We have investigated the spontaneous polarization(P_(s))of Ba_(1-x)Ca_(x)TiO_(3)(BCT)by polarization hysteresis measurements using single crystals and by density functional theory(DFT)calculations.Single crystals of B...We have investigated the spontaneous polarization(P_(s))of Ba_(1-x)Ca_(x)TiO_(3)(BCT)by polarization hysteresis measurements using single crystals and by density functional theory(DFT)calculations.Single crystals of BCT(x=0:07)were grown by a top-seeded solution growth(TSSG)method.The polarization measurements show that the crystals(x¼0:07)have a Ps of 26.0μC/cm^(2),which is slightly small compared with BaTiO_(3)(27.3μC/cm^(2)).Our DFT calculations based on a supercell approach show that Ca atoms are markedly displaced cooperatively with the adjacent Ti atoms along the Ps direction.It is suggested that the CaTiO_(3)-like octahedral rotation is constructed in the BCT supercell around the Ca atoms,which is the origin of the smaller Ps observed for the BCT crystals.展开更多
Single crystals of x(Bi,K)TiO_(3)-(1-x)(Bi,Na)TiO_(3)(0.11≤x≤0.47) were grown by a flux method and their polarization and piezoelectric properties were investigated along h100i cubic at 25℃.Rietveld analysis of pow...Single crystals of x(Bi,K)TiO_(3)-(1-x)(Bi,Na)TiO_(3)(0.11≤x≤0.47) were grown by a flux method and their polarization and piezoelectric properties were investigated along h100i cubic at 25℃.Rietveld analysis of powder X-ray diffraction data provides a tentative phase diagram in this system.rhombohedral R3c for x≤0.22,pseudocubic for 0.22<x<0.3 and tetragonal P4mm for 0.3≤x.Piezoelectric strain properties show that the crystals(x=0.38)exhibited an extremely large piezoelectric strain constant of 637 pm/V.展开更多
基金This research is partly granted by the Japan Society for the Promotion of Science(JSPS)through the Funding Program for Next Generation World-Leading Researchers(NEXT Program),initiated by the Council for Science and Technology Policy(CSTP)The SR experiments were carried out with the approval of the Japan Synchrotron Radiation Research Institute(JASRI+1 种基金Proposal Nos.2011B1386,2012A1359 and 2012B1243)supported by a Grant-in-Aid for Research Fellows of the Japan Society for the Promotion of Science(No.11J06837).
文摘We have investigated the spontaneous polarization(P_(s))of Ba_(1-x)Ca_(x)TiO_(3)(BCT)by polarization hysteresis measurements using single crystals and by density functional theory(DFT)calculations.Single crystals of BCT(x=0:07)were grown by a top-seeded solution growth(TSSG)method.The polarization measurements show that the crystals(x¼0:07)have a Ps of 26.0μC/cm^(2),which is slightly small compared with BaTiO_(3)(27.3μC/cm^(2)).Our DFT calculations based on a supercell approach show that Ca atoms are markedly displaced cooperatively with the adjacent Ti atoms along the Ps direction.It is suggested that the CaTiO_(3)-like octahedral rotation is constructed in the BCT supercell around the Ca atoms,which is the origin of the smaller Ps observed for the BCT crystals.
基金This study was partly supported by Grant-in-Aid for Scientific Research on Priority Areas"Novel States of Matter Induced by Frustration"(19052002)the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy,Republic of Korea。
文摘Single crystals of x(Bi,K)TiO_(3)-(1-x)(Bi,Na)TiO_(3)(0.11≤x≤0.47) were grown by a flux method and their polarization and piezoelectric properties were investigated along h100i cubic at 25℃.Rietveld analysis of powder X-ray diffraction data provides a tentative phase diagram in this system.rhombohedral R3c for x≤0.22,pseudocubic for 0.22<x<0.3 and tetragonal P4mm for 0.3≤x.Piezoelectric strain properties show that the crystals(x=0.38)exhibited an extremely large piezoelectric strain constant of 637 pm/V.
