A general approach to first order phase transitions and the anomalous behavior of coexisting phases in the magnetic case

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

14 Scopus Citations
View graph of relations

Author(s)

  • Sergio Gama
  • Ariana De Campos
  • Adelino A. Coelho
  • Cleber S. Alves
  • Flávio Garcia
  • Dennis E. Brown
  • Luzeli M. Da Silva
  • A. Magnus C. Carvalho
  • Flávio C. G. Gandra
  • Adenilson O. Dos Santos
  • Lisandro P. Cardoso
  • Pedro J. Von Ranke

Detail(s)

Original languageEnglish
Pages (from-to)942-949
Journal / PublicationAdvanced Functional Materials
Volume19
Issue number6
Publication statusPublished - 24 Mar 2009
Externally publishedYes

Abstract

First order phase transitions for materials with exotic properties are usually believed to happen at fixed values of the intensive parameters (such as pressure, temperature, etc.) characterizing their properties.. It is also considered that the extensive properties of the phases (such as entropy, volume, etc.) have discontinuities at the transition point, but that for each phase the intensive parameters remain constant during the transition. These features are a hallmark for systems described by two thermodynamic degrees of freedom. In this work it is shown that first order phase transitions must be understood in the broader framework of thermodynamic systems described by three or more degrees of freedom. This means that the transitions occur along intervals of the intensive parameters, that the properties of the phases coexisting during the transition may show peculiar behaviors characteristic of each system, and that a generalized Clausius-Clapeyron equation must be obeyed, These features for the magnetic case are confirmed, and it is shown that experimental caforimetric data agree well with the magnetic Clausius-Clapeyron equation for MnAs. An estimate for the point in the temperature-field plane where the first order magnetic transition turns to a second order one is obtained (the critical parameters) for MnAs and Gd<sub>5</sub>Ce<sub>2</sub>Si<sub>2</sub> compounds. Anomalous behavior of the volumes of the coexisting phases during the magnetic first order transition is measured, and it is shown that the anomalies for the individual phases are hidden in the behavior of the global properties as the volume. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.

Bibliographic Note

Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to lbscholars@cityu.edu.hk.

Citation Format(s)

A general approach to first order phase transitions and the anomalous behavior of coexisting phases in the magnetic case. / Gama, Sergio; De Campos, Ariana; Coelho, Adelino A.; Alves, Cleber S.; Ren, Yang; Garcia, Flávio; Brown, Dennis E.; Da Silva, Luzeli M.; Carvalho, A. Magnus C.; Gandra, Flávio C. G.; Dos Santos, Adenilson O.; Cardoso, Lisandro P.; Von Ranke, Pedro J.

In: Advanced Functional Materials, Vol. 19, No. 6, 24.03.2009, p. 942-949.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review