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• 作者：Iwona P?owa? ; Gra?yna Bator ; Ryszard Jakubas ; Jan Baran
• 关键词：Thermal properties ; Chloroantimonates(III) and chlorobismuthates(III) ; Dielectric properties ; Phase transitions ; Infrared and Raman spectroscopy
• 刊名：Vibrational Spectroscopy
• 出版年：2012
• 出版时间：September, 2012
• 年：2012
• 卷：62
• 期：Complete
• 页码：121-132
• 全文大小：1244 K

文摘

The allylammonium hexachlorobismuthate(III), [C₃H₅NH₃]₃[BiCl₆], and the allylammonium pentachloroantimonate(III), [C₃H₅NH₃]₃[SbCl₅]Cl, compounds have been synthesized and studied by means of differential scanning calorimetry, thermal expansion, dielectric and infrared (IR) techniques. [C₃H₅NH₃]₃[BiCl₆] exhibits three solid-solid structural phase transitions (PTs) at: 304/304 K (I ? II) (upon cooling/heating), 195/197 K (II ? III) and 155/156 K (III ? IV). In turn [C₃H₅NH₃]₃[SbCl₅]Cl exhibits two PTs at: 221/221 K (I ? II) and 181/185 K (II ? III). The dielectric studies have been made in the frequency range of 2 kHz-1 MHz between 100 and 350 K. The dielectric relaxation processes are observed in both crystals. The activation energy (E_A) value of the dielectric relaxation process for [C₃H₅NH₃]₃[BiCl₆] amounts to about 43 and 72 kJ molp>?1p> for the low- and high-temperature relaxation, respectively, whereas for [C₃H₅NH₃]₃[SbCl₅]Cl E_A = 15 kJ molp>?1p>. The infrared spectra of [C₃H₅NH₃]₃[BiCl₆] and [C₃H₅NH₃]₃[SbCl₅]Cl have been recorded over the wavenumber range between 3800 and 40 cmp>?1p> at selected temperatures (10-310 K). The mechanisms of PTs in the title compounds are discussed.