scholarly journals Crystallization and Dielectric Properties of BaO-SrO-PbO-TiO2-Nb2O5-SiO2 Glass-Ceramic Composites with La2O3 Addition

2021 ◽  
Vol 2085 (1) ◽  
pp. 012036
Author(s):  
Qingmeng Zhang ◽  
Junyou Chen ◽  
Min Zhou ◽  
Yanyun Zhao
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Glass Ceramic ◽  
Glass Sample ◽  
Tungsten Bronze ◽  
Ceramic Composites ◽  
Ceramic System ◽  
Ceramic Phase ◽  
Addition Amount

Abstract Glass-ceramic composite samples with different La2O3 content were prepared via melt-quenching followed by controlled crystallization. X-ray diffraction(XRD) analysis reveals that when the addition amount of La2O3 in the glass sample is less than 1mol%, two phases of perovskite structure and tungsten-bronze structure are formed after annealing at 1000°C for 3h. When the addition amount of La2O3 in the glass sample is increased to 2mol%, a new phase of pyrochlore structure is formed. Moreover, the addition of La2O3 causes the change in the lattice parameters of the glass-ceramic crystal phase. The microstructure observed that the ceramic phase grain size is in the nanometer level. The shape of some grains becomes an elongated structure when the La2O3 content in the sample increases to 2 mol%, and the grain size is increased significantly. The dielectric constant of the BaO-SrO-PbO-TiO2-Nb2O5-SiO2 glass-ceramic system is decreased with the increase of La2O3 addition, and the dielectric loss of the sample is decreased to the range of 0.003-0.008. The electric field stability of the dielectric constant was significantly improved with the addition of La2O3, indicating that adding a certain proportion of La2O3 to the BaO-SrO-PbO-TiO2-Nb2O5-SiO2 glass-ceramic system can effectively improve the dielectric properties, and it has a promising application as a dielectric material.

scholarly journals Formation and Properties of the Ta-Y2O3, Ta-ZrO2, and Ta-TaC Nanocomposites

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
J. Jakubowicz ◽  
M. Sopata ◽  
G. Adamek ◽  
P. Siwak ◽  
T. Kachlicki
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Ceramic Composites ◽  
Ceramic Phase ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Bulk Nanocrystalline

The nanocrystalline tantalum-ceramic composites were made using mechanical alloying followed by pulse plasma sintering (PPS). The tantalum acts as a matrix, to which the ceramic reinforced phase in the concentration of 5, 10, 20, and 40 wt.% was introduced. Oxides (Y2O3 and ZrO2) and carbides (TaC) were used as the ceramic phase. The mechanical alloying results in the formation of nanocrystalline grains. The subsequent hot pressing in the mode of PPS results in the consolidation of powders and formation of bulk nanocomposites. All the bulk composites have the average grain size from 40 nm to 100 nm, whereas, for comparison, the bulk nanocrystalline pure tantalum has the average grain size of approximately 170 nm. The ceramic phase refines the grain size in the Ta nanocomposites. The mechanical properties were studied using the nanoindentation tests. The nanocomposites exhibit uniform load-displacement curves indicating good integrity and homogeneity of the samples. Out of the investigated components, the Ta-10 wt.% TaC one has the highest hardness and a very high Young’s modulus (1398 HV and 336 GPa, resp.). For the Ta-oxide composites, Ta-20 wt.% Y2O3 has the highest mechanical properties (1165 HV hardness and 231 GPa Young’s modulus).

Grain Size Dependence of the Microstructure and Dielectric Properties of Potassium Niobate-Barium Titanate Ceramics

2013 ◽  
Vol 566 ◽  
pp. 34-37
Author(s):  
Kenta Yamashita ◽  
Ichiro Fujii ◽  
Kouichi Nakashima ◽  
Nobuhiro Kumada ◽  
Yoshihiro Kuroiwa ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Barium Titanate ◽  
Size Dependence ◽  
Potassium Niobate ◽  
Titanate Ceramics

In this study, 0.8 KNbO3(KN) -0.2 BaTiO3(BT) ceramics were prepared using KN powder with the diameter of 100 nm and BT powders with the diameter of 100, 300, or 500 nm. The relative densities were more than 96 % of the theoretical densities of the samples. The dielectric constant of the samples was temperature-stable at temperatures between-50 and 300 °C and it was found that the dielectric constant of the 0.8KN-0.2BT ceramics increased as the BT diameter increased.

scholarly journals The investigation of electrical properties and microstructure of ZnO-doped Ba0.9Sr0.1TiO3 ceramics

2017 ◽  
Vol 07 (01) ◽  
pp. 1750007 ◽  
Author(s):  
Gang Liu ◽  
Wentao Jiang ◽  
Jingyong Jiao ◽  
Li Liu ◽  
Ziyang Wang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Solid State ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Electrical Breakdown Strength

Ba[Formula: see text]Sr[Formula: see text]TiO3 ceramics with or without ZnO have been prepared by traditional solid state reaction method. The XRD analysis showed that the doped Zn[Formula: see text] ions diffused into the BST crystal lattice, resulting in the variation of dielectric properties. Especially the dielectric constant at Curie point decreased with doping ZnO content when it is lower than 0.5[Formula: see text]mol%. Due to the promotion of sintering, doping ZnO can enhance the density of ceramics but increase grain size. However, ZnO is a kind of semiconductor and can lead to the decrease in electrical breakdown strength value.

scholarly journals Effect of Milling Time on Microstructure, Crystallite Size and Dielectric Properties of Srtio3 Ceramic Synthesized via Mechanical Alloying Method

2011 ◽  
Vol 364 ◽  
pp. 388-392
Author(s):  
Yick Jeng Wong ◽  
Hassan Jumiah ◽  
Mansor Hashim ◽  
Swee Yin Wong ◽  
Leow Chun Yan
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Mechanical Alloying ◽  
Crystallite Size ◽  
Single Phase ◽  
Milling Time ◽  
Average Grain Size ◽  
Average Lattice ◽  
Milled Powders

SrTiO3 sample has been successfully prepared by mechanical alloying (MA) method. The effect of milling time on microstructure, crystallite size and dielectric properties of SrTiO3 were studied. The results revealed that the mean crystallite size of milled powders decreased from 84.56 to 12.87 nm with increasing milling time. However, the average lattice strain of milled powders increased from 0.2 to 0.93% with increasing milling time. A single phase SrTiO3 could not be formed with milling alone and required annealing process. A transformation of anatase-TiO2 to rutile-TiO2 was observed at 16 h of milling. After the milled powders were subjected to sintering process at 1200°C, formation of single-phase SrTiO3-type cubic (Pm-3m) perovskite structure was observed. The peak intensities of the sintered SrTiO3 samples decreased as the milling time was increased. For microstructural observations, the average grain size of the sintered SrTiO3 sample milled for 8 h showed the largest. For dielectric measurements, the dielectric constant of the sintered SrTiO3 sample milled for 8 h showed the highest among others. This could be due to the largest grain size obtained for sintered SrTiO3 sample milled for 8 h. The decrease in the grain size with increasing milling time resulted to the decrease in dielectric constant.

Effect of Sr/Ba Ratio on Dielectric Properties of BSTN Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 125-128 ◽  
Author(s):  
Zong Hui Zhou ◽  
Xin Cheng ◽  
Pi Yi Du ◽  
Jun Chang ◽  
Shi Feng Huang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Phase Composition ◽  
Dielectric Properties ◽  
Perovskite Phase ◽  
Tungsten Bronze ◽  
Dielectric Constants ◽  
Composite Ceramics ◽  
Impedance Analyzer ◽  
Applied Frequency ◽  
Two Phases

The phase composition of (1-x)BaO·xSrO·0.7TiO2·0.3Nb2O5 (BSTN) composite ceramics was analyzed by XRD, and the effect of Sr/Ba ratio on the dielectric properties of BSTN was investigated by impedance analyzer. The results showed that any sample with different x value contained two phases-the perovskite phase and the tungsten bronze phase. The dielectric constants of BSTN basically decreased while the tanδ increased with the increase in x value. Both dielectric constant and tanδ decreased with the applied frequency increased for the same x value. There were two Curie points for BSTN composite ceramics. The first one belonging to the perovskite phase decreased with the increase in x value, but the second one belonging to the tungsten bronze phase kept almost constant at about 300°C.

Effect of grain size and mechanical processing on the dielectric properties of BaTiO3

1995 ◽  
Vol 10 (6) ◽  
pp. 1418-1423 ◽  
Author(s):  
B.W. Lee ◽  
K.H. Auh
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Domain Switching ◽  
External Pressure ◽  
Coarse Grained ◽  
One Dimensional ◽  
Fine Grained ◽  
Average Grain Size ◽  
Coarse Grained Material

Dielectric properties of polycrystalline BaTiO3 ceramics having grain sizes of 1 to 40 μm have been studied. Fine-grained ceramic BaTiO3 of 1 μm average grain size has 90°domains and has shown higher dielectric constant, lower ferroelectric transition temperature (Tc), and lower transition energy than coarser-grained material. 90°domain switching was preferentially produced in the fine-grained BaTiO3 as a result of abrasion. For the fine-grained BaTiO3, the dielectric constant decreased with one-dimensional pressure, whereas, for the coarse-grained material, the dielectric constant increased before decreasing with the pressure. The one-dimensional pressure resulted in increased Tc of both the fine- and coarse-grained BaTiO3, with the effect being the greatest for the coarse-grained material. The relationship between these results and internal stress, and the effect of external pressure imposed on internally stressed lattice, were discussed.

Sign in / Sign up

Export Citation Format

Share Document