43 research outputs found
Enhanced microwave heat susceptor crucible / Muhammad Azwadi Sulaiman ... [et al.]
No full textMicrowave (MW) irradiation is an attractive technique of material processing. Reasons for the growing interest in the use of microwave energy are including rapid heating, enhanced densification rate, decreased sintering active energy and improved microstructure. MW heating also has the
potential for energy and cost savings when comparing with conventional heating. The use of microwave in ceramic processing is a relatively recent development. The technique can be applied effectively and efficiently to heat and sinter ceramic object. In this study, the microwave heat
susceptor crucible was formulated and enhanced to convert the microwave energy to heat at very high efficiency. The performance was surpassing the existing product in market and the invention was patented for commercialization
Effects Of Electrode Materials On Electrical Properties Of Cacu3ti4o12 At 100 Hz – 1 Ghz
No full textCaCu3Ti4O12 (CCTO) has attracted much interest because of its extraordinary high dieletric constant of 100,000 at room temperature and very small temperature dependence in a broad temperature range from 100 K to near 400 K. This high dielectric constant offers opportunities in miniaturization of electronic application nowadays. However, CCTO also possesses high dielectric loss which is undesirable in electronic applications. To lower the dielectric loss, it is necessary to understand the origin of polarization responds and relaxation mechanism in CCTO. Using wide frequency impedance spectroscopy (IS) from 100 Hz to 1 GHz, the origins of polarization effect can be revealed. One of the important origins is the used of different electrode materials which determine the contact condition to the bulk CCTO. A research was carried out to study the effect of electrode materials to the electrical properties of CCTO at the frequencies of 100 Hz to 1 GHz. Samples were prepared through solid state reaction methods and starting materials of CaCO3, CuO and TiO2 has been used. After the characterization, the starting materials were mixed for 1 hour and thermal analysis was done. Mixed powder was calcined at 900 to 1000ºC for 3 to 6 hours. Phase analyses and microstructure observation was carried out. Calcination at 1000ºC for 3 hours produced almost single phase of CCTO. The calcined powder was pressed into pellet forms and the sintering processes were done between 1000 to 1050ºC for 3 to 10 hours. X-ray diffraction (XRD) analisys indicated that sintering at 1030ºC and below increased the lattice parameter and long soaking time until 10 hours at 1040ºC has decreased the lattice parameter. Longer soaking times are also increasing the crystallite size and 6 hours of soaking time or
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more produced large grains (>100μm). The IS reported the dielectric constants and dielectric loss are also increased with the sintering soaking time. Relaxation peak at 10 MHz is suggested due to the loss of grain boundaries polarization effects. High frequency curve of impedance complex was observed and modeled as domain and domain boundary contribution in equivalence circuit analyses. The current-voltage characteristic reported the non-linearity and proved the Schottky’s barrier of CCTO. Sample sintered at 1040ºC for 4 hours have stable and high dielectric constant and low dielectric loss over the frequency range. Heat treatment study to the electrode from room temperature to 400ºC in argon gas revealed the increase of dielectric constant with the increasing of treatment temperature. The dielectric constant improvement was due to more Schottkys contact formation after the treatment. Treatment at 300ºC is the most suitable temperature to produce high dielectric constant CCTO with low dielectric loss. Schottky’s effect to the contact were observed by applying different electrode material, gold, platinum, silver and aluminium and non-linear of current-voltage characteristic was revealed on Pt and Au electrode. This is due to both electrodes have higher work function than the other electrodes. Samples with Au electrode showed high dielectric constant at 1 MHz (4,398) and low dielectric loss (0.03 at 1.58 kHz). Wide frequency measurement of the electrical properties shows the responds from grain, grain boundary, domain and domain boundary through impedance complex plane curve fitting method. Their resistivities have changed with the study parameters and high frequency respond associated with domain boundary resistivities has been modelled according the equivalence circuit analysis
A Review on Microwave Processing Technique in the Synthesis of CaCu3Ti4O12
No full textMicrowave heating has a high potential technique to be used as an effective substitute for traditional furnace heating techniques in today\u27s ceramic industries, including the synthesis of promising very high dielectric materials with relative permittivity, er = 105 of CaCu3Ti4O12 (CCTO). The microwave processing approach employs microwave radiation to heat materials more efficiently and uniformly to promote uniform densification. Hence, this approach improved the material’s characteristics tremendously compared to the traditional furnace. As microwave heating lowers the reaction times, it has the potential to save both money and energy compared to conventional heating techniques. In CCTO processing, microwave energy was commonly used to replace the heating technique in the calcination stage, sintering stage, or both. This review delves into the historical development and advancements in microwave processing methods within ceramic manufacturing, particularly focusing on CCTO electroceramics. The aim is to assess the viability of microwave processing as a complete substitute for conventional furnace heating techniques in the production of CCTO
Synthesis and characterization of titanium dioxide doped nickel oxide dielectric materials
No full textNickel oxide (NiO) belongs to the transition metal oxide family, having good dielectric constantwith the range of 103 – 105, but it has high dielectric loss. In this research, the effect of titaniumdioxide (TiO2) addition into NiO was investigated. Generally, TiO2 was used in the application ofelectrical ceramic, catalysts, electric conductors and chemical intermediates. Ni1-xTixO1+x wasprepared via solid-state reaction method with 6 different TiO2 compositions. The preparation startedwith the powder mixing process for 24 hours and followed by calcination process at 950 °C for 4hours. Then, the calcined powders were compacted into 6 mm pellet shape under pressure of 250MPa pressure. Three pellets were made for each TiO2 composition. Those pellets were sintered at1250 °C for 5 hours. XRD results showed that pure NiO at 0.01 and 0.02 mole % of TiO2compositions produced single NiO crystalline phase, while 0.03, 0.05 and 0.10 mol % of TiO2showed the TiO2, instead of NiO phases. SEM analysis showed that increasing TiO2 concentrationmake the grain size increase, with 0.02 mole % of TiO2 gave the largest grain size, shows that 0.02mole % is the optimum TiO2 concentration for grain size enlargement. Furthermore, the bulkdensity of Ni1xTixO1+xpellet was reduces at higher TiO2 concentration. In dielectric test, the additionof 0.03 mole % of TiO2 gave the highest dielectric constant with value of 4.51 x 1014 and 0.05 mole% of TiO2 gives the result of lowest dielectric loss (0.53)
Characterization of barium titanate reinforced acrylonitrile butadiene rubber composites for flexible electronic applications: influences of barium titanate content
No full textEvaluation of cure characteristic, physico‐mechanical, and dielectric properties of calcium copper titanate filled acrylonitrile‐butadiene rubber composites: Effect of calcium copper titanate loading
No full textNanoscale Investigation of Nb-Doped CaCu<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> Grains
No full textCaCu3Ti4O12 (CCTO) is a promising material for microelectronic and microwave device applications due to its unique properties that posses high dielectric constant in the wide temperature range. In this work, atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses were applied for nanoscale imaging of Nb-doped CCTO grains. The Nb-doped CCTO pellets (CaCu3Ti4-xNbxO12+x/2; x = 0, 0.01, 0.03, 0.05, 0.1) were prepared via solid state reaction method and thermally etched at 940°C for an hour. From AFM and SEM images found that tiny bumped as well as terrace type domains are distributed within a grain. The domain size is ranging from 20 to 180 nm measured by AFM. The existence of domains on grain will produce grain boundary and domain boundary resistance inside CCTO. Both domain and grain resistance are believed to strongly influence the electrical properties of CCTO.</jats:p
Bacto-Agar and Commercial Agar as Binder for Porous Zinc Anode
No full textThe use of synthetic binder led to environmental issues due to undergo chemical processes in manufacturing sector and even made it expensive material. Therefore, the present study focused on use of natural binder for porous zinc (Zn) anode because its advantages of abundance in raw material, biodegradable, environmental acceptability and cost effectiveness. Bacto-agar and commercial agar powder were selected as natural binder and both agars were characterized their morphologies using the scanning electron microscopy (SEM). The SEM images showed the difference in morphological structure between porous Zn anode with Bacto-agar binder and porous Zn anode with commercial agar binder. Bacto-agar binder possesses smooth surface compare to commercial agar binder indicated that Zn powder successfully mix with Bacto-agar.</jats:p
Mechanical Properties of Annealed Soda Lime Silica Glass with Various Potassium Salt by Ion Exchange
No full textThis work studied the effect of ion exchange parameters on the glass properties. The regular soda lime silica glass was annealed at 600 ºC for 16 hours, followed by the chemical treatment process. The chemical treatment was carried out using different types of potassium salts at two different temperatures. Different ion exchange media in salt paste were prepared using KNO3, KCl, and K2SO4 and heat treated at 425 ºC and 465 ºC for 4 hours. The mechanical properties of the glass before and after ion exchange treatment were analyzed using the 3-point bending and Vickers hardness method. The results show the highest flexural strength was obtained after the annealed glass was treated with KCl for 4 hours at 425 ºC. Meanwhile, treatment with KNO3 at 425 ºC resulted in the highest Vickers hardness strength and glass fracture toughness compared to samples treated with other potassium salts. From both characterization techniques, the K2SO4 salt medium showed the lowest flexural strength, hardness, and fracture toughness values. Additionally, ion exchange treatment at 465 ºC reduced the glass\u27s mechanical properties as higher treatment temperatures lead to surface structure stress relaxation
