Anomalous electrical behaviour of single-crystal glycine near room temperature

Electrical impedance measurements of single-crystal glycine reveal anomalou s temperature dependence of the conductance and capacitance. Upon cooling t he crystal from 50 degrees C the conductance decreases smoothly from an ini tial value of 0.1 nS to about 0.02 nS at 31 degrees C. Further cooling, how ever, causes a dramatic increase in conductance with a magnitude approachin g 100 nS at 21 degrees C. Similar anomalous behaviour is exhibited by the c oncurrently measured capacitance; it is approximately temperature independe nt above 31 degrees C but decreases precipitously below this temperature. T his unusual electrical behaviour is not explained readily by the conduction mechanisms expected to apply to these materials but is consistent with the onset of pyroelectricity at 31 degrees C.