The dielectric properties of Ba(Mg 1/3 Nb 2/3 )O 3 (BMN)-substituted BaTiO 3 (BT) (xBMN-(100 − x)BT) ceramics, where x = 0-5 mol%, were prepared by a high-temperature solid-state reaction technique. It was found that the substitution of Mg 2+ and Nb 5+ at the Ti-site of the BMN-BT ceramics caused compositional inhomogeneity, leading to a diffuse phase transition (DPT). Discontinuous grain growth accompanied with excellent dielectric diffuseness was found in 3-5 mol% BMN specimens. The maximum solubility limit of Mg/Nb substitution was assumed to be between 3 < x < 4 mol% BMN. A dielectric study of these compounds as a function of temperature suggested that, for the ceramics with x > 2 mol%, the maximum dielectric constant decreased and the Curie temperature shifted downwards on the lower temperature side.
The purpose of this work was to study the effect of ZnO on properties of P2O5-CaO-Na2O glass system for bone substituting applications. The glass formula used in this study is 45P2O5- (30-x)CaO - 25Na2O - xZnO where x = 0, 1 , 3, and 5 mol%. The corresponding glasses were prepared by conventional glass melting technique at 1000 °C for 1 h. Thermal parameters of each glass were studied by differential thermal analysis (DTA). These glasses were investigated in terms of infrared spectra and in vitro bioactivity. DTA results gave the glass transition temperatures in a range 227-280°C and crystallization temperatures in the range 521-529°C. Form FTIR results, the infrared spectra of all glass samples showed vibrations of phosphate network and the transmittance intensity of glass systems decreased with increasing ZnO content. All glass samples were exhibited the growth of apatite cells at the surface after immersed in SBF for 7 days. The optimum composition was found for the glass samples containing 5 mol% ZnO which contained the most apatite layer formation.
he glass ceramics from the PbO-Bi3O2-GeO2 system have been investigated. An excellent transparent glass can be obtained from the stoichiometric (S) composition, Pb3Bi2(GeO4)3, but only by rapid-quenching to give very thin samples. This glass could not therefore be used to make good glass-ceramic samples for measuring the dielectric properties. The A-composition (34.50%PbO :11.49%Bi2O3: 54.01%GeO2) and B-composition (25.90%PbO: 8.63%Bi2O3: 65.47%GeO2) have been prepared to form more stable glasses. These two compositions gave good transparent and thick glass samples. DTA analysis has been used to examine the crystallisation temperatures of all glasses. The controlled heat treatment process has been applied to all crystallisation temperatures and glass-ceramic samples were obtained. It was found that S glass-ceramic contained Pb3Bi2(GeO4)3 and Bi2GeO5 while A glass-ceramic contained only Pb3Bi2(GeO4)3 and was suitable for using in dielectric measurement. B glass-ceramic gave difficulty in identifying the phases. However, it was concluded that the glass-ceramic from this composition had three phases, which are PbGe4O9, PbGeO5 and Bi4(GeO4)3. Since this glass gave no PbO-Bi2O3-GeO2 ternary phase, the dielectric measurement concentrates only on the A glass-ceramic. The frequency dependence of eeee²²²² for the A glass-ceramic sample gave a loss peak at low frequency.
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