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Dielectric properties of BZT ceramics for microwave applications

A. IOACHIM1,* , M. I. TOACSĂN1, L. NEDELCU1, M. G. BANCIU1, C. A DUŢU1, E. ANDRONESCU2, S. JINGA2, P. NITA3, H. V. ALEXANDRU4

Affiliation

  1. National Institute of Materials Physics, P.O. Box MG-7, RO 077125, Bucharest-Magurele, Romania
  2. University “Politehnica” of Bucharest, Romania
  3. METAV S.A, Bucharest, Romania
  4. University of Bucharest, Romania

Abstract

High permittivity dielectric materials ( ε r > 20) are used in mobile communications due to low dielectric loss in microwaves and millimeter waves, specific temperature dependence of the dielectric properties and high dielectric permittivity, which allows device miniaturization. Preparation of Ba(Zn1/3 Ta2/3)O3 ceramic materials (BZT) with optimal properties for applications requires special thermal treatments due to the difficult control of the cationic ordering. The samples were prepared by using solid-state reaction, doped with Eu2O3, ZrO2, Nb2O5, or Al2O3-Y2O3 and sintered at the following temperatures: 1400, 1500, 1550 oC for 2 or 3 hours. In order to improve the microwave properties, annealing treatments at 1410 oC for 10 h or 30 h were performed on ceramic samples. XRD was used for compositional and structural characterization. The XRD data allowed the study of the transition from the pseudo-cubic cell to the hexagonal cell. The dielectric properties were measured in the microwave range and were correlated with additives and structural properties. Sintering temperatures greater than 1500 oC are required for doped BZT compositions, in order to obtain high dielectric constant ( ε r ~ 28) and high quality factor (Q = 10000 at 10 GHz)..

Keywords

Tantalates, Sintering parameters, Additives, Dielectric properties, High quality factor.

Submitted at: Nov. 14, 2006
Accepted at: June 15, 2007

Citation

A. IOACHIM, M. I. TOACSĂN, L. NEDELCU, M. G. BANCIU, C. A DUŢU, E. ANDRONESCU, S. JINGA, P. NITA, H. V. ALEXANDRU, Dielectric properties of BZT ceramics for microwave applications, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 6, pp. 1833-1838 (2007)