Lim AR. 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.
SOLID STATE NUCLEAR MAGNETIC RESONANCE 2011;
39:14-20. [PMID:
21481572 DOI:
10.1016/j.ssnmr.2011.03.003]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 01/31/2011] [Accepted: 03/15/2011] [Indexed: 05/30/2023]
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.
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