A series of Mn-doped TiO2 nanowires(NWs) were prepared by hydrothermal method at the mole fraction of Mn changing from 0 to 12.0%.X-ray powder diffraction(XRD) analysis shows that all the samples have pure anatase str...A series of Mn-doped TiO2 nanowires(NWs) were prepared by hydrothermal method at the mole fraction of Mn changing from 0 to 12.0%.X-ray powder diffraction(XRD) analysis shows that all the samples have pure anatase structure.SEM and TEM studies show that the diameter and the length of the Mn-doped TiO2 NWs are larger than those of the undoped TiO2 NWs.Energy dispersive X-ray spectroscopy(EDX) reveals that the samples are composed of Ti,Mn and O.According to magnetization measurements,all samples show ferromagnetic behavior,but only the undoped TiO2 NWs are completely ferromagnetic with a saturated magnetization about 1.0 mA·m2/kg.Mn-doped TiO2 samples exhibit antiferromagnetic and ferromagnetic(AF-FM) behaviors simultaneously.Photoluminescence(PL) spectra demonstrate the existence of MnO2 sublattice.These observations indicate that an AF-WF crossover is induced by the coexistence of TiO2 sublattice and MnO2 sublattice.展开更多
The coexistence of magnetic ordering and ferroelectricity, ing on the origin of ferroelectricity, multiferroic materials known as multiferroics, has drawn a lot of research effort. Depend can be classified into differ...The coexistence of magnetic ordering and ferroelectricity, ing on the origin of ferroelectricity, multiferroic materials known as multiferroics, has drawn a lot of research effort. Depend can be classified into different groups. In this paper, we review re cent progress in the field of multiferroics induced by different forms of charge ordering. In addition to a general description of charge order and electronic ferroelectricity, we focus on two specific systems： （1） charge order with frustration in RFe2O4 （R=Lu, Yb） system; （2） charge ordered perovskite manganites of the type （R1-xCax）MnO3 （R=La, Pr）. The charge ordering can be tuned by external electric fields, which results in pronounced magnetoelectric effects and strong dielectric tunability. Other materials and possible candidates with charge order induced multiferroics are also briefly summarized.展开更多
基金Project(06JJ2031) supported by Natrual Science Foundation of Hunan Province, ChinaProject(06A065) supported by Education Department of Hunan Province, China
文摘A series of Mn-doped TiO2 nanowires(NWs) were prepared by hydrothermal method at the mole fraction of Mn changing from 0 to 12.0%.X-ray powder diffraction(XRD) analysis shows that all the samples have pure anatase structure.SEM and TEM studies show that the diameter and the length of the Mn-doped TiO2 NWs are larger than those of the undoped TiO2 NWs.Energy dispersive X-ray spectroscopy(EDX) reveals that the samples are composed of Ti,Mn and O.According to magnetization measurements,all samples show ferromagnetic behavior,but only the undoped TiO2 NWs are completely ferromagnetic with a saturated magnetization about 1.0 mA·m2/kg.Mn-doped TiO2 samples exhibit antiferromagnetic and ferromagnetic(AF-FM) behaviors simultaneously.Photoluminescence(PL) spectra demonstrate the existence of MnO2 sublattice.These observations indicate that an AF-WF crossover is induced by the coexistence of TiO2 sublattice and MnO2 sublattice.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11074293,51021061 and 50831006)
文摘The coexistence of magnetic ordering and ferroelectricity, ing on the origin of ferroelectricity, multiferroic materials known as multiferroics, has drawn a lot of research effort. Depend can be classified into different groups. In this paper, we review re cent progress in the field of multiferroics induced by different forms of charge ordering. In addition to a general description of charge order and electronic ferroelectricity, we focus on two specific systems： （1） charge order with frustration in RFe2O4 （R=Lu, Yb） system; （2） charge ordered perovskite manganites of the type （R1-xCax）MnO3 （R=La, Pr）. The charge ordering can be tuned by external electric fields, which results in pronounced magnetoelectric effects and strong dielectric tunability. Other materials and possible candidates with charge order induced multiferroics are also briefly summarized.
