Search results for "ELECTRICITY"
showing 10 items of 1225 documents
Parameters of microdischarges occuring at surfaces of repolarized ferroelectrical materials
1993
Parameters of the microdischarges occuring at the surfaces of the repolarized ferroelectric materials have been investigated. It has been found that in the case of BaTiO3ceramic the number of microdischarges increases linearly with increasing repolarizing voltage Upp, the photoelectric parameters of individual discharges being unchanged. The photoelectric and current parameters for system with TGS are very similar but the dependence of the amplitude of the current pulses on the repolarizing voltage differs distinctly from that for BaTiO3.
Dielectric Dispersion and Ion Conductivity in High-Pressure LixNaw1-xNbO3Solid Solutions
2009
Thermal behaviour and dispersion of dielectric permeability and thermal behaviour of conductivity measured in ferroelectric ceramic solid solutions of Li x Na 1−x NbO 3 (x = 0.17, 0.25) synthesized at high pressure and possessing extended region of homogeneity are reported. The Li x Na 1−x NbO 3 (x = 0.17, 0.25) solid solutions of perovskite structure are found to be super-ionic conductors at rather low temperatures O ≥ 400 K. Dielectric dispersion and anomalous behaviour of dielectric permeability are observed in the thermal range of super-ionic conductivity corresponding to structural transformations in the high-pressure solid solutions.
Electrical Transport in Lead-Free [(1−x)(Na0.5Bi0.5)-xBa]Zr1 - yTiyO3Ceramics (x = 0, 0.06, and y = 0, 0.96)
2009
Lead-free ceramics based on (Na 0.5 Bi 0.5 TiO 3 , NBT)-(Ba(Ti,Zr)O 3 , BTZ) were prepared by solid phase hot pressing sintering process and their ac (σ ac ) and dc (σ dc ) conductivity have been studied (303–753 K). Low frequency (100 Hz–100 kHz) ac conductivity obeys power law σ ac ∼ ω s characteristic for disordered materials. The frequency exponent s is a decreasing function of temperature and tends to zero at high temperatures. Dc conductivity has thermally activated character and possesses four linear parts with four different activation energies and some discontinous changes. However, σ ac (T) possesses two linear parts with two different activation energies and more discontinuous ch…
Dielectric and Ferroelectric Properties of Lead-Free NKN and NKN-Based Ceramics
2011
Lead-free ceramics of Na0.5K0.5NbO3 (NKN), Na0.5K0.5(Nb0.94Sb0.06)O3 (NKNS6) and Na0.5K0.5(Nb0.94Sb0.06)O3 + 0.5%MnO2 (NKNS6 + 0.5%MnO2) have been prepared by a solid phase hot pressing sintering process. X-ray diffraction results show that the obtained samples possess the perovskite structure. The micrograph of the fractured surface showed a dense structure in a good agreement with that of 91–94% relative density determined by the Archimedes method. An average grain size decreases with Sb and Mn doping (from about 20 μm for NKN to about 5 and 2 μm for NKNS6 and NKNS6 + 0.5%MnO2, respectively). Low frequency (100 Hz–200 kHz) investigations revealed the diffuse phase transitions. It was foun…
Processing and properties of nanocrystalline Pb(Sc0.5Ta0.5)O3, Pb(Sc0.5Nb0.5)O3, Pb(Mg1/3Nb2/3)O3and Pb0.76Ca0.24TiO3films and ferroelectric/ relaxor…
2001
Abstract Thin films of relaxor materials, namely Pb(Sc0.5Ta0.5)O3 (PST), Pb(Sc0.5Nb0.5)O3 (PSN) and Pb(Mg1/3Nb2/3)O3 (PMN), and of Pb0.76Ca0.24TiO3 (PTC), which is a classical ferroelectric as bulk material, have been produced to examine whether nanocrystalline relaxor materials show influences in their properties if their grain size is reduced to dimensions known from their nanodomains and to investigate effects in a superlattice of nanocrystalline ferroelectric and relaxor films. At first amorphous films of the different materials were deposited onto a Ti/Pt coated Silicon (100) wafer by reactive rf-sputtering. Different grain sizes could be prepared by a controlled annealing process. The…
Dielectric properties of reactor irradiated ferroelectric thin films
2001
Abstract Radiation effects in highly oriented Pb1Zr0.53Ti0.47O3 (PZT), Pb0.94La0.06Zr0.65Ti0.35O3 (PLZT-6), and PbiZriO3 (PZ) ferroelectric (FE) and antiferroelectric (AF) thin films are investigated in view of their possible application as a temperature sensitive element in a new bolometer system for ITER (International Thermonuclear Experimental Reactor). The dielectric properties (i.e. hysteresis loops, dielectric constants) of the films were investigated in a frequency range from 20 to 105 Hz and at temperatures up to 450 °C, before and after neutron irradiation to a neutron fluence of 5×1021 m−2 (E<0.1 MeV). The dielectric constant was measured during cooling with 1.7 °Cmin−1. The diel…
The Effect of Grain Size of the Stock on Electrical Characteristics of the Li0.03Na0.97Ta0.05Nb0.95O3Perovskite Ceramics
2012
The microstructure and electrical properties of two samples of the ferroelectric Li0.03Na0.97Ta0.05Nb0.95O3 ceramic solid solution prepared from initial charge stocks of different dispersity by conventional ceramics technology are compared. The average size of grains and concentration of pores in the samples are found to be of little difference while the electrical properties of the ceramics are strongly affected by the grain size of the initial mixture. The difference in properties is due to conditions at the diffusion stage of the solid-phase synthesis caused by differences in composition of larger grains rather than the grain size itself.
Complete band gap in a pillar-based piezoelectric phononic crystal slab
2016
In this paper we have shown that it is possible to obtain the complete phononic band gaps in a square lattice of pillar-based phononic crystal. Bigger phononic band gap width can be obtained by increasing the height of pillar and it filling fraction, f. It is shown that the gap-to-mid-gap ratio of pillar at h/a = 0.5 has increased by 21.2% when it height increased to 1.25 and the gap-to-mid-gap ratio has increased by 12% when the filling fraction is increased from r/a = 0.3 to 0.45. The study also shows bigger band gap width and higher central frequency can be obtained by increasing the filling fraction of pillar.
Behavior Modification of Nanostructured PbO2 Electrodes in Lead Acid Batteries Changing Electrolyte Concentration and Separator
2019
Currently, lead acid battery is extensively investigated owing to its prevalent use as a startinglighting and ignition device. An essential role for electrochemical reactions is played by the surface area available for conversion reactions and a possible approach is the use of nanostructured electrodes. In this work, lead dioxide nanostructured electrodes were tested in order to investigate the dependence of the charge and discharge behaviour on some parameters such as electrolyte concentration, and a new type of thin separator. In this last case, it is possible to reduce the size of the cell by using a very thin separator comparable to the nanostructured electrode thickness. Besides, a low…