Titre du document / Document title

Heat capacities, third-law entropies and thermodynamic functions of the negative thermal expansion materials, cubic α-ZrW₂O₈ and cubic ZrMo₂O₈, from T = (0 to 400) K

Auteur(s) / Author(s)

STEVENS Rebecca ⁽¹⁾ ; LINFORD Jessica ⁽¹⁾ ; WOODFIELD Brian F. ⁽¹⁾ ; BOERIO-GOATES Juliana ⁽¹⁾ ; LIND Cora ⁽²⁾ ; WILKINSON Angus P. ⁽²⁾ ; KOWACH Glen ⁽³⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, ETATS-UNIS
⁽²⁾ School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, ETATS-UNIS
⁽³⁾ Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, NJ 07974, ETATS-UNIS

Résumé / Abstract

The molar heat capacities of crystalline cubic α-ZrW₂O₈ and cubic ZrMo₂O₈ have been measured at temperatures from (0.6 to 400) K. At T = 298.15 K, the standard molar heat capacities are (207.01 ± 0.21) J.K^-1.mol^-1 for the tungstate and (210.06±0.42) J.K^-1.mol^-1 for the molybdate. Thermodynamic functions have been generated from smoothed fits of the experimental results. The standard molar entropies for the tungstate and molybdate are (257.96±0.50) J.K^-1.mol^-1 and (254.3±1) J.K^-1.mol^-1, respectively. The uncertainty of the entropy of the cubic ZrMo₂O₈ is larger due to the presence of small chemical and phase impurities whose effects cannot be corrected for at this time. The heat capacities of the negative thermal expansion materials have been compared to the weighted sums of their constituent binary oxides. Both negative thermal expansion materials have heat capacities which are significantly greater than the sum of the binary oxides over the entire temperature region.

Revue / Journal Title

Journal of chemical thermodynamics   ISSN 0021-9614   CODEN JCTDAF 

Source / Source

2003, vol. 35, n^o6, pp. 919-937 [19 page(s) (article)] (43 ref.)

Langue / Language

Anglais

Editeur / Publisher

Elsevier, Kidlington, ROYAUME-UNI  (1969) (Revue)

Mots-clés anglais / English Keywords

Transition metal Compounds ; Adiabatic calorimeter ; Thermal analysis ; Molybdenum Oxides ; Tungsten Oxides ; Zirconium Oxides ; Ternary compound ; Thermal expansion coefficient ; Entropy ; Thermodynamic properties ; Heat capacity ; Thermal properties ; Experimental study ;

Mots-clés français / French Keywords

Métal transition Composé ; Mo O Zr ; ZrMo2O8 ; O W Zr ; ZrW2O8 ; Calorimètre adiabatique ; Analyse thermique ; Molybdène Oxyde ; Tungstène Oxyde ; Zirconium Oxyde ; Composé ternaire ; Coefficient dilatation thermique ; Entropie ; Propriété thermodynamique ; Capacité calorifique ; Propriété thermique ; Etude expérimentale ;

Mots-clés espagnols / Spanish Keywords

Metal transición Compuesto ; Calorímetro adiabático ; Análisis térmico ; Molibdeno Óxido ; Wolframio Óxido ; Zirconio Óxido ; Compuesto ternario ; Coeficiente dilatación térmica ; Entropía ; Propiedad termodinámica ; Capacidad calorífica ; Propiedad térmica ; Estudio experimental ;

Mots-clés d'auteur / Author Keywords

Negative thermal expansion materials ; Heat capacity ; Entropy ; Thermodynamic functions ;

Localisation / Location

INIST-CNRS, Cote INIST : 14300, 35400011955516.0060