Lead-free relaxor ferroelectrics with 'TTB' structure

Preparation and dielectric characterisations of a great number of TTB-type ceramics have allowed us to show that some of them present relaxor behaviour, due to the occupation of the same crystallographic site by two different cations or anions. One of the cation in the octahedral site has to be ferroelectrically active. The relaxor effect is correlated to either cationic distribution disorder in the same site or dilution of the ferroelectric character