Effect of Dopants on Microwave Dielectric Properties of Ba(Zn_(1/3)Ta_(2/3))O_3 Ceramics

摘要

Ba(Zn_(1/3)Ta_(2/3))O_3 (BZT) has been prepared with various amounts of different dopants such as oxides of divalent, trivalent, tetravalent, pentavalent and hexavalent elements. Effect of these dopants on microwave dielectric properties of BZT is investigated. Some of the dopants are found to increase quality factor (Q). Most of the dopants increase the temperature coefficient of resonant frequency (τ_f). Annealing undoped BZT increased the order parameter and quality factor. Small amounts of dopants such as that of oxides of Zr, Ga, Cr, Ce, Sn, In, Mn and Sb increased the quality factor. The doped ions substitute for the ordered B ions decreasing the order parameter. Annealing Ga and In doped BZT decreased the Q factor where as it increased for Zr, Cr, Ce, Sn, Mn, Sb doped samples. Doping BZT with Zr, Ga, Cr, Ce, Sn, In, Mn, Sb decreased the order parameter but at the same time increased the quality factor indicating that order parameter alone is a poor indicator of quality factor. The quality factor is found to depend on the dopant ionic radii and dopant concentration. The quality factor increased when the ionic radius of the dopant is close to the ionic radius of the B site ions Zn or Ta.