Articles you may be interested in 4,4′-, 5,5′-, and 6,6′-dimethyl-2,2′-bipyridyls: The structures, phase transitions, vibrations, and methyl group tunneling of their complexes with chloranilic acid J. Chem. Phys. 135, 044509 (2011); 10.1063/1.3613640Dielectric and structural characterization of high-temperature ferroelectric xBi(Zn1/2Ti1/2)O3−yPbZrO3-zPbTiO3 perovskite ternary solid solution A new pyridinium compound, (C 5 H 5 NH͒ 5 Bi 2 Br 11 , has been synthesized. The x-ray diffraction studies indicate that its structure is built up of four independent pyridinium cations and isolated Bi 2 Br 11 5Ϫ groups. At room temperature it crystallizes in the monoclinic space group P2 1 /n. Two phase transitions of second-and first-order type are detected by the differential scanning calorimetry measurements at 118 and 405/403 K ͑on heating-cooling͒, respectively. The corresponding anomalies in the linear thermal expansion at 118 and 405 K are observed along three crystallographic directions. The dielectric investigations reveal dielectric absorption and dispersion in the radio-frequency region. The experimental results were analyzed on the basis of dielectric formula which represents the sum of two independent relaxators. The pyroelectric measurements reveal that (C 5 H 5 NH͒ 5 Bi 2 Br 11 becomes ferroelectric below 118 K and is characterized by the appearance of spontaneous polarization of the order of 3•10 Ϫ3 C/m 2 along the b axis.

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