Microwave dielectric properties of La^sub 5^(Ti^sub 4^B)O^sub 17^ and Nd^sub 5^(Ti^sub 4^B)O^sub 17^ (B = Cr, Fe) ceramics

• Published in: Journal of materials science. Materials in electronics Vol. 26; no. 3; p. 1918
• Main Authors: Muhammad, Raz, Iqbal, Yaseen, Rambo, Carlos Renato
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01.03.2015
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-014-2630-7

Compositions in the A^sub 5^B^sub 5^O^sub 17^ (A = La, Nd, B = Cr, Fe) series were processed through a mixed oxide solid state sintering route. X-ray diffraction revealed an orthorhombic (Pnnm) symmetry for La^sub 5^Ti^sub 4^FeO^sub 17^ and monoclinic (P2^sub 1^/b) symmetry for Nd^sub 5^Ti^sub 4^FeO^sub 17^, associated with the higher tolerance factor of Nd^sub 5^Ti^sub 4^FeO^sub 17^ than Nd^sub 5^Ti^sub 4^CrO^sub 17^. The compounds exhibited relative permittivity [straight epsilon]^sub r^ ~27-37, Quality factor Q × f ^sub o^ ~5,735-7,419 GHz and temperature coefficient of resonance frequency τ^sub f^ ~ -23.86 to -104 ppm/^sup o^C. The observed low density indicated that the microwave dielectric properties can be improved by improving the density, and τ^sub f^ can be tuned through zero via partial substitution of Sr at the A-site.