Correlation between Valence and Electronic Structure as Studied by Exafs in RM2X2 Compounds

  • C. Godart
  • J. P. Kappler
  • J. D. Thompson
  • G. Krill
  • L. C. Gupta


In the RM2X2 materials (R = Rare Earth, M = Transition Metal, X = Si, Ge …) many changes from one ground state to another under the influence of physical or chemical pressure have been reported. Even moderate pressures or substitutions create large variations of the electronic properties which are therefore associated with small changes of the crystallographic characteristics. EXAFS (Extented X Absorption Fine Structure) may give information about the local environment of the R ion (pair correlation). Unfortunately, in such non cubic structures, atomic relaxations cannot be evidenced. However, some correlation can be established between the R valence and the (R−M) and (R−X) distances or overlap in the CeM2 Si2 system and in EuPd2 Si2 versus temperature. Recent results on XANES (X Absorption Near Edge Structure) of intermediate valence YbPd2Si2−xGex (0 ≤ x < 1) seem very promising to obtain local information on the chemical environment in such systems.


Heavy Fermion Valence Change Atomic Relaxation Valence Fluctuation Mixed Valent Compound 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • C. Godart
    • 1
    • 6
  • J. P. Kappler
    • 2
    • 6
  • J. D. Thompson
    • 3
    • 6
  • G. Krill
    • 4
    • 6
  • L. C. Gupta
    • 5
    • 6
  1. 1.ER 209 “Chemie Métallurgiques des Terres Rares”CNRSMeudonFrance
  2. 2.LMSESUniversité L. PasteurStrasbourgFrance
  3. 3.Los Alamos Nat. Lab.USA
  4. 4.Université de Nancy IVandoeuvreFrance
  5. 5.Tata Institute of Funcamental ResearchBombayIndia
  6. 6.LURE — L.P. CNRSUniversité Paris SudOrsayFrance

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