Characterization and dielectric behavior of willemite and TiO2-doped willemite ceramics at millimeter-wave frequency

• Published in: Journal of the European Ceramic Society Vol. 26; no. 10-11; pp. 1827 - 1830
• Main Authors: YIPING GUO, OHSATO, Hitoshi, KAKIMOTO, Ken-Ichi
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Oxford Elsevier 2006
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electrotechnical and electronic ceramics; Exact sciences and technology; Permittivity (dielectric function); Physics; Technical ceramics; Scanning electron microscopy; Zinc silicate; Electrical properties; Dielectric properties; Willemite; Experimental study; X ray diffraction; Oxide ceramics; Substrates; Manufacturing; Microstructure; Microstructure final; Electroceramics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2005.09.008

Willemite ceramics (Zn2SiO4) have been prepared in the temperature range 1280-1340 C. They possess excellent millimetre-wave dielectric properties: a dielectric constant epsilonr value of 6.6, a quality factor Qxf value of 219000 GHz and a temperature coefficient of resonant frequency tauf value of -61 ppm/C. By adding TiO2 with a large positive tauf value (450 ppm/C), near zero tauf value can be achieved in a wide sintering temperature range. With 11 wt% of TiO2, an epsilonr value of 9.3, a Qxf value of 113000 GHz, and a tauf value of 1.0 ppm/C are obtained at 1250 C. The relationship between microstructure and properties was also studied. The results show that willemite with appropriate TiO2 is an ideal temperature stable, low epsilonr and high Qxf dielectric for millimetre-wave application. 6 refs.