View in EDS

BCTZ lead free thin films with Ce doping gradient: enhanced piezoelectricity and relaxor behaviour

Saved in:
Bibliographic Details
Title: BCTZ lead free thin films with Ce doping gradient: enhanced piezoelectricity and relaxor behaviour
Authors: Wolfman, Jérôme, Negulescu, Béatrice, Nadaud, Kevin, Nataf, Guillaume F., Jaber, Nazir, Bah, Micka, Giovannelli, F., Andreazza, Pascal
Contributors: Wolfman, Jerome
Publisher Information: 2024.
Publication Year: 2024
Subject Terms: [CHIM.MATE] Chemical Sciences/Material chemistry, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Description: Barium titanate-based lead-free ferroelectrics are promising materials for a wide range of applications, such as energy storage devices, tuneable microwave capacitors or electro-mechanical transducers. In this work, we investigate the relaxor ferroelectric properties of (1-x)Ba0.7Ca0.3TiO3 – xBaZr0.2Ti0.8O3 (BCT-BZT) thin films grown by pulsed laser deposition. As the functional properties of these materials are extremely sensitive to the cationic composition, we use a high throughput combinatorial chemistry approach to fabricate composition gradient films. We focus on compositions with x=0.5 known to provide high piezoelectric coefficients (~ 490 pC/N) and soft ferroelectric behaviours with Curie temperatures near 100°C in ceramics, making them promising as an alternative to PZT. In particular, we show that Ce doping (from 0% to 0.2%) modifies the lattice parameter, reduces the remnant polarisation, and shifts the maximum permittivity temperature (Tmax) value. For compositions with Tmax close to room temperature, we measure an enhanced room-temperature d33 piezoelectric coefficient. We then use dielectric spectroscopy coupled with the Rayleigh analysis to identify the contribution of domain wall motion to the ferroelectric response of the films, as a function of temperature. We observe residual ferroelectricity above Tmax, similar to what has been observed for (Ba,Sr)TiO3. In addition, measurement of the third harmonic dielectric response reveals the evolution from a conventional ferroelectric character to a relaxor one with increasing temperature. A peculiar phase angle of the third harmonic, which consists of −180◦ → −225◦ → +45◦ → 0◦, instead of the −180◦ → −90◦ → 0◦ found for relaxors, is also observed in several samples and tentatively attributed to changes in the correlations between polar nanoregions.
Document Type: Conference object
Language: English
Access URL: https://univ-tours.hal.science/hal-04794693v1
Accession Number: edsair.dedup.wf.002..98d43fe9b54ce2981901b4da6e500fd8
Database: OpenAIRE
Description
Abstract:Barium titanate-based lead-free ferroelectrics are promising materials for a wide range of applications, such as energy storage devices, tuneable microwave capacitors or electro-mechanical transducers. In this work, we investigate the relaxor ferroelectric properties of (1-x)Ba0.7Ca0.3TiO3 – xBaZr0.2Ti0.8O3 (BCT-BZT) thin films grown by pulsed laser deposition. As the functional properties of these materials are extremely sensitive to the cationic composition, we use a high throughput combinatorial chemistry approach to fabricate composition gradient films. We focus on compositions with x=0.5 known to provide high piezoelectric coefficients (~ 490 pC/N) and soft ferroelectric behaviours with Curie temperatures near 100°C in ceramics, making them promising as an alternative to PZT. In particular, we show that Ce doping (from 0% to 0.2%) modifies the lattice parameter, reduces the remnant polarisation, and shifts the maximum permittivity temperature (Tmax) value. For compositions with Tmax close to room temperature, we measure an enhanced room-temperature d33 piezoelectric coefficient. We then use dielectric spectroscopy coupled with the Rayleigh analysis to identify the contribution of domain wall motion to the ferroelectric response of the films, as a function of temperature. We observe residual ferroelectricity above Tmax, similar to what has been observed for (Ba,Sr)TiO3. In addition, measurement of the third harmonic dielectric response reveals the evolution from a conventional ferroelectric character to a relaxor one with increasing temperature. A peculiar phase angle of the third harmonic, which consists of −180◦ → −225◦ → +45◦ → 0◦, instead of the −180◦ → −90◦ → 0◦ found for relaxors, is also observed in several samples and tentatively attributed to changes in the correlations between polar nanoregions.