Transparent, luminescent and functional nanocomposites demonstrate interesting optical and mechanical properties suitable for many optoelectronic applications. Transparent polymethyl methacrylate （PMMA） polymer nano...Transparent, luminescent and functional nanocomposites demonstrate interesting optical and mechanical properties suitable for many optoelectronic applications. Transparent polymethyl methacrylate （PMMA） polymer nanocornposites modified with thenoyl- trifluoroacetonate （TAA） were fabricated by in situ polymerization and used as hosts for homogenous dispersion of 3 mol.% Eu^3＋：Ca10（PO4）6（OH）2 （Eu^3＋：HA） hydroxyapatite -20 nm large nanocrystals. The emission, excitation and transmission spectra as well as the fluorescence decay rates of bare Eu^3＋：HA nanocrystallites, Eu^3＋：HA embedded in the PMMA and and Eu：HA embedded in the PMMA/TTA rtanocomposites were studied. The improvement of transparency was demonstrated with the addition of TTA as well as europium doped hydroxyapatites in comparison to pure PMMA matrix. The Judd-Ofelt analysis of f-f transitions of Eu^3＋：HA nanocrystallites, the PMMA/Eu^3＋：HA and the PMMA＋TTA/Eu^3＋：HA was performed to investigate the optical behavior of the polymeric composites.展开更多
In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that...In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu^3＋ dopant to the NC （nanocrystallites） size. This was achieved by varying the calcinations temperature between 900 and 1100 ℃. The average NC size varied accordingly between -36 and -75 nm. We found that size effect manifested mainly in the expansion of the cell volume and broadening of XRD peaks as indicated by Rietveld analysis. Moreover the emission and excitation spectra, although typical for Eu^3＋ ions, demonstrated some degree of variability with calcinations temperature and doping concentration. To explain these differences a detailed analysis of luminescence spectra by the Judd-Ofelt theory was performed.展开更多
Nowadays,photovoltaic effect has been widely studied in various ferroelectric materials due to its ap-plications as optoelectronic devices.In this work,with BiFeO_(3)(BFO)films as the photovoltaic materials,we report ...Nowadays,photovoltaic effect has been widely studied in various ferroelectric materials due to its ap-plications as optoelectronic devices.In this work,with BiFeO_(3)(BFO)films as the photovoltaic materials,we report the effects of Eu^(3+)doping content on the phase structure,ferroelectric and optical properties of BFO films grown on Ca_(0.96) Ce_(0.04) MnO_(3)/YAlO_(3)(001)substrate.We found that a small doping level of 0.05 could induce a phase change of BFO from tetragonal to rhombohedral,due to the shrinking of the lattice upon Eu^(3+)doping and the breaking of surface terrace structure induced by Ca_(0.96) Ce_(0.04) MnO_(3) layer.This results in a sharp band gap reduction from 3.30 eV to 2.60 eV,and a decrease in the coercivity of ferroelectric polarization switching.Based on these findings,we investigate the photovoltaic effects of ITO/Eu_(x) Bi_(1-x) FeO_(3)/Ca_(0.96) Ce_(0.04) MnO_(3) vertical capacitors.It is found that the short-circuit current density(J_(sc))decreases with increasing Eu^(3+)doping,whereas the open-circuit voltage(V_(oc))first increases to a level of 0.1 V and then decreases with further Eu^(3+)doping.This could be explained by the combined ef-fect of Schottky-junction and depolarization field on the photovoltaic process.Our research suggests that a moderate Eu^(3+)doping is helpful for enhancing the photovoltaic effect of BFO thin film devices.展开更多
Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microsco...Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microscope(SEM),transmission electron microscope(TEM),dispersive X-ray spectrometer(EDS)and selected area electron diffraction(SAED)techniques.t-NdVO4 nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm,which grow orientally along the direction of(112)crystalline plane and self-assemble to form nanorod-arrays.The results show that Eu^3+-doping interrupts the formation of NdVO4 nanorod-arrays,and then leads to the red-shift of the strongest luminescence emission of Nd3+transition from 4D3/2 state to 4I11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply.The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.展开更多
基金Project supported by Polish Ministry of National Education (N N507 584938)
文摘Transparent, luminescent and functional nanocomposites demonstrate interesting optical and mechanical properties suitable for many optoelectronic applications. Transparent polymethyl methacrylate （PMMA） polymer nanocornposites modified with thenoyl- trifluoroacetonate （TAA） were fabricated by in situ polymerization and used as hosts for homogenous dispersion of 3 mol.% Eu^3＋：Ca10（PO4）6（OH）2 （Eu^3＋：HA） hydroxyapatite -20 nm large nanocrystals. The emission, excitation and transmission spectra as well as the fluorescence decay rates of bare Eu^3＋：HA nanocrystallites, Eu^3＋：HA embedded in the PMMA and and Eu：HA embedded in the PMMA/TTA rtanocomposites were studied. The improvement of transparency was demonstrated with the addition of TTA as well as europium doped hydroxyapatites in comparison to pure PMMA matrix. The Judd-Ofelt analysis of f-f transitions of Eu^3＋：HA nanocrystallites, the PMMA/Eu^3＋：HA and the PMMA＋TTA/Eu^3＋：HA was performed to investigate the optical behavior of the polymeric composites.
基金Project supported by the Polish Ministry of Science and Higher Education (NN 204331537)National Science Centre (N N507 372335)
文摘In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu^3＋ dopant to the NC （nanocrystallites） size. This was achieved by varying the calcinations temperature between 900 and 1100 ℃. The average NC size varied accordingly between -36 and -75 nm. We found that size effect manifested mainly in the expansion of the cell volume and broadening of XRD peaks as indicated by Rietveld analysis. Moreover the emission and excitation spectra, although typical for Eu^3＋ ions, demonstrated some degree of variability with calcinations temperature and doping concentration. To explain these differences a detailed analysis of luminescence spectra by the Judd-Ofelt theory was performed.
基金supported by the National Natural Science Foundation of China (Nos.61974147 and 52031014)。
文摘Nowadays,photovoltaic effect has been widely studied in various ferroelectric materials due to its ap-plications as optoelectronic devices.In this work,with BiFeO_(3)(BFO)films as the photovoltaic materials,we report the effects of Eu^(3+)doping content on the phase structure,ferroelectric and optical properties of BFO films grown on Ca_(0.96) Ce_(0.04) MnO_(3)/YAlO_(3)(001)substrate.We found that a small doping level of 0.05 could induce a phase change of BFO from tetragonal to rhombohedral,due to the shrinking of the lattice upon Eu^(3+)doping and the breaking of surface terrace structure induced by Ca_(0.96) Ce_(0.04) MnO_(3) layer.This results in a sharp band gap reduction from 3.30 eV to 2.60 eV,and a decrease in the coercivity of ferroelectric polarization switching.Based on these findings,we investigate the photovoltaic effects of ITO/Eu_(x) Bi_(1-x) FeO_(3)/Ca_(0.96) Ce_(0.04) MnO_(3) vertical capacitors.It is found that the short-circuit current density(J_(sc))decreases with increasing Eu^(3+)doping,whereas the open-circuit voltage(V_(oc))first increases to a level of 0.1 V and then decreases with further Eu^(3+)doping.This could be explained by the combined ef-fect of Schottky-junction and depolarization field on the photovoltaic process.Our research suggests that a moderate Eu^(3+)doping is helpful for enhancing the photovoltaic effect of BFO thin film devices.
基金Project(51202066)supported by the National Natural Science Foundation of ChinaProject(NCET-13-0784)supported by the Program for New Century Excellent Talents of the Education Ministry,China。
文摘Tetragonal structural(t-NdVO4)nanorod-arrays were fabricated by simple one-pot hydrothermal method.The phase,morphology and microstructure of NdVO4 were characterized by X-ray diffractometer,scanning electron microscope(SEM),transmission electron microscope(TEM),dispersive X-ray spectrometer(EDS)and selected area electron diffraction(SAED)techniques.t-NdVO4 nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm,which grow orientally along the direction of(112)crystalline plane and self-assemble to form nanorod-arrays.The results show that Eu^3+-doping interrupts the formation of NdVO4 nanorod-arrays,and then leads to the red-shift of the strongest luminescence emission of Nd3+transition from 4D3/2 state to 4I11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply.The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.
