Ultralow dielectric constant nickel–zinc ferrites using microwave sintering

2003 ◽  
Vol 18 (10) ◽  
pp. 2292-2295 ◽  
Author(s):  
Ramesh Peelamedu ◽  
Craig Grimes ◽  
Dinesh Agrawal ◽  
Rustum Roy ◽  
Purushotham Yadoji
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
High Frequency ◽  
Microwave Field ◽  
Domain Walls ◽  
Microwave Sintering ◽  
Starting Material ◽  
Nickel Zinc ◽  
Magnetic And Dielectric Properties

Ultralow dielectric constant values were measured on Ni–Zn ferrites prepared using Fe2O3 as a starting material and sintered in a microwave field. Significant differences in microstructure, magnetic, and dielectric properties were observed between microwave-sintered Ni–Zn ferrites prepared using Fe3O4 (T34) and those starting with Fe2O3 (T23) ingredients. Higher magnetization values observed in T23 ferrite are attributed to large grain size, possibly containing abundant domain walls and the presence of fewer Fe2+ ions. The ultralow dielectric constant values observed on T23 ferrites show that this procedure is highly suitable to prepare Ni–Zn ferrites for high-frequency switching applications.

Microstructural and Dielectric Responses of Calcium Copper Titanate Added Soda-Lime Glass for High Frequency Devices

2020 ◽  
Vol 1010 ◽  
pp. 233-238
Author(s):  
Mohd Fariz Ab Rahman ◽  
Mohd Fadzil Ain ◽  
Julie Juliewatty Mohamed ◽  
Siti Roshayu binti Hassan ◽  
Zainal Arifin Ahmad
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
High Frequency ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Glass Addition ◽  
Calcium Copper Titanate ◽  
High Frequency Devices ◽  
Xrd Patterns

The microstructures and dielectric responses of calcium copper titanate (CCTO) ceramics with soda-lime glass addition was investigated. The addition of soda lime glass was varied from 0-5 wt.% by solid-state reaction. The dielectric properties of CCTO indicated that dielectric constant was increased while dielectric loss was decreased after glass addition. The SEM micrographs showed the grain size of CCTO was decreased while the grain boundaries area of CuO + glass were increased after the addition of soda-lime glass. Both XRD patterns of CCTO and CCTO-soda lime glass sintered samples showed the formation of CCTO phase with minor peaks of CuO phase, respectively. These results indicated that soda-lime glass addition gave a significant effect on the microstructural and dielectric responses of CCTO ceramics.

Influence of Ca-Doping on Structural, Magnetic and Dielectric Properties of Ba3Co2-xCaxFe24O41 Hexaferrite Powders

2015 ◽  
Vol 241 ◽  
pp. 226-236 ◽  
Author(s):  
Neha Solanki ◽  
Rajshree B. Jotania
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Sol Gel ◽  
Calcium Content ◽  
Combustion Method ◽  
Dielectric Behavior ◽  
Dielectric Parameters ◽  
Ca Doping ◽  
Auto Combustion ◽  
Magnetic And Dielectric Properties

Influence of Ca substitution on structural, magnetic and dielectric properties of Ba3Co2-xCaxFe24O41(where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), prepared by Sol-Gel auto-combustion method, has been investigated in present studies. The obtained powder was sintered at 950 oC for 4 hrs. in the static air atmosphere. Structural analysis of Ca-doped Ba3Co2-xCaxFe24O41powders revealed pure Z-type hexaferrite phase at low temperature. The frequency dependent dielectric constant (Єʹ) and magnetic properties such as remanent magnetization (Mr), saturation magnetization (Ms) and coercivity (Hc) were studied. It is observed that coercivity increased gradually with increase in calcium content. The real dielectric constant (Єʹ) and dielectric loss tangent (tan δ) were studied in the frequency range of 20Hz to 2MHz. The dielectric parameters for all samples show normal dielectric behavior as observed in hexaferrites. Contents of Paper

Photosensitive Polyimide having low loss tangent for RF application

2018 ◽  
Vol 2018 (1) ◽  
pp. 000476-000482 ◽  
Author(s):  
Masao Tomikawa ◽  
Hitoshi Araki ◽  
Yohei Kiuchi ◽  
Akira Shimada
Keyword(s):  
Molecular Structure ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
High Frequency ◽  
Low Dielectric Constant ◽  
Low Loss ◽  
Elongation At Break ◽  
Low Dielectric ◽  
The Poor

Abstract Progress of 5G telecommunication and mm radar for autopilot, high frequency operation is required. Insulator materials having low loss at high frequency is desired for the applications. We designed the low dielectric constant, and low dielectric loss materials examined molecular structure of the polyimide and found that permittivity 2.6 at 20GHz, dielectric loss 0.002. Furthermore, in consideration of mechanical properties such as the toughness and adhesion to copper from a point of practical use. Dielectric properties largely turned worse when giving photosensitivity. To overcome the poor dielectric properties, we designed the photosensitive system. After all, we successfully obtained 3.5 of dielectric constant and 0.004 of dielectric loss, and 100% of elongation at break. In addition, we offered a B stage sheet as well as varnish. These materials are applicable to re-distribution layer of FO-WLP, Interposer and other RF applications for microelectronics.

scholarly journals Investigation of AC-Measurements of Epoxy/Ferrite Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 492 ◽  
Author(s):  
Moustafa A. Darwish ◽  
Alex V. Trukhanov ◽  
Oleg S. Senatov ◽  
Alexander T. Morchenko ◽  
Samia A. Saafan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Frequency ◽  
Precipitation Method ◽  
Semiconductor Behavior ◽  
Ferrite Composites ◽  
Co Precipitation ◽  
Theoretical Results ◽  
Composite Samples

A pure ferrite and epoxy samples as well as the epoxy/ferrite composites with different 20 wt.%, 30 wt.%, 40 wt.%, and 50 wt.% weight ferrite contents have been prepared by the chemical co-precipitation method. AC-conductivity and dielectric properties such as the dielectric constant and dielectric loss of the prepared samples have been studied. The obtained results showed that the samples had a semiconductor behavior. The dielectric constant of the composites has been calculated theoretically using several models. For the composite sample that contains 20 wt.% of ferrites, these models give satisfactory compliance, while for the composite samples with a higher percentage of nanofillers, more than 30 wt.% theoretical results do not coincide with experimental data. The investigated polymer has very low conductivity, so this type of polymer can be useful for high-frequency applications, which can reduce the losses caused by eddy current. Thus, the prepared samples are promising materials for practical use as elements of microwave devices.

Surface Dissolution of Hydroxyapatite Prepared by Microwave Sintering

2007 ◽  
Vol 330-332 ◽  
pp. 227-230
Author(s):  
Dong Seok Seo ◽  
Hwan Kim ◽  
Kyu Hong Hwang ◽  
Jong Kook Lee
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Heating Rate ◽  
Microwave Sintering ◽  
Starting Material ◽  
Dissolution Behavior ◽  
Distilled Water ◽  
Sintering Process ◽  
Conventional Sintering ◽  
Boundary Dissolution

The aim of this study was to prepare dense hydroxyapatite (HA) by microwave sintering and to evaluate the dissolution behavior in distilled water. Commercially-obtained HA powders having Ca/P ratio of 1.67 were used as a starting material. The as-received powder of granular type consists of nano-sized particles. Microwave sintering was operated at 1200°C for 5 min with a heating rate of 50°C/min. Microwave sintering process reduced grain size of HA, compared with the case of conventional sintering. During the immersion in distilled water for 3-14 days, grain boundary dissolution occurred and the dissolution extended into the bulk following this path. As a result, particles were separated from the structure leaving micron-scale defects.

Grain Size Dependence of the Microstructure and Dielectric Properties of Potassium Niobate-Barium Titanate Ceramics

2013 ◽  
Vol 566 ◽  
pp. 34-37
Author(s):  
Kenta Yamashita ◽  
Ichiro Fujii ◽  
Kouichi Nakashima ◽  
Nobuhiro Kumada ◽  
Yoshihiro Kuroiwa ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Barium Titanate ◽  
Size Dependence ◽  
Potassium Niobate ◽  
Titanate Ceramics

In this study, 0.8 KNbO3(KN) -0.2 BaTiO3(BT) ceramics were prepared using KN powder with the diameter of 100 nm and BT powders with the diameter of 100, 300, or 500 nm. The relative densities were more than 96 % of the theoretical densities of the samples. The dielectric constant of the samples was temperature-stable at temperatures between-50 and 300 °C and it was found that the dielectric constant of the 0.8KN-0.2BT ceramics increased as the BT diameter increased.

High density BaCeO3 ceramics sintered using microwave irradiation

2005 ◽  
Vol 906 ◽  
Author(s):  
Alexander Sergeevitch Vanetsev ◽  
Andrei Vladimirovitch Orlov ◽  
Yurii Dmitrievitch Tretyakov
Keyword(s):  
Grain Size ◽  
High Power ◽  
Microwave Field ◽  
Microwave Sintering ◽  
Barium Cerate ◽  
High Power Microwave ◽  
High Power Microwaves ◽  
Thermal Fields ◽  
Average Grain Size ◽  
Power Microwave

AbstractThe goal of this work was to investigate the capabilities of high-power microwaves in manufacture of small-grained barium cerate ceramics. Having compared the samples sintered in the microwave and the thermal fields, we inferred that the microwave sintering occurs at far higher rates. It is also noteworthy that microwave sintering provides a record-breaking low temperature of barium cerate sintering (900°C). Having studied the effect of a microwave field on the microstructure of sintering products, we found that high-power microwave processing significantly reduces the average grain size of barium cerate ceramics.

scholarly journals The investigation of electrical properties and microstructure of ZnO-doped Ba0.9Sr0.1TiO3 ceramics

2017 ◽  
Vol 07 (01) ◽  
pp. 1750007 ◽  
Author(s):  
Gang Liu ◽  
Wentao Jiang ◽  
Jingyong Jiao ◽  
Li Liu ◽  
Ziyang Wang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Solid State ◽  
Breakdown Strength ◽  
Electrical Breakdown ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Electrical Breakdown Strength

Ba[Formula: see text]Sr[Formula: see text]TiO3 ceramics with or without ZnO have been prepared by traditional solid state reaction method. The XRD analysis showed that the doped Zn[Formula: see text] ions diffused into the BST crystal lattice, resulting in the variation of dielectric properties. Especially the dielectric constant at Curie point decreased with doping ZnO content when it is lower than 0.5[Formula: see text]mol%. Due to the promotion of sintering, doping ZnO can enhance the density of ceramics but increase grain size. However, ZnO is a kind of semiconductor and can lead to the decrease in electrical breakdown strength value.

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