Dielectric Relaxation in Bi 12 SiO 20 : Cr Crystals

A study is reported of the temperature and frequency dependences of the permittivity and losses in Cr-doped Bi12SiO20 crystals at sonic frequencies and in the range 300–800 K. A number of dielectric anomalies and a close-to-linear Cole-Cole diagram have been observed. The results are discussed by invoking the concepts of electron hopping and screening of the induced polarization through the relaxation of local lattice distortions.