0000000000909423
AUTHOR
Jan Baran
On structural phase transitions inn-butylammonium chloroantimonate(III) and chlorobismuthate(III) crystals: x-ray, differential scanning calorimetry, dilatometric and dielectric dispersion studies
Numerous structural phase transitions are detected in new crystals of the n-butylammonium compounds: , and by means of differential scanning calorimetry, dilatometric and dielectric dispersion (1 kHz - 1 MHz) studies. For the transitions the basic thermodynamic data are determined. Interesting dielectric properties are found in a metastable form of the crystals. Debye-like dispersion of the electric permittivity between 30 and 800 MHz is observed around the 310 K phase transition for this crystal. The activation energy of the reorientation of the n-butylammonium cations is found to be 16 kJ . The structure of ( form) has been refined to R = 0.0439 and shows isolated units and two non-equiva…
Phase transitions in i-butylammonium halogenoantimonate(III) and bismuthate(III) crystals
Abstract Differential scanning calorimetry, dielectric, thermal expansion, infrared and preliminary X-ray diffraction studies on i-butylammonium halogenoantimonate(III) and bismuthate(III) crystals are reported. All crystals: (i-C4H9NH3)2BiCl5, (i-C4H9NH3)2SbBr5, (i-C4H9NH3)3BiCl6, (i-C4H9NH3)3Bi2Br9, (i-C4H9NH3)3Sb2Br9, show one or more structural phase transitions of first order type. The values of the transition entropies suggest that the most of the phase transitions are of the order-disorder type. The infrared studies confirmed the contribution of the i-butylammonium cations in the phase transition mechanism.