Microwave dielectric properties of (Pb,Ca,La)(Fe,Nb)O3+δ ceramics substituted by Ti for B-site

Microwave dielectric properties of B-site substitution by Ti4+ in [(Pb0.5Ca0.5)0.95La0.05][(Fe0.5Nb0.5)1−yTiy]O3+δ (PCLFNT) system were investigated. Qf values and grain sizes of PCLFNT specimens decreased with the increase of Ti4+ content. Dielectric constant εr increased with the increase of Ti4+ content even though the ionic polarizability of Ti4+ ion (αTi=2.93 Å) was lower than that of (Fe,Nb)4+ ions (αB-site=3.13 Å). This is due to the increase of rattling of B-site ions by the smaller Ti4+ substitution. Especially, the microwave dielectric properties of PCLFNT specimens with εr=116.6, Qf=4950 GHz and TCF=+17.4 ppm/°C were obtained at y=0.10.