Rashmi Rani

Investigation of dielectric and electrical properties of Mn doped sodium potassium niobate ceramic system using impedance spectroscopy

A single perovskite phase formation of polycrystalline samples of (Na0.52K0.44Li0.04) (Nb0.86-x Ta0.1Sb0.04Mnx) (where x = 0.00, 0.01, 0.03, and 0.05) here by denoted as NKNLST and Mn doped NKNLST were prepared by mixed oxide method. The preliminary structural studies were carried out by x-ray diffraction technique showing the formation of single perovskite phase with orthorhombic symmetry for all compositions. Addition of Mn in NKNLST system lowered the sintering temperature by 75 °C. Detail study of impedance parameters shows the non-Debye temperature of relaxation phenomena in the system. This analysis enables us to separate grain and grain boundary contribution of the materials. Above the ferroelectric–paraelectric phase transition temperature, the electrical conduction is governed by the thermal excitation of carriers from oxygen vacancies exhibiting Negative temperature coefficient (NTCR) behaviour.

Study of the structural and electrical behavior of Bi(Mg,Ti)O3 modified (Ba,Ca)TiO3 ceramics

The ability of BaTiO3 to form solid solutions with different dopants (both iso- and aliovalent) makes it versatile for various applications. In the present study, (Ba,Ca)TiO3 (BCT) is modified with Bi(MgTi)O3 (BMT) in search for new lead-free ferroelectric material and improve their properties. For this purpose, BCT acts as a main base material and BMT acts as a modifier to fabricate a multifunctional material. In this study, we report the structural and electrical properties of lead free piezo-ceramics (1−x)(Ba0.8Ca0.2)TiO3–xBi(Mg0.5Ti0.5)O3 with x=0.2, 0.4, 0.5 prepared by solid-state sintering technique. Single perovskite phase with tetragonal structure is obtained for all the compositions, which is reconfirmed by the Raman Spectroscopic study. Dielectric study confirm the temperature stable behavior of the dielectric permittivity values above 300∘C. The dielectric constant value decreases with increase in BMT doping content. Impedance Spectroscopic study confirms non-Debye type dielectric relaxation in the specimen. The Nyquist plot and conductivity studies show the negative temperature coefficient of resistance behavior (NTCR) of the samples.