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Ceramics of BaTiO 3 co-doped with Gd and Cr at Ba-site was synthesized via solid-state reaction route. Surface morphology shows the increase in grain size with the increase of Cr-content below 3 mol%. The high value of ε in the synthesized samples is associated with space charge polarization and inhomogeneous dielectric structure. Gd is diffused well into the most of Ba sites and vacancies leaving very few defects or voids for the generation of absorption current which results in dielectric loss. Below 3 mol% of Cr-concentration, dissipation factor was improved. Increase in a.c. conductivity with rise of temperature is due to increase in thermally activated electron drift mobility of charges according to the hopping conduction mechanism. Moreover, samples show the positive temperature coefficient of conductivity, which is most desirable for developing highly sensitive thermal detectors and sensors. Also, higher frequency indicates motion of charges in the ceramic samples.

Environmentally safe and lead free La-modified bismuth titanate (BLT) was synthesized by conventional solid state reaction method. The thermal, dielectric, Microstructural behaviors of BLT ceramic have been investigated. Based on the thermal stability of BLT, samples were calcined at 750 0 C, percentage weight loss and thermal behavior was studied by TGA/DSC. The influence of La on crystal structure of BLT showed orthorhombic crystal structure. Increase of La concentration does not show a secondary phase. Among all the La-doped BLT ceramic samples, x = 0.60 exemplified good results. Dielectric permittivity of BLT is higher at x = 0.60 comparing to other, microstructure study of sintered ceramic sample showed plate-like shape with enhanced density. The results show that the La 3+ doped BLT ceramics may be used as a probe for the phase transition of the ferroelectric materials.

The temperature dependence of the impedance of alkanethiol self-assembled monolayers Appl. Phys. Lett. 97, 043110 (2010); 10.1063/1.3469911Temperature dependence of acoustic impedance for specific fluorocarbon liquids Abstract. Temperature dependent impedance behavior in the frequency range 100 Hz to 1 MHz of (Ba 0.6 Sr 0.4 ) (Zr 0.65 Ti 0.35 )O 3 ceramic is reported in this paper. Plots of Zc and Zs vs. frequency at different temperature indicate the significant difference in the magnitude of real and imaginary component of Z. However, these results did not expose the relaxing species definitely. This may be because of the variation of resistance with increasing temperature, displaying shifting of the relaxation frequency in the polarization process at typical frequency with increasing temperature. Hence, it is not clear whether the relaxing species is the oxygen vacancy itself, or electrons released from the oxygen vacancy, which can be the source of the space charge polarization.