Dipak Kumar Khatua

Coupled domain wall motion, lattice strain and phase transformation in morphotropic phase boundary composition of PbTiO3-BiScO3 piezoelectric ceramic

High energy synchrotron X-ray diffraction, in situ with electric field, was carried out on the morphotropic phase boundary composition of the piezoelectric alloy PbTiO3-BiScO3. We demonstrate a strong correlation between ferroelectric-ferroelastic domain reorientation, lattice strain and phase transformation. We also show the occurrence of the three phenomena and persistence of their correlation in the weak field regime.

Investigating the electrical conduction and relaxation phenomena in rare earth erbium doped lead free 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 by impedance spectroscopy

Rare earth erbium (Er3+) doped 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (NBT-6BT) was prepared via a solid state synthesis route as per the nominal formula 0.94Na0.5Bi0.5-xErxTiO3-0.06BaTiO3 (0 ≤ x ≤ 0.05). Detailed impedance spectroscopy studies, invoking complex impedance and modulus formalisms, were carried out in order to investigate the influence of erbium doping on the long range electrical conduction and localized relaxation in the system. Our results suggest that a low concentration (x = 0.005) of rare earth doping significantly reduces the long range ionic conductivity (with respect to the undoped NBT-6BT value) and decreases the local relaxation, making the system electrically homogeneous. At a higher doping concentration (x ≥ 0.01), enhancement in the electrical conductivity occurs and local relaxation increases in the system. Observed trends are rationalized on the basis of a model, which hypothesizes phase segregation at a higher concentration of Er-doping. Such segregation leads to the formation of pur...

Enhanced thermal stability of dielectric, energy storage, and discharge efficiency in a structurally frustrated piezoelectric system: Erbium modified Na0.5Bi0.5TiO3-BaTiO3

We have systematically investigated the effect of rare earth erbium (Er3+) substitution on the structural, ferroelectric, piezoelectric, and dielectric behaviour of the morphotropic phase boundary lead-free piezoelectric 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (NBT-6BT). We found that the system shows very good thermal stability of energy density, discharge efficiency, and dielectric permittivity. Detailed structural studies confirmed that Er modification induces a great deal of structural frustration which causes the system to thermally evolve towards the paraelectric state in a very sluggish manner. Our results seem to suggest that, among other factors, this sluggish temperature variation of the structural distortion is an important factor which imparts thermal stability to the energy storage and dielectric properties.