A structural analysis concerning the incorporation of dysprosium into A-and/or B-sites of the lead titanate is shown.The two"boundary"refinements are presented,i.e.,Dy^(2+)substitutes for Pb^(2+)(Dy^(3+)subs...A structural analysis concerning the incorporation of dysprosium into A-and/or B-sites of the lead titanate is shown.The two"boundary"refinements are presented,i.e.,Dy^(2+)substitutes for Pb^(2+)(Dy^(3+)substitutes for Ti^(4+))and Dy^(3+)substitutes for Pb^(2+)(Dy^(3+)substitutes for Ti^(4+)).The results offer quantitative information about the incorporation into both crystallographic sites.The increase of Dy^(3+)fraction into B-site provides the increase of the Ti^(4+)atomic displacement along the[001]direction and the tetragonal distortion.展开更多
The electrocaloric effect(ECE)is studied in(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3) relaxor ferroelectric ceramic by using an“indirect method”.The electric dependence for the polarization(hysteresis...The electrocaloric effect(ECE)is studied in(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3) relaxor ferroelectric ceramic by using an“indirect method”.The electric dependence for the polarization(hysteresis loops)has been obtained for several temperatures showing typical relaxor characteristics.The temperature change△T,which is associated with the ECE,is calculated by using the temperature dependence for the polarization.A maximum value for△T is observed for temperatures close above the freezing temperature,showing an indirect evidence of that critical temperature.The results are discussed considering the contribution of the polar nanoregions to the polarization.展开更多
基金the ICTP for financial support of the Latin-American Network of Ferroelectric Materials(NTE-43)Tongji University,Shanghai,China.
文摘A structural analysis concerning the incorporation of dysprosium into A-and/or B-sites of the lead titanate is shown.The two"boundary"refinements are presented,i.e.,Dy^(2+)substitutes for Pb^(2+)(Dy^(3+)substitutes for Ti^(4+))and Dy^(3+)substitutes for Pb^(2+)(Dy^(3+)substitutes for Ti^(4+)).The results offer quantitative information about the incorporation into both crystallographic sites.The increase of Dy^(3+)fraction into B-site provides the increase of the Ti^(4+)atomic displacement along the[001]direction and the tetragonal distortion.
基金The author wishes to thank to the Third World Academy of Sciences(RG/PHYS/LA No.99-050,02-225 and 05-043)for financial support and to ICTP for financial support of LatinAmerican Network of Ferroelectric Materials(NET-43).
文摘The electrocaloric effect(ECE)is studied in(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3) relaxor ferroelectric ceramic by using an“indirect method”.The electric dependence for the polarization(hysteresis loops)has been obtained for several temperatures showing typical relaxor characteristics.The temperature change△T,which is associated with the ECE,is calculated by using the temperature dependence for the polarization.A maximum value for△T is observed for temperatures close above the freezing temperature,showing an indirect evidence of that critical temperature.The results are discussed considering the contribution of the polar nanoregions to the polarization.
