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Ajit R Kulkarni

Publications and source records attributed to Ajit R Kulkarni.

2 recordsLinked to original sources

Performance of dopamine modified 0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 filler in PVDF nanocomposite as flexible energy storage and harvester

We demonstrate the potential of dopamine modified 0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 filler incorporated poly-vinylidene fluoride (PVDF) composite prepared by solution cast method as both flexible energy storage and harvesting devices. The introduction of dopamine in filler surface functionalization acts as bridging elements between filler and polymer matrix and results in a better filler dispersion and an improved dielectric loss tangent (<0.02) along with dielectric permittivity ranges from 9 to 34 which is favorable for both energy harvesting and storage. Additionally, a significantly low DC conductivity (< 10-9 ohm-1cm-1) for all composites was achieved leading to an improved breakdown strength and charge accumulation capability. Maximum breakdown strength of 134 KV/mm and corresponding energy storage density 0.72 J/cm3 were obtained from the filler content 10 weight%. The improved energy harvesting performance was characterized by obtaining a maximum piezoelectric charge constant (d33) = 78 pC/N, and output voltage (Vout) = 0.84 V along with maximum power density of 3.46 microW/cm3 for the filler content of 10 wt%. Thus, the results show 0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3/PVDF composite has the potential for energy storage and harvesting applications simultaneously that can significantly suppress the excess energy loss arises while utilizing different material.

cond-mat.mtrl-sci

Dielectric relaxation and electrical conductivity in lead-free (100-x)(Li0.12Na0.88)NbO3-xBaTiO3 (0 to x to 40) piezoelectric ceramics: An impedance spectroscopic study

Dielectric behavior and conductivity mechanism in lead-free (100-x)(Li0.12Na0.88)NbO3-xBaTiO3 (0 to x to 40) piezoelectric ceramics were investigated using impedance spectroscopy over a wide temperature (-100 oC to500 oC) and frequency range (0.1 Hz to1 MHz). The grain and grain boundary response as well as the relaxation processes at different frequencies and temperatures were also discussed. A low frequency dispersion in dielectric permittivity (LFDD), a typical characteristic of high-temperature behavior was observed both below and above the ferro-paraelectric phase transition temperature, Tm. Oxygen-defect-related complexes generated due to acceptor type doping were found to play an important role in LFDD and hopping conduction. The dielectric relaxation follows Jonscher universal law, however LFDD is found to be associated with quasi-DC process (QCD). The activation energies of DC conduction confirm the mechanism as the thermal motion (short range hopping) of doubly ionized oxygen vacancies. At high temperature, the conductivity relaxation mechanism is dominated by grain boundary conduction through hopping electron created by the charge compensating oxygen vacancies.

cond-mat.mtrl-sci