The generalised phonon density of states of (CH3NH3)2MnCl4: experiments and model calculations
- 20 March 1980
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 13 (8) , 1391-1402
- https://doi.org/10.1088/0022-3719/13/8/010
Abstract
The generalised phonon density of states has been studied by neutron inelastic scattering from powder samples of (CH3NH3)2MnCl4 at 4.2, 77, 195, 300 and 405K for the frequency range of the external modes of these molecular crystals. The experimental results are compared with lattice dynamical calculations employing a rigid-ion model. The effects of anharmonicity are partly taken into account by including a finite phonon linewidth increasing with frequency and with temperature in the calculations. The results show that the main peak in the generalised phonon density states is due to modes with a high portion of rotational motion of the molecules which exhibit a rather drastic frequency shift with increasing temperature. At 300K, a completely deuterated sample was also studied for comparison.Keywords
This publication has 23 references indexed in Scilit:
- Elastic properties of the layer-structure material (CH3NH3)2MnCl4Journal of Physics C: Solid State Physics, 1979
- Phonons in perovskite-type layer structuresJournal of Physics C: Solid State Physics, 1979
- Model of structural phase transitions in Cd-type compoundsPhysical Review B, 1978
- Invariance and stability conditions in lattices with rigid moleculesZeitschrift für Physik B Condensed Matter, 1978
- Single-crystal infrared and Raman spectroscopic study of methylammonium and propylammonium tetrachloromanganate(II), (MAMC and PAMC)Journal of Physics C: Solid State Physics, 1978
- Low-frequency raman spectra and phase transitions in perovskite-type layer compounds. (CH3NH3)2MnCl4 and (CH3NH3)CdCl4Physica Status Solidi (a), 1977
- Interlayer and intralayer forces in halide perovskite-type layer structuresIl Nuovo Cimento B (1971-1996), 1977
- X-ray study of structural phase transitions in the perovskite-type layer compound (CH3NH3)2CdCl4Physica Status Solidi (a), 1976
- On the second-order phase transition in (CH3NH3)2MnCl4. A single-crystal neutron diffraction study at 404 and 293 KPhysica Status Solidi (a), 1975
- X-Ray study of the structural first-order phase transition (Cmca-P42/ncm) in (CH3NH3)2CdCl4Physica Status Solidi (a), 1975