Search

Lanthanum and calcium modified barium titanate, Ba(1−x)LaxTi(1−x/4)O3/BLT and Ba(1−x)CaxTiO3/BCT, where x = 0.02, ferroelectric ceramic samples were synthesized in single perovskite phase by microwave processing technique. Sintering temperature was optimized at 1100 °C for 1h. Presence of pore free micron size uniform grains suggested the advantage of using microwave sintering process. Transition temperature (Tc) decreases with the substitution of La content in BT system. Temperature coefficient of capacitance is negligible from RT temperature to 75 °C for BLT ceramic samples. Polarization vs. electric field (P‐E) hysteresis loop study confirms the ferroelectric nature of the modified BT ceramic samples.

Barium titanate (BaTiO3/BT) ferroelectric system was synthesized in single perovskite phase by modified solid state reaction (MSSR) and solid state reaction (SSR) routes. With the modification of SSR route, calcination temperature lowered down by 200 °C. Dense packing of grains with average grain size ∼12μm was observed in BT samples synthesized by MSSR route. Room temperature (RT) dielectric constant (er) and dielectric loss (tanδ) at 1 kHz frequency of BT samples synthesized by MSSR route were found to be ∼1630 and 0.008. Transition temperature (Tc) is lowered and remnant polarization is increased of BT samples synthesized by MSSR route.

The nanometer dimensions of the carbon nanotubes (CNT) together with the unique electronic structure of a graphene sheet make the electronic properties of these one‐dimensional structures highly unusual. Since carbon nanotubes are metals or semiconductors depending sensitively on their structures. The introduction of pentagon‐heptagon pair defects into the hexagonal network of carbon nanotube can change the helicity of carbon nanotube and fundamentally alter its electronic structure. In addition to the ideal tubes, results on the quantum conductance of nanotube junctions and tubes with defects will be discussed. On‐tube metal‐semiconductor, semiconductor‐semiconductor, and metal‐metal junctions have been studied. Other defects such as substitutional impurities and pentagon‐heptagon defect pairs on tube walls are shown to produce interesting effects on the conductance. The effects of static external perturbations on the transport properties of metallic nanotubes and doped semiconducting nanotubes are exami...