Articles

All articles  |  Recent articles

Liquid Phase Effect of Bi₂O₃ and La₂O₃ on Densification, Microstructure and Microwave Dielectric Properties of MgTiO₃ Ceramics

T. Santhosh Kumar¹, D. Goswami², D. Pamu¹

¹ Department of Physics, Indian Institute of Technology Guwahati, Guwahati-781039, India
² Department of Electronics & Communication Engineering, Indian Institute of Technology Guwahati, Guwahati-781039, India

received March 13, 2013, received in revised form April 25, 2013, accepted May 29, 2013

Vol. 4, No. 3, Pages 145-150   DOI: 10.4416/JCST2013-00004

Abstract

MgTiO₃ (MTO) ceramics were prepared by means of the solid-state reaction method with the addition of 0.5 – 1.5 wt% Bi₂O₃ or La₂O₃ as a sintering aid. The effect of Bi₂O₃ or La₂O₃ on the densification, microstructure and microwave dielectric properties of MTO ceramics was investigated. The sintering temperature of MTO ceramics with the addition of Bi₂O₃ or La₂O₃ was lowered to 1200 and 1300 °C, respectively. The lower sintering temperatures were attributed to the liquid phase effect and smaller particle sizes. The microwave dielectric properties showed profound dependence on the sintering temperature as well as the additive concentration. The maximum Q׃₀ values of 71.9 and 136.9 THz were obtained for MTO ceramics with 0.5 wt% Bi₂O₃ and 0.5 wt% La₂O₃, respectively. The microwave dielectric properties of the MTO ceramics showed significant dependence on relative density, average grain size and secondary phases.

Keywords

Keywords: Microwave ceramics, sintering, dielectric properties, scanning electron microscopy, x-ray diffraction

References

¹ Kim, W.S., Kim, E.S., Yoon, K.Y.: Effects of Sm³⁺ substitution on dielectric properties of Ca_1-xSm_2x/3TiO₃ ceramics at microwave frequencies, J. Am. Ceram. Soc., 82, 2111 – 2115, (1999).

² Wang, S.F., Hsu, Y.F., Wang, Y.R., Chang, L.T., Hsu, Y.C., Chu, J.P., Huang, Y.: Densification, microstructural evolution and dielectric properties of Ba_6 – 3x(Sm_1-yNd_y)_8+2xTi₁₈O₅₄ microwave ceramics, J. Eur. Ceram. Soc., 26, 1629 – 1635, (2006).

³ Abothu, I.R., Prasada Rao, A.V., Komarneni, S.: Nanocompo­site and monophasic synthesis routes to magnesium titanate, Mater. Lett., 38, 186 – 189, (1999).

⁴ Wakino, K.: Recent development of dielectric resonator materials and filters in japan, Ferroelectrics, 91, 69 – 86, (1989).

⁵ Takada, T., Wang, S.F., Yoshikawa, S.Y., Jang, S.J., Newnham, R.E.: Effects of glass additions on (Zn,Sn)TiO₄ for microwave applications, J. Am. Ceram. Soc., 77, 2485 – 2488, (1994).

⁶ Zhang, Q.L., Yang, H.: Low-temperature sintering and microwave dielectric properties of MgTiO₃ ceramics, J. Mater Sci: Mater Electron, 18, 967 – 971, (2007).

⁷ Belnou, F., Bernard, F., Houivet, D., Haussonne, J.M.: Low temperature sintering of MgTiO₃ with bismuth oxide based additions, J. Eur. Ceram. Soc., 25, 2785 – 2789, (2005).

⁸ Hakki, B.W., Coleman, P.D.: A dielectric resonator method of measuring inductive capacities in the millimeter range, IEEE Trans. Microwave Theory Tech., 8, 402 – 410, (1960).

⁹ Courtney, W.E.: Analysis and evaluation of a method of measuring the complex permittivity and permeability microwave insulators, IEEE Trans. Microwave Theory Tech., 18, 476 – 485, (1970).

¹⁰ Ferreira, V.M., Baptista, J.L., Petzelt, J., Komandin, G.A., Voitsekhovskii, V.V.: Loss spectra of pure and La-doped MgTiO₃ microwave ceramics, J. Mater. Res., 10, 2301 – 2305, (1995).

¹¹ Rehaman, M.N: Sintering of ceramics, CRC press, London, New York, 2008.

¹² German, R.M., Suri, P., Park, S. J.: Review: liquid phase sintering, J. Mater Sci., 44, 1 – 39, (2009).

¹³ Kim, W.S., Kim, T.H., Kim, E.S., Hoon, K.H.: Microwave dielectric properties and far infrared reflectivity spectra of the (Zr_0.8Sn_0.2) TiO₄ ceramics with additives, Jpn. J. Appl. Phys., 37, 5367 – 5371, (1998).

¹⁴ Cho, W.W., Kakimoto, K., Ohsato, H.: High-Q microwave dielectric SrTiO₃-doped MgTiO₃ materials with near-zero temperature coefficient of resonant frequency, Jpn. J. Appl Phys., 43, 6221 – 6224, (2004).

¹⁵ Yoon, K.H., Kim, Y.S, Kim, E. S.: Microwave dielectric properties of (Zr_0.8Sn_0.2)TiO₄ ceramics with pentavalent additives, J. Mater. Res., 10, 2085 – 2090, (1995).

¹⁶ Petzelt, J., Pacesova, S., Fousek, J., Kamba, S., Zeleny, V., Koukal, V., Schwarzbach, J., Gorshunov, B.P, Volkov, A.A.: Dielectric spectra of some ceramics for microwave applications in the range of 10¹⁰-10¹⁴ hz, Ferroelectrics, 93, 77 – 85, (1989).

¹⁷ Huang, C.L, Weng, M.H., Chen, H.L.: Effect of additives on microstructure and microwave dielectric properties of (Zr,Sn)TiO₄ ceramics, Mater. Chem. Phys., 71, 17 – 22, (2001).

Copyright

Göller Verlag GmbH