Newly developed ternary (Ca, Sr, Ba) zirconate ceramic system for microwave resonators

Yamaguchi, T.; Komatsu, Y.; Otobe, T.; Murakami, Yosuke

doi:10.1080/00150198008226116

Cited by 57 publications

(18 citation statements)

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“…The dielectric constant was found to be 18.5 for BaZrO 3 , which is lower than the values reported earlier (ranging from 32 to 36 depending on the sintering temperature and method of synthesis) [93][94][95]. The variation of dielectric constant with temperature was also marginal.…”

Section: Dielectric Propertiescontrasting

confidence: 67%

Microemulsion route to the synthesis of nanoparticles

Ganguli

Ahmad

Vaidya

et al. 2008

Pure and Applied Chemistry

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Nanoparticles of several titanates and zirconates in the range of 20-60 nm have been obtained using the reverse micellar route. Important oxides like CeO 2 (mixture of nanorods; 7 nm diameter and 30 nm length and nanoparticles; 10 nm), ZrO 2 (3-4 nm) and SnO 2 (8 nm) have also been synthesized. Nanorods and nanoparticles of CaCO 3 in all three forms (aragonite, vaterite, and calcite) have been obtained using reverse micelles as nanoreactors. The specific reactions vary depending on the nature of the target nanomaterial. For synthesis of ternary oxides like BaTiO 3 , a modified and convenient route using microemulsions (avoiding Ba-alkoxide) has evolved. Monophasic tin dioxide (SnO 2 ) was obtained when liquid NH 3 was used as precipitating agent. Transmission electron microscopy (TEM) studies show that the SnO 2 nanoparticles are highly uniform and particle size was found to be 6-8 nm at 500 °C. The gas sensing characteristics of SnO 2 have also been investigated using n-butane, which shows high sensitivity and fast recovery time. Reverse micelles have been used, for the first time, to mimic the conditions suitable for the room-temperature synthesis of the high-temperature and -pressure orthorhombic phase of calcium carbonate (aragonite). Other forms of calcium carbonate (vaterite and calcite) could be obtained by varying the atmospheric conditions. At a lower temperature (5°C), homogeneous and monodisperse spheres of vaterite are obtained. The spherical particles aggregate after longer aging (168 h) to form nanorods, and the self-assembly is clearly seen at various stages by electron microscopy images. The samples were well characterized using powder X-ray diffraction (PXRD), line-broadening studies, TEM, variation in the dielectric properties with frequency and temperature, were measured on disks sintered at high temperature.

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Section: Dielectric Propertiescontrasting

confidence: 67%

Microemulsion route to the synthesis of nanoparticles

Ganguli

Ahmad

Vaidya

et al. 2008

Pure and Applied Chemistry

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“…Calcium zirconate (CaZrO 3 ) is a kind of perovskite structure with: high chemical stability, a high melting temperature (∼2345 • C), good thermal shock resistance, a relatively low thermal expansion coefficient and a phase stability in contrast to zirconia. Therefore, CaZrO 3 has received much attention for mechanical and electrical applications, such as: fuel cells [1], filler [2], coating [3], capacitors [4], resonator for microwave telecommunication [5] and temperature compensating materials of capacitance in multilayer ceramic capacitors.…”

Section: Introductionmentioning

confidence: 99%

Effect of Firing Temperatures on Phase and Morphology Evolution of CaZrO₃Ceramics Synthesized Using the Combustion Technique

2010

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The effects of calcination temperatures (900-1400 • C) and sintering temperatures (1400-1650 • C) on phase and morphology evolution of perovskite CaZrO 3 ceramics were studied. The results obtained from DTA-TGA analysis were used to determine the processed conditions of various calcination temperatures. The highest purity of the orthorhombic perovskite phase was obtained from powder calcined at 1200 • C and the pure phase was detected in sintered ceramic samples below 1650 • C. The SEM results showed that the average particle size and the average grain size of samples increased with the increase of firing temperatures. The shrinkage of ceramics increased as the sintering temperatures increased. The calcium zirconate, which had around 97.6% of the theoretical density, was obtained from the sample sintered at 1500 • C for 2 h. More importantly, the highest density with low sintering temperature were be improved by the combustion technique.

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“…Calcium zirconate (CaZrO 3 ) ceramic is a potential candidate for mechanical filters [3], coatings [4] and electrical applications such as resonators and capacitors [5][6][7][8] which is a perovskite having general formula ABO 3 , with a Pcmn space group and can be used for capacitors or dielectric resonators for microwave applications due to their low loss tangent (tan δ) and high-dielectric constant (ε r ) [7,8]. It has a dielectric constant around 30, quality factor (Q = 1/tan δ) of about 3000 at about 5.6 GHz, and a temperature coefficient of resonant frequency (τ f ) of −26.5 ppm/ • C when prepared in conventional solid state synthesis [9].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and microwave dielectric properties of nanocrystalline CaZrO3 ceramics

Prasanth

Kumar

Pazhani

et al. 2008

Journal of Alloys and Compounds

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Newly developed ternary (Ca, Sr, Ba) zirconate ceramic system for microwave resonators

Cited by 57 publications

References 4 publications

Microemulsion route to the synthesis of nanoparticles

Microemulsion route to the synthesis of nanoparticles

Effect of Firing Temperatures on Phase and Morphology Evolution of CaZrO₃Ceramics Synthesized Using the Combustion Technique

Synthesis, characterization and microwave dielectric properties of nanocrystalline CaZrO3 ceramics

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Newly developed ternary (Ca, Sr, Ba) zirconate ceramic system for microwave resonators

Cited by 57 publications

References 4 publications

Microemulsion route to the synthesis of nanoparticles

Microemulsion route to the synthesis of nanoparticles

Effect of Firing Temperatures on Phase and Morphology Evolution of CaZrO3Ceramics Synthesized Using the Combustion Technique

Synthesis, characterization and microwave dielectric properties of nanocrystalline CaZrO3 ceramics

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Product

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Effect of Firing Temperatures on Phase and Morphology Evolution of CaZrO₃Ceramics Synthesized Using the Combustion Technique