Microwave dielectric properties of new complex perovskites: (Ba < inf > 1/3 < /inf > Ln < inf > 2/3 < /inf > )(Zn < inf > 1/3 < /inf > Ti < inf > 2/3 < /inf > )O < inf > 3 < /inf > (Ln = La, Pr, and Nd) and (Ba < inf > (1+X)/3 < /inf > La < inf > (2-X)/3 < /inf > )(Zn < inf > 1/3 < /inf > Ti < inf > (2-X)/3 < /inf > Nb < inf > X/3 < /inf > )O < inf > 3 < /inf >

Abstract

Complex perovskites of the formula (Ba1/3Ln2/3) (Zn1/3Ti2/3)O3 (Ln = La, Pr, and Nd) and (Ba(1+X)/3La(2-X)/3)(Zn1/3Ti (2-X)/3NbX/3)O3 (Ln = La, Pr, and Nd) and (Ba1+x/3La2-x/3)(Zn1/3Ti2-x/3Nbx/3)O3 (x = 0:5; 0:75; 1:0; 1:25) have been synthesized by solid state reactions and are found to crystallize in the cubic structure (space group Pm3̄m) from Rietveld refinement of powder X-ray data. The lattice parameter and the grain size increases with Nb substitution. Among the above oxides, (Ba1/3Ln2/3)(Zn 1/3Ti2/3)O3 (Ln = La, Pr, and Nd) and (Ba (1+X)/3La(2-X)/3)(Zn1/3Ti (2-X)/3NbX/3)O3 shows the best dielectric properties with quality factor (Q) of 3139 at 6.67GHz and a temperature coefficient of resonant frequency (τf) of -10:8 ppm/°C. Further, the temperature coefficient of resonant frequency (τf) shows a large and systematic variation (with a continued decrease and a change of sign from positive to negative) with increase in Nb content. © 2009 The Japan Society of Applied Physics.