Search results for " ceramic"

Phase State and Structure of Ferroelectric Ceramics under Irradiation

1997

Radiation effects in transparent ferroelectric ceramics

1997

Radiation of different types ((gamma) -rays, electrons, neutrons) and fluence has been used to study the defect processes as well as the change of physical parameters in PLZT X/65/35 (X equals 4.5 - 11 at.%) and PbSc 0.5 Nb 0.5 O 3 (PSN) ceramics and to evaluate critical irradiation conditions. Effects on optical (extinction) spectra and dielectric characteristics (polarization, thermal and frequency dependences of dielectric permittivity (epsilon) and losses), dependent on composition and state of phase and polarization have been analyzed by means of annealing in isochronic and prolonged time regimes. A gradual shift of extinction edge to longer wavelengths, reduction of polarization and (…

Dielectric nonlinearity of the PBB′B″O3 ferroelectric solid solutions

2001

Abstract Obtaining of novel thin film materials for electrically tuneable capacities is one of the current problems of ferroelectric material application. Suitable ferroelectric compounds exhibiting broad phase transitions and small dielectric loss in the paraelectric phase have been searched for the purpose. Lead-containing niobates PbMg1/3Nb2/3O3 (PMN), PbNi1/3Nb2/3O3 (PNN) and PbZn1/3Nb2/3O3 (PZN) and their solid solutions have been found as most appropriate. Materials have been synthesized by solid phase reactions from the relevant oxides; ceramic samples were obtained by conventional ceramic technology. Results of the studies of thermal dependence of dielectric permeability and loss fa…

Specifics of polarisation switching in PbNi1/3Nb2/3O3–PbTiO3–PbZrO3 ferroelectric ceramics

2004

Abstract The growing interest in disordered relaxor ferroelectrics is due to unusual properties mainly related to the existence of broad phase transitions characteristic to the systems. The effects of bias field on the dielectric response and polarisation switching are studied in the 0.5 PbNi 1/3 Nb 2/3 O 3 – x PbTiO 3 –(0.5− x ) PbZrO 3 system at different PbTiO 3 :PbZrO 3 ratio. Thermal behaviour of normalised remnant polarisation P r / P max of compositions with content of lead titanate x =0.33 and x =0.35 at frequency 0.1 Hz and different values of field E o are measured. Results of measured polarisation and depolarisation currents are compared with characteristics of polarisation switc…

EoP250. Recent advances in transparent ferroelectric ceramics research and applications

1992

Abstract The studies of field-induced lattice rearrangement and field-induced phase transition (PT), laser beam effects in transparent ferroelectric ceramics (TFC), dopant and radiation effects in PLZT, Kerr effect demonstration and application of an intracavity matrix-addressed spatial-time modulator are discussed.

Phase transitions and upconversion luminescence in oxyfluoride glass ceramics containing Ba4Gd3F17 nanocrystals

2017

This is the peer reviewed version of the following article: G. Krieke, A. Sarakovskis, R. Ignatans, J. Gabrusenoks "Phase transitions and upconversion luminescence in oxyfluoride glass ceramics containing Ba4Gd3F17 nanocrystals", Journal of the European Ceramic Society, 2017, 37 (4), which has been published in final form at https://www.sciencedirect.com/science/article/abs/pii/S0955221916306768 This article may be used for non-commercial purposes in accordance with Elsevier Terms and Conditions for Sharing and Self-Archiving.

Polar nanodomains and local ferroelectric phenomena in relaxor lead lanthanum zirconate titanate ceramics

2005

Transparent Pb0.9125La0.0975(Zr0.65Ti0.35)0.976O3 ceramics (conventionally abbreviated as PLZT 9.75/65/35) is a typical relaxor characterized by the absence of the ferroelectric order at the macroscopic scale. In this letter, we report on the observation of complex polar structures on the surface of this material via piezoresponse force microscopy (PFM). The irregular polarization patterns are associated with the formation of a glassy state, where random electric fields destroy the long-range ferroelectric order. The measure of the disorder, the correlation length of ∼50nm, was directly deduced from the PFM images. Local poling of relaxor ceramics resulted in the formation of a stable micro…

Photoelectric Current and Dielectric Properties of Barium-Strontium Niobate Ceramics under UV and Visible Irradiation

2015

A study of photocurrent kinetics and dielectric response to infra-low frequencies in the range of the broad phase transition in the Ba0.25Sr0.75Nb2O6 (BSN-75) relaxor ceramics under visible and ultraviolet radiation is reported. Anomalies are revealed in the dependence on field intensity of dielectric permittivity and dielectric loss determined from measurements of polarisation loops before and after illumination. The effects of pyro-electric space charge, polarisation and photovoltaic contributions on behaviour of the measured photocurrent are discussed. Results of the kinetics of photocurrent and dielectric response to infra-low frequency studied at different temperatures are discussed as…

An insight into the interaction between functionalized thermoplastic elastomer and layered double hydroxides through rheological investigations

2018

Abstract Nanocomposites based on maleated poly(styrene-(ethylene-co-butylene)-styrene) copolymer (SEBSgMA) and organo-modified layered double hydroxide (OLDH) have been formulated with the aim to investigate the effects of interfacial interactions between the grafted maleic anhydride groups of the copolymer and the OLDH nanolayers on the rheological properties of nanocomposites. The spectroscopic analysis indicates the establishment of specific polymer/nanofiller interactions, whose extent has been highlighted through morphological and rheological investigations. Specifically, oscillatory melt rheology and shear relaxation tests have been considered in order to deeply investigate the interf…

Theory of vibrational anomalies in glasses

2015

Abstract The theory of elasticity with spatially fluctuating elastic constants (heterogeneous-elasticity theory) is reviewed. It is shown that the vibrational anomalies associated with the boson peak can be qualitatively and quantitatively explained in terms of this theory. Two versions of a mean-field theory for solving the stochastic equation of motion are presented: the coherent-potential approximation (CPA) and the self-consistent Born approximation (SCBA). It is shown that the latter is included in the former in the Gaussian and weak-disorder limit. We are able to discuss and explain cases in which the change of the vibrational spectrum by varying an external parameter can be accounted…