Effects of Relative High Density Preparation of Interfacial Coated Pb(Zr0.52Ti0.48)O3 on CaCu3Ti4O12 with Short Sintering Time on its Dielectric Properties

2012 ◽  
Vol 557-559 ◽  
pp. 1838-1843
Author(s):  
Rajabtabar Darvishi Ali ◽  
Wei Li Li ◽  
Sheikhnejad Bishe Ommeaymen ◽  
Li Dong Wang ◽  
Zhe Liu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Grain Boundary ◽  
Relative Density ◽  
Sol Gel ◽  
Composite Particles ◽  
Composite Ceramics ◽  
Practical Applications ◽  
Cold Press ◽  
Sintering Time

Pb(Zr0.52Ti0.48)O3was coated on the surface of CaCu3Ti4O12particles that prepared using sol-gel method. Then the composite particles were sintered into composite ceramics using cold press with the two different pressures and pressing time to achieve sufficient higher relative density after sintering. Afterward, the composite particles were sintered into composite ceramics with various sintering time at the same temperature to reach smaller grain size and higher relative density. The results show that the ceramics are composed of Pb(Zr0.52Ti0.48)O3and CaCu3Ti4O12phases, and Pb(Zr0.52Ti0.48)O3phase is mainly exist at the grain boundary even the composite particles sintered for 2h before pellet making. The results exhibit when density of CaCu3Ti4O12/Pb(Zr0.52Ti0.48)O3composite ceramic is kept in higher level using this simple technology, not only The dissipation loss in these giant-dielectric constant materials was reduced to a considerable level of practical applications but also dielectric constant enhance to very high level in the large frequency range. The results show that the improvement of the dielectric loss and dielectric constant enhancing mainly comes from the increase in the density of the CaCu3Ti4O12/Pb(Zr0.52Ti0.48)O3composite ceramics using suitable pressure in cold press, suitable short sintering time that lead to smaller grain size and sufficient grain boundary.

The Effect of Holding Time on the Mechanical Properties and Microstructure of Sintered NbC Composite

2010 ◽  
Vol 123-125 ◽  
pp. 803-806
Author(s):  
Duck Soo Kang ◽  
Kee Do Woo ◽  
Sang Hyuk Kim ◽  
In Jin Shon ◽  
Ji Young Kim ◽  
...  
Keyword(s):  
Grain Size ◽  
Relative Density ◽  
High Frequency ◽  
Holding Time ◽  
Full Width ◽  
Petch Relation ◽  
Sintering Time ◽  
Rapid Sintering ◽  
Sintering Method ◽  
High Frequency Induction

High frequency induction heated sintering (HFIHS) method is one of the rapid sintering methods. The advantage of rapid sintering method is that grain growth can be prevented during sintering at high temperature. Refinement of grains was known to increase the yield and flow stresses of crystals. The relation between the yield stress and the grain size is known as Hall-Petch relation. NbC-10vol.%Co, Ni and Fe composites were fabricated by HFIHS at 1060°C for 0 and 3 min as holding times under a pressure of 80MPa.The relative density of NbC-10vol.%Co, Ni and Fe composites which were sintered at 1060°C for 0min as holding time under 80MPa were 91.90%, 91.26% and 91.26%, respectively. These composites are difficult to use industrial parts due to low relative density. The longer sintering time was conducted for increasing relative density in this study. Nano-sized specimens, which were calculated grain size by full-width at half maximum (FWHM), can be obtained by HFIHS. The value of hardness and fracture toughness was investigated using 20kgf load Vickers indenter.

Influence of Sintering Temperature on KNN-BF-LS Piezoelectric Ceramic

2016 ◽  
Vol 859 ◽  
pp. 8-12 ◽  
Author(s):  
Guo Yuan Cheng ◽  
Xing Hua Fu ◽  
Wen Hong Tao ◽  
Yu Zhang ◽  
Wen Xin Ma ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Loss ◽  
Piezoelectric Ceramic ◽  
Electromechanical Coupling ◽  
Sintering Temperature ◽  
Sol Gel ◽  
Electromechanical Coupling Coefficient ◽  
Structure And Properties ◽  
Maximum Value

In this paper, (K0.5Na0.53)0.932Nb0.932O3-0.008BF-0.06LS (abbreviated as KNN-BF-LS) piezoelectric ceramic was prepared by sol-gel method. Structure and properties of ceramics were analyzed.Through analysis of the results, when sintering temperature is 1080°C, ceramic has good perovskite structure. At this temperature, grain size is more uniform, and structure is the most dense. Piezoelectric constant d33, electromechanical coupling coefficient Kp, dielectric constant εr reached the maximum value, respectively, 113pC/N, 0.33, 591. Dielectric loss tanδ reached the minimum 0.11.

Synthesizing Nano-Scale Titanium Nitride Powders by Solvothermal and Carbothermal Methods

2007 ◽  
Vol 336-338 ◽  
pp. 2079-2081
Author(s):  
Guo Qiang Tan ◽  
Hui Jun Ren ◽  
Hong Yan Miao ◽  
Min Dong ◽  
Ao Xia
Keyword(s):  
Grain Size ◽  
Titanium Nitride ◽  
Raw Materials ◽  
Sol Gel ◽  
Nitrogen Atmosphere ◽  
Sintering Time ◽  
Mean Grain Size ◽  
Ir Analysis ◽  
Precursor Powders ◽  
Excess Glucose

Xerogel was prepared by the sol-gel method using butyl titanate, alcohol, carbamide and glucose as raw materials. The precursor powders were obtained after xerogel was solvothermally treated at 220oC for 2 h. The IR analysis suggests that the precursor with 10% excess glucose gave an absorption peak at 1084.37cm-1, which was assigned to Ti-OH bond, while no such a peak can be observed for that with 30% excess glucose. The prepared precursor powders were then sintered at 1400oC in nitrogen atmosphere. XRD and SEM results indicated that the sintering time and the contents of glucose had great effects on synthesizing titanium nitride powders. The titanium nitride powders with a high purity and a mean grain size of about 35 nm could be prepared by heating the precursor with 10% excess glucose at 1400oC for 6.5 h.

Preparation of TiB2-TiN and TiN-B Powders and their Processing

2012 ◽  
Vol 527 ◽  
pp. 32-37
Author(s):  
J. Grabis ◽  
Ints Šteins ◽  
Dz. Rašmane
Keyword(s):  
Grain Size ◽  
Relative Density ◽  
Grain Growth ◽  
Spark Plasma Sintering ◽  
Amorphous Boron ◽  
Reactive Sintering ◽  
Plasma Technique ◽  
Sintering Time ◽  
Plasma Sintering ◽  
Spark Plasma

TiN and TiN/TiBSubscript text2 nanoparticles with crystallite size of TiN in the range of 27–38 nm and TiBSubscript text2 in the range of 55–90 nm have been prepared by thermal plasma technique. The prepared nanoparticles and mechanical mixture of TiN with amorphous boron have been densified using spark plasma sintering and the microstructure and density of the samples were compared. The relative density of the samples with content of TiBSubscript text2 about 36 wt.% is in the range of 95.9–97.1% in dependence on the precursors. The higher relative density of the samples provided reactive sintering of TiN/B powder. The grain size of the composites in the range of 0.5–3 µm testified that spark plasma sintering intensified the grain growth in despite of the short sintering time.

Influence of Strontium Concentration on the Microstructure and Electrical Properties of Sol-Gel Derived Barium Strontium Titanate Thin Films

1996 ◽  
Vol 433 ◽  
Author(s):  
M.C. Gust ◽  
L.A. Momoda ◽  
M.L. Mecartney
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Grain Size ◽  
Barium Strontium Titanate ◽  
Sol Gel ◽  
Heat Treating ◽  
Si Substrates ◽  
Barium Strontium ◽  
Average Grain Size ◽  
Alkoxide Precursors

AbstractBaxSrl−xTiO3 thin films with varying Sr concentration were prepared on Pt coated Si substrates using methoxypropoxide based alkoxide precursors. Films were crystallized by heat treating at 700°C for 30 minutes in an oxygen atmosphere after deposition of each layer. Film thickness ranged from 230 to 260 nm. No evidence of tetragonality was observed in any of the compositions. Films with higher Sr concentrations had a larger average grain size, larger grain size distribution, and increased (111) orientation on (111) oriented Pt. The highest dielectric constant of ˜400 was found for Ba 0.5Sr0.5TiO3, although no direct correlation could be made between the composition and dielectric properties.

Method of Improving Dielectric Properties of AlN Ceramic

2012 ◽  
Vol 535-537 ◽  
pp. 844-850
Author(s):  
Hui Na Ma ◽  
Zhi Min Yang ◽  
Jun Du
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Sol Gel ◽  
Weight Fraction ◽  
Composite Ceramics ◽  
Plasma Sintering ◽  
Dielectric Constant And Loss ◽  
Direct Current Magnetron Sputtering ◽  
Spark Plasma ◽  
Mo Content

AlN-Mo composite ceramics were prepared by spark plasma sintering (SPS) with AlN and Mo, introduction of Mo particles into the AlN matrix was through direct current magnetron sputtering, sol-gel and blending technology methods. The effect of Mo particles on densification, electrical conduction and dielectric properties of AlN ceramic was studied by XRD, SEM, dielectric frequency spectrum. The results indicate that dielectric constant of AlN-0.26vol.%Mo composite ceramics obtained by sputtering increase by 22.5% at 1MHz as compared to the pure AlN sample; AlN-18vol.%Mo composite ceramics prepared with Mo powder coated with Al2O3 show insulator character and good dielectric properties; dielectric constant and loss of the composite ceramics increase with increasing the content of the elongated shape Mo particles, the highest dielectric constant and loss will be obtained when AlN-12vol.%Mo content is 30wt.% ( =98.41, tgδ=0.018 at 1MHz), the value of electrical resistivity decreases rapidly from 1.32×104 to 3.16×101Ω•cm when AlN-12vol.%Mo weight fraction increases from 30% to 40%.

Bi Effect on the Microstructure and Dielectric Properties of SrTiO3 Thin Films

2006 ◽  
Vol 514-516 ◽  
pp. 245-249 ◽  
Author(s):  
Olena Okhay ◽  
Vitor M.X. Bergano ◽  
Ai Ying Wu ◽  
Paula M. Vilarinho
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Sol Gel ◽  
Lattice Parameter ◽  
Dielectric Anomaly ◽  
Second Phase ◽  
Si Substrates

Crystalline (Sr1-1.5xBix)TiO3 (SBiT) thin films (0.002 ≤ x ≤ 0.5) were prepared by sol-gel on Pt/TiO2/SiO2/Si substrates. Cubic monophasic SBiT films were obtained for samples with x ≤ 0.167. For films with x ≥ 0.267 a second phase identified as Bi4Ti3O12 was observed. The lattice parameter of SBiT films increases with increasing Bi content, similar to the variation observed in SBiT ceramics. No obviously variation of the grain size with the Bi content was observed. The dielectric constant ε´ at room temperature increases with increasing of Bi concentrations up to x ≤ 0.1. The loss tangent of Bi doped SrTiO3 films is approximately 0.05 and lower than undoped ST films at 10kHz. The higher values of ε´ of Bi doped ST films with x=0.1 and x=0.167 in comparison with undoped films may suppose the appearance of a dielectric anomaly at low temperatures, which will be dependent on the Bi content.

scholarly journals A comparative study on the dielectric and multiferroic properties of Co0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 composite ceramics

2019 ◽  
Vol 13 (4) ◽  
pp. 349-359
Author(s):  
Xiaofeng Qin ◽  
Ruicheng Xu ◽  
Heng Wu ◽  
Gao Rongli ◽  
Zhenhua Wang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Leakage Current ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Secondary Phase ◽  
Molar Ratio ◽  
Intensity Increase ◽  
Composite Ceramics ◽  
Multiferroic Properties

Co0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 (CZFO/BST) composite ceramics with different molar ratios (1:3, 1:2, 1:1, 2:1 and 3:1) were prepared by combining chemical co-precipitation and sol-gel method. Effects of molar ratio on the microstructure, dielectric and multiferroic properties were investigated. The formation of the individual phases and the composites was confirmed by XRD results and small amount of secondary phase (Ba2Fe2Ti4O13) was observed. The grain sizes of magnetic (CZFO) and ferroelectric phase (BST), measured by SEM, were about 5 ?m and 0.5 ?m, respectively. The sample with molar ratio (1:2) has the largest dielectric constant, while the sample with molar ratio (3:1) shows the lowest dielectric constant. A distinct loss peak can be observed for all the samples. Both the peak position and peak intensity increase with the frequency, indicating relaxation polarization process generated by space charge or interface polarization. The ceramics with molar ratio (1:1) shows the smallest leakage current (~ 10?7 A/cm at 1.5 kV/cm), while the leakage current (~ 10?5 A/cm at 1.5 kV/cm) of the sample with molar ratio (3:1) is the largest. The ferroelectric hysteresis loop is not apparent due to the low Curie temperature of the ferroelectric phase, but the sample with molar ratio (2:1) shows the best ferroelectric properties. It was found that with the increase of CZFO content, the values of saturation (Ms) and remnant (Mr) magnetization increase at first and then decrease. The sample with molar ratio (3:1) has the maximum Ms value (about 50.34 emu/g), while the sample with molar ratio (1:2) shows the minimal Mr value (about 0.46 emu/g). This anomalous magnetic property is induced by the interface interaction between the two phases.

Effect of CaO on Barium Zinc Tantalate (BZT) Dielectric Properties

2013 ◽  
Vol 845 ◽  
pp. 446-450
Author(s):  
Hidayani Jaafar
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Relative Density ◽  
Microwave Dielectric Properties ◽  
Microwave Dielectric ◽  
Average Grain Size ◽  
Constant E ◽  
Tan Δ

The effect of CaO on microstructure and dielectric properties of Ba (Zn1/3Ta2/3)O3(BZT) ceramics was investigated. The addition of CaO disturbed the 1:2 ordering to 1:1 ordering structure of BZT ceramic. The average grain size significantly increased with the addition of CaO and formed a more compacted structure. The relative density increased with the addition of a small amount of CaO, but it decreased when the CaO content was increased. The dielectric constant (ɛr) value of the BZT significantly improved with the addition of the CaO for the specimens sintered at 1250°C and it could be explained by the increased of the relative density. However, for the specimens sintered at 1300°C, the dielectric constant value decreased with the addition of CaO which is attributed to the decrease of the relative density. The tan δ of the CaO doped with BZT ceramics is lower than pure BZT ceramics, and decreases as the CaO content increases. Meanwhile, for the percentage of bandwidth (%BW) it is shown that the best result is when it is doped with 0.5 mol% CaO and sintered at 1250°C. The best microwave dielectric properties obtained are ɛr=70.44, tan δ = 0.025 which occur for the 0.5 mol% doped CaO and when sintered at 1250°C/4 h.

scholarly journals Effects of molar ratio on dielectric, ferroelectric and magnetic properties of Ni0.5Zn0.5Fe2O4-BaTiO3 composite ceramics

2020 ◽  
Vol 14 (2) ◽  
pp. 91-101
Author(s):  
Xiaodong Luo ◽  
Hong Wang ◽  
Rongli Gao ◽  
Xinliang Li ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Magnetic Properties ◽  
Sol Gel ◽  
Low Frequency ◽  
Molar Ratio ◽  
Composite Ceramics ◽  
Molar Ratios ◽  
Magnetoelectric Composite ◽  
Relaxation Polarization ◽  
Two Peaks

Ni0.5Zn0.5Fe2O4-BaTiO3 (NZFO-BTO) magnetoelectric composite ceramics with different molar ratios (mNZFO:mBTO = 1:1.5, 1.5:1 and 2:1, defined as N1B1.5, N1.5B1 and N2B1, respectively) were prepared successfully by using a joint hydrothermal method and sol-gel technique and sintering at 1000 ?C. Meanwhile, the dielectric, ferroelectric and magnetic properties of the composites were investigated. The presence of bi-phase structure in the composites was verified with X-ray diffraction analyses. The scanning electron microscopy images and energy dispersion spectrum results confirmed that the bulk-like grains (2 to 5 ?m) and spherelike grains (_0.5 ?m) could be attributed to NZFO and BTO, respectively. The dielectric constant and loss increased with increasing NZFO/BTO molar ratio because the carrier concentration of NZFO is higher than that of BTO. Thus, the dielectric constant of the N2B1 ceramics is more than 7800 at low frequency of 100Hz and room temperature, while only less than 2000 for the N1B1.5 composite. Two peaks can be observed in the temperature dependence of the dielectric constant curves. One is near 120 ?C, which corresponds to the Curie temperature of BTO, while the other peak occurs at about 320 ?C, corresponding to the relaxation polarization. The remanent polarization increases with increasing the content of ferroelectric BTO. The maximum value at 1 kHz was observed for the N1B1.5 sample and it is larger than 4.5 ?C/cm2, while the minimal value was obtained for the N2B1 composite and is only 1.2 ?C/cm2. Magnetic properties were also measured and it was observed that magnetization increases with increasing the molar ratio. The largest saturation magnetization has the N2B1 composite (_51.74 emu/g) due to the larger concentration of NZFO phase. However, the sample N1B1.5 shows the largest coercive field due to the highest interface interaction. This study provides guidelines for the fabrication of NZFO-BTO magnetoelectric composite ceramics.

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