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Tunable Sr4Ta2O9-B’2O3 [B’ = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er and Yb] microwave dielectrics; A novel method of synthesis
L. Abdul Khalam
The Sr4Ta2O9+ (x)BÂ’2O3 ceramics, [BÂ’ = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er and Yb] for x = 0-15 have been synthesized by a different solid state ceramic route without any sintering aid. Sr(BÂ’1/2Ta1/2)O3 perovskites were prepared by Sr4Ta2O9: BÂ’2O3 = 1:1 method. The microwave dielectric properties of the ceramics were investigated and could be tuned by varying the BÂ’2O3 content. The structure and microstructure of the ceramics have been characterized byX-ray diffraction and SEMtechniques. The dielectric properties of Sr(BÂ’1/2Ta1/2)O3 ceramics depends on RE- ionic radii. Nearly zero ôf for Sr4Ta2O9+ (x)Sm2O3was obtained for x = 13. The Sr4Ta2O9+BÂ’2O3 ceramics [BÂ’ = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er and Yb] have år= 27.9- 33.2, Qu × f = 6200-56400 GHz and ôf = -71 to -35 ppm/oC.Aslight deviation from stoichiometry affects the dielectric properties of these ceramics.
