Niyaz Ahamad Madhar

Tuning of dielectric, pyroelectric and ferroelectric properties of 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 ceramic by internal clamping

This study systematically investigates the phenomenon of internal clamping in ferroelectric materials through the formation of glass-ceramic composites. Lead-free 0.715Bi(0.5)Na(0.5)TiO(3)-0.065BaTiO(3)-0.22SrTiO(3) (BNT-BT-ST) bulk ferroelectric ceramic was selected for the course of investigation. 3BaO - 3TiO(2) - B2O3 (BTBO) glass was then incorporated systematically to create sintered samples containing 0%, 2%, 4% and 6% glass (by weight). Upon glass induction features like remnant polarization, saturation polarization, hysteresis losses and coercive field could be varied as a function of glass content. Such effects were observed to benefit derived applications like enhanced energy storage density similar to 174 k J/m(3) to similar to 203 k J/m(3) and pyroelectric coefficient 5.7x10(-4) Cm-2K-1 to 6.8x10(-4) Cm-2K-1 by incorporation of 4% glass. Additionally, BNT-BT-ST depolarization temperature decreased from 457K to 431K by addition of 4% glass content. Glass incorporation could systematically increases diffuse phase transition and relaxor behavior temperature range from 70 K to 81K and 20K to 34 K, respectively when 6% and 4% glass content is added which indicates addition of glass provides better temperature stability. The most promising feature was observed to be that of dielectric response tuning. It can be also used to control (to an extent) the dielectric behavior of the host ceramic. Dielectric permittivity and losses decreased from 1278 to 705 and 0.109 to 0.107 for 6% glass, at room temperature. However this reduction in dielectric constant and loss increases pyroelectric figures of merit (FOMs) for high voltage responsivity (F-v) high detectivity (F-d) and energy harvesting (F-e) from 0.018 to 0.037 m(2)C(-1), 5.89 to 8.85 mu Pa-1/2 and 28.71 to 61.55 Jm(-3)K(-2), respectively for 4% added ceramic-glass at room temperature. Such findings can have huge implications in the field of tailoring ferroelectric response for application specific requirements

An experimental study on thermal energy harvesting using Ca0.15(Sr0.5Ba0.5)0.85Nb2O5 pyroelectric ceramics

Abstract Pyroelectric materials can be used for energy harvesting in integrated Micro-Electro-Mechanical-Systems (MEMS) and low power electronics devices. This paper considers the thermal energy harvesting using Ca0.15(Sr0.5Ba0.5)0.85Nb2O5 (CSBN) pyroelectric ceramics. Hot/cold air was used to generate a continuous temporal temperature profile on the material surfaces. The maximum open circuit voltage was observed as 0.26V. The maximum stored energy was 1.9 μJ in 47 μF capacitor (without load resistance). The maximum power was found to be 2.07nW across 3 MΩ and 47 μF.

Pyroelectric Energy Harvesting Using (Ba0.85Ca0.15) (Zr0.1Ti0.89Fe0.01)O3 Ceramics

There has been a significant increase in the research on waste thermal energy harvesting in recent years. This paper describes harvesting thermal energy using (Ba0.85Ca0.15) (Zr0.1Ti0.89Fe0.01)O3 (BCZTO-Fe) pyroelectric ceramics. The poled sample was placed in front of hot and cold blowers alternatively in order to have continuous electric signal. A simple electrical circuit consists of full wave rectifier with different value of capacitor and load resistance was connected to the pyroelectric material. Maximum value of stored energy was 3.9μJ at 47μF without load resistance. Maximum power output was found to be 106nW across load resistance of 5MΩ and 10 μF.

Giant energy harvesting potential in (100)-oriented 0.68PbMg1/3Nb2/3O3–0.32PbTiO3 with Pb(Zr0.3Ti0.7)O3/PbOx buffer layer and (001)-oriented 0.67PbMg1/3Nb2/3O3–0.33PbTiO3 thin films

This work emphasis on the competence of (100)-oriented PMN–PT buffer layered (0.68PbMg1/3Nb2/3O3–0.32PbTiO3 with Pb(Zr0.3Ti0.7)O3/PbOx buffer layer) and (001)-oriented PMN–PT (0.67PbMg1/3Nb2/3O3–0.33PbTiO3) for low grade thermal energy harvesting using Olsen cycle. Our analysis (based on well-reported experiments in literature) reveals that these films show colossal energy harnessing possibility. Both the films are found to have maximum harnessable energy densities (PMN–PT buffer layered: 8 MJ/m3; PMN–PT: 6.5 MJ/m3) in identical ambient conditions of 30–150°C and 0–600 kV/cm. This energy harnessing plausibility is found to be nearly five times higher than the previously reported values to date.

Application Oriented Selection of Optimal Sintering Temperature from User Perspective: A Study on K0.5Na0.5NbO3 Ceramics

This work presents a novel user oriented approach that can relate materials science with technological applications in a more transparent, systematic and efficient manner. We have made an attempt to figure out the optimal (corresponding to best combination of material properties) sintering temperature of K0.5Na0.5NbO3 (KNN) for transducer and electrical energy storage applications. The weights and priority of vital physical properties for applications understudy are calculated using the quality function deployment (QFD) method. Losses (tanδ), charge storage properties (ϵr, Pr and EC) and elastic compliance (sE12 and sE11) are found to have negative priority for transducer application while in the other case d31, tanδ, sE12 and sE11 are spotted to have negative priority. Priority order for transducer and energy storage application is d31>kp>QM>Tc>tanδ>ϵr>Pr=EC=sE12=sE11>ρ and ϵr>d31=tanδ>sE12=sE11>Tc>Pr>EC>kp>ρ>QM, respectively. Finally, 1080°C (transducer) and 1120°C (capacitor) are the found to be the most appropriate solutions among the alternatives under using modified analytic hierarchy process (AHP).

Cyclic Piezoelectric Energy Harvesting in PMN-PT Single Crystals

Ferroelectric materials are used in a number of applications such as sensors, transducers, actuators, health monitoring and micro-electromechanical systems. The ability of these materials to combine electrical and mechanical responses has led to the establishment of many energy harvesting and conversion systems. Energy harvesting from mechanical vibrations using ferroelectric (subclass of piezoelectric) materials has been extensively studied over the last several decades. However, most of these possess low energy conversion density. Many researchers are working in the direction of improving energy conversion density in these materials. In this study, an attempt has been made to shed some light on the mechanical energy harvesting potential of ferroelectric Pb(Mn1/3Nb2/3)O3-32PbTiO3 (PMN-PT) single crystal through the use of Olsen-like (Ericson) cycle. A maximum energy conversion density of 160 kJ/m3 is obtained for operation parameters of 0–1.5 MV/m and 2–28 MPa stress interval at 80°C. The reported energy density is higher than that of most of other energy harvesting techniques using PMN-PT. The results motivate possible use of this technique for mechanical energy harvesting in ferroelectric materials.

Effect of sintering parameters on the dynamic hysteresis scaling behavior of Ba0.85Sr0.15Zr0.1Ti0.9O3 ceramics

ABSTRACT This article presents the effect of processing parameters on the ferroelectric hysteresis behavior of Ba0.85Sr0.15Zr0.1Ti0.9O3 (BSZT) ceramics. The ferroelectric hysteresis scaling relations for coercive field (Ec) and remnant polarization (Pr) as a function of temperature have been proposed. The power law temperature exponents based on scaling were systematically established for all the hysteresis parameters. The temperature dependent scaling of Ec and Pr at sintering temperature of 1400, 1425, 1450 and 1475°C yields EcαT0.43, EcαT0.84, EcαT0.50, EcαT0.37 and PrαT−1.73, PrαT−1.55, PrαT−1.73, PrαT−1.69 respectively. Additionally, the scaling relations for the samples sintered at 1450°C at different time intervals of 3, 4, 5 and 6 hrs were also established. Finally, to understand the domain dynamics, back switching polarization (Pbc) as a function of temperature (T) was also estimated by Arrhenius law and the average activation energy was evaluated.

Effect of Stress on Energy Conversion and Storage Characteristics of (1-x-y)PIN-xPMN-yPT Single Crystals

Ferroelectric materials are used in many applications including, high-voltage generator, sonar, medical, electro-acoustic coupling, filters circuits and many more. In this work, the compositional dependence and stress dependence of the electromechanical properties of [011]C relaxor ferroelectric (1-x-y)Pb(In1/2Nb1/2)O3–xPb(Mg1/3Nb2/3)O3–yPbTiO3 (PIN-PMN-PT) single crystals has been determined. The specimens were subjected to mechanical loading and mechanical energy converted was found out by using Olsen-like cycle. It can be inferred that as the applied stress increases, converted energy density also increases. The maximum energy converted was found out to be 98.8 kJ/m3 for composition 0.32PIN-0.38PMN-0.30PT between 0 to 36 MPa. Also, the energy storage density for the specimens was found out. The maximum energy stored was found to be 98.8kJ/m3 for 0.24PIN-0.46PMN-0.30PT.

Rational molecular dynamics scheme for predicting optimum concentration loading of nano-additive in phase change materials

The present study deals with the diffusion and phase transition behaviour of paraffin reinforced with carbon nano-additives namely graphene oxide (GO) and surface functionalized single walled carbon nanotubes (SWCNT). Bulk disordered systems of paraffin hydrocarbons impregnated with carbon nano-additives have been generated in realistic equilibrium conformations for potential application as latent heat storage systems. Ab initio molecular dynamics(MD) in conjugation with COMPASS forcefield has been implemented using periodic boundary conditions. The proposed scheme allows determination of optimum nano-additive loading for improving thermo-physical properties through analysis of mass, thermal and transport properties; and assists in determination of composite behaviour and related performance from microscopic point of view. It was observed that nanocomposites containing 7.8 % surface functionalised SWCNT and 55% GO loading corresponds to best latent heat storage system. The propounded methodology could serve as a by-pass route for economically taxing and iterative experimental procedures required to attain the optimum composition for best performance. The results also hint at the large unexplored potential of ab-initio classical MD techniques for predicting performance of new nanocomposites for potential phase change material applications.