Abstract:
Nb-doped SrTiO
3 ceramics were prepared via sintering without extra pressure.Effects of Nb
2O
5 contents on the phase composition,microstructures and microwave dielectric loss of SrTiO
3 ceramics were investigated.Results showed that Nb
2O
5 doping has no evident impact on phase composition but hinders the densification and promotes the grain growth of samples to some extent.Upon increasing the amount of Nb
2O
5 doping,the permittivity (
εr) of SrTiO
3 ceramics decreased from 296 to 230 and the temperature coefficient reduced from 1.714×10
-3 to 1.629×10
-3℃
-1 gradually,while the
Q×
f value increased sharply at first and then decreases slowly.When 0.15% (mass fraction) Nb
2O
5 were doped,the dielectric loss of SrTiO
3 ceramics was the lowest,and the
Q×
f reached 6 281 GHz (the dielectric constant was about 270 and the temperature coefficient 1.684×10
-3℃
-1),which is about 5.5 times as high as that of the un-doped samples (1 145 GHz). The reasons for the changes of microstructures,dielectric constants,temperature coefficients especially the dielectric loss were also discussed.