P. Gredin - Academia.edu (original) (raw)

Papers by P. Gredin

Optics Express, 2009

Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diod... more Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diode into absorption band of Yb 3+ , the laser-induced temperature rise up to 800°C has been detected in the nanoparticles by measuring the ratio of the intensities of the thermalised upconversion luminescence bands 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 of Er 3+ . These results show that a controlled optical heating of the nanoparticles and their surrounding nano-volumes can be realised, while the location and temperature rise of the nanoparticles and heated nano-volumes can be detected distantly by means of luminescence. concentration effect in the spectroscopic properties and energy transfer in Yb 3+ /Er 3+ co-doped tellurite glasses," J. Phys. D Appl. Phys. 41(9), 095102 (2008). 16. D. Saurel, V. K. Tikhomirov, V. V. Moshchalkov, C. Görller-Walrand, and K. Driesen, "Zeeman splitting and confinement effects in Er 3+ -doped nano-glass-ceramics in magnetic fields up to 50 Tesla," Appl. Phys. Lett.

Physical review letters, Jan 15, 2014

We report on an experimental technique to quantify the relative importance of electric and magnet... more We report on an experimental technique to quantify the relative importance of electric and magnetic dipole luminescence from a single nanosource in structured environments. By attaching a Eu^{3+}-doped nanocrystal to a near-field scanning optical microscope tip, we map the branching ratios associated with two electric dipole and one magnetic dipole transitions in three dimensions on a gold stripe. The relative weights of the electric and magnetic radiative local density of states can be recovered quantitatively, based on a multilevel model. This paves the way towards the full electric and magnetic characterization of nanostructures for the control of single emitter luminescence.

Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diod... more Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diode into absorption band of Yb 3+ , the laser-induced temperature rise up to 800°C has been detected in the nanoparticles by measuring the ratio of the intensities of the thermalised upconversion luminescence bands 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 of Er 3+ . These results show that a controlled optical heating of the nanoparticles and their surrounding nano-volumes can be realised, while the location and temperature rise of the nanoparticles and heated nano-volumes can be detected distantly by means of luminescence. concentration effect in the spectroscopic properties and energy transfer in Yb 3+ /Er 3+ co-doped tellurite glasses," J. Phys. D Appl. Phys. 41(9), 095102 (2008). 16. D. Saurel, V. K. Tikhomirov, V. V. Moshchalkov, C. Görller-Walrand, and K. Driesen, "Zeeman splitting and confinement effects in Er 3+ -doped nano-glass-ceramics in magnetic fields up to 50 Tesla," Appl. Phys. Lett.

Zeitschrift für anorganische und allgemeine Chemie, 1998

The fluorides CuMoF 6 and CrNbF 6 are triclinic, isostructural with CuSnF 6 . Their crystal struc... more The fluorides CuMoF 6 and CrNbF 6 are triclinic, isostructural with CuSnF 6 . Their crystal structures were solved in the space group P1, by the Rietveld method using the data of their X-ray powder patterns. Both crystal structures can be described as a three-dimensional framework of alternating 6 corner-sharing [M II F 6 ] and [M' IV F 6 ] octahedra (M II = Cr, Cu; M' IV = Nb, Mo) with ferrodistortive Jahn-Teller ordering.

Optics Express, 2010

We have prepared and studied the PbF 2 :(Yb 3+ ,Er 3+ ) co-doped nanoparticles, with chemical for... more We have prepared and studied the PbF 2 :(Yb 3+ ,Er 3+ ) co-doped nanoparticles, with chemical formula (Yb-Er) x Pb 1-x F 2+x , where x = 0.29, Yb 3+ /Er 3+ = 6, and estimated the energy efficiency for their cathodoluminescence, mostly of Yb 3+ , and up-conversion photoluminescence of Er 3+ to reach more than 0.5% and 20%, respectively, which may be the highest to date for rare-earth doped nanoparticles. Electron beam induced temperature rise in the nanoparticles has been estimated by measuring the ratio of green emission bands of Er 3+ . These high efficiencies are due to high doping level of nanoparticles and due to low phonon energy of the PbF 2 host.

Optics Express, 2008

Er 3+ /Yb 3 + codoped pyrochlore-type (Y 0.99-x Er 0.01 Yb x ) 2 Ti 2 O 7 (x =0, 2.5, 5.0, 7.5, 1... more Er 3+ /Yb 3 + codoped pyrochlore-type (Y 0.99-x Er 0.01 Yb x ) 2 Ti 2 O 7 (x =0, 2.5, 5.0, 7.5, 10.0 and 12.5 mol%) nanocrystals have been successfully prepared by the sol-gel process with citric acid as chelator. The samples annealed at 800°C for 1 h exhibit good crystallinity and narrow size distribution with average size of 20-30 nm. Upon 980 nm excitation at room temperature, green (at~525 and 545 nm) and red (at~660 nm) upconversion emissions were observed, which are ascribed to the ( 2 H 11/2 , 4 S 3/2 ) → 4 I 15/2 and 4 F 9/2 → 4 I 15/2 transitions, respectively. And also, it has been found that the annealing temperatures and the Yb 3 + ion doping concentrations have greatly influenced on the upconversion luminescence intensity. The results show that Y 2 Ti 2 O 7 is an excellent host material for efficient upconversion nanophosphors.

Journal of Alloys and Compounds, 2008

PbF2:Yb–Er nanoparticles were synthesized by two different ways: a pseudo-micellar route and the ... more PbF2:Yb–Er nanoparticles were synthesized by two different ways: a pseudo-micellar route and the selective dissolution of the oxide glassy matrix of an oxyfluoride composite glass–ceramic obtained by Yb–Er induced nucleation of PbF2 inside the GeO2:PbO:PbF2 glass.Both nanoparticles exhibit strong visible up-conversion fluorescence after infrared excitation. 4S3/2 level lifetime of Er3+ ions reflects the high specific surface of the particles and their ability to adsorb quenching centres.

Advanced Materials, 2005

... unpublished. CoNi Nanowires Synthesized by Heterogeneous Nucleation in Liquid Polyol** By Dia... more ... unpublished. CoNi Nanowires Synthesized by Heterogeneous Nucleation in Liquid Polyol** By Diane Ung, Guillaume Viau,* Christian Ricolleau, Fabienne Warmont, Patrick Gredin, and Fernand FiØvet Metal nanoparticles ...

Optics Express, 2009

Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diod... more Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diode into absorption band of Yb 3+ , the laser-induced temperature rise up to 800°C has been detected in the nanoparticles by measuring the ratio of the intensities of the thermalised upconversion luminescence bands 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 of Er 3+ . These results show that a controlled optical heating of the nanoparticles and their surrounding nano-volumes can be realised, while the location and temperature rise of the nanoparticles and heated nano-volumes can be detected distantly by means of luminescence. concentration effect in the spectroscopic properties and energy transfer in Yb 3+ /Er 3+ co-doped tellurite glasses," J. Phys. D Appl. Phys. 41(9), 095102 (2008). 16. D. Saurel, V. K. Tikhomirov, V. V. Moshchalkov, C. Görller-Walrand, and K. Driesen, "Zeeman splitting and confinement effects in Er 3+ -doped nano-glass-ceramics in magnetic fields up to 50 Tesla," Appl. Phys. Lett.

Physical review letters, Jan 15, 2014

We report on an experimental technique to quantify the relative importance of electric and magnet... more We report on an experimental technique to quantify the relative importance of electric and magnetic dipole luminescence from a single nanosource in structured environments. By attaching a Eu^{3+}-doped nanocrystal to a near-field scanning optical microscope tip, we map the branching ratios associated with two electric dipole and one magnetic dipole transitions in three dimensions on a gold stripe. The relative weights of the electric and magnetic radiative local density of states can be recovered quantitatively, based on a multilevel model. This paves the way towards the full electric and magnetic characterization of nanostructures for the control of single emitter luminescence.

Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diod... more Yb 3+ -Er 3+ co-doped fluoride nanoparticles have been prepared. When pumped by 975 nm laser diode into absorption band of Yb 3+ , the laser-induced temperature rise up to 800°C has been detected in the nanoparticles by measuring the ratio of the intensities of the thermalised upconversion luminescence bands 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 of Er 3+ . These results show that a controlled optical heating of the nanoparticles and their surrounding nano-volumes can be realised, while the location and temperature rise of the nanoparticles and heated nano-volumes can be detected distantly by means of luminescence. concentration effect in the spectroscopic properties and energy transfer in Yb 3+ /Er 3+ co-doped tellurite glasses," J. Phys. D Appl. Phys. 41(9), 095102 (2008). 16. D. Saurel, V. K. Tikhomirov, V. V. Moshchalkov, C. Görller-Walrand, and K. Driesen, "Zeeman splitting and confinement effects in Er 3+ -doped nano-glass-ceramics in magnetic fields up to 50 Tesla," Appl. Phys. Lett.

Zeitschrift für anorganische und allgemeine Chemie, 1998

The fluorides CuMoF 6 and CrNbF 6 are triclinic, isostructural with CuSnF 6 . Their crystal struc... more The fluorides CuMoF 6 and CrNbF 6 are triclinic, isostructural with CuSnF 6 . Their crystal structures were solved in the space group P1, by the Rietveld method using the data of their X-ray powder patterns. Both crystal structures can be described as a three-dimensional framework of alternating 6 corner-sharing [M II F 6 ] and [M' IV F 6 ] octahedra (M II = Cr, Cu; M' IV = Nb, Mo) with ferrodistortive Jahn-Teller ordering.

Optics Express, 2010

We have prepared and studied the PbF 2 :(Yb 3+ ,Er 3+ ) co-doped nanoparticles, with chemical for... more We have prepared and studied the PbF 2 :(Yb 3+ ,Er 3+ ) co-doped nanoparticles, with chemical formula (Yb-Er) x Pb 1-x F 2+x , where x = 0.29, Yb 3+ /Er 3+ = 6, and estimated the energy efficiency for their cathodoluminescence, mostly of Yb 3+ , and up-conversion photoluminescence of Er 3+ to reach more than 0.5% and 20%, respectively, which may be the highest to date for rare-earth doped nanoparticles. Electron beam induced temperature rise in the nanoparticles has been estimated by measuring the ratio of green emission bands of Er 3+ . These high efficiencies are due to high doping level of nanoparticles and due to low phonon energy of the PbF 2 host.

Optics Express, 2008

Er 3+ /Yb 3 + codoped pyrochlore-type (Y 0.99-x Er 0.01 Yb x ) 2 Ti 2 O 7 (x =0, 2.5, 5.0, 7.5, 1... more Er 3+ /Yb 3 + codoped pyrochlore-type (Y 0.99-x Er 0.01 Yb x ) 2 Ti 2 O 7 (x =0, 2.5, 5.0, 7.5, 10.0 and 12.5 mol%) nanocrystals have been successfully prepared by the sol-gel process with citric acid as chelator. The samples annealed at 800°C for 1 h exhibit good crystallinity and narrow size distribution with average size of 20-30 nm. Upon 980 nm excitation at room temperature, green (at~525 and 545 nm) and red (at~660 nm) upconversion emissions were observed, which are ascribed to the ( 2 H 11/2 , 4 S 3/2 ) → 4 I 15/2 and 4 F 9/2 → 4 I 15/2 transitions, respectively. And also, it has been found that the annealing temperatures and the Yb 3 + ion doping concentrations have greatly influenced on the upconversion luminescence intensity. The results show that Y 2 Ti 2 O 7 is an excellent host material for efficient upconversion nanophosphors.

Journal of Alloys and Compounds, 2008

PbF2:Yb–Er nanoparticles were synthesized by two different ways: a pseudo-micellar route and the ... more PbF2:Yb–Er nanoparticles were synthesized by two different ways: a pseudo-micellar route and the selective dissolution of the oxide glassy matrix of an oxyfluoride composite glass–ceramic obtained by Yb–Er induced nucleation of PbF2 inside the GeO2:PbO:PbF2 glass.Both nanoparticles exhibit strong visible up-conversion fluorescence after infrared excitation. 4S3/2 level lifetime of Er3+ ions reflects the high specific surface of the particles and their ability to adsorb quenching centres.

Advanced Materials, 2005

... unpublished. CoNi Nanowires Synthesized by Heterogeneous Nucleation in Liquid Polyol** By Dia... more ... unpublished. CoNi Nanowires Synthesized by Heterogeneous Nucleation in Liquid Polyol** By Diane Ung, Guillaume Viau,* Christian Ricolleau, Fabienne Warmont, Patrick Gredin, and Fernand FiØvet Metal nanoparticles ...