60884-92-6Relevant articles and documents
Water-vapor assisted photochemical fabrication of YBa2Cu3O7-x superconducting films with high critical current density
Bian, Weibai,Chen, Yuanqing,Li, Lingwei,Zhao, Gaoyang,Li, Na,Wu, Huimin,Ma, Qinghua,You, Caiying
, p. 1036 - 1043 (2017)
A novel water-vapor assisted photochemical solution deposition method was put forward to fabricate high-performance YBa2Cu3O7-x (YBCO) superconducting films. The dip-coated gel films derived from YBCO solution with Y:Ba:Cu:F = 1:2:3:4 were exposed to deep UV light at a low temperature of 150 °C. During the UV exposure, water-vapor was artificially introduced to produce hydroxyl radicals (*OH) with strong oxidizing ability. After that, photon-activated amorphous oxide precursor films were obtained. It was found that the high-energy photons and *OH species promoted the cleavage of organic groups, enhanced the removal of residual organics, and improved the density of the YBCO films. Thus, YBCO superconducting films with improved superconducting properties were obtained after the crystallization process. The YBCO superconducting film that was UV-irradiated for 100 min with water vapor had a maximum critical current density (Jc) of 8.69 MA/cm2 (77 K and 0 T).
Does BaYF5 nanocrystals exist? - The BaF2-YF3 solid solution revisited using photoluminescence spectroscopy
Karbowiak, Miros?aw,Cichos, Jakub
, p. 258 - 264 (2016)
During thermolysis of metal trifluoroacetates in high boiling organic solvents the two Ba1-xRExF2+x phases with cubic fluorite-type structure are formed in BaF2-YF3 system. In contrast to previous reports formation of so-called 'BaYF5' nanocrystals was not observed. Besides the X-ray diffraction analysis the samples doped with optically active Eu3+ and Er3+ ions were characterized with photoluminescence spectroscopy and results provided by both methods corroborates each other. Upconversion emission observed under excitation at 980 nm for the Ba1-xYxF2+x phase co-doped with Yb3+ and Er3+ ions is strongly composition dependent. Its intensity increases with increasing of REF3 content for 0.2 0.45 and upconversion emission is totally quenched for x > 0.6. The important outcome of the present study is that compositions other than that with x = 0.5 should be probed to fully benefit from photoluminescence potential of Ba1-xRExF2+x nanofluoride phases activated with lanthanide ions.
Open-Framework Structures of Anhydrous Sr(CF3COO)2 and Ba(CF3COO)2
Dissanayake, K. Tauni,Mendoza, Laura M.,Martin, Philip D.,Suescun, Leopoldo,Rabuffetti, Federico A.
, p. 170 - 176 (2016)
Anhydrous Sr(CF3COO)2 and Ba(CF3COO)2 open-framework structures featuring three-dimensional connectivity of metal-oxygen polyhedra were crystallized from a mixture of water and CF3COOH. Crystallization was induced via evaporation of the solvent mixture under a dry nitrogen flow. This approach differs from that routinely employed for crystallization of metal trifluoroacetates, which achieves solvent evaporation by heating under air and yields hydrated salts. Thermogravimetric and differential thermal analysis as well as single-crystal and synchrotron powder X-ray diffraction were employed to characterize the alkaline-earth trifluoroacetate products. Neither thermal analysis nor single-crystal X-ray diffraction detected the presence of crystallization water molecules, demonstrating these trifluoroacetates can be obtained in anhydrous form. Single-crystal X-ray diffraction studies showed that Sr(CF3COO)2 and Ba(CF3COO)2 are isostructural and crystallize in the rhombohedral R3ˉ space group. Both compounds belong to the class of organic-inorganic extended hybrids and exhibit an open-framework structural motif with three-dimensional connectivity of the metal-oxygen polyhedra and one-dimensional channels along the c axis. The channels are decorated with the trifluoromethyl groups of the trifluoroacetate ligands, and their average (minimum) diameters are ～3.75 (2.60) and 3.45 (2.25) ? for Sr(CF3COO)2 and Ba(CF3COO)2, respectively. This size range is comparable to the kinetic diameter of small molecules such as hydrogen (2.3 ?). Chemical substitution of barium for strontium affects not only the diameter of the channels but also the spatial arrangement of the trifluoromethyl groups within the channels and the coordination environment of the metal atoms. The different coordination requirements of the strontium and barium atoms are accommodated through the displacement of one of the two chemically distinct trifluoroacetate ligands relative to the metal center.
Core-shell BaYbF5:Tm@BaGdF5:Yb,Tm nanocrystals for in vivo trimodal UCL/CT/MR imaging
Zhang, Peng,He, Yangyang,Liu, Jianhua,Feng, Jing,Sun, Zhiqiang,Lei, Pengpeng,Yuan, Qinghai,Zhang, Hongjie
, p. 14283 - 14289 (2016/02/18)
Lanthanide-doped nanocrystals have been researched extensively and used for bioimaging because of their optical properties, magnetic properties and X-ray absorption. Core-shell-structured lanthanide-doped nanocrystals have been developed and characterized
