Development of superparaelectric BaTiO3 system ceramics through heterovalent Mn-Nb co-doping for DC-bias free dielectrics

BaTi(1-2x)Mn (x) Nb (x) O-3 ceramics with 0 <= x <= 0.10 were fabricated and the crystal structure, microstructure, dielectric, and ferroelectric properties were investigated. The samples with x >= 0.06 showed a pseudo-cubic symmetry in a wide temperature range from -150 degrees C to 200 degrees C but exhibited domain structures and a non-linear polarization-electric field response. The dielectric constant for these samples exhibited a comparatively flat response with temperature. The DC-bias dependence of the dielectric constant improved drastically from the samples with x = 0.06. A qualitative model of chemical grain size (CGS), defined by the distance between the co-dopant ions, was proposed which expressed the phonon propagation length in a wide temperature range and thus induced superparaelectricity in the ceramics. A critical CGS = 810 pm was determined geometrically for the sample with x = 0.06 such that samples with x >= 0.06 were superparaelectric in nature.

Automated summary

The crystal structure, microstructure, dielectric, and ferroelectric properties of BaTi(1-2x)Mn(x)Nb(x)O-3 ceramics were investigated. It was found that the samples with x>=0.06 exhibited pseudo-cubic symmetry over a wide temperature range, but also showed domain structures and non-linear polarization-electric field response. The dielectric constant showed improved DC-bias dependence in the sample with x=0.06, and a qualitative model of chemical grain size (CGS) was proposed to explain the superparaelectricity in the ceramics.