INFLUENCE OF n ON STRUCTURE AND MICROWAVE DIELECTRIC PROPERTIES OF SOME AnBn - 1O3n PEROVSKITES

2011 ◽  
Vol 01 (01) ◽  
pp. 135-140
Author(s):  
LIANG FANG ◽  
ZHAO YANG ◽  
HUI ZHANG ◽  
CHUNCHUN LI ◽  
HEPING SU
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
General Formula ◽  
Microwave Dielectric Properties ◽  
Structure And Properties ◽  
Quality Factors ◽  
Microwave Dielectric

Two series of B-site deficient perovskites Ba 5+m Ti m Nb 4 O 15+3m(m = 1, 2, 3) and Sr 3+m LaTi m Nb 3 O 12+3m(m = 0, 1, 2) with the general formula A n B n - 1 O 3n(n = 4 - 8; A = Ba , Sr , La ; B = Nb , Ti ) have been synthesized, and their structure and microwave dielectric properties have been investigated. The effects of n (number of octahedra layers within a perovskite blocks) on structure and properties are investigated. The values of dielectric constant εr and temperature coefficient of resonant frequency τf gradually increase, but quality factors Q × f values significantly decreases as the values of n increase.

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.

Dielectric properties of La-substituted Pb0.5Ca0.5[(Mg1/3Nb2/3)0.5Ti0.5]O3 ceramics

2001 ◽  
Vol 16 (7) ◽  
pp. 2053-2056
Author(s):  
X. J. Lu ◽  
X. M. Chen
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Microwave Dielectric Properties ◽  
Present Approach ◽  
Calculated Temperature ◽  
Microwave Dielectric ◽  
La Substitution ◽  
Dielectric Ceramics

Modification of Pb0.5Ca0.5[(Mg1/3Nb2/3)0.5Ti0.5]O3 dielectric ceramics was performed by up to 20 mol% La substitution for Pb and Ca. The temperature coefficient of dielectric constant was significantly reduced by the present approach, while an increased Qf factor was achieved. Good microwave dielectric properties were obtained in a composition Pb0.425Ca0.425La0.1[(Mg1/3Nb2/3)0.5Ti0.5]O3: ε = 125; Qf = 3150 GHz; calculated temperature coefficient of resonant frequency δf = +253 ppm/°C.

Effects of CuO and V2O5 Addition on Sintering Behavior and Microwave Dielectric Properties of (1-x)Ca2P2O7-xTiO2

2007 ◽  
Vol 336-338 ◽  
pp. 279-282
Author(s):  
In Sun Cho ◽  
Sang Gu Kang ◽  
Dong Wan Kim ◽  
Kug Sun Hong
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Quality Factor ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Sintering Behavior ◽  
Microwave Dielectric

The effects of CuO and V2O5 addition on sintering behaviors and microwave dielectric properties of 0.7Ca2P2O7-0.3TiO2 ceramics were investigated. With CuO and V2O5 addition, the sintering temperature of 0.7Ca2P2O7-0.3TiO2 can be effectively reduced from 1150 to 950oC. The dielectric constant of the low fired 0.7Ca2P2O7-0.3TiO2 ceramics was not significantly changed while the quality factor was affected by additives. The temperature coefficient of resonant frequency value was increased in negative value with the additive contents. V2O5 and CuO additives effectively improved the densification and dielectric properties of 0.7Ca2P2O7-0.3TiO2 ceramics. The correlation between the phase constituents and the dielectric properties was investigated with additive contents.

Effects of Ti4+ Substitution on Microstructure and Microwave Dielectric Properties of ZnNb2(1-x)TixO(6-3x) Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 19-22
Author(s):  
Ying Chun Zhang ◽  
Zhen Xing Yue ◽  
Jin Wang ◽  
Zhi Lun Gui ◽  
Long Tu Li
Keyword(s):  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Microwave Dielectric Properties ◽  
Network Analyzer ◽  
Quality Factors ◽  
Microwave Frequencies ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
Ti Content

The microstructure and microwave dielectric properties of dielectric ceramics comprised of ZnNb2(1-x)TixO(6-3x) (x = 0 ~ 1) were investigated systematically using X-ray powder diffraction, SEM and a network analyzer in this study. The results showed that four phases were observed in this system. The dielectric properties at microwave frequencies exhibit a significant dependence on the composition and crystal structure of the ceramics. The dielectric constant ( er) of ZnNb2(1-x)TixO(6-3x)ceramics increases with increasing Ti content and the quality factors (Q ×f) significantly decreased. However, the temperature coefficient of resonant frequency ( t f ) changes from –59.08 ppm/oC at x = 0 to + 25.1 ppm/oC at x = 1, and a zero temperature coefficient of resonant frequency ( t f ) for this ceramics system was obtained at x = 0.84.

Shifting τf Value of (Mg0.95Co0.05)TiO3 Ceramics by Ca0.61Nd0.78/3TiO3 Addition

2013 ◽  
Vol 807-809 ◽  
pp. 2703-2706
Author(s):  
Ping Cheng Chen ◽  
Chung Long Pan ◽  
Wei Cheng Lin ◽  
Chun Hsu Shen
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Significant Role ◽  
Microwave Dielectric Properties ◽  
Dielectric Measurement ◽  
Zero Temperature ◽  
Microwave Dielectric

Modification of (Mg0.95Co0.05)TiO3ceramics by Ca0.61Nd0.78/3TiO3addition was investigated. The Ca0.61Nd0.78/3TiO3content plays a significant role in improving the dielectric properties. Microwave dielectric measurement showed an increase in dielectric constant (εr) and temperature coefficient of the resonant frequency (τf) and a decrease inQvalue with increasing Ca0.61Nd0.78/3TiO3content. By properly adjusting the Ca0.61Nd0.78/3TiO3content, zero temperature coefficient of resonate frequencyτfcan also be obtained. It becomes more promising in the application of wireless system.At 1375°C, the 0.85(Mg0.95Co0.05)TiO3-0.15Ca0.61Nd0.78/3TiO3ceramics possesses excellent microwave dielectric properties: a dielectric constant εr of 24.37, aQfvalue of 66200 ( at 7 GHz ) and a τf value of-1.4 ppm/°C.

Structures and microwave dielectric properties of Ba6−3x(Nd,Biy)8+2xTi18O54 (x = 2/3) solid solution

2001 ◽  
Vol 16 (6) ◽  
pp. 1734-1738 ◽  
Author(s):  
Yong Jun Wu ◽  
Xiang Ming Chen
Keyword(s):  
Solid Solution ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Solid Solubility ◽  
Microwave Dielectric Properties ◽  
Solubility Limit ◽  
Solid Solubility Limit ◽  
Continuous Increase ◽  
Microwave Dielectric

The effects of Bi substitution for Nd in Ba6−3xNd8+2xTi18O54 (x = 2/3) solid solution upon the microstructures and microwave dielectric properties were investigated. The solid solubility limit of Bi in Ba6−3xNd8+2xTi18O54 (x = 2/3) solid solution was about 15 mol%, the same as that for x = 0.5, and densification of the present solid solutions could be performed well at lower temperatures. However, the variation tendency of microwave dielectric properties with composition in the present ceramics quite differed from that for x = 0.5: (1) The temperature coefficient of resonant frequency in the present ceramics showed a continuous variation from positive to negative and did not indicate extreme value at the solid solubility limit. (2) Near-zero temperature coefficient of resonant frequency combined with high-ε and high-Qf values could be obtained in the present ceramics, while that for x = 0.5 had a lower limit of +15 ppm/°C. (3) The dielectric constant also showed a continuous increase for the present compositions, while that in x = 0.5 had an extreme at solid solubility limit. Ceramics with composition of Ba6−3x(Nd0.85,Bi0.15)8+2xTi18O54 (x = 2/3) showed excellent dielectric properties of ε = 99.1, Qf = 5290 GHz, and τf = −5.5 ppm/°C.

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