Pb(1-3x/2)LaxZr0.65Ti0.35O3 (x = 6, 7, 8 and 9%) show diffusivity values as 1.55, 1.72, 1.94 and 2.18, respectively. The differential permittivity strongly depends on temperature and electric field and get maximum value at certain temperature and fields. These temperatures and fields vary with La-content. The maximum energy storage density observed is 131.90 mJ/cm3 with an efficiency of 82.26% for 6% doped sample. With increasing La-doping it is found to decrease. For 9% doped sample, it is 92 mJ/cm3 with an efficiency of 65%. The bandgap changes from 3.37 eV (6% La) to 3.26 eV (9% La). © 2019, © 2019 Taylor &amp; Francis Group, LLC.

Sankaranarayanan V

Department Of Physics

Kanikrishnan Sethupathi

Shibnath Samanta

Electric fields

Energy gap

Energy Storage

Permittivity

Doped sample

ENERGY STORAGE DENSITY

LA DOPING

Relaxors

temperature dependence

Temperature distribution

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IIT Madras

Temperature Dependence of Energy Storage Density and Differential Permittivity and Bandgap Study of Relaxor (Pb,La)Zr0.65Ti0.35O3

Integrated Ferroelectrics

Diffusivity is the quantitative measure of the relaxor nature of a ferroelectric material. The observed electrocaloric effect of the relaxor ferroelectrics due to the change of diffusivity are reported in this article. Four samples with diffusivities 1.55, 1.72, 1.94 and 2.18 are prepared by precisely doping La in Pb (Zr0.65Ti0.35)O3 [i.e. PZT (65/35)], from 6% to 9%. These values are deduced from the dielectric measurements which are performed in the frequency range from 100&nbsp;Hz to 10&nbsp;MHz at different temperatures ranging from 173&nbsp;K to 573&nbsp;K. The temperature (Tm), where the dielectric constant is the highest, is also found to decrease with increasing La concentration. For 6% doped sample, the transition occurs around 483&nbsp;K and for 9%, it is around 364&nbsp;K. As the value of diffusivity is varied from 1.55 to 2.18, both the values of entropy and temperature changes (ΔS and ΔT) get reduced. The highest ΔS observed is around 0.37&nbsp;J&nbsp;kg−1&nbsp;K−1 and the corresponding ΔT is 0.49&nbsp;K for the diffusivity of 1.55. For the highest diffusivity, the values of ΔS and ΔT are found to be 0.12&nbsp;J&nbsp;kg−1&nbsp;K−1 and 0.11&nbsp;K, respectively. Apart from these changes, it is also observed that as the transition temperature decreases with increasing diffusivity, the maximum ΔS and ΔT values occur at lower temperatures which is consistent with the change of Tm. © 2019, The Minerals, Metals &amp; Materials Society.

Journal of Electronic Materials

Electrocaloric Effect with Variations of Diffusivity in Relaxor Ferroelectric Materials

A comparative study correlating structure and ferroelectricity in La-doped PbZr0.52Ti0.48O3 [PZT] for La = 0–4% has been carried out. Due to increase in tetragonality, 2% La doped PZT shows highest polarization. A modified low cost, but highly proficient method of Double Atmospheric Layer Protected Sintering (DALPS) has been developed to sinter pyrochlore free 2% La-doped PbZr0.52Ti0.48O3 prepared by a modified sol-gel synthesis. The DALPS method enhances the remnant polarization by 29% and dielectric constant by 23% with around 50% decrease in dielectric loss tangent. The effectiveness of DALPS in preventing lead loss is confirmed by EDS analysis. As a result of the employment of the modified sol-gel synthesis and DALPS, a remnant polarization value as high as 49.25 μC cm−2 with nearly ideal hysteresis loop is observed in bulk Pb0.97La0.02Zr0.52Ti0.48O3. The squareness factor of the P-E loop is 99.7% of an ideal value. The Positive Up Negative Down (PUND) measurement shows enhanced remnants with polarizations: the values of +dPr and –dPr are 112 and 117 μC cm−2 respectively. The dielectric loss is also sufficiently low and at room temperature and the value of tan δ is 0.016 with dielectric constant of 1369 at 1 kHz. © 2018 Elsevier Ltd

Vacuum

Enhanced ferroelectricity in PLZT ceramic by precise La-doping, minimizing pyrochlore phase and lead loss

The studies on the effect of simultaneous doping of donor (Nb) and acceptor (Fe) (0–8&nbsp;at.% of each dopant) in PLZT (Pb0.97La0.02Zr0.52Ti0.48O3), on the dielectric response, ac conductivity and ferroelectricity are reported in this article. It is observed that the value of dielectric constant decreases, dielectric loss increases (moderately) and coercive field increases upon doping of Nb and Fe together. These indicate a hardening like effect as a result of the donor–acceptor co-doping. The ferroelectric to paraelectric phase transition occurs at lower temperatures for higher doping concentrations. For undoped PLZT the Curie temperature is around 353&nbsp;°C which shifts to 305&nbsp;°C for 8% Nb–Fe co-doped PLZT. Microstructure studies on the surface, as well as the interior of the samples are carried out which reveal a clear difference. The grain size is observed to decrease with doping concentration. The “true switchable polarization” is deduced by positive up negative down (PUND) tests and found to decrease with doping. Fatigue behavior is found to be positively enhanced upon co-doping of 2% Nb and Fe. Leakage current tests are carried out and it is found that the samples become more ‘leaky’ upon co-doping of Nb and Fe. The energy storage density is also investigated for these Nb–Fe co-doped PLZT ceramics. The highest recoverable energy storage density is observed for 2% Nb–Fe co-doped PLZT sample and it is around 134&nbsp;mJ/cm3 with an efficiency of 0.28. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Materials Science: Materials in Electronics

Effect of Nb and Fe co-doping on microstructure, dielectric response, ferroelectricity and energy storage density of PLZT

Nb and Fe co-doped PLZT (Pb0.97La0.02(Zr0.52Ti0.48)1−2x(Nb0.5Fe0.5)2xO3 for x&nbsp;=&nbsp;0.00, 0.02, 0.04, 0.06 and 0.08) samples have been prepared using sol–gel method. X-ray diffraction (XRD) and Raman spectroscopy studies confirmed that the samples are single phase even for the highest tested doping of 8&nbsp;mol% of Nb and Fe. Incorporation of Nb and Fe atoms into PLZT lattice has been confirmed by XRD study where a systematic peak shift has been observed with increasing dopant concentration. The lattice parameters are found to decrease gradually with increase in Nb and Fe contents. From Raman spectroscopic investigation, redshift of several modes has been observed. Rietveld refinement has been performed to correlate XRD results with the fitting of Raman spectra. A total of 14 distinguished modes have been identified by de-convolution of Raman spectra, and they are in good agreement with the theoretically calculated modes for PbTiO3 and also with those reported on PZT and PLZT previously. The Burstein–Moss shift of absorption edge has been observed by diffuse reflectance spectroscopy experiment, and the analysis shows change in band gap from 3.21&nbsp;eV (for x&nbsp;=&nbsp;0.00) to 2.59&nbsp;eV (for x&nbsp;=&nbsp;0.08). The underlying mechanisms and the observed electronic behavior have been confirmed and analyzed by photoluminescence study which revealed several transitions and supported the effect of Nb and Fe co-doping as observed from XRD and Raman spectroscopy. © 2017, Springer Science+Business Media, LLC.

Journal of Materials Science

Band gap reduction and redshift of lattice vibrational spectra in Nb and Fe co-doped PLZT

Journal of Applied Physics

Investigation of La and Al substitution on the spontaneous polarization and lattice dynamics of the Pb(1-x)LaxTi(1-x)AlxO3 ceramics

Journal	Data powered by TypesetIntegrated Ferroelectrics
Publisher	Data powered by TypesetTaylor and Francis Ltd.
ISSN	10584587
Open Access	No