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EXAFS study of cation reordering in NaYF_4:Yb^(3+),tb^(3+) up-conversion luminescence materials

Journal of Rare Earths 2014年第3期32卷 226-229页

作者： H.F.Brito J.Hls t.laamanen t.Laihinen M.Lastusaari L.Pihlgren L.C.V.Rodrigues t.Soukka Instituto de Química Universidade de S?o Paulo Department of Chemistry University of Turku turku University Centre for Materials and Surfaces (MatSurf) Department of Chemistry University of Turku FI-20014 Turku Finland turku University Centre for Materials and Surfaces (MatSurf) Turku Finland University of turku Graduate School (UtUGS) Doctoral Programme in Physical and Chemical Sciences Graduate School of Materials Research (GSMR) Department of Biochemistry University of Turku

the NaYF4：yb3＋,tb3＋（Xyb： 0.20, Xtb： 0.04） materials were prepared using the co-precipitation method, lne as-preparea material was washed either with or without water in addition to ethanol and thereafter annealed for 5 h at 500℃. this resulted in materials with moderate or very high up-conversion luminescence intensity, respectively. the structural study carried out with X-ray powder diffraction revealed microstrains in the rare earth （R） sublattice that were relaxed for the material with very high up-conversion intensity thus decreasing energy losses. the local structural details were investigated with R LⅢ and Y K edge ex- tended X-ray absorption fine structure （EXAFS） using synchrotron radiation. Around 10 tool.% of the Yb3＋ ions were found to occupy the Na site in the material with very high up-conversion intensity. these Yb species formed clusters with the tb3＋ ions occupying the regular Na/R sites. Such clustering enhanced the energy transfer between Yb3＋ and tb3＋ thus intensifying the up-conversion emission.

关键词： EXAFS up-conversion ytterbium terbium cation reordering

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Environmental impact improvements due to introducing automation into underground copper mines

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International Journal of Mining Science and technology 2021年第6期31卷 1159-1167页

作者： Kyle Moreau Corey laamanen Ron Bose Helen Shang John Ashley Scott School of Engineering Laurentian UniversitySudburyON P3E 2C6Canada XPS–Glencore Greater SudburyON P0M 1S0Canada

A life-cycle assessment(LCA) model was developed to comparatively analyze the use of manual and automated mining equipment in underground copper mine *** and key variables that were determined to contribute to the environmental impact of operations were identified for six mine sites in a range of geographical locations around the *** model successfully calculated carbon dioxide(CO_(2) eq.) emissions to within 4.9% of the reported annual emissions from the site's respective *** implementation of automation was found to decrease global warming potential by a range of 11.4%-18.0% or 3.9-17.9 kg CO_(2) eq./t *** model was also used to estimate the average reductions across several impact potentials including,acidification(11.9%-17.8%),eutrophication(7.6%-13.7%),and human toxicity(16.0%-20.0%).World-wide the mining industry is moving toward introducing significantly more automation to enhance productivity and *** novel work demonstrates an important third dimension that can support this move,reduced environmental impact.

关键词： Automation Underground copper mines Environmental improvements Life cycle assessment Modelling

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