Narrow Results

The tetragonal Ca₉Nd₂W₄O₂₄ (CNW) ceramic was prepared by the conventional solid state ceramic route and their dielectric properties were investigated in the radio and microwave frequencies. The CNW ceramics sintered at 1450 °C for 4 h showed a densification 92 % with ε_r = 16 and tanδ = 0.004 at 15.1 GHz. The thermal conductivity of ceramic at room temperature was found to be 1.6 W m⁻¹K⁻¹ and coefficent of thermal expansion of CNW ceramics was 4.2 ppm/°C measured in the range of 25 to 600 °C. The dielectric and thermal properties of CNW ceramic are reported for the first time.

Aluminium phosphate (AlPO₄)-Magnesium fluoride (MgF₂) composite has been prepared through solid state ceramic route. The formation of composite has been confirmed by X-ray diffraction studies. The variation in ε_r and tanδ of the composite with frequency in the range (1K Hz – 3 MHz) has been studied. The AlPO₄-MgF₂ has a small temperature dependence of ε_r. The composite shows low relative permittivity of 3 and low dielectric loss (tanδ = 7×10⁻³) at 5.85 GHz.

The binary glassy systems 60V₂O₅-(40-x)P₂O₅ –xB₂O₃ were prepared by melt quenching technique. The mole of B₂O₃ was varies from 5 to 20 mol % with constant mol % of V₂O₅ during preparation of glass samples. The dc electrical conductivity of samples was measured in temperature range 303-473 K and found to be higher for sample 60 V₂O₅-20P₂O₅ –20B₂O₃. Using the Arrhenius equation of conductivity, the activation energy of conduction is estimated. The conduction in these glasses is takes place by phonon-assisted hopping between the localized states.