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Spectroscopic study of the Pr-doped BiBO glass and Ca_4GdO(BO_3)_3 single crystals

Journal of Rare Earths 2009年第4期27卷 612-615页

作者： A.Majchrowski M.G.Brik G.A.Kumar K.Ozga I.Sildos A.Suchocki A.lezak T.Lukasiewicz I.V.Kityk institute of Applied Physics Military University of technology Kaliskiego Warsaw 00-908 Poland institute of Physics University of Tartu Riia 142 Tartu 51014 Estonia Department of Material Science and Engineering The State University of New Jersey NJ 08854-8065 USA institute of Biology and Biophysics Czestochowa University of Technology Al.Armii Krajowej 36B Czestochowa 42-200 Poland institute of Physics Polish Academy of Science Al.Lotników 32/46 Warsaw 02-668 Poland institute of electronic materials technolog wolczanska 133 Warsaw 01-919 Poland Electrical Engineering Department Technological University of Czestochowa Al.Armii Krajowej 17/19 Czestochowa Poland

Detailed spectroscopic studies of Pr3＋ ions in BiBO glass and Ca4GdO（BO3）3 crystal were performed. Experimental absorption spectra were measured at room temperature and assigned. The first principles discrete variational multielectron method was used to model the polarized absorption spectra of the Ca2GdO（BO3）3：Pr3＋; without any fitting parameters, the overall appearance of the spectra was reproduced satisfactorily. The energy intervals between different molecular orbitals in the [PrO6] cluster were estimated. The conventional Judd-Ofelt theory was used to calculate the oscillator strengths of the 4f-4f transitions in the BiBO：Pr3＋ system; the set of the phenomenological intensity parameters was determined.

关键词： rare earth doped materials praseodymium absorption spectra

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Genesis and soil environmental implications of intact in-situ rhizoliths in dunes of the Badain Jaran Desert,northwestern China

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Acta Geochimica 2022年第5期41卷 811-822页

作者： Qingfeng Sun Kazem Zamanian Arnaud Huguet Omid Bayat Hong Wang Hanan SBadawy Key Laboratory of Resource Environment and Sustainable Development of Oasis Northwest Normal University730070 LanzhouGansu ProvinceGansuPR China Key Laboratory of Eco-function Polymer materials of the Ministry of Education Northwest Normal University730070 LanzhouGansuPR China institute of Soil Science Leibniz University of HannoverHerrenhäuser Straße 230419 HannoverGermany Sorbonne Université CNRSEPHEUMR METISF-75005 ParisPSLFrance Department of Soil Science Isfahan University of Technology84156-83111 IsfahanIran Interdisciplinary Research Center of Earth Science Frontier Beijing Normal University100875 BeijingPR China Department of Geology Faculty of ScienceBeni-Suef University62521 Beni-SuefEgypt School of Geographical Sciences Nanjing University of Information Science and Technolog210044NanjingChina

Desert rhizoliths are generally found as weathered,broken and scattered samples on dune field surface,but rarely insitu in their initial states buried under the soil of desert in the Badain Jaran Desert,northwest *** study off ers an assessment of the morphological,mineralogical,and chemical properties of intact and in-situ rhizoliths found in soils of swales and depressions among dune *** characteristics of these rare and precious objects were assessed using optical polarizing microscopy,cathodoluminescence,scanning electronic microscopy,radiocarbon dating,and stable isotopic analyses,providing the opportunity for discussion of the rhizolith formation mechanisms and associated environmental *** and laboratory investigations showed that the in-situ intact rhizoliths were formed only in the places where Artemisia shrubs are living,and the remaining root relicts within rhizoliths belong to this *** spatial distribution of rhizoliths also suggested that low topographic positions on a landscape provided soil moisture,and redox environments favored rhizolith formation.A semi-closed redox environment in the subsoil at swales and depressions,where water is always present,along with the sandy soil texture,facilitated fast water percolation to deeper depths and *** a soil environment not only provides water for Artemisia growth,but also for the weathering of minerals such as felspars and calcite from primary carbonates,and for the decomposition of root ***,harsh climatic conditions,such as strong winds and solar radiation,led to water evaporation through dead root channels and triggered the calcification along the root *** entrapped lithogenic carbonates and to a lesser extent the decomposition of Artemisia roots provided the carbon sources for the rhizoliths formation,while the weathering of soil minerals,particularly feldspars and carbonates,was the main source of *** in the Badain Jaran des

关键词： Rhizoliths Calcification Leptic regosols Artemisia roots Decomposition Soil moisture

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Current Density-Dependent Thermal Stability of ZnSe Nanowire in M-S-M NanostructureD

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Chinese Physics Letters 2014年第12期31卷 134-137页

作者：谭玉王岩国 Science College Hunan Agricultural University Changsha 410128 Beijing National Laboratory of Condensed Matter Physics Institute of Physics

Due to semiconductor nanowire （NW） having a very tiny diameter, the electronic devices based on metal-semiconductor NW-metal （M-S-M） nanostruc- ture can carry a very large current density com- pared to electronics based on bulk semiconductors. A small mass of a NW also means a small heat capacitance. In this case, any small energy trans- fer from the current-carry electrons to local ionic or/and lattice vibrations in NWs may cause a sub- stantial self-heating of the NWs. Thus thermal insta- bility of NWs in M-S-M nanostructure due to Joule heating has become a fundamentally and technolog- ically important issue concerning the performance of semiconductor NW-based nanoelectronics and has at- tracted a lot of attention. The failure behaviors of various semiconductor and metallic NWs inves- tigated by in situ transmission electron microscopy （TEM） and confocal micro-Raman spectroscopy re- spectively have confirmed semiconductor NWs includ- ing Si, Ge, GaN, ZnO, Sn02, Ti02, ZnSe and ZnTe NWs electrically broken by thermal evaporation due to Joule heating and metallic NWs electrically de- stroyed by electromigration. Electron-phonon in- teraction that transfers energy from conduction elec- trons to the ions in the material causes Joule heating. Electromigration due to the transfer of the momentum of conduction electrons to the ions causes migration of atoms in the material when high current density flows through a circuit. The different failure mechanisms of these NWs are significantly materials-dependent due to the difference of their chemical and physical prop- erties and have a very close relation with the param- eters governing the electron transport mechanism at the metal-semiconductor （M-S） nanocontact such as Schottky barrier and bias polarity .

关键词： Thermal stability Electron microscopy

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