DIELECTRIC PROPERTIES OF Ca(1-x)ZnxLa4Ti5O17 CERAMICS AT MICROWAVE FREQUENCIES

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1179-1184 ◽  
Author(s):  
Yih-Chien Chen ◽  
Jian-Min Tsai
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Microwave Dielectric Properties ◽  
Maximum Density ◽  
Zero Temperature ◽  
Microwave Frequencies ◽  
Microwave Dielectric ◽  
Diffraction Peaks ◽  
Quality Factor Q

In this paper, the microwave dielectric properties of Ca (1- x ) Zn x La 4 Ti 5 O 17 ceramics have been studied. The diffraction peaks of Ca (1- x ) Zn x La 4 Ti 5 O 17 ceramics shift to higher angles as x increases from 0 to 0.01 and nearly unchanged with x increasing from 0.01 to 0.03. A maximum density of dielectric constant value of 57 and a quality factor ( Q × f ) of 15000 GHz can be obtained for Ca 0.99 Zn 0.01 La 4 Ti 5 O 17 ceramic sintered at 1450°C for 4h. A near-zero temperature coefficient of resonant frequency (τ f ) of -8.1 ppm/°C can be obtained for Ca 0.99 Zn 0.01 La 4 Ti 5 O 17 ceramic sintered at 1450°C for 4h.

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.

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.

Dielectric Properties of a New Ceramic System (1-x)(Mg0.95Zn0.05)2TiO4-x(Ca0.8Sr0.2)TiO3 at Microwave Frequencies

2020 ◽  
Vol 830 ◽  
pp. 37-42
Author(s):  
Shih Sheng Liu ◽  
Shiuan Ho Chang ◽  
Yuan Bin Chen
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Low Loss ◽  
Microwave Frequencies ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
System 1 ◽  
Quality Factor Q

The microwave dielectric properties and microstructures of the (1-x)(Mg0.95Zn0.05)2TiO4-x (Ca0.8Sr0.2)TiO3 ceramics prepared using the conventional solid-state route were investigated. The structure and microstructure were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Ilmenite-structured (Mg0.95Zn0.05)TiO3 was detected as a second phase. The coexistence of the second phase, however, did not degrade the dielectric properties of the specimen because the phases were compatible. At x = 0.07, a dielectric constant (εr) of ~17.86, a quality factor (Q×f) value of ~ Q×f~133,600 Hz (at 10 GHz), and a temperature coefficient of resonant frequency (τf) of ~ –5ppm/°Cwere obtained for 0.93(Mg0.95Zn0.05)2TiO4-0.07(Ca0.8Sr0.2)TiO3 ceramic sintered at 1240°C for 4 hr. The dielectric is proposed as a candidate material for low-loss microwave and millimeter wave applications.

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.

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