Variation of Resonant Frequency with Temperature in Ceramic Resonators Based on Ba₂Ti₉O₂₀ Compositions

Abstract:

Ceramic samples based on barium nanotitanate (Ba₂Ti₉O₂₀) have been produced for application as dielectric resonators aiming at good microwave properties as high dielectric permittivity, low dielectric loss, and high frequency stability. Two different samples were prepared: first a Ba₂Ti₉O₂₀ specimen and second a 1wt% Nb₂O₅-added Ba₂Ti₉O₂₀ composition, using BaO and TiO₂ as precursor materials. Variation of resonant frequency with temperature is commonly represented by temperature coefficient. Experimental tests were carried out to determine the dielectric permittivity (ε) and the temperature coefficient (τ) using a metal box where the specimen was placed between parallel metal surfaces. The resonant frequencies were measured as function of temperature from-20°C to +50°C in a programmable climatic chamber. As a result, the ceramics presented relatively good microwave properties: ε₁=34.6, τ₁=20.5 ppm/°C from initial frequency f₁=7.23 GHz for the former composition, and ε₂=27.5, τ₂=10.1ppm/°C from initial frequency f₂=7.80 GHz for the latter.

• Periodical: Materials Science Forum (Volumes 727-728)
• Pages: 539-544
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.727-728.539
• Online since: August 2012
• Authors: Pedro José Castro, Maria do Carmo de Andrade Nono, José Vitor C. Souza, Sergio Luiz Mineiro
• Keywords: Barium Nanotitanate, Ceramic Resonator, Frequency Stability, Microwave Properties, Temperature Coefficient

References

[1] P.J. Castro: Dielectric resonators and their applications in microwave oscillators., 360 p. Doutorate (Thesis). São Paulo, 1989. Universidade de São Paulo (USP-Eletrica). SP. (In Portuguese).

DOI: 10.29381/0103-8559/20213103334-44

[2] M.C.A. Nono, S.T. Fonseca, P.J. Castro and Yu. Koldayeva: Materials Science Forum Vol. 498-499 (2005), p.324.

[3] J.V.C. Souza, P.J. Castro, M.C.A. Nono and A.R. Siqueira: Materials Science Forum Vol. 591-593 (2008), p.381.

[4] P.J. Castro and M.C.A. Nono: Journal of Microwaves and Optoelectronics Vol. 1 (1999), p.12.

[5] H.M. O´Bryan and J. Thomson: Journal of the American Ceramic Society Vol. 66 (1983), p.66.

[6] W. Wong-Ng et al.: Journal of Research of the National Institute of Standards and Technology Vol. 106 (2001), p.1197.

[7] N. Wetchakun and S. Phanichphant: Current Applied Physics (2008), p.343.

[8] D.W. Kim, D.Y. Kim and K.S. Hong: Journal of Materials Research Vol. 15 (2000), p.1331.

[9] D.W. Kim, K.H. Ko, D.K. Kwon and K.S. Hong: Journal of the American Ceramic Society Vol. 85 (2002), p.1169.

[10] B.W. Hakki and P.D. Coleman: IRE Transactions on Microwave Theory and Techniques Vol. 8 (1960), p.402.

[11] E.C. Collin: Foundations for Microwave Engineering, ch. 7, McGraw-Hill, Singapore (1992).