Nucleation efficiency of erbium and ytterbium fluorides in transparent oxyfluoride glass-ceramics

2005 ◽  
Vol 20 (2) ◽  
pp. 472-481 ◽  
Author(s):  
G. Dantelle ◽  
M. Mortier ◽  
D. Vivien ◽  
G. Patriarche

Oxyfluoride glasses (GeO2–PbO–PbF2) doped with erbium and/or ytterbium fluorides were prepared. Highly transparent glass-ceramics, containing β–PbF2 nanocrystallites, were successfully obtained by controlled glass devitrification and were studied as they could lead to promising optical applications. To characterize the samples, differential thermal analysis, x-ray diffraction, and transmission electron microscopy were performed, revealing a variation of the crystallites size, the crystallites number and β–PbF2 crystallization temperature according to the doping ion. Indeed, the analyses indicated differences between erbium and ytterbium fluorides in promoting the crystallization of the fluoride phase. Although both fluorides act as seeds for β–PbF2 heterogeneous nucleation, erbium fluoride has higher nucleation efficiency than ytterbium fluoride and runs the nucleation process in co-doped samples. Energy dispersive x-ray microanalysis insured high rare-earth segregation into the crystallites, proving the formation of a solid solution Pb1−x−yErxYbyF2 +x+y, also confirmed by the unit cell parameter study.

2016 ◽  
Vol 16 (4) ◽  
pp. 3744-3748 ◽  
Author(s):  
Yuan Gao ◽  
Yuebo Hu ◽  
Dacheng Zhou ◽  
Jianbei Qiu

Transparent oxyflouride glass ceramics composed of SiO2–Al2O3–Na2O–NaF–YF3 tri-coped with Nd3+/Yb3+/Ho3+ were prepared by thermal treatment. Segregation of NaYF4 nanocrystals in the matrix was confirmed from structural analysis by means of X-ray diffraction and transmission electron microscopy. Compared with glass samples, very strong green upconversion (UC) luminescence due to the Ho3+:(4F5, 5S2)→5I8 transition was observed in the glass ceramics under 808 nm excitation. It was found that upconversion intensity of Ho3+ strongly depends on the Nd3+ concentration, and the energy transfer process from Nd3+ to Ho3+ via Yb3+ was proposed.


RSC Advances ◽  
2018 ◽  
Vol 8 (71) ◽  
pp. 40787-40793 ◽  
Author(s):  
Yuao Guo ◽  
Lijuan Zhao ◽  
Yuting Fu ◽  
Pan Dong ◽  
Liying Guo ◽  
...  

Oxyfluoride glass ceramics (GCs) doped with trivalent lanthanide ions (Ln3+) have been prepared using a conventional melting–quenching method and studied by X-ray diffraction (XRD).


2015 ◽  
Vol 749 ◽  
pp. 211-214
Author(s):  
Dong Seon Kim ◽  
Jin Ho Lee ◽  
Ki Soo Lim

Glass-ceramic was precipitated on the oxyfluoride glass surface by thermal annealing with a CO2 laser and a heat gun. Micro x-ray diffraction showed the formation of CaF2 ain the exposed region to the laser. Dopant distribution in glass ceramics was probed by confocal fluorescence microscope by observing much strong emission from Eu ions than the glassy area under 405 nm excitation. Much enhanced visible emissions under 365 nm excitation also showed well incorporation of Eu3+ ions into a crystalline environment.


2007 ◽  
Vol 280-283 ◽  
pp. 521-524
Author(s):  
Li Qiong An ◽  
Jian Zhang ◽  
Min Liu ◽  
Sheng Wu Wang

Yb3+ and Ho3+ co-doped Lu2O3 nanocrystalline powders were synthesized by a reversestrike co-precipitation method. The as-prepared powders were examined by the X-ray diffraction and transmission electron microscopy. The phase composition of the powders was cubic and the particle size was in the range of 30~50 nm. Emission and excitation spectra of the powders were measured by a spectrofluorometer and the possible upconversion luminescence mechanism was also discussed.


2021 ◽  
Vol 19 (4) ◽  
pp. 283-294
Author(s):  
Basma A.A. Balboul ◽  
A.K. Nohman ◽  
Randa F. Abd El-baki ◽  
Moutera S. Elshemery

Holmia supported γ-alumina nanocatalyst was prepared by impregnation of γ-alumina with aqueous solution of holmium acetate hydrate Ho(CH3COO)3.3.5 H2O. The physicochemical characteristics of the nanocatalyst calcined at 600°C were established by different techniques, using surface adsorption–desorption of N2 (SBET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectroscopy (DRS). The recorded optical reflectance of the sample showed that the new self-assembled nanocatalyst is excellent as host material for advanced optical applications. Moreover, the catalyst showed enhanced catalytic activity toward Isopropyl alcohol decomposition.


2016 ◽  
Vol 690 ◽  
pp. 137-142
Author(s):  
Thanaporn Boonchoo ◽  
Pratthana Intawin ◽  
Wilaiwan Leenakul

In this study, the effects of heat treatment temperatures on structural and magnetic properties in MnFe2O4(MF)/SiO2-Na2O-CaO-P2O5 (bioglass) bioactive glass ceramics were investigated. The MF/SiO2-Na2O-CaO-P2O5 bioactive glass ceramics were fabricated under various heat treatment temperatures in a range of 600-1000 °C. X-ray diffraction (XRD) technique, the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize phase and microstructure. The magnetic properties were determined from Vibrating Sample Magnetometer (VSM). The X-ray diffraction peaks presented two major crystalline phases: MnFe2O4 and Na2Ca2Si3O9. It was found that the heat treatment temperatures are the most influential parameter on microstructure and magnetic properties of the bioactive glass ceramics. The highest magnetic properties of studied ceramics were found in the sample heated at 1000 °C with adding 20 wt%. MF. The microstructural properties of the studies samples were investigated and the results were then correlated with the characteristics of heat treatment temperatures as well as the microstructure of the bioactive glass ceramic.


2012 ◽  
Vol 535-537 ◽  
pp. 855-860
Author(s):  
Jian An Liu ◽  
Mei Mei Zhang ◽  
Xue Na Yang ◽  
Wen He

Based on the SrO-Fe2O3-FeO-SiO2-B2O3 system, the M-type strontium hexaferrites glass ceramics has been prepared through heat treating the melted glass. Using the aqueous solution solvent evaporation and melt method, we obtained the glass precursor of molecular-scale homogenously mixed compound. The precursor was completely melted in a lidded platinum crucible placed in an electric furnace at 1480°C for 1h and then annealed in a furnace at 550°C for 40min. The crystallization of the glass systems with different component has been systematically investigated by using X-ray diffraction (XRD), Transmission Electron Micrographs (TEM) as well as Vibrating Sample Magnetometer (VSM). It is found that Fe3O4 crystal precipitated during naturally cooling the melt from 1480°C to anneal temperature. Moreover, the hexaferrite glass ceramics with the main crystal phase of SrFe12O19 was obtained after heat-treated at 860°C for 2 hours. The magnetic properties of the obtained hexaferrite glass ceramics indicated that the saturation magnetization and the coercivity were 8.1A•m2/kg and 114KA/m, respectively.


2017 ◽  
Vol 10 (05) ◽  
pp. 1750061 ◽  
Author(s):  
Qiu Jin ◽  
Chaoyin Nie ◽  
Qianqian Shen ◽  
Yusheng Xu ◽  
Yanzhong Nie

Cobalt (Co) and sulfur (S) co-doped titanium dioxide (TiO2) catalysts were synthesized via sol–gel method. The structure of TiO2was characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The valence states of elements were studied by X-ray photoelectron spectroscopy (XPS), and the optical-absorption properties of the catalysts were tested using the ultraviolet–visible (UV–Vis) spectrophotometer. The results showed that the grain sizes of Co and S co-doped TiO2 decreased with the increase of Co and S doping concentration within a certain range, and then the catalysts had obvious red shift on the absorption of visible light. Sample (2%Co–5%S–TiO2) showed excellent light absorption characteristics and the photo-response threshold increased significantly to about 760[Formula: see text]nm. Also, the further degradation test under visible light shows the 2%Co–5%S-TiO2 sample exhibit apparently improved degradation efficiency for Rhodamine B compared to the undoped one.


2021 ◽  
Author(s):  
Imen Ben Elkamel ◽  
Nejeh Hamdaoui ◽  
Amine Mezni ◽  
Ridha Ajjel ◽  
Lotfi Beji

Abstract Here, we have used a simple method for polyol synthesis, analysis, and testing of Au/Cu-doped ZnO Ultraviolet (UV) photodetectors (PD). Our results are reported and discussed by X-ray diffraction (XRD) to ensure that the manufactured samples show a hexagonal wurtzite ZnO structure. Transmission electron microscopy (TEM) confirmed the nanoparticle growth in the hexagonal sample on the surface, which is the key to improving the light response. Our prepared UV PD Au/Cu codoped ZnO showed a rapid time at a power density of 7.6 mW. the highest responsivity of R = 575 mA/W and sensitivity 103 obtained at 7.6 mW with an applied voltage of 1V. Our results demonstrate the obvious substitution of Au and Cu in ZnO, thereby improving the UV-sensing light response.


2014 ◽  
Vol 70 (a1) ◽  
pp. C959-C959
Author(s):  
Julio Pellicer-Porres ◽  
Alfredo Segura ◽  
Gema Martínez-Criado ◽  
Ulises Rodríguez-Mendoza ◽  
Víctor Lavín

Lead-aluminosilicate oxyfluoride transparent glass–ceramics doped with RE3+ ions have been revealed to be unique in the field of optical material engineering. This kind of material consists of a beta_x000C_-PbF2 fluoride nanocrystalline phase in an aluminosilicate glassy amorphous phase. In this way, the macroscopic properties of this material are characteristic of aluminosilicate glass, whereas the spectroscopic properties of the RE3+ ions remain those of low-phonon-energy fluoride crystals. The optical properties of the RE3+ ions, and therefore their interest for photonic applications, depend on the final environment of these ions in a host matrix. Exploration of the local structure of the Eu3+ ions as well as characterization of the amorphous matrix demands structural techniques that do not rely on long range order. Given the complexity of the system under study, chemical selectivity is also required. In this work [1], we describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu3+ doped, transparent, oxyfluoride glass and nanostructured glass–ceramic samples. The spectra were measured at the Pb and Eu–LIII edges. The Eu environment in the glass samples is observed to be similar to that of EuF3. Complementary x-ray diffraction experiments show that thermal annealing creates _x000C_beta-PbF2 type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb–LIII edge shows that after the thermal treatment most lead atoms form a PbO amorphous phase and that only 10% of the lead atoms remain available to form _x000C_beta-PbF2 type nanocrystals. Both x-ray diffraction and absorption point to a high Eu content in the nanocrystals. Our study suggests new approaches to the oxyfluoride glass–ceramic synthesis in order to further improve their properties.


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