Some dielectric properties of strontium titanate doped with some metal oxides.

SrTio3 and SrTiO3 doped with CeO2, Gd2O3 and CuO were prepared according to the recommended procedure using the ceramic method. The doping concentrations ranged from 0.5 to 5 mole% and the prepared materials were structurally investigated by X-ray diffraction and IR absorption spectrum. The dielectric constant and loss were measured within the frequency band 105 to 107 Hz and the temperature range from 20 to 50 degree. The dielectric relaxation proces and its thermodynamic parameters, the activation enthalpy and the entropy changes [delta H epsilon and delta S epsilon] were calculated using the usual rate equations. The results were correlated with the structure of the titanates and the effect of doping was discussed

Some electrical and dielectric properties of titanium substituted Li-Zn ferrites

The mixed ferrites used have the stoichiometry Li0.35 Zn0.30 Tix Fe2.35-x O4 [where x=0.0 to 0.25 in steps of 0.05] prepared by a ceramic method and sintered at 1150. The a.c. electrical conductivity, the dielectric constant [epsilon '], and dielectric loss factor [epsilon "] of the prepared specimens were measured within the frequency range 105 to 107 Hz and the temperature range 20 to 60. The electronic conductance mechanism was considered involving electronic exchange between Ti4+ and Fe3+, beside ionic conduction, as influenced by parameters such as temperature and frequency

Molecular association in binary mixtures of polyethylene glycol and some aldehydes

Dipole-dipole association in mixtures of polyethylene glycol [400] with both propionaldehyde and benzaldehyde, as representative aliphatic and aromatic aldehydes, has been studied. Decreases in molar volume were calculated from density measurements at different temperatures using the intercept method. The results indicated the formation of the associated aggregates in the ratio [2 propionaldehyde: 1 polyethylene glycol] and [1 benzaldehyde: 1 polyethylene glycol], which mean that the association between the aliphatic aldehyde and polyethylene glycol is greater than that for the aromatic aldehyde. This result is in an agreement with the thermodynamic parameters of dielectric relaxation and viscous flow; namely, the apparent activation energy of dielectric relaxation delta H epsilon and the enthalpy of activation of viscous flow delta Hv calculated from dielectric and viscosity measurements for the two systems

Dipole moment of human hemoglobin in normal working condition and leukemic cases

The human hemoglobin dipole moments are measured in working conditions for normal and leukemic cases. Use is made of Rizk-Elanwar and Kirkwood's equations to calculate the dipole moment at 37 degree. The concentration of the used dilute aqueous solutions of hemoglobin are ranged from:-0.685 X 10[-5] to 5.48 X 10[-5] mole/liter. The obtained results are discussed and correlated to the molecular structure