The lambda-phase transition in NH4Br

Yurtseven H. H., Gulec M., Sherman W.

PHASE TRANSITIONS, vol.56, no.3, pp.137-146, 1996 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 56 Issue: 3
  • Publication Date: 1996
  • Doi Number: 10.1080/01411599608207842
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.137-146
  • Middle East Technical University Affiliated: No


This study gives the predicted frequencies for the Raman modes of v(7)TA(56 cm(-1)), v(5)LO(177 cm(-1)) and v(2)(1684 cm(-1)) of NH4Br at various temperatures for zero pressure across the lambda-phase transition in this crystal system. We calculate the Raman frequencies by means of a constant mode Gruneisen parameter for each mode across the lambda-phase change region of NH4Br.