The correlation between τɛ and the tolerance factor in (Sr, Ca) (Ti, Zr)O3 microwave dielectric ceramics

1998 ◽  
Vol 13 (5) ◽  
pp. 1107-1109 ◽  
Author(s):  
Chae-Il Cheon ◽  
Jeong-Seog Kim ◽  
Hyeung-Gyu Lee
Keyword(s):  
Solid Solution ◽  
Dielectric Constant ◽  
Temperature Coefficient ◽  
Composition Range ◽  
Microwave Dielectric Properties ◽  
Tolerance Factor ◽  
Microwave Dielectric Ceramics ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
The Relationship

Microwave dielectric properties and the relationship between the temperature coefficient of the dielectric constant (τ ɛ) and the tolerance factor were investigated in (Sr0.2Ca0.8) (Ti1–xZrx)O3 ceramics. The τɛ increased linearly as the tolerance factor decreased from 0.984 to 0.929 in the whole composition range of the (Sr0.2Ca0.8) (Ti1–xZrx)O3 solid solution. At the composition of (Sr0.2Ca0.8) (Ti0.04Zr0.96)O3, the dielectric constant was 34 and Q · f was 10,938 GHz and the temperature coefficient of the resonance frequency (τɛ) was supposed to be near zero.

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.

Electric State and Chemical Bonding of (Mg4−xMnx)Nb2O9 Microwave Dielectric Ceramics

2005 ◽  
Vol 20 (9) ◽  
pp. 2456-2461 ◽  
Author(s):  
Akinori Kan ◽  
Hirotaka Ogawa ◽  
Atsushi Yokoi
Keyword(s):  
Cluster Model ◽  
Single Phase ◽  
Composition Range ◽  
Microwave Dielectric Properties ◽  
Molecular Orbital Calculation ◽  
Microwave Dielectric Ceramics ◽  
Density Of State ◽  
Microwave Dielectric ◽  
Overlap Population ◽  
Dielectric Ceramics

Solid solutions of (Mg4−xMnx)Nb2O9 (MMN), which have a corundum-type structure, showed a single phase over the entire composition range, and lattice parameters of MMN linearly increased with increased composition x. From the calculation of cation–oxygen bonds in NbO6 and MO6 (M = Mg and Mn) octahedra, it was found that the covalency of the Nb–O bond was decreased by the Mn substitution for Mg; the molecular orbital calculation in (NbM12O45)−61 cluster models also revealed that the covalency of the Nb–O bond in the (NbMn12O45)−61 cluster model is smaller than that of the Nb–O bond in the (NbMg12O45)−61 cluster model. This result is attributed to the differences in the density of state, which arise from the overlap population of Mg-3d, Mn-3d, Nb-5s, and O-2p orbitals. The dielectric constant and Q⋅f values varied from 11 to 16 and from 210,000 to 50,000 GHz, respectively. Thus, it is considered that these variations in the microwave dielectric properties may be related to the covalency of the cation–oxygen bonds.

Temperature Compensated (1-x)(Na0.5La0.5)TiO3+xCeO2 Microwave Dielectric Ceramics Incorporated with Copper Oxide

2007 ◽  
Vol 336-338 ◽  
pp. 290-292
Author(s):  
M.Z. Hu ◽  
Hao Shuang Gu ◽  
J. Qian ◽  
G. Xiong ◽  
Jun Zhao
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Copper Oxide ◽  
Microwave Dielectric Properties ◽  
Mixed Phase ◽  
Microwave Dielectric Ceramics ◽  
Composite Ceramics ◽  
Microwave Dielectric ◽  
Dielectric Ceramics

The microstructures and microwave dielectric properties of temperature compensated composite ceramics (1-x)(Na0.5La0.5)TiO3+xCeO2 doped with 1wt%CuO were investigated. Dense and mixed phase samples were produced in the range of 0.1 ≤ x ≤ 0.9. As x value increases the Qf increases nonlinearly while the dielectric constant decreases almost linearly. The compensated τf value is obtained in 0.1(Na0.5La0.5)TiO3 + 0.9CeO2 + 1wt%CuO ceramic with the Qf and εr being 8240GHz and 32.0 respectively.

Modification of Ba6-3xSm8+2xTi18O54 (x=2/3)Microwave Dielectric Ceramics by Nd/Bi Co-Substitution on A-Site

2007 ◽  
Vol 280-283 ◽  
pp. 57-60 ◽  
Author(s):  
N. Qin ◽  
X.M. Chen
Keyword(s):  
Solid Solution ◽  
Dielectric Constant ◽  
Single Phase ◽  
Tungsten Bronze ◽  
Sem Analysis ◽  
Microwave Dielectric Ceramics ◽  
Co Substitution ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
A Site

Ba6-3xSm8+2xTi18O54 microwave dielectric ceramics were modified by Nd/Bi co-substitution for Sm on A-site. According to XRD and SEM analysis, a single-phase solid solution with new tungsten bronze-type structure was formed in low-Bi-substituted region. Bi was effective on increasing dielectric constant, while led to a decreased Qf value and an increased negative tf. The co-substituting approach exhibited the advantage in improving e and compensating Qf and tf value.

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.

Structure and Microwave Dielectric Properties of (Ca0.9375Sr0.0625)0.25 (Li0.5Sm0.5)0.75TiO3 Ceramics with B2O3-CuO Sintering Aids

2011 ◽  
Vol 284-286 ◽  
pp. 1442-1446
Author(s):  
Yue Ming Li ◽  
Zong Yang Shen ◽  
Zhu Mei Wang ◽  
Hua Zhang ◽  
Yan Hong ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Microwave Dielectric Ceramics ◽  
Sintering Aids ◽  
Oxide Mixture ◽  
High Permittivity ◽  
Microwave Dielectric ◽  
Dielectric Ceramics

The B2O3-CuO oxide mixture (abbreviated as BC) was selected to lower the sintering temperature of (Ca0.9375Sr0.0625)0.25(Li0.5Sm0.5)0.75TiO3 (abbreviated as CSLST) microwave dielectric ceramics by solid sate reaction technique. The effects of BC doping amounts on the crystal structure, microstructure and microwave dielectric properties of the ceramics were investigated. For the ceramic sample with the composition of CSLST + 5 wt% BC, its sintering temperature was reduced to 1000 °C as compared to 1200 °C for pure CSLST. In addition to the obtained good microwave dielectric properties as follows: εr = 80.4, Q×f = 1380 GHz, τf = -32.89 ×10-6/°C, this ceramic was a desirable high-permittivity microwave dielectric candidate for low-temperature cofired ceramic (LTCC) applications.

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.

B-O Bond Character and Microwave Dielectric Properties of (1-x)CaTiO3-xCa(Zn1/3Nb2/3)O3 Perovskite Ceramics

2009 ◽  
Vol 421-422 ◽  
pp. 69-72
Author(s):  
Jie Shen ◽  
Wen Chen ◽  
Jing Zhou ◽  
Jie Zhu ◽  
Qiong Lei
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Dielectric Materials ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
Identical Result ◽  
Microwave Dielectric ◽  
Calculation Results ◽  
The Relationship

The relationship between the character of the B-site cation–oxygen bond and the microwave dielectric properties in perovskites dielectric materials was studied in this paper. The atomic net charge of CaTiO3 (CT) and Ca(Zn1/3Nb2/3)O3 (CZN) was calculated respectively. The calculating result implies that the covalency of B-O bonds in CZN is stronger than that in CT. This predicted that the dielectric constant and loss of the ceramics will decrease after CZN incorporated in CT. To confirme the prediction, (1-x)CT-xCZN microwave dielectric ceramics were prepared by solid state reaction method with ZnNb2O6 as precursor. The structure analysis in terms of tolerance factor gives an identical result as calculation. The microwave dielectric properties, such as dielectric constants, Q×f values and τf were studied as a function of composition. With x increasing from 0.2 to 0.8, the dielectric constant linearly decreases from 109 to 49.37, the Q×f value increases from 8,340 to 13,200 GHz, and τf decreases from 321 to -18 ppm/°C. The properties trends are consistent with the previous calculation results, and confirm the relationship between the character of B-O bond and dielectric properties.

Low Temperature Sintering of (Ca0.9375Sr0.0625)0.25(Li0.5Sm0.5)0.75TiO3 Microwave Dielectric Ceramics

2010 ◽  
Vol 663-665 ◽  
pp. 1028-1031
Author(s):  
Yue Ming Li ◽  
Hua Zhang ◽  
Zhu Mei Wang ◽  
Yan Hong ◽  
Zong Yang Shen
Keyword(s):  
Dielectric Properties ◽  
Low Temperature ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Sintering Behavior ◽  
Low Temperature Sintering ◽  
Microwave Dielectric Ceramics ◽  
Microwave Dielectric ◽  
Dielectric Ceramics

The sintering behavior and microwave dielectric properties of the (Ca0.9375Sr0.0625)0.25(Li0.5Sm0.5)0.75TiO3 (CSLST) ceramics doped with different amounts of Li2O-B2O3-SiO2-CaO-Al2O3 (LBSCA) glass were investigated. The sintering temperature of the CSLST ceramics can be effectively reduced over 200oC due to the addition of LBSCA glass. For the 5 wt% LBSCA-doped CSLST ceramics, which are sintered at only 1000 oC for 5 h, show optimum microwave dielectric properties as follows: εr=84.74, Qf=2446 GHz and τf=-12.48 ppm/oC.

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