Structural phase transitions in dimethylammonium perchlorate
β Scribed by T.K.K. Srinivasan; M. Mylrajan
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 350 KB
- Volume
- 182
- Category
- Article
- ISSN
- 0009-2614
No coin nor oath required. For personal study only.
β¦ Synopsis
Raman and infrared spectra (20-5000 cm-') of ( CH3),NH2C104 and its N-deuterated analogue were investigated in the temperature range 90-350 K. A temperature dependent study of widths and frequencies of prominent bands confirms (a) the existence of phase transitions at 309 and 311 K and (b) in the high temperature phases II and I, the cations and anions undergo reorientational motions.
π SIMILAR VOLUMES
Order+disorder structural phase transitions in alkali perchlorates MClO 4 (M β«Ψβ¬ Na, K, Rb, Cs) are investigated using molecular dynamics simulation. The potentials in the simulations are based on the Gordon+Kim modi5ed electron gas formalism extended to molecular ions. The simulations yield 5rst-or
Using Landau theory of phase transitions it is shown that in the langbeinite structure (space group T4) four spatially homogeneous structural phase transitions are possible. 'Three of them are improper ferroelectric and result from a phonon instability at the M point of the Brillouin zone. The fourt