Jablan Dojčilović

Temperature dependence of electric permittivity of linear dielectrics with ionic and polar covalent bonds

Results are presented of experimental verification of the relation describing temperature dependence of permittivity of linear dielectrics with ionic and polar covalent bonds. The relation has been derived by means of the thermodynamic method [1]. The verification has been realized on sodium chloride, sulfates, phosphates and arsenates of magnesium and cobalt, as well on barium titanate in paraelectric phase. The experimental results confirm the theoretical relation and, at the same time, indicate the possibility of determining the linearity region of properties of these dielectrics.

STRUCTURAL PHASE TRANSITIONS IN CO(II) AND NI(II) DIPHOSPHATES IN THE TEMPERATURE RANGE 290-1000 K

Abstract This paper presents a study of the temperature dependence of the dielectric permittivity, electric resistivity and magnetic susceptibility of the diphosphate M2P2O7, where M = Co(II) andNi(II). The study, which was carried out in the temperature range 290–1000 K, indicated that both compounds sustain three phase transitions each. The existing literature offers a description of one phase transition for both compounds (α → β).

Synthesis, crystallization and characterization of PbCo2(PO4)2 and Pb2Co(PO4)2☆

Abstract Synthesis, Bridgman-Stockbarger crystallization and some characterization data of two new substances, PbCo2(PO4)2 and Pb2Co(PO4)2 are presented. The size and the shape of the crystals as a function of various growth parameters were studied. The dielectric permitivity suggests a high purity and perfection of the grown crystals. The unit cell parameters of the monoclinic crystals were also determined. Optical reflection spectra indicate that Co2+ ions in both structures have a regular octahedral symmetry.

Valence State Stability in SrTiO3 Doped with ME/RE-Ions

A study of the electronic structure, dielectric and spectral parameters of pure and doped strontium titanate single crystals at temperature ranging from 10 to 300 K is presented. Change in the oxidation state of Ti+4 ions toward Ti+3 as well as change in the compound stoichiometry and formation of clusters with Ti+3 and Me+3 ions lead to different properties of SrTiO3 crystals. The charge transfer, the tunnelling current, the change of the oxidation states and anomalies in spectral properties for the crystals doped with Me and/or RE ions are discussed in detail.