To investigate the upconversion emission, this paper synthesizes Tm^3＋ and Yb^3＋ codoped Y2O3 nanoparticles, and then coats them with TiO2 shells for different coating times. The spectral results of TiO2 coated nano...To investigate the upconversion emission, this paper synthesizes Tm^3＋ and Yb^3＋ codoped Y2O3 nanoparticles, and then coats them with TiO2 shells for different coating times. The spectral results of TiO2 coated nanoparticles indicate that upconversion emission intensities have respectively been enhanced 3.2, 5.4, and 2.2 times for coating times of 30, 60 and 90 min at an excitation power density of 3.21× 10^2 W. cm^-2, in comparison with the emission intensity of non-coated nanoparticles. Therefore it can be concluded that the intense upconversion emission of Y2O3：Tm^3＋, Yb^3＋ nanoparticles can be achieved by coating the particle surfaces with a shell of specific thickness.展开更多
Complex oxide heterointerfaces can host a rich of emergent phenomena,and epitaxial growth is usually at the heart of forming these interfaces.Recently,a strong crystalline-orientation-dependent two-dimensional superco...Complex oxide heterointerfaces can host a rich of emergent phenomena,and epitaxial growth is usually at the heart of forming these interfaces.Recently,a strong crystalline-orientation-dependent two-dimensional superconductivity was discovered at interfaces between KTaO_(3)single-crystal substrates and films of other oxides.Unexpectedly,rare of these oxide films was epitaxially grown.Here,we report the existence of superconductivity in epitaxially grown LaVO_(3)/KTaO_(3)(111)heterostructures,with a superconducting transition temperature of~0.5 K.Meanwhile,no superconductivity was detected in the(001)-and(110)-orientated LaVO_(3)/KTaO_(3)heterostructures down to 50 mK.Moreover,we find that for the LaVO_(3)/KTaO_(3)(111)interfaces to be conducting,an oxygen-deficient growth environment and a minimum LaVO_(3)thickness of~0.8 nm(~2 unit cells)are needed.展开更多
Ferroelectric polymers,such as poly(vinylidene fluoride-trifluoroethylene)[P(VDF-TrFE)or PVTF]have attracted growing interest in developing flexible devices because of their excellent ferroelectricity and piezoelectri...Ferroelectric polymers,such as poly(vinylidene fluoride-trifluoroethylene)[P(VDF-TrFE)or PVTF]have attracted growing interest in developing flexible devices because of their excellent ferroelectricity and piezoelectricity.High coercive field(E c)inherent to PVTF for switching its polarization,however,is not beneficial for practical memory or sensor device application.Different strategies,including irradiation and interface control,have been thus developed to reduce E c.Despite many efforts,a facile approach to tailoring intrinsic E_(c) of PVTF has not been documented.In this work,an optically controlled E_(c) was reported,which is achieved for the first time by introducing photosensitive MAPbI3 nanocrystals into PVTF matrix.When exposed to the irradiation of 532 nm laser light,a decreased E_(c) of the composites can be achieved reversibly by increasing the light density.The decreased level of E_(c) increases as the MAPbI3 content enhanced,and a 10.7%reduction of E_(c) can be achieved in 15%(mass fraction)MAPbI3/PVTF samples.These results could be attributed to loading an internal stress on PVTF,which was generated by the photostriction of MAPbI3 nanocrystals.This explanation was further supported by in-situ XRD results under irradiation of 532 nm laser light.Our findings may offer the opportunity to optically modulate the ferroelectric properties of PVTF composites for optimized device performances.展开更多
Oxide heterointerface is a platform to create unprecedented two-dimensional electron gas, superconductivity and ferromagnetism, arising from a polar discontinuity at the interface. In particular, the ability to tune t...Oxide heterointerface is a platform to create unprecedented two-dimensional electron gas, superconductivity and ferromagnetism, arising from a polar discontinuity at the interface. In particular, the ability to tune these intriguing effects paves a way to elucidate their fundamental physics and to develop novel electronic/magnetic devices. In this work, we report for the first time that a ferroelectric polarization screening at SrTiO_(3)/PbTiO_(3) interface is able to drive an electronic construction of Ti atom, giving rise to room-temperature ferromagnetism. Surprisingly, such ferromagnetism can be switched to antiferromagnetism by applying a magnetic field, which is reversible. A coupling of itinerant electrons with local moments at interfacial Ti3d orbital was proposed to explain the magnetism. The localization of the itinerant electrons under a magnetic field is responsible for the suppression of magnetism. These findings provide new insights into interfacial magnetism and their control by magnetic field relevant interfacial electrons promising for device applications.展开更多
文摘To investigate the upconversion emission, this paper synthesizes Tm^3＋ and Yb^3＋ codoped Y2O3 nanoparticles, and then coats them with TiO2 shells for different coating times. The spectral results of TiO2 coated nanoparticles indicate that upconversion emission intensities have respectively been enhanced 3.2, 5.4, and 2.2 times for coating times of 30, 60 and 90 min at an excitation power density of 3.21× 10^2 W. cm^-2, in comparison with the emission intensity of non-coated nanoparticles. Therefore it can be concluded that the intense upconversion emission of Y2O3：Tm^3＋, Yb^3＋ nanoparticles can be achieved by coating the particle surfaces with a shell of specific thickness.
基金the National Natural Science Foundation of China(Grant Nos.11934016 and 12074334)the Key R&D Program of Zhejiang Province,China(Grant Nos.2020C01019 and 2021C01002)the Fundamental Research Funds for the Central Universities of China.
文摘Complex oxide heterointerfaces can host a rich of emergent phenomena,and epitaxial growth is usually at the heart of forming these interfaces.Recently,a strong crystalline-orientation-dependent two-dimensional superconductivity was discovered at interfaces between KTaO_(3)single-crystal substrates and films of other oxides.Unexpectedly,rare of these oxide films was epitaxially grown.Here,we report the existence of superconductivity in epitaxially grown LaVO_(3)/KTaO_(3)(111)heterostructures,with a superconducting transition temperature of~0.5 K.Meanwhile,no superconductivity was detected in the(001)-and(110)-orientated LaVO_(3)/KTaO_(3)heterostructures down to 50 mK.Moreover,we find that for the LaVO_(3)/KTaO_(3)(111)interfaces to be conducting,an oxygen-deficient growth environment and a minimum LaVO_(3)thickness of~0.8 nm(~2 unit cells)are needed.
基金Natural Science Foundation of Zhejiang Province,China(No.LR21E020004)National Natural Science Foundation of China(No.U1909212)Project of the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,China(No.2021SX-FR007).
文摘Ferroelectric polymers,such as poly(vinylidene fluoride-trifluoroethylene)[P(VDF-TrFE)or PVTF]have attracted growing interest in developing flexible devices because of their excellent ferroelectricity and piezoelectricity.High coercive field(E c)inherent to PVTF for switching its polarization,however,is not beneficial for practical memory or sensor device application.Different strategies,including irradiation and interface control,have been thus developed to reduce E c.Despite many efforts,a facile approach to tailoring intrinsic E_(c) of PVTF has not been documented.In this work,an optically controlled E_(c) was reported,which is achieved for the first time by introducing photosensitive MAPbI3 nanocrystals into PVTF matrix.When exposed to the irradiation of 532 nm laser light,a decreased E_(c) of the composites can be achieved reversibly by increasing the light density.The decreased level of E_(c) increases as the MAPbI3 content enhanced,and a 10.7%reduction of E_(c) can be achieved in 15%(mass fraction)MAPbI3/PVTF samples.These results could be attributed to loading an internal stress on PVTF,which was generated by the photostriction of MAPbI3 nanocrystals.This explanation was further supported by in-situ XRD results under irradiation of 532 nm laser light.Our findings may offer the opportunity to optically modulate the ferroelectric properties of PVTF composites for optimized device performances.
基金supported by the National Natural Science Foundation of China (U1909212, U1809217, and 11474249)supported by the U.S. Department of Energy, Office of Basic Energy Science, Division of Materials Sciences and Engineering (Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358)。
文摘Oxide heterointerface is a platform to create unprecedented two-dimensional electron gas, superconductivity and ferromagnetism, arising from a polar discontinuity at the interface. In particular, the ability to tune these intriguing effects paves a way to elucidate their fundamental physics and to develop novel electronic/magnetic devices. In this work, we report for the first time that a ferroelectric polarization screening at SrTiO_(3)/PbTiO_(3) interface is able to drive an electronic construction of Ti atom, giving rise to room-temperature ferromagnetism. Surprisingly, such ferromagnetism can be switched to antiferromagnetism by applying a magnetic field, which is reversible. A coupling of itinerant electrons with local moments at interfacial Ti3d orbital was proposed to explain the magnetism. The localization of the itinerant electrons under a magnetic field is responsible for the suppression of magnetism. These findings provide new insights into interfacial magnetism and their control by magnetic field relevant interfacial electrons promising for device applications.
