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Doping and Atomic Site Substitution in the Dielectric Ceramics Ti(Al)O 2 Rutile and (1− x )Ca 2/5 Sm 2/5 TiO 3 – x Li 1/2 Sm 1/2 TiO 3 Perovskite
Author(s) -
Yamashita Toru,
Barry John,
Taylor Richard
Publication year - 2010
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2009.03318.x
Subject(s) - materials science , lattice constant , orthorhombic crystal system , dielectric , rietveld refinement , analytical chemistry (journal) , doping , powder diffraction , crystal structure , perovskite (structure) , crystallography , mineralogy , diffraction , chemistry , optics , physics , optoelectronics , chromatography
Temperature‐stable, high‐permittivity (high‐dielectric constant) ceramics are used as resonators for microwave telecommunications. Research and development in this area is aimed at increasing the dielectric constant (in order to reduce component size) while maintaining very high quality factor (low dielectric loss). This present work is a synchrotron X‐ray powder diffraction study of high quality factor, high permittivity ceramics of the Ti(Al)O 2 and (1− x )Ca 2/5 Sm 2/5 TiO 3 – x Li 1/2 Sm 1/2 TiO 3 families. The synchrotron powder diffraction was used to investigate doping of Al onto the Ti site in Ti(Al)O 2 . It was found that the lattice parameters in Ti(Al)O 2 are not affected by the Al doping. Although this null result does not give any evidence for substitution of Al on the Ti site, it does not exclude the possibility that a small proportion of the Al ions do substitute for Ti in Ti(Al)O 2 . In (1− x )Ca 2/5 Sm 2/5 TiO 3 – x Li 1/2 Sm 1/2 TiO 3 the variation of lattice parameters and crystal structure versus x , and the possibility of substitution of Li onto the Ti site were investigated. Single phase samples with the orthorhombic CaTiO 3 perovskite structure were obtained for 0.20< x <0.50. It was found that the unit cell volume increased in an inverse linear relationship with the (decreasing) vacancy concentration. Rietveld analysis of the powder diffraction data shows that there is no substitution of Li on the Ti site in (1− x )Ca 2/5 Sm 2/5 TiO 3 – x Li 1/2 Sm 1/2 TiO 3 .