Origin of negative thermal expansion in cubic ZrW2O8 revealed by high pressure inelastic neutron scattering

Physical Review Letters

Volumn 86, Issue 20, 2001, Pages 4692-4695

  Mittal, R ^a   Chaplot, S L ^a   Schober, H ^b   Mary, T A ^c  

^a BHABHA ATOMIC RESEARCH CENTRE   (India)

^b INSTITUT LAUE LANGEVIN   (France)

^c INDIRA GANDHI CENTRE FOR ATOMIC RESEARCH   (India)

Author keywords

[No Author keywords available]

Indexed keywords

BRILLOUIN SCATTERING; HIGH PRESSURE EFFECTS; MATHEMATICAL MODELS; NEUTRON SCATTERING; POLYCRYSTALLINE MATERIALS; THERMAL EXPANSION;

HIGH PRESSURE INELASTIC NEUTRON SCATTERING;

PHONONS;

EID: 0035858586     PISSN: 00319007     EISSN: None     Source Type: Journal    
DOI: 10.1103/PhysRevLett.86.4692     Document Type: Article

References (17)

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16. The experimental and the calculated phonon density of states are compared in two respects: (i) the overall shape and (ii) the softening due to pressure. We regard the agreement on the first count as very good considering the known inherent limitations both in experiment (e.g., incoherent approximation) and theory. The second point is quantitatively better illustrated in Fig. 3 and again shows a very good agreement.
17. Figure 4(a) shows the volume thermal expansion up to 300 K. It is nearly constant above 70 K. Above 300 K, the behavior is modified by two important contributions as noted in Ref. [11], namely, (i) an order-disorder phase transition at about 400 K which causes a volume drop of about 0.4% which is not accounted for in the lattice dynamical model and (ii) corrections due to anharmonicity of phonons. As shown in Ref. [11], the observed negative thermal expansion is accounted for over the entire range of temperature up to 1050 K by the anomalous phonon behavior by taking into account the above mentioned factors.