3). pp. 251-288. ISSN 0304-4289

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Coherent inelastic neutron scattering techniques are employed to measure several branches of the phoon dispersion relation in KNO3 in its orthorhombic (α-phase or phase II) form at room temperature. Group theoretical selection rules for external modes of the crystal have been used in the measurements along the three symmetry directions Σ(ξ00), Δ(0ξ0) and Λ(00ξ). Theoretical investigation of the lattice dynamics of the crystal is carried out on the basis of a rigid molecular-ion model using the external mode formalism. A two-body potential consisting of the Coulombic interaction and the Born-Mayer type short range interaction is assumed. The effective charges and radii of different atoms are determined by applying the stability criterion for the crystal. Dispersion curves are calculated, representation by representation, making use of group theoretical information. Comparison of theoretical results with experimental information on elastic constants, optical data and neutron results are made. Agreement between theoretical and the various experimental results may be considered very satisfactory.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Lattice Dynamics; Potassium Nitrate; Inelastic Neutron Scattering; Neutron Scattering Selection Rules; Group Theoretical Analysis
ID Code:12411
Deposited On:10 Nov 2010 06:28
Last Modified:16 May 2016 21:46

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