Repozytorium

Structure and phase transitions in guanidinium halogenobismuthates(III).

Autorzy

Grażyna Bator

Th. Zeegers-Huyskens

Ryszard Jakubas

J. Zaleski

Rok wydania

2001

Czasopismo

Journal of Molecular Structure

Numer woluminu

570

Strony

61-74

DOI

10.1016/S0022-2860(01)00490-2

Kolekcja

Naukowa

Język

Angielski

Typ publikacji

Artykuł

Streszczenie

Differential scanning calorimetry (DSC), dilatometric and dielectric measurements have been used to study the phase transitions in [C(NH2)3]3BiBr6. The [C(NH2)3]3BiBr6 crystal undergoes four phase transitions: at 419, 429, 475 and 495 K (on heating). The high-temperature phase transition is clearly of first-order type and its high entropy effect allows classifying it as of the order–disorder type. X-ray diffraction studies showed that [C(NH2)3]3BiBr6 crystallises in monoclinic, centrosymmetric space group, C2/c. The anionic sublattice is composed of isolated BiBr63− octahedra. The infrared between 100 and 350 K and Raman spectra at room temperature in the frequency range related to the internal vibrations of guanidinium cations were studied for [C(NH2)3]3BiBr6, [C(NH2)3]3Bi2Br9, [C(NH2)3]3BiCl6xCl2 and C(NH2)3Cl to analyse the dynamical state of cations. At room temperature, the cations in the studied guanidinium halogenobismuthates(III) are almost rigid, so the mechanism of high-temperature phase transitions is probably connected with the release of rotation of the cations.

Słowa kluczowe

Guanidinium halogenobismuthates(III), Infrared, Raman, DSC, Dilatometry, Phase transition

Adres publiczny

https://doi.org/10.1016/S0022-2860(01)00490-2

Strona internetowa wydawcy

http://www.elsevier.com

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