A new highly sensitive cryogenic luminescent MOF thermometer built with pyromellitic acid

A ratiometric thermometer based on a mixed Eu-Tb metal-organic framework is reported with a maximum relative thermal sensitivity of 16.1% K-1 at 11 K making this material one of the best-performing thermometers currently reported in the literature. The sensing mechanism of {[Tb2-xEux(H(2)Btec)(Btec)(H2O)(2)]& BULL;4H(2)O}(n) (Btec = 1,2,4,5 Benzenetetracarboxylic acid) has been attributed to a phonon-assisted energy migration between neighboring Tb3+ ions in the structure.MOFs à base de lanthanides pour une application de nanothermomètres luminescent

Synthesis and characterization of F-doped zinc oxides, Al-doped zinch hydroxyfluoride, and oxide—fluoride composites for transparent visible/infrared absorbers

International audienceAmong the most promising transparent conductive oxides, F-doped SnO2 can be prepared, for instance, by spray pyrolysis or hydrothermal routes and can exhibit rather good transparency in visible range and high infrared absorption associated to its electronic conductivity due to n charge carriers. F-doping in ZnO is more difficult to control, and the n-type conductivity is lower than that of F-doped SnO2 or M3+ (M = Al, Ga)-doped ZnO. However, the F concentration remains very low in these oxygenated networks and does not contribute significantly to reduce the refractive index related to the transparency in the visible range. Then, the exploration of other systems such as zinc hydroxyfluoride or even pure fluoride should allow tuning the transparency in the visible range. Various Zn(OH,F)2 hydroxyfluoride can be prepared by coprecipitation route at various pH in fluorinated medium, and the fluorine content varies with the pH. X-ray diffraction and 19F magic angle spinning–nuclear magnetic resonnance (MAS-NMR) analyses contribute to identify the F/OH atom distributions and locations in this network. Al3+ doping into Zn(OH,F)2 matrix leads to slightly increase the infrared absorption of Zn(OH,F)2 compound which remains very low in comparison with Al/Ga-doped Zn oxides. No Al3+ ions can be incorporated into ZnF2 obtained by annealing under anhydrous-HF of previous Al-doped Zn(OH,F)2. In order to improve the transparency in visible range, the zinc oxide–fluoride core–shell seems to be an alternative interesting solution. This composite material can be prepared from the fluoride sol filtration through a ZnO powder bed followed by an annealing stage. Then, the ZnO@MgF2 composite coatings with 99%:1% compositions exhibit 80% average transparency in visible range whereas the pure ZnO films have an average transparency around 50%

Synthesis and characterization of F-doped zinc oxides, Al-doped zinch hydroxyfluoride, and oxide—fluoride composites for transparent visible/infrared absorbers

Among the most promising transparent conductive oxides, F-doped SnO2 can be prepared, for instance, by spray pyrolysis or hydrothermal routes and can exhibit rather good transparency in visible range and high infrared absorption associated to its electronic conductivity due to n charge carriers. F-doping in ZnO is more difficult to control, and the n-type conductivity is lower than that of F-doped SnO2 or M3+ (M = Al, Ga)-doped ZnO. However, the F concentration remains very low in these oxygenated networks and does not contribute significantly to reduce the refractive index related to the transparency in the visible range. Then, the exploration of other systems such as zinc hydroxyfluoride or even pure fluoride should allow tuning the transparency in the visible range. Various Zn(OH,F)2 hydroxyfluoride can be prepared by coprecipitation route at various pH in fluorinated medium, and the fluorine content varies with the pH. X-ray diffraction and 19F magic angle spinning–nuclear magnetic resonnance (MAS-NMR) analyses contribute to identify the F/OH atom distributions and locations in this network. Al3+ doping into Zn(OH,F)2 matrix leads to slightly increase the infrared absorption of Zn(OH,F)2 compound which remains very low in comparison with Al/Ga-doped Zn oxides. No Al3+ ions can be incorporated into ZnF2 obtained by annealing under anhydrous-HF of previous Al-doped Zn(OH,F)2. In order to improve the transparency in visible range, the zinc oxide–fluoride core–shell seems to be an alternative interesting solution. This composite material can be prepared from the fluoride sol filtration through a ZnO powder bed followed by an annealing stage. Then, the ZnO@MgF2 composite coatings with 99%:1% compositions exhibit 80% average transparency in visible range whereas the pure ZnO films have an average transparency around 50%

Synthesis and characterization of F-doped zinc oxides, Al-doped zinch hydroxyfluoride, and oxide—fluoride composites for transparent visible/infrared absorbers

Among the most promising transparent conductive oxides, F-doped SnO2 can be prepared, for instance, by spray pyrolysis or hydrothermal routes and can exhibit rather good transparency in visible range and high infrared absorption associated to its electronic conductivity due to n charge carriers. F-doping in ZnO is more difficult to control, and the n-type conductivity is lower than that of F-doped SnO2 or M3+ (M = Al, Ga)-doped ZnO. However, the F concentration remains very low in these oxygenated networks and does not contribute significantly to reduce the refractive index related to the transparency in the visible range. Then, the exploration of other systems such as zinc hydroxyfluoride or even pure fluoride should allow tuning the transparency in the visible range. Various Zn(OH,F)2 hydroxyfluoride can be prepared by coprecipitation route at various pH in fluorinated medium, and the fluorine content varies with the pH. X-ray diffraction and 19F magic angle spinning–nuclear magnetic resonnance (MAS-NMR) analyses contribute to identify the F/OH atom distributions and locations in this network. Al3+ doping into Zn(OH,F)2 matrix leads to slightly increase the infrared absorption of Zn(OH,F)2 compound which remains very low in comparison with Al/Ga-doped Zn oxides. No Al3+ ions can be incorporated into ZnF2 obtained by annealing under anhydrous-HF of previous Al-doped Zn(OH,F)2. In order to improve the transparency in visible range, the zinc oxide–fluoride core–shell seems to be an alternative interesting solution. This composite material can be prepared from the fluoride sol filtration through a ZnO powder bed followed by an annealing stage. Then, the ZnO@MgF2 composite coatings with 99%:1% compositions exhibit 80% average transparency in visible range whereas the pure ZnO films have an average transparency around 50%

A Chemical Route Towards Single-Phase Materials with Controllable Photoluminescence

International audienc

Wet-Route Synthesis and Characterization of Yb:CaF 2 Optical Ceramics

International audienc

Stabilization of β-octamolybdate with large counterions

International audienc

Plasmonic properties of an Ag@Ag 2 Mo 2 O 7 hybrid nanostructure easily designed by solid-state photodeposition from very thin Ag 2 Mo 2 O 7 nanowires

International audienceA new Ag@m-Ag2Mo2O7 plasmonic hybrid nanostructure was designed by an easy two-step synthesis method. Firstly, very thin photosensitive monoclinic m-Ag2Mo2O7 nanowires (NWs) were synthesized under ambient pressure and at low temperature by using Ag2Mo3O10·2H2O NWs as a pre-nanostucturated starting material. This innovative soft chemistry route offers some precise control over the purity, the structure and the nanostructuration of the m-Ag2Mo2O7 NWs that exhibit a very thin diameter of around 100 nm and a superior specific surface area compared to previously reported synthesis methods. Secondly, the plasmonic hybrid nanostructure Ag@m-Ag2Mo2O7 was easily in situ obtained via an all solid-state photodeposition method, by irradiating the m-Ag2Mo2O7 NWs under low energy and low-power UV-light. The composition, morphology and plasmonic properties of the nanocomposite were investigated by a combination of energy-dispersive X-ray spectroscopy, high-resolution scanning transmission electron microscopy, X-ray photoelectron spectroscopy and Auger spectroscopy, and near-infrared, Raman and UV-vis spectroscopies as well as spatially-resolved electron energy-loss spectroscopy. A plausible mechanism explaining the formation of the nano-heterostructure under irradiation was also discussed. The Ag@m-Ag2Mo2O7 nanostructure manifests interesting plasmonic properties particularly high surface-enhanced Raman scattering (SERS) sensitivity probed using 2,2′-bipyridine