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Title: Pressure-induced phase transitions in rubidium azide: Studied by in-situ x-ray diffraction

We present the in-situ X-ray diffraction studies of RbN{sub 3} up to 42.0 GPa at room temperature to supplement the high pressure exploration of alkali azides. Two pressure-induced phase transitions of α-RbN{sub 3} → γ-RbN{sub 3} → δ-RbN{sub 3} were revealed at 6.5 and 16.0 GPa, respectively. During the phase transition of α-RbN{sub 3} → γ-RbN{sub 3}, lattice symmetry decreases from a fourfold to a twofold axis accompanied by a rearrangement of azide anions. The γ-RbN{sub 3} was identified to be a monoclinic structure with C2/m space group. Upon further compression, an orthogonal arrangement of azide anions becomes energetically favorable for δ-RbN{sub 3}. The compressibility of α-RbN{sub 3} is anisotropic due to the orientation of azide anions. The bulk modulus of α-RbN{sub 3} is 18.4 GPa, quite close to those of KN{sub 3} and CsN{sub 3}. By comparing the phase transition pressures of alkali azides, their ionic character is found to play a key role in pressure-induced phase transitions.
Authors:
; ; ; ; ;  [1] ;  [1] ;  [2]
  1. State Key Laboratory of Superhard Materials, Jilin University, Changchun, Jilin 130012 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22310873
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; COMPRESSIBILITY; COMPRESSION; EXPLORATION; MONOCLINIC LATTICES; PHASE TRANSFORMATIONS; PRESSURE RANGE GIGA PA; RUBIDIUM; RUBIDIUM NITRATES; SPACE GROUPS; TEMPERATURE RANGE 0273-0400 K; X-RAY DIFFRACTION