Eur. Phys. J. B 13, 643-651 (2000)
https://doi.org/10.1007/s100510050081

Elastic anomalies and orientational glass transition in Na(CN)_xCl_1-x mixed crystals. A Brillouin spectroscopic study

Fachrichtung Experimentalphysik 10.2, Universität des Saarlandes, Bau 38, Postfach 151150, 66041 Saarbrücken, Germany

Received: 8 April 1999
Revised: 3 June 1999
Published online: 15 February 2000

Abstract

High performance Brillouin spectroscopy (BS) has been used to study the elastic properties (static and dynamic) of the orientational glassy state of Na(CN)_xCl samples ). The temperature behaviour of the elastic properties reveals a more complex scenario for the orientational glass transition than generally believed. The shear elastic constant shows the well-known anomaly, indicated by a minimum, found in other cyanide mixed crystals. The results obtained for the hypersonic attenuation are in clear contradiction with the dynamic character of the -minimum. The temperature behaviour of the longitudinal elastic constant c₁₁ of very dilute Na(CN)_xCl samples shows two striking features: i) Similar to the anomalous temperature behaviour of , lowering the temperature first decreases, goes through a minimum and then rises again. The minimum takes place at a temperature above the temperature, , where reaches its minimum value. ii) A kink-like anomaly of is observed at lower temperatures. This second anomaly is similar to the classical one observed in canonical glasses at their glass transition temperature T_g.