Structure and dielectric properties of yttrium-doped Ca0.28Ba0.72Nb2O6 ceramics

An unfilled tungsten bronze-structured ferroelectric ceramic, Ca0.28Ba0.72Nb2O6 (CBN28), has been doped with Y3+ to produce ceramics a nominal composition, (Ca0.28Ba0.72)1–3w/2YwNb2O6 [0 ≤ w 0.05]. The substitution of for Ca2+/Ba2+, and consequent additional vacancy formation, is assumed occur on the A1/A2 sites. This resulted in minor reduction c lattice parameter, unit cell volume. For undoped CBN28, there was slightly diffuse relative permittivity-temperature (εr-T) peak at 268 ⁰C. became much broader sample compositions = 0.04 0.05 temperature showed level frequency dependence consistent weak relaxor behaviour. polarisation-electric field loops narrower samples 0.05, corresponding remnant polarisation value, from 2.4 0.8 µC cm−2 (30 kV cm−1). Y exhibited stable permittivity over wide range, variation being within± 15% median value 36 ⁰C 218 when measured 1 kHz. Consequently, we suggest that A site donor-doping aliovalent B doping CBN holds potential industry standard, stable, high dielectrics (ɛr ≥ 500 ± - 55–250 + ⁰C).