Predominant factors for quantum paraelectric-quantum ferroelectric transition in SrTiO3-based oxides

We have tried to modify the low-temperature quantum paraelectric state of S rTiO3 by small amount of A-site doping. Investigation of the dielectric pro perties of D0.001Sr0.99TiO3 (D = Li, Ba, Ca, Mg, La, Y, Sm) polycrystalline samples showed that isovalent and heterovalent substitutions have differen t effects on the dielectric behavior. It is found that not only the atomic radius of dopant D but also oxygen vacancies and A-site vacancies determine the low-temperature states of the samples. (C) 2000 Elsevier Science B.V. All rights reserved.