Structural Control and Surface Modifications of Rare Earth Nanomaterials

2012 ◽  
pp. 43-82
Author(s):  
Gautom Das ◽  
Timothy Tan
Keyword(s):  
Rare Earth ◽  
Structural Control ◽  
Surface Modifications

scholarly journals APATITE-ALBITE METASOMATITES (ACEITES) OF THE EASTERN ALDAN-STANOVOY SHIELD

2021 ◽  
Vol 40 (5) ◽  
pp. 59-73
Author(s):  
V.E. Kirillov ◽  
Keyword(s):  
Rare Earth ◽  
Structural Control ◽  
Earth Element ◽  
Rare Metal ◽  
Igneous Rocks ◽  
Metamorphic Rocks ◽  
Intrusive Rocks ◽  
Characteristic Features ◽  
Metasomatic Zoning ◽  
Geochemical Specialization

The paper summarizes the findings of research on Riphean ore-bearing apatite-albite metasomatites (aceites) identified in metamorphic, volcanic and intrusive rocks in the eastern Aldan-Stanovoy shield. The characteristic features of lithological and structural control of aceites, their mineral and petrochemical composition, geochemical associations, ontogeny, metasomatic zoning, and geochemical specialization are outlined. Aceites in metamorphic rocks are assigned to the albite-chlorite-apatite facies and in igneous rocks to the albite-apatite facies. Apatite-albite metasomatites host mineralization of two types: uranium (in aceites after metamorphic rocks) and uranium – rare earth element – rare metal (in aceites after volcanic and intrusive rocks).

scholarly journals Structural control of thermomechanical properties of monoclinic rare earth calcium oxoborates

2019 ◽  
Vol 75 (a2) ◽  
pp. e278-e278
Author(s):  
Marie Münchhalfen ◽  
Jürgen Schreuer ◽  
Christoph Reuther ◽  
Erik Mehner ◽  
Hartmut Stöcker
Keyword(s):  
Rare Earth ◽  
Structural Control ◽  
Thermomechanical Properties

scholarly journals Heat-Induced Transformation of Luminescent, Size Tuneable, Anisotropic Eu:Lu(OH)2Cl Microparticles to Micro-Structurally Controlled Eu:Lu2O3 Microplatelets

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 992
Author(s):  
Madeleine Fellner ◽  
Alberto Soppelsa ◽  
Alessandro Lauria
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Structural Control ◽  
Thermal Evolution ◽  
Luminescence Spectroscopy ◽  
Great Promise ◽  
Lutetium Oxide ◽  
Transmission Electron ◽  
Interesting Approach ◽  
Rare Earth Sesquioxides

Synthetic procedures to obtain size and shape-controlled microparticles hold great promise to achieve structural control on the microscale of macroscopic ceramic- or composite-materials. Lutetium oxide is a material relevant for scintillation due to its high density and the possibility to dope with rare earth emitter ions. However, rare earth sesquioxides are challenging to synthesise using bottom-up methods. Therefore, calcination represents an interesting approach to transform lutetium-based particles to corresponding sesquioxides. Here, the controlled solvothermal synthesis of size-tuneable europium doped Lu(OH)2Cl microplatelets and their heat-induced transformation to Eu:Lu2O3 above 800 °C are described. The particles obtained in microwave solvothermal conditions, and their thermal evolution were studied using powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical microscopy, thermogravimetric analysis (TGA), luminescence spectroscopy (PL/PLE) and infrared spectroscopy (ATR-IR). The successful transformation of Eu:Lu(OH)2Cl particles into polycrystalline Eu:Lu2O3 microparticles is reported, together with the detailed analysis of their initial and final morphology.

scholarly journals Prospects of the Tymoshivsko-Znamianskyi potential rare-metal ore area of Inhulskyi megablock of the Ukrainian Shield

2020 ◽  
pp. 3-12
Author(s):  
G. A. Kalashnyk
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Structural Control ◽  
Great Part ◽  
Rare Metal ◽  
Raw Material ◽  
Ukrainian Shield ◽  
Material Base ◽  
Hydrothermal Mineralization ◽  
Genetic Types

The article presents the results of the assessment of the prospects for discovery of industrial concentrations of rare and rare-earth elements in the Tymoshivsko-Znamianskyi potential rare-metal ore area of Inhulskyi megablock of the Ukrainian Shield. The results of studies of regularities of raremetalmineralization’s placement in Tymoshivsko-Znamianskyi potential ore region of the Inhulskyi megablock of the Ukrainian Shield are presented. The structural control of the great part of the detected geochemical anomalies, geochemical halos, manifestations and ore manifestations by certain systems of rupture faults and their intersection nodes is determined. The typical local features of manifestations of rare metal mineralization in small uranium deposits and large ore manifestations of this region and uranium mineralization of different genetic types, in particular hydrothermal mineralization of vein-stockwork type in mineralized fault zones are presented. According to the degree of manifestation of the complex of criteria, prospective ore and potentially ore nodes are discovered for possible detection of industrial concentrations of rare metals and rare-earth elements within the Tymoshivsko- Znamianskyi potential ore region, as well as uranium ores of various genetic types, in particular superimposed rich hydrothermal mineralization of vein-stockwork type. There were developed recommendations for further research in the Tymoshivsko-Znamianskyi potential ore region with the aim of farther development of rare and rare-earth elements raw material base.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Bronchial stereocilia in the immotile cilia syndrome: A case report

1984 ◽  
Vol 42 ◽  
pp. 52-53
Author(s):  
George Price ◽  
Lizardo Cerezo
Keyword(s):  
Surface Modifications ◽  
Respiratory Epithelium ◽  
Immotile Cilia ◽  
Kartagener's Syndrome ◽  
Membrane Blebs ◽  
Radial Spokes ◽  
Males And Females ◽  
Dynein Arms ◽  
Ultrastructural Finding ◽  
Ultrastructural Findings

Ultrastructural defects of ciliary structure have been known to cause recurrent sino-respiratory infection concurrent with Kartagener's syndrome. (1,2,3) These defects are also known to cause infertility in both males and females. (4) Overall, the defects are defined as the Immotile, or Dyskinetic Cilia Syndrome (DCS). Several ultrastructural findings have been described, including decreased number of cilia, multidirection orientation, fused and compound cilia, membrane blebs, excess matrix in the axoneme, missing outer tubular doublets, translocated doublets, defective radial spokes and dynein arms. A rare but noteworthy ultrastructural finding in DCS is the predominance of microvilli-like structures on the luminal surface of the respiratory epithelium. (5,6) These permanent surface modifications of the apical respiratory epithelium no longer resemble cilia but reflect the ultrastructure of stereocilia, similar to that found in the epidydimal epithelium. Like microvilli, stereocilia are devoid of microtubular ultrastructure in comparison with true cilia.

Study of segregation in La1.8Sr0.2CuO4 superconductor by STEM-EDS microanalysis

1987 ◽  
Vol 45 ◽  
pp. 54-55
Author(s):  
T. F. Kelly ◽  
P. J. Lee ◽  
E. E. Hellstrom ◽  
D. C. Larbalestier
Keyword(s):  
Rare Earth ◽  
High Field ◽  
Transport Current ◽  
Total Thickness ◽  
New Class ◽  
Ceramic Superconductors ◽  
Current Densities ◽  
Group Ii ◽  
Eds Microanalysis

Recently there has been much excitement over a new class of high Tc (>30 K) ceramic superconductors of the form A1-xBxCuO4-x, where A is a rare earth and B is from Group II. Unfortunately these materials have only been able to support small transport current densities 1-10 A/cm2. It is very desirable to increase these values by 2 to 3 orders of magnitude for useful high field applications. The reason for these small transport currents is as yet unknown. Evidence has, however, been presented for superconducting clusters on a 50-100 nm scale and on a 1-3 μm scale. We therefore planned a detailed TEM and STEM microanalysis study in order to see whether any evidence for the clusters could be seen.A La1.8Sr0.2Cu04 pellet was cut into 1 mm thick slices from which 3 mm discs were cut. The discs were subsequently mechanically ground to 100 μm total thickness and dimpled to 20 μm thickness at the center.

Biomimetic materials: An introduction

1992 ◽  
Vol 50 (2) ◽  
pp. 1020-1021 ◽  
Author(s):  
M. Sarikaya ◽  
J. T. Staley ◽  
I. A. Aksay
Keyword(s):  
Self Assembly ◽  
Structural Control ◽  
Hierarchical Structures ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Length Scale ◽  
Spider Webs ◽  
Biomimetic Materials ◽  
Synthetic Materials ◽  
All Ceramic

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).

Microstructural characterization of a cast RENi5-based alloy

1993 ◽  
Vol 51 ◽  
pp. 1176-1177
Author(s):  
G. M. Micha ◽  
L. Zhang
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Microstructural Characterization ◽  
Binary Compound ◽  
Nickel Metal ◽  
Cast Material ◽  
Nickel Metal Hydride ◽  
Transmission Electron ◽  
Cast Condition

RENi5 (RE: rare earth) based alloys have been extensively evaluated for use as an electrode material for nickel-metal hydride batteries. A variety of alloys have been developed from the prototype intermetallic compound LaNi5. The use of mischmetal as a source of rare earth combined with transition metal and Al substitutions for Ni has caused the evolution of the alloy from a binary compound to one containing eight or more elements. This study evaluated the microstructural features of a complex commercial RENi5 based alloy using scanning and transmission electron microscopy.The alloy was evaluated in the as-cast condition. Its chemistry in at. pct. determined by bulk techniques was 12.1 La, 3.2 Ce, 1.5 Pr, 4.9 Nd, 50.2 Ni, 10.4 Co, 5.3 Mn and 2.0 Al. The as-cast material was of low strength, very brittle and contained a multitude of internal cracks. TEM foils could only be prepared by first embedding pieces of the alloy in epoxy.

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