Phase Transitions in (CH3NH3)5Bi2X11 (X=Cl, Br) Crystals
H. Pykacz, J. Mróz
Institute of Physics, Technical University of Wrocław, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland

and R. Jakubas
Institute of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland
Received: April 30, 1993; revised version: July 20, 1993
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Electric properties of (CH3NH3)5Bi2Cl11 and (CH3NH3)5Bi2Br11 single crystals in the direction of the crystallographic b-axis were studied. The samples tested were natural crystal seeds in the form of thin plates, whose crystallographic b-axis coincides with the normal to the plate. Measurements of the pyroelectric coefficient were performed near the high temperature phase transition and spontaneous polarization from the paraelectric phase down to helium temperature. The attempt of explanation of the anomalous electric properties of these crystals has been presented.
DOI: 10.12693/APhysPolA.84.1085
PACS numbers: 77.70.+a