Published in Materials
Terahertz time-domain spectroscopy (THz-TDS) was employed for estimation of intrinsic dielectric loss of Zr0.8Sn0.2TiO4 (ZST) ceramics. Single-phase ZST dielectric resonators (DRs) with various synthesis parameters and, consequently, different extrinsic losses, were prepared by conventional ceramic technology. Even though the DRs exhibit a similar ...
Published in MATEC Web of Conferences
A microwave miniaturized bandpass filter using (Mg0.95Ca0.05)TiO3 (abbreviated as 95MCT hereafter) ceramic substrate is investigated in the present paper. The paper studies the sintering and microwave dielectric properties of Al2O3, La2O3 and SiO2 co-doped 95MCT. The XRD pattern shows that a secondary phase MgTi2O5 is easily segregated in 95MCT cer...
Published in Materials Science-Poland
Several types of multiphase ceramic materials with excellent microwave (MW) dielectric properties have been considered. Studied materials were based on complex niobates and titanates with various crystal structures in which very high values of the MW quality factors (Q) can be attained. Slight compositional changes in the complex oxide systems have...
Temperature stable, low loss dielectric ceramics find application as resonators in communication systems operating at microwave frequencies. Candidate materials need to exhibit high relative permittivity, high dielectric Q value and near zero temperature coefficient of resonant frequency. Current materials include a range of complex perovskites, pr...
Bismuth zinc niobate pyrochlores Bi1.5ZnNb1.5O7 (alpha-BZN), and Bi2(Zn1/3Nb2/3)2O 7 (beta-BZN) have been synthesized by chemical method based on the polymeric precursors. The pyrochlore phase was investigated by differential scanning calorimetry, infrared spectroscopy, and X ray diffraction. Powder and sintered pellets morphology was examined by s...
The effect of excess Al2O3 on the densification, structure and microwave dielectric properties of Ca0.7Ti0.7La0.3Al0.3O3 (CTLA) was investigated. CTLA ceramics were prepared using the conventional mixed oxide route. Excess Al2O3 in the range of 0.1-0.5 wt% was added. It was found that Al2O3 improved the densification. A phase rich in Ca and Al was ...
Published in Journal of Electroceramics
Microwave dielectric ceramics such as Ba(Mg1/3Ta2/3)O3 and Ba2Ti9O20 possess high dielectric constant and low dielectric loss in microwave frequency regime and have tremendous potential for device applications. In these materials, the presence of extrinsic defects, such as secondary phases, usually altered the microwave dielectric properties of the...
Published in Journal of Electroceramics
Microwave dielectric properties of Ba(Mg1/3Ta2/3)O3-series materials were investigated using Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The normal vibration modes of these spectra were assigned, and the origin of dielectric response of the materials was deduced. Among the prominent normal vibration modes in the FTIR spec...
Published in Journal of Electroceramics
Modification of Pb0.6Ca0.4Zr0.6(Fe1/2Nb1/2)0.4O3 dielectric ceramics was performed by Zr substitution for (Fe, Nb). The XRD patterns showed that the single phase with orthorhombic distortion unit cell was obtained in the present ceramics. The decreasing dielectric constant by Zr substitution was due to its smaller value of α/r3ion. The calculated p...
Actuellement, les céramiques diélectriques suscitent de nombreux travaux pour des applications microondes (résonateurs diélectriques accordables ou déphaseurs). Pour cela, elles devront être commandables - modification de la constante diélectrique sous l'action d'un champ électrique – avoir une permittivité modérée (de 30 à 1000) et des tangentes d...
