Characteristic Phonon Spectrum of Negative Thermal Expansion Materials with Framework Structure through Calorimetric Study of Sc2M3O12(M = W and Mo)

• DOI: 10.1021/cm900965p
• Publication Date: 2009-06-11T15:39:27Z
• Authors: Yasuhisa Yamamura; Satoaki Ikeuchi; Kazuya Saito
• Keywords: Negative Thermal Expansion; Atmospheric temperature range

To study the relation between structural characteristics and phonon property in negative thermal expansion (NTE) compounds, heat capacities of Sc2W3O12 Sc2Mo3O12 were measured. Spectrum analysis capacity provided their effective densities states (DOS). The DOS shows three features; low-energy modes with mode-Grüneisen parameter (γi) around 5 meV, high-energy modes, separation into two regions a wide gap. relative contribution γiCi, where Ci is each vibrational mode i, reveals that γi cause NTE latter features are necessary to maintain temperature range. has γi. This fact indicates potentially even its low-temperature phase showing positive expansion. A comparison other oxides common related chemical characteristics, "strong bond" "framework structure". finding gives us an important guide search for new actual and/or potential compounds.