Zn doping-induced enhanced dielectric response of quantum paraelectric SrTiO3

The dielectric and ferroelectric behaviors of Zn2+-doped SrTiO3 (STO-Zn) have been investigated to explore the effects of Zn-doping on quantum fluctuations and ferroelectric instability. Structurally, the smaller Zn2+ ions occupy the Sr2+ sites at low substitution level up to 0.9% and an over-substitution may lead to impurity phase. It is found that no ferroelectric or relaxor-like anomaly emerges, while significantly enhanced dielectric constant and broad dielectric plateau are identified upon the substitution. These phenomena observed in Zn2+-doped STO are slightly different from well investigated Ca2+-doped STO and additional mechanism besides the off-centrality of Zn2+ ions at Sr2+ sites is possible. The transverse-field Ising model is consulted to explain self-consistently the observed effects. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3703070]