DIELECTRIC-DISPERSION AND PIEZOELECTRIC RESONANCE IN AN ORGANIC ELECTROOPTIC CRYSTAL - (-)-2-ALPHA-METHYLBENZYLAMINO-5-NITROPYRIDINE

The frequency response of the dielectric constant (epsilon(r)), dielec tric loss tangent (tan delta) and impedance (Z) of an organic electro- optic crystal, (-)-2-alpha-methylbenzylamino-5-nitropyridine (MBA-NP) monitored along the polar axis, is characterized by the presence of st rong peaks in the kHz region. The observed resonance behavior, which i s strongly dependent on the geometric size and shape of the sample, is attributed to its piezoelectric nature. The resonance peaks were foun d to shift steadily towards lower frequencies with increasing temperat ure and towards higher frequencies with increasing pressure. The tempe rature dependence of the stiffness coefficient (C) of the crystal has been defined using the resonance data. The temperature dependence of t he damping of these piezoelectric vibrations has been monitored by the resonance-anti-resonance method. The influence of the application of pressure and the variation of temperature on epsilon(r), monitored alo ng the polar axis of the crystal, has been studied. (C) 1997 American Institute of Physics.