Microwave Dielectric Properties of Sr(B′_1/2Nb_1/2)O₃ [B′=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb, and In] Ceramics

Abstract

Sr(B′1/2Nb1/2)O3 [B′=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb, and In] ceramics were prepared by the conventional solid‐state ceramic route. The crystal structure and microstructure of the ceramics were characterized by X‐ray diffraction and scanning electron microscopic methods, and the dielectric properties were measured in the microwave range. Addition of a small amount of CeO2 as a sintering aid improved the densification and dielectric properties of the ceramics. The effects of cation substitution and glass addition on the microwave dielectric properties of the ceramics were also investigated. Glass addition resulted in the lowering of the processing temperature of the materials without much affecting the dielectric properties, whereas cation substitution resulted in the variation of the temperature coefficient of resonant frequencies. A correlation of dielectric properties with the tolerance factor and ionic radii of B′‐site elements of the ceramics has been observed.

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

“…However a low‐quality factor ( Q u × f =11 000 GHz) was obtained for Ca(Gd 1/2 Nb 1/2 )O 3 ceramic. In general B′=Gd‐based A(B′ 1/2 B″ 1/2 )O 3 type ceramics were reported 16,17,35,36 to have relatively low‐quality factors. The Ca ion has smaller ionic size and is comparable with B′‐site ions.…”

“…(A) (1−x)Ca(Y 1/2 Nb 1/2 )O 3 –xBa(Y 1/2 Nb 1/2 )O 3 : It has been reported 17 that the Ba(Y 1/2 Nb 1/2 )O 3 has ɛ r =29, Q u × f =49 600 GHz and τ f =15 ppm/°C. As Ba(Y 1/2 Nb 1/2 )O 3 has positive τ f with high‐quality factor, it is used to tailor the dielectric properties of Ca(Y 1/2 Nb 1/2 )O 3 which has a negative τ f , by solid solution formation.…”

“…As Ba(Y 1/2 Nb 1/2 )O 3 has positive τ f with high‐quality factor, it is used to tailor the dielectric properties of Ca(Y 1/2 Nb 1/2 )O 3 which has a negative τ f , by solid solution formation. Ba(Y 1/2 Nb 1/2 )O 3 was reported 17,18 with cubic symmetry whereas Ca(Y 1/2 Nb 1/2 )O 3 is orthorhombic. We have prepared the (1− x )Ca(Y 1/2 Nb 1/2 )O 3 – x Ba(Y 1/2 Nb 1/2 )O 3 for different values of x by conventional solid state method.…”

“…Since the 1970s several materials, like Ba(Mg 1/3 Ta 2/3 )O 3 , 5 Ca–Li 2 O–Ln 2 O 3 –TiO 2 , 6 Ba 2 Ti 9 O 20 , 7 MgTiO 3 –CaTiO 3 , 8 (Zr,Sn)TiO 4 , 9 Ba(Zr,Zn,Ta)O 3 , 10 etc., have been developed for microwave use. Other complex perovskite‐related structures, especially niobium and tantalum based oxides, 11–17 have been found to be good candidates for novel dielectric applications. Many of these oxides are complex ternary or quaternary niobium/tantalum‐containing compounds having ordered perovskite‐related structures 18,19 .…”

Relaxations in Ba2BiSbO6 double complex perovskite ceramics

“…[8][9][10][11][12][13][14] For the 1:1 ratio case, one common application is as microwave dielectrics. [15][16][17][18][19] For this ratio the structure normally shows ordering in the BЈ and BЉ ion distributions that occur in an alternate form along with the three crystalline axes. This ordering is commonly called NaCl ordered and the aristotype structure is cubic with Fm3m symmetry.…”