Negative thermal expansion in framework compounds

Pramana

R Mittal1 2¹ 

[1] Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science, C/O TU München, Lichtenbergstr 1, 85747 Garching, Germany$$

关键词: Inelastic neutron scattering;    lattice dynamics;    negative thermal expansion.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

We have studied negative thermal expansion (NTE) compounds with chemi- cal compositions of NX2O8 and NX2O7 (N=Zr, Hf and X=W, Mo, V) and M2O (M=Cu, Ag) using the techniques of inelastic neutron scattering and lattice dynamics. There is a large variation in the negative thermal expansion coefficients of these compounds. The inelastic neutron scattering experiments have been carried out using polycrystalline and single crystal samples at ambient pressure as well as at high pressures. Experimental data are useful to confirm the predictions made from our lattice dynamical calculations as well as to check the quality of the interatomic potentials developed by us. We have been able to successfully model the NTE behaviour of these compounds. Our studies show that unusual phonon softening of low energy modes is able to account for NTE in these compounds.

【 授权许可】

Unknown