Search Results

Now showing 1 - 4 of 4

Some of the metrics are blocked by your
consent settings
Microstructures and dielectric relaxation behaviors of pure and tellurium doped CaCu3Ti4O12 ceramics prepared via vibro-milling method
(2013-05-01)
Makcharoen, Worawut
;
Tunkasiri, Tawee
In this work, we have reported microstructures and the dielectric properties of CaCu<inf>3</inf>Ti<inf>4</inf>O<inf>12</inf> (CCTO) ceramics doped with different proportions of TeO<inf>2</inf> dopant (mol%, x=0, 0.5%, 1.0%, 2.0%). The pure and tellurium doping CCTO ceramics were prepared by a conventional solid-state reaction method and the effects of TeO<inf>2</inf> doping on the electrical properties and microstructures of these ceramics were investigated. XRD analysis confirmed the formation of single-phase material in samples. Scanning electron microscopy (SEM) is used in the micro structural studies of the specimens, which showed that TeO<inf>2</inf> doping can reduce the mean grain size and increasing size of an abnormal grain growth. Lattice parameter increases slightly with tellurium doping in CCTO, the dielectric constant reached a value as high as 18,000 (at 1 kHz) at a tellurium-doping concentration of 2.0 mol% and showed temperature stability at high frequency. The loss tangent of Te-doped CCTO ceramics was less than 0.05 at 1 kHz region below 105 °C. The loss tangent properties could be interpreted by the internal barrier layer capacitor model and the impedance measurement data. © 2012 Elsevier Ltd and Techna Group S.r.l.
Some of the metrics are blocked by your
consent settings
Low temperature fabrication of lead-free KNN-LS-BS ceramics via the combustion method
(2013-05-01)
Wattanawikkam, Chakkaphan
;
Vittayakorn, Naratip
;
Bongkarn, Theerachai
Lead-free piezoelectric 0.992(0.95K<inf>0.5</inf>Na<inf>0.5</inf>NbO <inf>3</inf>-0.05LiSbO<inf>3</inf>)-0.008BiScO<inf>3</inf>; KNN-LS-BS ceramics were successfully prepared using the combustion method. The highest % perovskite phase was found in the sample calcined at 700 °C for 1 h. The structural phase of orthorhombic structure was also detected in this sample. For the sintered ceramics, a pure tetragonal perovskite phase was observed in the samples sintered between 1025 and 1100 °C. The microstructure of ceramics showed a square or rectangular shape and the average grain size increased with increasing of sintering temperature. The density of the ceramics increased with increasing of sintered temperature up to 1075 °C, were it reached 97.5% of theoretical density and then dropped in value when the sintered temperature further increased. The excellent electrical properties of ε<inf>r</inf> at T<inf>c</inf>=6600, tanδ at T<inf>c</inf>=0.04, P<inf>r</inf> (at 40 kV/cm)=19.4 μC/cm2 and E<inf>c</inf> (at 40 kV/cm)=24.1 kV/cm were obtained in the most dense ceramic. The results indicate that the KNN-LS-BS ceramics are promising lead-free piezoelectric materials. © 2012 Elsevier Ltd and Techna Group S.r.l.
Some of the metrics are blocked by your
consent settings
Crystal structure, microstructure and electrical properties of (1-x-y)Bi0.5Na0.5TiO3-xBi0.5K 0.5TiO3-yBiFeO3 ceramics near MPB prepared via the combustion technique
(2013-05-01)
Sumang, Rattiphorn
;
Vittayakorn, Naratip
;
Bongkarn, Theerachai
(1-x-y)Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-xBi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf>-yBiFeO<inf>3</inf> (BNKFT-x/y with 0.12≤x≤0.24, 0≤y≤0.07) lead-free piezoelectric ceramics have been prepared by the combustion technique. The effects of amounts of x and y on structures and electrical properties were examined. Powders and ceramics can be well calcined and sintered at 750 °C for 2 h and 1025-1050 °C, respectively. The results indicated that the crystalline structure and microstructure changed with the increase of x and y concentrations. XRD results of BNKFT-x/0.03 and BNKFT-0.18/y ceramics with 0.12≤x≤0.24 and 0≤y≤0.07 showed the rhombohedral-tetragonal morphotropic phase boundary (MPB). The addition of y caused a promoted grain growth while the addition of x suppressed the grain growth. The highest density (ρ=5.85 g/cm3), superior dielectric properties at T<inf>c</inf> (ε<inf>r</inf>=7846 and tan δ=0.02), remnant polarization measured at 40 kV/cm (P<inf>r</inf> = 20.1 μC/cm2) and piezoelectric coefficient (d<inf>33</inf>=213 pC/N) were obtained for x=0.18 and y=0.03. © 2012 Elsevier Ltd and Techna Group S.r.l.
1
Some of the metrics are blocked by your
consent settings
Fabrication and electrical properties of Pb(Co1/3Nb2/3)O3 ceramics
(2009-01-01)
Unruan, M.
;
Vittayakorn, N.
;
Wongmaneerung, R.
;
Prasatkhetragarn, A.
;
Ananta, S.
Pb(Co<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf> (PCN) ceramics have been produced by sintering PCN powders synthesized from lead oxide (PbO) and cobalt niobate (CoNb<inf>2</inf>O<inf>6</inf>) with an effective method developed for minimizing the level of PbO loss during sintering. Attention has been focused on relationships between sintering conditions, phase formation, density, microstructural development, dielectric and ferroelectric properties of the sintered ceramics. From X-ray diffraction analysis, the optimum sintering temperature for the high purity PCN phase was found at approximately 1050 and 1100 °C. The densities of sintered PCN ceramics increased with increasing sintering temperature. However, it is also observed that at very high temperature the density began to decrease. PCN ceramic sintered at 1050 °C has small grain size with variation in grain shape. There is insignificant change of dielectric properties with sintering temperature. The P-E hysteresis loops observed at -70 °C are of slim-loop type with small remanent polarization values, which confirmed relaxor ferroelectric behavior of PCN ceramics. © 2008 Elsevier Ltd and Techna Group S.r.l.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results