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RESEARCH PRODUCT
The structure and phase transition of mixed crystals
R. DecressainGrażyna BatorJacek ZaleskiAdam PietraszkoRyszard Jakubassubject
CrystalPhase transitionCrystallographyChemistryStereochemistryPhase (matter)Spin–lattice relaxationSecond moment of areaGeneral Materials ScienceDielectricAtmospheric temperature rangeCondensed Matter PhysicsIondescription
The phase transition and molecular motions of methylammonium cations are studied in the temperature range from 110 to 450 K in the (x = 0.22, 0.345) (MACAB) crystal by x-ray DSC, dilatometric, dielectric and NMR techniques. It is shown that MACAB (x = 0.22) undergoes a structural phase transition at 222 K. The second moment of the NMR line () and the temperature dependence of spin lattice relaxation time () results are interpreted in terms of ( ion dynamics. In the high-temperature phase (I) the cations undergo isotropic reorientations. In the low-temperature phase (II) only one of three cations is still disordered, whereas the two others perform a type of reorientation about their C - N axes. It is revealed that substitution of Sb by Bi atoms influences the dynamics of the methylammonium cations and the nature of the structural phase transition.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1996-01-22 | Journal of Physics: Condensed Matter |