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.

Effect of Sintering Temperature on CuO Doped Barium Zinc Tantalate (BZT) Dielectric Properties

2016 ◽  
Vol 840 ◽  
pp. 8-13
Author(s):  
Hidayani Jaafar ◽  
Zainal Arifin Ahmad ◽  
Mohd Fadzil Ain
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Relative Density ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Constant E ◽  
State Method ◽  
Tan Δ

The structure and dielectric properties of Barium Zinc Tantalate (BZT) doped by copper oxide (CuO) with a variety of values of mol% doping from 0, 0.1, 0.25, 1.0, 1.5 and 2.5 were prepared using a solid state method. The addition of CuO did not disturb the 1:2 ordering structure of the BZT ceramic. The grain size increased when the addition of doping increased. A small amount of doping elements increased the relative density. The dielectric constant (ɛr) value of the BZT significantly improved with the addition of the CuO for the specimens sintered at 1250°C and it could be explained by the increase of the relative density. The tan δ of the CuO doped with BZT ceramics is lower than pure BZT ceramics, and decreases as the CuO content increases. Meanwhile, for the percentage of bandwidth (%BW) it is shown that the best result is produced when it is doped with 0.25 mol% CuO and sintered at 1250°C. The best microwave dielectric properties obtained were ɛr=70.28, tan δ = 0.024, %BW = 7.83 which occurred for the 0.25 mol% doped CuO and when sintered at 1250°C/4 h.

Low-Temperature Firing and Microwave Dielectric Properties of Zn3Nb2O8 Ceramics with CuO-V2O5-Bi2O3

2010 ◽  
Vol 434-435 ◽  
pp. 224-227
Author(s):  
Xu Ping Lin ◽  
Jing Tao Ma ◽  
Bao Qing Zhang ◽  
Ji Zhou
Keyword(s):  
Dielectric Constant ◽  
Phase Composition ◽  
Dielectric Properties ◽  
Relative Density ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Sintering Behavior ◽  
Co Doping ◽  
Microwave Dielectric ◽  
Quality Factor Q

The influence of CuO-V2O5-Bi2O3 addition on the sintering behavior, phase composition, microstructure and microwave dielectric properties of Zn3Nb2O8 ceramics were investigated. The co- doping of CuO, V2O5 and Bi2O3 can significantly lower the sintering temperature of Zn3Nb2O8 ceramics from 1150°C to 900°C. The Zn3Nb2O8-0.5wt% CuO-0.5wt% V2O5-2.0wt% Bi2O3 ceramic sintered at 900°C showed a relative density of 97.1%, a dielectric constant (εr) of 18.2, and a quality factor (Q×f) of 36781 GHz. The dielectric properties in this system exhibited a significant dependence on the relative density, content of additives and sintering temperature. The relative density and dielectric constant (εr) of Zn3Nb2O8 ceramics increased with increasing CuO-V2O5-Bi2O3 additions. And also the relative density and dielectric constant of Zn3Nb2O8 ceramics increased by the augment of the sintering temperature.

Sintering, Microstructure and Dielectric Properties of Ca-Al-B-Si-O Glass/Al2O3 Composites with Various SiO2 Content

2011 ◽  
Vol 130-134 ◽  
pp. 1516-1519
Author(s):  
Ming Liu ◽  
Hong Qing Zhou ◽  
Hai Kui Zhu ◽  
Min Liu ◽  
Jian Xin Zhao
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Silicon Dioxide ◽  
Bulk Density ◽  
Microwave Dielectric Properties ◽  
Microwave Dielectric ◽  
Tan Δ ◽  
Silicon Dioxide Content

The effects of silicon dioxide addition on the sintering, microstructure and microwave dielectric properties of Ca-Al-B-Si-O glass/Al2O3 composites were investigated. Results show that: Increasing the silicon dioxide content in the glass leads to the corresponding rise of bulk density, dielectric constant of the LTCC materials and the decrease of its dielectric loss and porosity. A bulk density of 2.92 g·cm-3, a porosity of 0.2%, aεr value of 7.11 and a tan δ value of 0.00096(measured at 10 MHz) are obtained for 68 wt% silicon dioxide of the samples sintered at 875°C for 30 min.

Optical and Microwave Dielectric Properties of Transparent MgAl2O4 Ceramics

2013 ◽  
Vol 647 ◽  
pp. 758-761
Author(s):  
Ping Fu ◽  
Wen Zhong Lu ◽  
Wen Lei ◽  
Yong Xu ◽  
Xian Long Lu
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Spark Plasma Sintering ◽  
Microwave Dielectric Properties ◽  
Temperature Range ◽  
Microwave Dielectric ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Spark Plasma ◽  
Sintering Processes

Transparent polycrystalline MgAl2O4ceramics were fabricated by using spark plasma sintering (SPS) technique at a temperature range from 1275 °C to 1400 °C. The average grain size of the samples fabricated at optimal sintering processes was 345 nm. The in-line transmittance of the sintered ceramics can be as high as 70% at 550 nm and 82% at 2000 nm, respectively. The optimal microwave dielectric properties (εr = 8.38, Q×f = 54000 GHz and τf = -74 ppm/°C) were achieved at 1325°C for 20 min.

Fabrication of Ba6-3x(Sm0.2Nd0.8)8+2xTi18O54(x=2/3) Ceramics by Solid State Reaction

2007 ◽  
Vol 336-338 ◽  
pp. 258-261
Author(s):  
Yong Zheng ◽  
Wen Lei ◽  
Hai Jian Bu ◽  
Xing Zhong Zhao
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Solid State ◽  
Resonant Frequency ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Sintered Ceramic ◽  
Temperature Coefficients ◽  
Microwave Dielectric

Effects of calcining and sintering temperatures on the microstructure and the microwave dielectric properties of Ba6-3x(Sm0.2Nd0.8)8+2xTi18O54(x=2/3) ceramics were studied. When the calcining temperature was lower (1373K), the dielectric constant ε and the Qf factor initially increased with increasing sintering temperature, but decreased when sintering temperature was higher than 1603K. As a whole, the temperature coefficients of the resonant frequency τf tended to increase with increasing sintering temperature. The microstructure of the sintered ceramic consisted mainly of columnar and block-shape grains. The grain size increased with increasing sintering temperature. When the calcining temperature was higher (1473K), εr and τf were nearly independent of sintering temperature. The excellent microwave dielectric properties were achieved in the Ba6-3x(Sm0.2Nd0.8)8+2xTi18O54 (x=2/3) ceramic calcined at 1373K and sintered at 1603K for 3 h: ε = 80.8, Qf = 8114 (GHz) and τf = 5.6.

Microstructure and Microwave Dielectric Properties of BaTi4O9 Ceramics Derived from a Sol-Gel Precursor

2011 ◽  
Vol 326 ◽  
pp. 127-130
Author(s):  
Xian Li Huang ◽  
Fu Ping Wang ◽  
Ying Song
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Sol Gel ◽  
Microwave Dielectric Properties ◽  
Sintering Process ◽  
Temperature Coefficients ◽  
Microwave Dielectric ◽  
Ceramic Samples ◽  
Quality Factor Q

In the present work, the microstructure and microwave dielectric properties of BaTi4O9 ceramics derived from a sol-gel precursor were presented. Density measuring results demonstrated that the largest densities of ceramic sample about 96.7% could be reached by virtue of a cool iso-static press and a sintering process at at 1300 °C for 6 hours. The dielectric constant (εr), quality factor (Q×f) and the temperature coefficients (τf) of the BaTi4O9 ceramic samples were 36.65, 28000 GHz, +20.2 ppm/°C, respectively. XRD, SEM and XPS were used to characterize the microstructure of the ceramics samples. Substantial Ti3+ was proposed to be the cause of dielectric loss.

Microwave dielectric properties of Ca[(Li1/3Nb2/3)1−xMx]O3−δ (M = Sn, Ti) ceramics

1999 ◽  
Vol 14 (9) ◽  
pp. 3567-3570 ◽  
Author(s):  
Ji-Won Choi ◽  
Chong-Yun Kang ◽  
Seok-Jin Yoon ◽  
Hyun-Jai Kim ◽  
Hyung-Jin Jung ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Quality Factor ◽  
Single Phase ◽  
Microwave Dielectric Properties ◽  
Multiphase Materials ◽  
Microwave Dielectric ◽  
Orthorhombic Perovskite

The microwave dielectric properties of Ca[(Li1/3Nb2/3)1−xMx]O3−δ (M = Sn, Ti, 0 ≤ x ≤ 0.5) ceramics were investigated. In general, the ceramics prepared were multiphase materials. However, single-phase specimens having orthorhombic perovskite structure similar to CaTiO3 could be obtained in the vicinity of Sn = 0.2 to 0.3, and Ti = 0.2. As Sn concentration increased, the dielectric constant (εr) decreased and the quality factor (Q) significantly increased within the limited Sn concentration. As Ti concentration increased, the dielectric constant (εr) increased, the quality factor (Q) decreased, and the temperature coefficient of resonant frequency (τf) changed from a negative to positive value. The temperature coefficient of resonant frequency of 0 ppm/°C was realized at Ti = 0.2. The Q · fo value and εr for this composition were found to be 26100 GHz and 38.6, respectively.

Effects of Nd2O3 on the microwave dielectric properties of BiNbO4 ceramics

1998 ◽  
Vol 13 (10) ◽  
pp. 2945-2949 ◽  
Author(s):  
Whan Choi ◽  
Kyung-Yong Kim ◽  
Myung-Rip Moon ◽  
Kyoo-Sik Bae
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Resonance Frequency ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Positive Direction ◽  
Microwave Dielectric ◽  
Triclinic Phase ◽  
Nd Substitution ◽  
Peak Value

Effects of Nd substitution with Bi on the microwave dielectric properties of BiNbO4 were studied. Bi1−xNdxNbO4 ceramics sintered at 920–980 °C consisted of orthorhombic and triclinic phases. The amount of triclinic phase increased with the increase in the Nd content, x, and sintering temperature. The apparent density and the dielectric constant decreased with the Nd content, but increased with sintering temperature, reached the peak values at 960 °C and then rapidly decreased. The Q × f0 value was between 11,000 and 13,000 GHz over all sintering temperatures for x < 0.05, but for x ≥ 0.05 it reached the peak value at 950 °C and then rapidly decreased. The temperature coefficient of resonance frequency increased in the positive direction with the Nd content and showed the minimum value of −1.82 ppm/°C for x = 0.025 sintered at 940 °C. However, it rapidly increased in the negative direction for sintering temperature over 960 °C.

Effect of Thermal Stress on the Microwave Dielectric Properties of (300-X) nm MgTiO3 /(X) nm CaTiO3 Thin Films

2006 ◽  
Vol 45 ◽  
pp. 2332-2336
Author(s):  
Ki Hyun Yoon ◽  
Ji Won Choi
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Microwave Dielectric Properties ◽  
Mixing Rule ◽  
Microwave Dielectric ◽  
Dielectric Layers

The microwave dielectric properties of (300-X) nm MgTiO3/(X) nm CaTiO3 thin films have been investigated with correlation between the interface and stress induced by dielectric layers with heattreatment. As the thickness (X) of CaTiO3 film increased, the dielectric constant increased and the temperature coefficient of the dielectric constant changed from the positive to the negative values by the dielectric mixing rule. The dielectric loss of (300-X) nm MgTiO3/(X) nm CaTiO3 thin films increased with an increase of the thickness (X) of CaTiO3 film because of higher thermal stress induced by the higher thermal expansion coefficient of CaTiO3 than that of MgTiO3.

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