Dielectric spectra of relaxor Pb(Mg1/3Nb2/3)O3 single crystal

We report the investigation of frequency dependence of dielectric responses of lead magnesium niobate (PMN) in the range from 1 mHz to 10 MHz at various temperatures (200 K-350 K). Three relaxations were obsereved in PMN single crystal, one at high frequency, one at intermediate frequency, and one at low frequency. The high frequency relaxation falls into the frequency range over I MHz. The spectral width of the intermediate frequency (range from similar to 1 Hz to similar to 1 MHz) relaxation, which dominates the dielectric behaviors in the so-called "diffuse phase transition" region (260 K-280 K), broadens rapidly at about 2 70 K, and is almost independent on temperature for T < 260 K. These facts are not in agreement ith the glass freezing picture. The low frequency relaxation shows an Arrhenius-type behavior with barrier height of 0.38 +/- 0.01 eV.