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Title: Apparent critical phenomena in the superionic phase transition of Cu2-xSe

The superionic phase transition of $${\mathrm{Cu}}_{2-x}\mathrm{Se}$$ accompanies drastic changes in transport properties. The Seebeck coefficient increases sharply while the electrical conductivity and thermal diffusivity drops. Such behavior has previously been attributed to critical phenomena under the assumption of a continuous phase transition. However, applying Landau's criteria suggests that the transition should be first order. Using the phase diagram that is consistent with a first order transition, we show that the observed transport properties and heat capacity curves can be accounted for and modeled with good agreement. The apparent critical phenomena is shown to be a result of compositional degree-of-freedom. In conclusion, understanding of the phase transition allows to explain the enhancement in the thermoelectric figure-of-merit that is accompanied with the transition.
 [1] ;  [2] ;  [1] ;  [2] ;  [2] ;  [1]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States). Dept. of Applied Physics and Materials Science; Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
  2. Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia). Bragg Institute
Publication Date:
OSTI Identifier:
Grant/Contract Number:
SC0001299; FA9550-12-1-0002
Accepted Manuscript
Journal Name:
New Journal of Physics
Additional Journal Information:
Journal Volume: 18; Journal Issue: 1; Journal ID: ISSN 1367-2630
IOP Publishing
Research Org:
Department of Materials Science and Engineering, Northwestern University, IL 60208, USA
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY phase transition; superioinic conductors; thermoelectrics; thermopower