Effects of core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO3

Abstract

Two sets of (Mg,Y)-doped BaTiO 3 samples were prepared to investigate the effects of the core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO 3 : one set with samples of the same grain size but different core sizes and the other with samples of the same core size but different shell thicknesses. The microstructural variation of the samples was characterized and their dielectric properties were measured. For both sets of samples, the temperature stability of the dielectric properties was generally improved with a reduction of the volumetric shell ratio regardless of the grain and core sizes. There existed, however, a limit of the reduction; for the studied range, shell thickness of one third of the core radius appeared to be an optimum thickness for the given amounts of dopants. It was concluded that the volumetric shell ratio should be optimized so as not to exceed a specific limit, for our case two thirds of the grain volume, to secure temperature stability of the dielectric properties of BaTiO 3 .

The relationship between the micro-mechanism and macroscopic dielectric properties in Ba 1−x Bi x Ti 1−x−y Zn 0.75x W 0.25x+y O 3+y systems

“…According to the principles of crystal chemistry and radiusmatching rule [30], the radius of Bi 3 þ (1.30 Å) is small than the value of Ba 2 þ (1.61 Å) owing to 12-fold coordination in A-site [27]. The equivalent radius of B-site ions Zn 2 þ (0.74 Å) and W 6 þ (0.60 Å) is considerably larger than that of Ti 4 þ (0.605 Å) in sixfold coordination [28][29][30][31][32].…”

“…The equivalent radius of B-site ions Zn 2 þ (0.74 Å) and W 6 þ (0.60 Å) is considerably larger than that of Ti 4 þ (0.605 Å) in sixfold coordination [28][29][30][31][32]. As a result, the substitution of A and B-site will suppress polarization of Ti-O octahedral.…”

Core–Shell Lead–Free Piezoelectric Ceramics: Current Status and Advanced Characterization of the Bi1/2Na1/2TiO3–SrTiO3 System

“…The core–shell approach is an alternative route to achieve high and reliable electromechanical properties with a reduced hysteresis. Core–shell materials have been successfully implemented into dielectrics with exceptional, temperature stable properties . Although this approach holds much promise for piezoelectrics, it has been to date barely studied.…”

Oxidation-induced strain relaxation and related dielectric-temperature behavior in core/shell grained BaTiO3

“…These chemical compositions of the samples are known to easily reveal the core/shell structure after sintering [20][21][22]. With a suitable amount, the two different rare-earth dopants, Y and Dy, can respectively maintain and loose the coherency at the core/shell interface [23,24], and thus the core/shell grains can have a high and low residual strain in them.…”