title: Study on the structural properties and relaxation mechanisms in LiRb(1-x)(NH₄)(x)SO₄ (x=0, 0.5, and 1) mixed crystals by ¹H, ⁷Li, and ⁸⁷Rb nuclear magnetic resonance.
abstract: LiRb(1-x)(NH₄)(x)SO₄ (x=0, 0.5, and 1) mixed crystals were grown using the slow evaporation method, and their lattice constants were determined by X-ray diffraction. The effects of replacing ammonium ions with rubidium on the phase transitions of and dynamics of LiRb(1-x)(NH₄)(x)SO₄ mixed crystals were studied. We investigated the structural properties and phase transition temperatures of the LiRb(1-x)(NH₄)(x)SO₄ mixed crystals by performing ¹H, ⁷Li, and ⁸⁷Rb NMR relaxation and DSC. When a fraction of rubidium ions in the pure LiRbSO₄ crystal is partially replaced by ammonium ions, we compare the structural properties for LiRbSO₄, LiRb₀.₅(NH₄)₀.₅SO₄, and LiNH₄SO₄ single crystals. The ¹H, ⁷Li, and ⁸⁷Rb NMR relaxation mechanisms of LiRb₀.₅(NH₄)₀.₅SO₄ are different from those of pure LiRbSO₄ and LiNH₄SO₄; the sequence of the structural phase transitions of LiRb₀.₅(NH₄)₀.₅SO₄ is different, which might be related to the dynamics and orientation of the sulfate tetrahedral groups in the crystal structure.
authors.affiliation: Department of Science Education, Jeonju University, Jeonju 560-759, Republic of Korea. aeranlim@hanmail.net
authors.forename: Ae Ran
authors.initials: AR
authors.lastname: Lim