26 documents found, page 1 of 3
Composition-dependent xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 bulk ceramics for...
Jayakrishnan, A. R.; Alex, Kevin V.; Thomas, Athul; Silva, J. P. B.; Kamakshi, K.; Dabra, Navneet; Sekhar, K. C.; Agostinho Moreira, J.; Gomes, M. J. M.This work reports the composition dependent microstructure, dielectric, ferroelectric and energy storage properties, and the phase transitions sequence of lead free xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 [xBZT-(1-x)BCT] ceramics, with x = 0.4, 0.5 and 0.6, prepared by solid state reaction method. The XRD and Raman scattering results confirm the coexistence of rhombohedral and tetragonal phases at room temperat...
Strain-engineered tetragonal phase and ferroelectricity in GdMnO3 thin films gr...
Machado, P; Figueiras, F. G.; Vilarinho, R.; Fernandes, J. R. A.; Tavares, P. B.; Soares, M. Rosário; Cardoso, S.; Silva, J. P. B.; Almeida, A.A previously unreported tetragonal phase has been discovered in a epitaxially strained GdMnO3 thin films deposited on (001)-oriented SrTiO3 substrates by radio frequency (RF) magnetron sputtering. The tetragonal axis of the films grown up to a 35 nm thickness is perpendicular to the film surface and the basal lattice parameters are imposed by the cubic structure of the substrate. Furthermore, the emergence of a...
Enhancing the dielectric relaxor behavior and energy storage properties of 0.6B...
Jayakrishnan, A. R.; Alex, Kevin V.; Kamakshi, K.; Silva, J. P. B.; Sekhar, K. C.; Gomes, M. J. M.Recently, relaxor ferroelectric materials have been attracting considerable attention as energy storage capacitors due to their potential applications in pulsed power systems. In this work, lead-free (1−x)[0.6Ba(Zr0.2Ti0.8)O3–0.4(Ba0.7Ca0.3)TiO3]–xSrTiO3 [(1−x)BZCT–xSTO] relaxor ceramics have been synthesized and their relaxor behavior is modulated via STO doping content. The incorporation of STO weakens the fe...
Narrow optical gap ferroelectric Bi2ZnTiO6 thin films deposited by RF sputtering
Figueiras, Fábio G.; Fernandes, J. Ramiro A.; Silva, J. P. B.; Alikin, Denis O.; Queirós, Eugénia C.; Bernardo, César Rui Freitas; Barcelay, Y. R.This work reports the deposition of single phase Bi2ZnTiO6 thin films onto Pt/Si-based substrates using the RF-sputtering method and the respective structural, morphological, optical and local ferroelectric characterization. The thin film grows in the polycrystalline form with tetragonal P4mm symmetry identified by X-ray diffraction. The lack of a spatial inversion centre was confirmed by the second harmonic ge...
Substrate temperature effect on microstructure, optical and glucose sensing cha...
Kamakshi, Koppole; Silva, J. P. B.; Sekhar, K. C.; Moreira, J. Agostinho; Almeida, A.; Pereira, Mário; Gomes, M. J. M.This work reports the substrate temperatureinfluenced change in the structural, morphological, optical, and glucose sensing properties of silver (Ag) nanoparticles (NPs) deposited on p-type Si (100) wafers. AgNP films grown at temperatures ranging from RT to 600 °C clearly show a dependence of orientation texture and surface morphology on substrate temperature (Ts). As Ts increases from RT towards 600 °C, the p...
Ferroelectric switching dynamics in 0.5Ba(Zr0.2Ti0.8)O-3-0.5( Ba0.7Ca0.3)TiO3 t...
Silva, J. P. B.; Kamakshi, K.; Negrea, R. F.; Ghica, C.; Wang, J.; Koster, G.; Rijnders, G.; Figueiras, F.; Pereira, Mário; Gomes, M. J. M.In this work, the ferroelectric characteristics of 0.5Ba(Zr0.2Ti0.8)O-3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) thin films grown on 0.7 wt. % Nb-doped (001)-SrTiO3 (Nb:STO) single-crystal have been investigated. High-resolution transmission electron microscopy and electron energy loss spectroscopy revealed a very sharp Nb:STO/BCZT interface, while selected area electron diffraction revealed the epitaxial growth of the BCZT ...
Ferroelectric photovoltaic characteristics of pulsed laser deposited 0.5Ba (Zr0...
Silva, J. P. B.; Sekhar, K. C.; Cortés-Juan, F.; Negrea, R. F.; Kuncser, A. C.; Connolly, J. P.; Ghica, C.; Moreira, J. AgostinhoIn this work, we investigate the photovoltaic response of Pt/0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3(0.5BZT-0.5BCT)/ITO structures through the insertion of a semiconductor ZnO layer at different positions. The values of short-circuit photocurrent density (Jsc) of the Pt/ZnO/0.5BZT-0.5BCT/ITO, Pt/0.5BZT-0.5BCT/ZnO/ITO and Pt/ZnO/0.5BZT-0.5BCT/ZnO/ITO capacitors are around 5.31, 0.0034 and 0.052 mA/cm2, respectiv...
Light controlled resistive switching and photovoltaic effects in ferroelectric ...
Silva, J. P. B.; Kamakshi, Koppole; Sekhar, K. C.; Nóvoa, X. R.; Queirós, E. C.; Moreira, J. Agostinho; Almeida, A.; Pereira, Mário; Tavares, P. B.In this work, the structural and ferroelectric properties of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (0.5BZT-0.5BCT) thin films deposited at different pulse repetition rates were studied. The films deposited at pulse repetition rate of 1 Hz display the optimum values of ferroelectric polarization and dielectric permittivity and are chosen for the investigation of resistive switching and photovoltaic studies. Th...
Enhanced resistive switching characteristics in Pt/BaTiO3/ITO structures throug...
Silva, J. P. B.; Faita, F. L.; Kamakshi, Koppole; Sekhar, K. C.; Moreira, J. Agostinho; Almeida, A.; Pereira, Mário; Pasa, A. A.; Gomes, M. J. M.An enhanced resistive switching (RS) effect is observed in Pt/BaTiO3(BTO)/ITO ferroelectric structures when a thin HfO2:Al2O3 (HAO) dielectric layer is inserted between Pt and BTO. The P-E hysteresis loops reveal the ferroelectric nature of both Pt/BTO/ITO and Pt/HAO/BTO/ITO structures. The relation between the RS and the polarization reversal is investigated at various temperatures in the Pt/HAO/ BTO/ITO struc...
Unraveling the resistive switching effect in ZnO/0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7C...
Silva, J. P. B.; Vorokhta, M.; Dvořák, F.; Sekhar, K. C.; Matolín, V.; Moreira, J. Agostinho; Pereira, Mário; Gomes, M. J. M.This work reports the effect of partial oxygen pressure, used in the deposition of the ZnO layer, on the band alignment at ZnO − 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (0.5BZT-0.5BCT) interface and on the resistive switching (RS) behavior of pulsed laser deposited ZnO/0.5BZT-0.5BCT heterostructures. X-ray photoelectron spectroscopy (XPS) has been employed to measure the valence band offset and the conduction b...