Low Loss Dielectrics in the Ca(B'1/2Nb1/2)O3[B'=Lanthanides, Y] System

Autor: Mailadil Thomas Sebastian, L. Abdul Khalam
Rok vydání: 2007
Předmět:
Zdroj: Journal of the American Ceramic Society. 90:1467-1474
ISSN: 1551-2916
0002-7820
DOI: 10.1111/j.1551-2916.2007.01547.x
Popis: The Ca(B′1/2Nb1/2)O3 [B′=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb, and In] complex perovskites have been prepared by conventional solid-state ceramic route. The structure and microstructure of the ceramics have been characterized by X-ray diffraction and scanning electron microscopy methods. The ceramics have dielectric constant (ɛr) in the range 23–32, normalized Q-factor (Qu×f) 11 000–38 000 GHz and temperature coefficient of resonant frequency (τf) −43–5.2 ppm/°C. The microwave dielectric properties of Ca(B′1/2Nb1/2)O3 ceramics are found to depend on the ionic radii of B′-site elements and tolerance factor (t). The substitution of Ba2+ and Sr2+ for Ca2+ resulted a phase transition in Ca(B′1/2Nb1/2)O3 ceramics. The (Ca0.05Ba0.95) (Y1/2Nb1/2)O3 has τf close to zero (1.2 ppm/°C) with ɛr=35 and Qu×f=48 500 GHz and is proposed as a useful material for base station applications. Dielectric properties of the Ca(B′1/2Nb1/2)O3 ceramics were tailored by the addition of TiO2 and CaTiO3.
Databáze: OpenAIRE