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Single-phase polycrystalline samples of lead titanate with perovskite structure have been synthesized using solid-state reaction technique. The processing parameters have been optimized to obtain phase pure, dense, crack-free, and homogeneous samples. The sintering behavior of PT-powders has been investigated using X-ray diffraction patterns. The X-ray powder diffraction data have been analyzed to confirm the phase formation and phase purity, to obtain unit cell parameters and unit cell volume. The porosity of the samples has been obtained through X-ray density and bulk density. The average particle sizes of the phase pure samples were obtained from the X-ray peak width using Scherrer's formula. The influence of sintering temperature and time on the microstructure of samples has also been studied by carrying out SEM investigations. The notable feature of this microstructure study shows that the samples sintered at 900 ∘ C for 12 hours possess a fairly uniform grain distribution. The electrical behavior (complex impedance Z * , complex permittivity * , etc.) of the samples sintered at 900 ∘ C for 12 hours has been studied by complex impedance spectroscopy. The temperature variation of real permittivity gives evidence of the ferroelectric phase transition as well as of the relaxation behavior.

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I Suppression of superconductivity in the (Er, --x -uPrxCay)Ba,Cu30, -( 0 4 (x, y ) 4 0.3) system R

Solid solution series, (Bi 2 O 3) 1-x (Y 2 O 3) x and (Bi 2 O 3) 1-x (Gd 2 O 3) x , for x = 0⋅ ⋅10, 0⋅ ⋅20, 0⋅ ⋅30 and 0⋅ ⋅40 were synthesized by standard ceramic technique. The structural phase characterization was carried out using X-ray powder diffraction technique. It was found that the solid solution containing 20-40 mole% of Y 2 O 3 had face-centred cubic structure. All samples of the solid solution series, (Bi 2 O 3) 1-x (Gd 2 O 3) x , had rhombohedral single phase in the concentration range 0⋅ ⋅10 ≤ ≤ x ≤ ≤ 0⋅ ⋅40. Lattice parameters of fcc phase of Y 2 O 3 doped samples were calculated from the X-ray diffraction data. The lattice constant 'a' gradually decreases with increasing content of dopant concentration (x) for the Y 2 O 3 doped system and obeys Vegard's rule. The unit cell parameters for the (Bi 2 O 3) 1-x (Gd 2 O 3) x doped samples showing rhombohedral phase were obtained on hexagonal setting.