Experimental Studies on Ferrielectricity in RbLiSO₄

Study on the structural properties and relaxation mechanisms in LiRb1−x(NH4)xSO4 (x=0, 0.5, and 1) mixed crystals by 1H, 7Li, and 87Rb nuclear magnetic resonance

“…Crystallographically inequivalent Li sites, Li(1) and Li (2), are present below T C2 in pure LiNH 4 SO 4 crystals, whereas crystallographically equivalent Li are obtained above T C2 . Moreover, the presence of a ferroelastic twin structure in pure LiRbSO 4 crystals was confirmed by examining the 7 Li and 87 Rb NMR spectra, and can be explained by the presence of three kinds of ferroelastic twin domain.…”

“…Below 285 K, the 7 Li NMR lines are split into two sets, which indicates that the crystal undergoes a phase transition to a new phase with symmetry lower than orthorhombic. These two sets of signals are associated with two physically inequivalent positions of the Li atoms in the unit cell, designated Li(1) and Li (2). Below 285 K, the two different Li resonance groups with different magnitudes of quadrupole splitting have previously been analyzed [27].…”

“…Microscopic observations have shown that phases IV and V are monoclinic and that the crystal system is orthorhombic above 458 K [4]. Ferroelectricity has been found in phase IV between 439 and 458 K [2,5]. The phase transitions of LiRbSO 4 can be approximately described as arising from changes of the orientations of the tetrahedral SO 4 groups.…”

“…LiRbSO 4 undergoes successive phase transitions at 477 K ( ¼T C1 ), 475 K (¼ T C2 ), 458 K ( ¼T C3 ), and 439 K ( ¼T C4 ) [1,2]. The successive phases in order of decreasing temperature are referred to as I, II, III, IV, and V. Phases I and V are paraelectric [2]. Phases II and III are ferroelectric and antiferroelectric, respectively [3].…”

A new diffractometer using a curved position-sensitive detector and its applications to X-ray crystallography

“…The crystal used is RbLiSO4 (abbreviated as LRS) which undergoes successive phase transitions at 439, 458, 475 and 477 K (Shiroishi & Sawada, 1979). The crystal structure at room temperature of LRS was reported by Tanisaki, Mashiyama, Hasebe, Shiroishi & Sawada (1980) (space group P1121/n with a = 5-288, b=9"105, c--8.731 .K and y=90-09°).…”