Behavior of ammonium ion in β-LiRb1−x (NH4)xSO4 mixed crystals (0.5 ≤ x ≤ 1.0)

Autor:	M. Herraiz, L. A. Shuvalov, L. S. Smirnov, Lourdes Mestres, M. L. Martinez Sarrion
Rok vydání:	2005
Předmět:	Phonon Chemistry Analytical chemistry chemistry.chemical_element General Chemistry Atmospheric temperature range Neutron scattering Condensed Matter Physics Rubidium Ion Crystallography Phase (matter) General Materials Science Orientational glass Phase diagram
Zdroj:	Crystallography Reports. 50:441-451
ISSN:	1562-689X 1063-7745
DOI:	10.1134/1.1927606
Popis:	The influence of replacement of an ammonium ion by rubidium on the x-T phase diagram in the concentration range 0.50 ≤ x ≤ 1.0 has been studied by X-ray and neutron powder diffraction over a wide temperature range. It is shown that a decrease in the ammonium concentration is accompanied by an increase in the temperature of the II ⇔ I phase transition and stabilization of phase II up to low temperatures (20 K). The changes occurring in the dynamics of mixed crystals are studied by inelastic incoherent neutron scattering. The spectra of the generalized vibrational density of states obtained allowed one to establish the difference in the phonon modes corresponding to phase III of β-LiNH4SO4 and phase II of β-LiRb1−x (NH4)xSO4 mixed crystal with x = 0.91 and x = 0.77 at 20 K. It is shown that a mixed crystal with x = 0.77 at 20 K is in the orientational glass state.
Databáze:	OpenAIRE
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