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An innovative CaSiO3 dielectric material from eggshells by sol–gel process


Calcium silicate (CaSiO3), wollastonite, with a molar ratio of CaO:SiO2 of 1:1, was synthesized by a sol–gel process and sintered at 1,100°C for 1 h. The synthesis of calcium silicate was carried out using chicken eggshells as the starting material possessing several advantages such as low cost, high purity, and less moisture sensitivity, when compared with those obtained from metal alkoxide precursors via the sol–gel process. The CaSiO3 samples have the triclinic or anorthic phase formations and good electrical properties. The dielectric constant and electrical conductivity are 62.59 ± 0.44 and 8.0052 × 10−4 (Ω.m)−1, respectively, at 25°C and 1 MHz. The transmission electron microscopy (TEM) images of the samples show a good dispersion and uniform particles with an average diameter of about 0.5 nm. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Simultaneous thermal analysis (STA) were used to verify the synthesis.

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The authors would like to thank the following: The Petroleum and Petrochemical College and the Scientific and Technological Research Equipment Centre of Chulalongkorn University; and, the Departments of Materials Engineering and Physics, at Kasetsart University for the use of the analytical equipment. We are also grateful for the grant support from the Kasetsart University Research and Development Fund, fiscal year 2009. AS would like to acknowledge the financial supports from the Conductive and Electroactive Polymers Research Unit, the Thailand Research Fund (TRF-BRG), and the Royal Thai Government (Budget of Fiscal Year 2552).

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Correspondence to Anuvat Sirivat.

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Tangboriboon, N., Khongnakhon, T., Kittikul, S. et al. An innovative CaSiO3 dielectric material from eggshells by sol–gel process. J Sol-Gel Sci Technol 58, 33–41 (2011).

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  • Sol–gel process
  • Calcium silicate
  • Dielectric materials
  • Eggshells