Wydział Chemii

Ryszard Jakubas

Anna Piecha

Adam Pietraszko

Grażyna Bator

2005

Physical Review B

72

1-8

10.1103/PhysRevB.72.104107

Naukowa

Angielski

Artykuł

Pentakis (imidazolium) undecachlorodibismuthate(III), (C3N2H5)5Bi2Cl11, has been synthesized and studied by means of the x-ray, differential scanning calorimetry (DSC), and dielectric methods over a wide temperature range. The room temperature crystal structure has been determined as monoclinic, space group P21∕n with a=13.616Å, b=14.684Å, c=9.045Å, and β=96.85°. Two solid–solid phase transitions: P¯4n2360K−−→P21/n (I→II), and P21/n166K−−→P21 (II→III), discontinuous and continuous in nature, respectively, have been revealed. The dielectric and pyroelectric measurements allow us to characterize the lowest temperature phase (III) as ferroelectric with the Curie point at 166K and saturated spontaneous polarization value of the order of 6×10−3Cm−2 along the b axis. The ferroelectric phase transition mechanism is governed by the dynamics of imidazolium cations. The room temperature, paraelectric phase (II) demonstrates additionally the ferroelastic properties.

http://dx.doi.org/10.1103/PhysRevB.72.104107