Angular dispersion of phonons in biaxial NaNO2

Bonilla, I.R. and Rutt, H.N. (1975) Angular dispersion of phonons in biaxial NaNO2. Physica Status Solidi (b), 69 (2), 395-398. (doi:10.1002/pssb.2220690210).

Record type: Article

Abstract

Angular dispersion curves for polar phonons in biaxial crystals are experimentally verified for sodium nitrite. Both crossing and repulsion of phonons are expected and observed, and an important difference between biaxial and uniaxial crystals is noted.

Die Dispersionskurven für richtungsabhängige polare Phononen in zweiachsigen Kristallen werden experimentell für Nattriumnitrit verifiziert. Sowhol Überkreuzung als auch Abstoßung von Phononenzweigen werden erwartet und experimentell bestätit. Es wird ein beträchtlicher Unterschied zwischen zweiachsigen und einachsigen Kristallen beobachtet.

This record has no associated files available for download.

More information

Published date: June 1975

Additional Information: The angular dispersion (kph ? ?/c) of polar phonons in the region of the ?3,-states of the SO42?-ions in biaxial MgSO4, · 7 H2O has been observed with Raman-scattering experiments at T = 300 K and T = 1.9 K. The agreement of the experimental data with the existing theories of angular dispersion is very satisfying. Some accidental degeneracies of transverse with longitudinal states of different symmetry could be observed. This degeneracy, where the two branches cross with equal slopes of opposite signs, can be lifted due to the temperature dependence of the frequencies. This behaviour is also interpreted theoretically and some simple relations are derived for the slopes and the curvature of dispersion branches, which relate these data to the effective charges and the dielectric function ?(?), and which characterize the critical points occuring on the dispersion branches. Text in English and German.

Organisations: Electronics & Computer Science

Learn more about Electronics & Computer Science research