Thermally stimulated depolarization and infrared studies in single-crystaldolomite (CaMg(CO3)(2))

The thermally stimulated depolarization current technique is employed so as to study the dipole relaxation in dolomite. We traced two dominant low-tem perature dispersions; one located at 140 K and another at 188 K. The first is characterized by the distribution in the relaxation time and the latter one has single-valued relaxation parameters. Standard characterization tech niques and annealing treatments on dolomite samples with different micro-st ructural features showed that the dipoles contributing to the 140 K peak ar e matrix defects, rather than hydrophilic sites in the pore network. The in frared spectroscopy established the absence of water molecules and the pres ence of hydroxyls, which probably constitute one type of defect dipoles. (C ) 2000 Elsevier Science Ltd. All rights reserved.