Abnormal capacitance–voltage behaviors of bismuth-doped CaCu3Ti4O12 ceramics

2017 ◽  
Vol 31 (20) ◽  
pp. 1750133 ◽  
Author(s):  
Ling Fang Xu ◽  
Kang Sun ◽  
Xing Feng ◽  
Hai Bo Xiao ◽  
Rui Long Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Negative Curvature ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Electric Modulus ◽  
Capacitance Voltage ◽  
Solid State Sintering ◽  
Sintering Method ◽  
Bismuth Doping ◽  
Special Frequencies

Ca[Formula: see text]Bi[Formula: see text]Cu3Ti4O[Formula: see text] ([Formula: see text] = 0.0, 0.1, 0.2 and 0.3; BCCTO) ceramics were prepared by traditional solid-state sintering method. All samples had pure cubic perovskite-like structure. A drastic grain size reduction was observed with bismuth doping. Dielectric spectra showed two obvious relaxation steps corresponding to two series of peaks in the imaginary part of electric modulus spectra and dielectric loss spectra too. Activation energy fitting by electric modulus spectra reflected different conducting segments in BCCTO ceramics of grains and oxygen vacancies below room temperature. Normalized capacitance dependent of extra bias showed different voltage–capacitance coefficients at special frequencies that suggested multirelaxation mechanisms related with grain and oxygen vacancy. A positive capacitance curvature implies dipolar relaxations in CCTO grains. Whereas a negative curvature suggests oxygen-related relaxations at the interface.

PHASE STRUCTURE, PIEZOELECTRIC AND MULTIFERRIOC BEHAVIOR OF (K0.48Na0.52)NbO3-Co2O3 PIEZOELECTRIC CERAMICS

2011 ◽  
Vol 04 (03) ◽  
pp. 225-229 ◽  
Author(s):  
WENJUAN WU ◽  
DINGQUAN XIAO ◽  
JIAGANG WU ◽  
JING LI ◽  
JIANGUO ZHU
Keyword(s):  
Room Temperature ◽  
Sintering Temperature ◽  
Magnetic Behavior ◽  
Orthorhombic Phase ◽  
Piezoelectric Ceramics ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Solid State Sintering ◽  
Sintering Method

( K 0.48 Na 0.52) NbO 3-x% Co 2 O 3 (x = 0, 0.03 and 0.05) (KNN-x% Co2O3 ) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. An orthorhombic phase was observed for all KNN-x% Co2O3 ceramics at room temperature, and two phase transitions were confirmed by the high temperature X-ray diffraction and the temperature dependence of the dielectric constant. The Co2O3 greatly improves the density and decreases the sintering temperature of KNN ceramics. The KNN-0.05 mol%Co2O3 ceramic exhibits good properties (d33 = 120 pC/N , k p = 0.41, Q m = 213 and T c = 407°C) and a good age stability. The multiferroic behavior was also observed at room temperature for the KNN-0.05 mol%Co2O3 ceramic, as confirmed by P–E loops and magnetic behavior.

Structure and Piezoelectric Properties of (1-X)K0.49Na0.51NbO3-XLiTaO3 Lead-Free Piezoceramics

2010 ◽  
Vol 663-665 ◽  
pp. 1310-1313 ◽  
Author(s):  
Yue Ming Li ◽  
Liang Jiang ◽  
Zhong Yang Shen ◽  
Run Hua Liao ◽  
Zhu Mei Wang
Keyword(s):  
Phase Transition ◽  
Room Temperature ◽  
Electromechanical Coupling ◽  
Piezoelectric Properties ◽  
Lead Free ◽  
Electromechanical Coupling Coefficient ◽  
Orthorhombic Symmetry ◽  
Coexistence Region ◽  
Solid State Sintering ◽  
Sintering Method

Lead-free (1-x)K0.49Na0.51NbO3-xLiTaO3 (x=0.00-0.07) piezoceramics were fabricated by the conventional solid-state sintering method, the effects of LiTaO3 content on the phase structure and piezoelectric properties of the ceramics were investigated. All the ceramics show single perovskite structure with a phase transition from an orthorhombic symmetry to a tetragonal one across an orthorhombic-tetragonal coexistence region with 0.04<x<0.06. For the ceramic sample with x=0.05, due to the coexistence of orthorhombic and tetragonal phases near room temperature, enhanced piezoelectric constant d33=236 pC/N and planar electromechanical coupling coefficient kp=40.9% are observed. In addition to other good electrical properties such as εr=969, tgδ=0.015 and Qm=41, this ceramic is a promising lead-free piezoelectric material.

Properties of Barium Stannate Titanate with Boron Oxide Addition

2009 ◽  
Vol 421-422 ◽  
pp. 239-242
Author(s):  
Nattaya Tawichai ◽  
Sukum Eitssayeam ◽  
Uraiwan Intatha ◽  
Kamonpan Pengpat ◽  
Gobwute Rujijanagul
Keyword(s):  
Boron Oxide ◽  
Room Temperature ◽  
Oxide Content ◽  
Sintering Aid ◽  
Oxide Addition ◽  
Barium Stannate ◽  
Multilayer Capacitor ◽  
Solid State Sintering ◽  
Titanate Ceramics ◽  
Sintering Method

In this study, barium stannate titanate ceramics with an addition of boron oxide were synthesized via a solid-state sintering method. The effect of sintering aid on electrical and mechanical properties of barium stannate titanate ceramics was investigated. It was found that, the ceramic with 2 wt% boron oxide showed the lowest porosity and the highest dielectric constant of ~ 13700 at room temperature. In addition, an increase in the boron oxide content was observed to enhance the hardness of the ceramics. These results may be helpful in the multilayer capacitor applications.

Pores Formation Mechanism of Undoped TiO2 Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1690-1695
Author(s):  
Jun Yuan ◽  
Ji Kang Yan ◽  
Guo You Gan ◽  
Jing Hong Du ◽  
Jian Hong Yi
Keyword(s):  
Grain Boundaries ◽  
Formation Mechanism ◽  
Oxygen Vacancies ◽  
Sintering Temperature ◽  
Materials Testing ◽  
Testing Methods ◽  
Ionic Valence ◽  
Solid State Sintering ◽  
Structure Measurement ◽  
Sintering Method

Formation mechanism of pores in undoped TiO2 ceramics was investigated through defects chemistry and materials testing methods. The undoped TiO2 ceramics samples were prepared from anatase TiO2 powders by a traditional solid-state sintering method. Microstructure, chemistry composition and ionic valence of undoped TiO2 ceramics were by SEM, EDS and XPS. Formation mechanism of pores was discussed by combination defect chemistry with materials structure measurement. The results show that there exist trivalence Titanium ion (Ti 3+) and grain boundaries absorbed oxygen in undoped TiO2 ceramics samples. Both content of absorbed oxygen in grain boundaries and Ti 3+ concentration increase with sintering temperature increasing. There are much gas pores in grains and grain boundarties of undoped TiO2 ceramics samples. The gas pores are mainly originated from lattice oxygen volatilization and oxygen vacancies segregation during high-temperature sintering.

scholarly journals Investigate The Sintering Behavior of IZO Ceramic Targets Prepared By Pressure Slip Casting

2021 ◽  
Author(s):  
Chaofei Liu ◽  
Xueyun Zeng ◽  
Xiaokai Liu ◽  
Benshuang Sun ◽  
Zhongheng Zuo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Oxygen Vacancies ◽  
Slip Casting ◽  
Casting Process ◽  
Sintering Behavior ◽  
Densification Process ◽  
Growth Activation ◽  
Ceramic Targets ◽  
Sintering Method

Abstract The density and phase structure uniformity of the IZO ceramic target would have an effect on the optoelectronic properties of the sputtered film. In this work, a uniformly dispersed IZO slurry was used to obtain high-density green IZO compacts by the slip casting process. Based on the grain size and shrinkage data of IZO ceramics, the densification process was investigated, while the apparent activation energy and growth activation energy were also calculated. The results of XPS showed that sintering in an oxygen atmosphere can increase the concentration of oxygen vacancies of IZO ceramic to improve its electrical properties. Finally, IZO ceramics with a grain size of 3-6 μm and resistivity of 1.5 mΩ·cm were obtained by a two-step sintering method.

Laser Engineering of Barrier Structures Based on Solid Solution ZnCdHgTe.

2002 ◽  
Vol 719 ◽  
Author(s):  
Galina Khlyap
Keyword(s):  
Room Temperature ◽  
Film Surface ◽  
Charge Carriers ◽  
Barrier Structure ◽  
Free Charge ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Laser Engineering ◽  
Charged Defects ◽  
Epilayer Surface

AbstractRoom-temperature electric investigations carried out in CO2-laser irradiated ZnCdHgTe epifilms revealed current-voltage and capacitance-voltage dependencies typical for the metal-semiconductor barrier structure. The epilayer surface studies had demonstrated that the cell-like relief has replaced the initial tessellated structure observed on the as-grown samples. The detailed numerical analysis of the experimental measurements and morphological investigations of the film surface showed that the boundaries of the cells formed under the laser irradiation are appeared as the regions of accumulation of derived charged defects of different type of conductivity supplying free charge carriers under the applied electric field.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

scholarly journals Thermal, Viscoelastic, Mechanical and Wear Behaviour of Nanoparticle Filled Polytetrafluoroethylene: A Comparison

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1940 ◽  
Author(s):  
Levente Ferenc Tóth ◽  
Patrick De Baets ◽  
Gábor Szebényi
Keyword(s):  
Room Temperature ◽  
Filler Content ◽  
Research Work ◽  
Tensile Modulus ◽  
Al2o3 Content ◽  
Wear Behaviour ◽  
X Ray ◽  
Mechanical Stirring ◽  
Wear Analysis ◽  
Sintering Method

In this research work, unfilled and mono-filled polytetrafluoroethylene (PTFE) materials were developed and characterised by physical, thermal, viscoelastic, mechanical, and wear analysis. The applied fillers were graphene, alumina (Al2O3), boehmite alumina (BA80), and hydrotalcite (MG70) in 0.25/1/4/8 and 16 wt % filler content. All samples were produced by room temperature pressing–free sintering method. All of the fillers were blended with PTFE by intensive dry mechanical stirring; the efficiency of the blending was analysed by Energy-dispersive X-ray spectroscopy (EDS) method. Compared to neat PTFE, graphene in 4/8/16 wt % improved the thermal conductivity by ~29%/~84%/~157%, respectively. All fillers increased the storage, shear and tensile modulus and decreased the ductility. PTFE with 4 wt % Al2O3 content reached the lowest wear rate; the reduction was more than two orders of magnitude compared to the neat PTFE.

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