Ch. Sameera Devi

Effect of Simultaneous Substitution of Sm and Pr Ions on Dielectric and Ferroelectric Properties of Strontium Bismuth Titanate

Sr Smx Bi(4−x) Ti(4−y) Pry O15 (for x = 0, y = 0 and x = 0.1, y = 0, 0.1 and 0.2 and also for x = 0.2, y = 0.1) ceramics were prepared by Sol-gel Pechni method. Single phase of compounds was confirmed by XRD analysis and Lattice parameters were calculated. Microstructure and chemical analysis were performed using SEM and EDS techniques. The effect of addition of Sm3+ and Pr3+ ions on dielectric and polarization properties of Sr Bi4 Ti4 O15 was studied and shift in transition temperature was observed. The dc conductivity of the samples measured as a function of temperature.

Spectroscopic and electrical studies on Nd3+, Zr4+ ions doped nano-sized BaTiO3 ferroelectrics prepared by sol–gel method

Lead free ferroelectric ceramics in the form of Ba(1-3x)Nd(2x)Ti(1-y)ZryO3 ((where x=0.025, y=0 (BT1), 0.025 (BT2), 0.05 (BT3)) were prepared using sol-gel method. The surface morphology and the orientation of grains of the present ceramics were examined using Field Emission Scanning Electron Microscope (FESEM) images. The effect of Nd(3+), Zr(4+) ions content on the BaTiO3 was studied using Raman and Fourier Transform Infrared (FTIR) spectroscopies. From the Raman analysis the band observed at ∼838 cm(-1) was attributed due to the presence of Nd(3+)-barium vacancy pairs. The FTIR studies suggested that the addition of Nd(3+) ions in A-site of BaTiO3 (ABO3) perovskite create lattice distortion by forming A-site vacancies and Zr(4+) ions in B-site of BaTiO3 induce the lattice distortion by forming ZrO6 octahedra in the place of TiO6 octahedra. Dielectric measurements of the samples were done at different frequencies from RT-150°C. Charge transportation phenomenon is explained using DC conductivity, which is found to increase with temperature.

Effect of Simultaneous Doping of Pr and Sm on Electrical Conductivity and Relaxation Process in BLSF-SrBi4Ti4O15

Polycrystalline ceramics SrBi4-xSmxTi3.9Pr0.1O15 (where x = 0, 0.1, 0.2 and 0.3) were prepared by sol-gel pechini method. The phase formation was confirmed using X-ray diffraction technique and was found to be orthorhombic. Complex impedance spectroscopy (CIS) technique revealed the presence of both grain and grain-boundary effects in the materials. Grain resistance and grain boundary resistance decreases with increasing temperature confirming the NTCR behaviour of the samples. The relaxation times obtained from impedance studies were used to interpret complex impedance nature of the samples. The temperature dependent conductivity obeys the Arrhenius relationship. The impedance studies indicate the non-Debye type of the frequency dispersion for all the samples.