The effects of the addition of H3BO3 on the microstructure, phase formation, and microwave dielectric properties of （Zn0.TMg0.3）TiO3 ceramics sintered at temperatures ranging from 890 ℃ to 950 ℃ are investigated. H3BO3 as a sintering agent can effectively lower the sintering temperature of ZMT ceramics below 950 ℃due to the liquid-phase effect. The microwave dielectric properties are found to strongly correlate with the amount of H3BO3. With the increase in H3BO3 content, the dielectric constant （er） monotonically increases, but the quality factor （Q x f） reaches a maximum at 1 wt% H3BO3, and the apparent density of ZMT ceramics with H3BO3〉 1 wt% gradually decreases. At 950 ℃, the ZMT ceramics with 1% H3BO3 exhibit excellent microwave dielectric properties： er = 19.8, and Q x f -- 43800 GHz （8.94 GHz）.
We report the design, fabrication, and characterization of a dual-band and polarization-insensitive metamaterial ab-sorber （MA）, which consists of periodically arranged fractal Koch curves acting as the top resonator array and a metallic ground plane separated by a dielectric spacer. Compared with conventional MAs, a more compact size and multi-frequency operation are achieved by using fractal geometry as the unit cell of the MA. Both the effective medium theory and the multi- reflection interference theory are employed to investigate the underlying physical mechanism of the proposed terahertz MA, and results indicate that the latter theory is not suitable for explaining the absorption mechanism in our investigated struc-ture. Two absorption peaks are observed at 0.226 THz and 0.622 THz with absorptivities of 91.3% and 95.6% respectively and good agreements between the full-wave simulation and experimental results are achieved.
Development and application of ferrite materials for low temperature co-fired ceramic （LTCC） technology are dis- cussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 ℃. These ferrite materials are research focuses and are applied in many ways in electronics.
The effects of BaCu（B2Os） （BCB） addition on the microstructure, phase formation, and microwave dielectric proper- ties of BasNb4015-BaWO4 ceramic are investigated. As a sintering aid, BaCu（B2Os） ceramic could effectively lower the sintering temperature of BasNb4015-BaWO4 ceramic from 1100 ℃ to 950 ℃ due to the liquid-phase effect. Meanwhile, BaCu（B2Os） addition effectively improves the densification of BasNb4015-BaWO4 ceramic and significantly influences the microwave dielectric properties. X-ray diffraction analysis reveals that BasNb4015 and BaWO4 coexist with no crystal phase of BaCu（B2Os） in the sintered ceramics. The BasNb4015-BaWO4 ceramics with 1.0 wt% BaCu（B2Os） sintered at 950 ℃ for 2 h presents good microwave dielectric properties of er = 19.0, high Q× f of 33802 GHz and low vf of 2.5 ppm/℃.
La-Co substituted M-type barium ferrites （BaM） were prepared by traditional solid state method and sintered at low tem- perature （1173 K）. X-ray diffraction （XRD）, scanning electron microscopy （SEM） and vibrating sample magnetometer （VSM） were employed to investigate the influence of La-Co on the structure and magnetic properties of the samples. By sintering at 1173 K for 6 h in air, single phase M-type barium ferrites with chemical composition of Ba（LaCo）xFel〉z^Oj9 （x=0.0~）.5） were formed. M-H curves showed that the magnetic properties of barium ferrites were obviously effected by La-Co substitution. The saturation magnetization （Ms） and coercivity （He） reached the maximum value of 65.15 AmZ/kg and 4165 Oe, respectively. This behavior was attributed to the sites of La-Co substitutions and the particles size. SEM revealed that the shape of ferrite particles was influenced by La-Co substitution.
