Hysteresis effects and mesoscopic domains: Precursors for the formation of orientational glass states

Institut für Physikalische Chemie, Johannes Gutenberg-Universität, 55099 Mainz, Germany

Received: 29 May 1998
Accepted: 10 August 1998

Abstract

single crystals were investigated using proton NMR for 0.8 < x < 1. They undergo a first-order transition from the orientationally disordered high-temperature α-phase into the low-temperature β-phase. This transition exhibits a thermal hysteresis which strongly increases upon lowering x. In the coexistence range evidence for nanoscopic domains was obtained using proton spin diffusion. The characteristic dimensions of the domains decrease as the critical concentration x_c is approached, below which an orientational glass state is stable at low temperature. This observation indicates that close to x_c the orientational glasses are to be characterized as nano domain states.