Effect of Divalent Dopants on Properties of Ba3.75Nd9.5Ti18O54 Microwave Dielectric Resonators

1996 ◽  
Vol 453 ◽  
Author(s):  
R. Ubic ◽  
I. M. Reaney ◽  
W. E. Lee ◽  
J. Samuels ◽  
E. Evangelinost
Keyword(s):  
Solid Solution ◽  
Dielectric Properties ◽  
Mixed Oxide ◽  
Theoretical Density ◽  
Dielectric Resonators ◽  
Ternary Solid Solution ◽  
Microwave Frequencies ◽  
Microwave Dielectric ◽  
Commercial Applications ◽  
Pb Substitution

AbstractPellets in the ternary solid-solution Ba6–3xNd8+2xTi18O54 (x=0.75) have been processed to near theoretical density by mixed-oxide synthesis, and their dielectric properties determined to be εr≈89, Qf> 10,000, and τf≈+60ppm/°C at microwave frequencies. Similar ceramics with Ca, Sr, and Pb partially substituted for Ba were also processed and analysed. Both Ca and Sr were found to increase εr to 100–105 but significantly lower Qf and inflate τf. While Pb substitution also lowered Qf, it had no significant effect on εr and beneficially suppressed τf to values from -16 to +8ppm/°C, tunable with Pb content, strongly suggesting that these materials may be useful for commercial applications.

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.

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.

Effect of bond valence on microwave dielectric properties of (Pb1−xCax)(Mg0.33Ta0.67)O3 ceramics

2001 ◽  
Vol 16 (3) ◽  
pp. 817-821 ◽  
Author(s):  
Heung Soo Park ◽  
Ki Hyun Yoon ◽  
Eung Soo Kim
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Bond Valence ◽  
Negative Deviation ◽  
Complex Perovskite ◽  
Microwave Frequencies ◽  
Microwave Dielectric ◽  
Dielectric Polarizability ◽  
A Site ◽  
The Relationship

The relationship between the dielectric properties of the complex perovskite (Pb1−xCax)(Mg0.33Ta0.67)O3 ceramics, where 0.45 ≤ × ≤ 0.60, and the dielectric polarizability, related to bond valences of A-site ions, was investigated at microwave frequencies. As the Ca content (x) increased, the deviation of the observed dielectric polarizabilities, calculated by the Clausius–Mosotti equation from the theoretical values calculated by the additivity rule of dielectric polarizability, decreased from −3% to −0.69%. It was found that this deviation was related to the bond valence of the A-site. Smaller negative deviation corresponded to the cations with lower bond valence, and larger negative deviation corresponded to the cations with higher bond valence. Also, the temperature coefficient of resonant frequency (TCF) was affected by the bond valence of the A-site, and then TCF decreased with decreasing bond valence of the A-site in ABO3 perovskite compounds.

Microwave dielectric properties of Ba4LaTi0.3Sn0.7Nb3O15 ceramic

2014 ◽  
Vol 28 (15) ◽  
pp. 1450092 ◽  
Author(s):  
Abdul Manan ◽  
Imtiaz Hussain
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Least Squares Method ◽  
Microwave Dielectric Properties ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Microstructural Investigation ◽  
Microwave Frequencies ◽  
Microwave Dielectric ◽  
Lcr Meter

Ba 4 LaTi 0.3 Sn 0.7 O 15 ceramic was prepared through conventional solid state mix oxide route followed by characterization using X-ray diffraction (XRD) and scanning electron microscope (SEM) for phase and microstructural investigation. The dielectric properties at low and microwave frequencies were measured using LCR meter and vector network analyzer. XRD results revealed single phase ceramics and the microstructure was comprised of compact grains with size ranging from 4–12 μm. The lattice parameters refined by the least squares method were a = b = 5.7680(2) Å, c = 11.7491(6) Å, V = 337.81 Å3 and Z = 1. Optimum properties i.e., εr~44.6, Qufo~15, 500 GHz and τf~2.05 ppm /° C were achieved for Ba 4 LaTi 0.3 Sn 0.7 Nb 3 O 15 ceramic sintered at 1475°C for 4 h.

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