Papers by Keyword: TiO2-ZrO2

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Authors: José Vitor C. Souza, Pedro José Castro, Maria do Carmo de Andrade Nono, Sergio Luiz Mineiro
Abstract: For microwave applications, including mobile and satellite communications, ceramic resonators should have a high dielectric constant, low dielectric losses, and high frequency stability. In this sense, TiO2-ZrO2 ceramics have been investigated as a function of sintering behavior, phase composition, and microstructure. The ceramics were densified reaching a value of about 86% of theoretical density at 1400°C sintering temperature. The ceramics are prepared by mixing raw materials with the following TiO2-ZrO2 weight % ratio: 100 to 0, 90 to 10, and 80 to 20, respectively. The measured dielectric constants are between 79 and 88 values, while the quality factor due to dielectric losses are between 2820 and 5170. These results point out the influence of Ti/Zr ratio on controlling the dielectric properties.
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Authors: Jae-Kil Han, Sung Min Choi, Ik Hyun Oh, Fumio Saito, Byung Teak Lee
Abstract: TiO2(1-.ZrO2. (.=- 0.2, 0.4, 0.6 and 0.8) composite powders having a homogeneous distribution and nanocrystalline were successfully synthesized by sol-gel process using titanium iso-propoxide as precursor. The particle sizes of TiO2-ZrO2 powders calcined at 600°C were measured ranging from 10nm to 19nm by XRD and TEM. For the comparison of photocatalytic activity, TiO2-ZrO2 composite powders were tested in the degradation of phenol and the photoreduction of inorganic pollutants. The degradation of phenol increased with increase the content of anatase TiO2 phase.
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Authors: José Vitor C. Souza, Pedro José Castro, Maria do Carmo de Andrade Nono, Sergio Luiz Mineiro
Abstract: Dielectric ceramics have been widely investigated and used for microwave applications such as resonators and filters. The present study deals with the influence of sintering temperature on microwave dielectric properties of TiO2 ceramics with 10, 20, and 30 wt% ZrO2. Three compositions have been developed through mixing procedures and then tested for each sintering temperature: 1500 and 1400 °C. X-ray diffraction and scanning electron microscopy are carried out aiming to explain the ceramic behavior of each sample. The dielectric constants of different ceramics for both temperatures varied from 85.4 to 62.6, while their quality factor due to dielectric losses varied from 3110 to 1630. The Q decrease is attributed to the non uniform grain growth and to the obtained crystalline phases. The best microwave parameters were obtained for the ceramics sintered at 1400 °C, which can be applied in microwave circuits as dielectric resonators.
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