749 Matching Results

Search Results

Advanced search parameters have been applied.

The Estimation of Heats of Formation

Description: The procedure for estimation of heats of formation of compounds is illustrated by discussion of compounds of several of the elements of the actinide series. The procedure is particularly suited for lanthanide and actinide elements because of the similarity of the ionic radii and types of bonding.
Date: February 2, 1948
Creator: Brewer, Leo
Partner: UNT Libraries Government Documents Department

The Determination of Rare Earths in Thorium

Description: Abstract: "A quantitative method for the determination of individual rare earths in thorium down to a level of 0.05 ppm, is described. The procedure consists of a chromatographic cellulose-columns separation followed by a solution-type spectrographic determination. Values are given for the recovery of a number of rare earths using this combined procedure."
Date: May 15, 1952
Creator: Center, E. J.; Henry, W. M. & Householder, R. D.
Partner: UNT Libraries Government Documents Department

Rediscovery of the Elements: The Rare Earths - The Beginnings

Description: This article explores the rare earths, the chemically similar elements that occupy the f-block of the Periodic Table and the Group III chemical family. The articles shows the locations that certain rare earths were originally found. It also gives details on where the elements can be found currently, as well as major production areas. The cover of the Fall 2015 Hexagon journal (Vol. 106, Issue 3) features the Mountain Pass rare earth ore body in Southern California, which is mentioned in the article on pages 40-45 of the journal. A description of the photo on the cover of the journal can be found on page 38.
Date: Autumn 2015
Creator: Marshall, James L., 1940- & Marshall, Virginia R.
Partner: UNT College of Arts and Sciences

Summary of the Research Progress Meeting

Description: This report discusses progress on the following topics: (1) some new isotopes in the rare earth region; (2) remarks on a new alpha series; (3) solid counters; (4) naphthalene crystals have been replaced with anthracite in one of the experimental counters and some excellent results are obtained; and (5) biological experiments with the deuteron bean of the 184-inch cyclotron.
Date: April 8, 1948
Creator: Wakerling, R.K.
Partner: UNT Libraries Government Documents Department

Thermal Expansion of Rare Earth Metals

Description: High temperature dilatometric investigation of the rare earth metals undertaken as part of a broad program of study of these elements, the ultimate goal being better understanding of metals in general.
Date: June 1956
Creator: Barson, Fred; Legvold, S. & Spedding, F. H.
Partner: UNT Libraries Government Documents Department

The Reactions of Mixed Crystals of Rare Earth Fluorides With Fluorine Gas

Description: Thesis discussing the reactions of mixed crystals of rare earth fluorides with fluorine gas. The reactions were "studied gravimetrically by determining the weight increases of mixed tetrafluoride samples upon exposure to fluorine at a pressure of 1 atmosphere and a temperature of 250°C...The nature of the phases produced upon fluorination was studied by x-ray diffraction methods."
Date: August 1957
Creator: Bryan, William Phelan
Partner: UNT Libraries Government Documents Department

Rediscovery of the Elements: The Rare Earths - The Confusing Years

Description: This article gives a timeline of research conducted on the rare earths, 17 elements found in the f-block and Group III chemical family of the Periodic Table. It covers discoveries made after the success of Swedish chemist, Carl Gustaf Mosander. The article describes the categorization of the rare earths that took place after Mosander's time, as well as separation techniques that developed.
Date: Winter 2015
Creator: Marshall, James L., 1940- & Marshall, Virginia R.
Partner: UNT College of Arts and Sciences

Reconnaissance Geology of Placer Deposits Containing Radioactive Minerals in the Bear Valley District, Valley County, Idaho

Description: From introduction: The Bear Valley district is situated in southwestern Idaho, in the drainage of the Middle Fork of the Salmon River (see fig. 1). The placer deposits were drilled by the U. S. Bureau of Mines in 1951 and 1952 to determine their content of monazite and "radioactive black minerals" (here referred to loosely as "radioactive blacks"). The purpose of the study outlined here was to provide a geologic background for an understanding of the origin and distribution of the placer minerals.
Date: January 1953
Creator: Mackin, J. Hoover & Schmidt, Dwight Lyman
Partner: UNT Libraries Government Documents Department

Brilliant Sm, Eu, Tb and Dy chiral lanthanide complexes withstrong circularly polarized luminescence

Description: The synthesis, characterization and luminescent behavior of trivalent Sm, Eu, Dy and Tb complexes of two enantiomeric, octadentate, chiral, 2-hydroxyisophthalamide ligands are reported. These complexes are highly luminescent in solution. Functionalization of the achiral parent ligand with a chiral 1-phenylethylamine substituent on the open face of the complex in close proximity to the metal center yields complexes with strong circularly polarized luminescence (CPL) activity. This appears to be the first example of a system utilizing the same ligand architecture to sensitize four different lanthanide cations and display CPL activity. The luminescence dissymmetry factor, g{sub lum}, recorded for the Eu(III) complex is one of the highest values reported, and this is the first time the CPL effect has been demonstrated for a Sm(III) complex with a chiral ligand. The combination of high luminescence intensity with CPL activity should enable new bioanalytical applications of macromolecules in chiral environments.
Date: July 10, 2006
Creator: Petoud, Stephane; Muller, Gilles; Moore, Evan G.; Xu, Jide; Sokolnicki, Jurek; Riehl, James P. et al.
Partner: UNT Libraries Government Documents Department

Pentamethylcyclopentadienyl Derivatives of the Trivalent Lanthanide Elements (Neodymium, Samarium, and Ytterbium)

Description: The anionic complexes of the type (ML{sub x})(Me{sub 5}C{sub 5}){sub 2}M'Cl{sub 2}, where M is lithium or sodium, L is diethyl ether or N,N,-N{prime},N{prime}-tetramethylethylenediamine, and M{prime} is neodymium, samarium, or ytterbium, have been prepared from the metal trichlorides and the pentamethylcyclopentadienide anion. The neutral species (Me{sub 5}C{sub 5}){sub 2}NdCl(THF), (Me{sub 5}C{sub 5}){sub 2}NdN(SiMe{sub 3}){sub 2}, and (Me{sub 5}C{sub 5}){sub 2}YbCl(THF) have also been prepared. The mono-ring derivatives (Na(OEt{sub 2}){sub 2})((C{sub 5}Me{sub 5})NdCl{sub 3}) and (Me{sub 5}C{sub 5})Nd(N(SiMe{sub 3}){sub 2}){sub 2} are also described.
Date: July 1, 1980
Creator: Tilley, T. Don & Andersen, R .A.
Partner: UNT Libraries Government Documents Department

Correlation Between the Atomic and Bulk Chemical Potentials of Low work Function Metals

Description: An attempt is made to identify preferred values for the work functions of the rare earth elements by correlating the atomic chemical potential with the work function of the bulk elements. Trends in the alkali and alkali earth metal are evaluated in the same context. Strong linear correlation between the two quantities is observed within the IA, 11A, and IIIB (Se, Y, La) groups. Within the lanthanide series the nature of the correlation between the metallic radius and the work function suggests a dependence on the total angular momentum.
Date: December 22, 1998
Creator: Drummond, T.J.
Partner: UNT Libraries Government Documents Department

Determination of Rare Earths in Refined Uranium : Topical Report

Description: Abstract: "Rare-earth analyses were performed on several samples of refined uranium oxide and nitrate, using a modified cellulose column procedure. Rare earths were not detectable in samples of 0.03 shotgun of less. Detection limits were from 0.0005 to 0.015 ppm. Negligible quantities of low-cross-section rare earths were found in less pure uranium samples, obtained during start-up operations of the pilot plant at the Feed Materials Production Center, primarily those rare earths of greater than average abundance in nature. No correlation was found between rare-earth content and shotgun values. Rare earths do not appear to be contributing significantly to the neutron absorption of refined uranium. A modified cellulose column procedure, which includes a preconcentration solvent-extraction step, is described. Radioactive tracer tests indicating rare-earth recoveries by the method of >98 per cent are reported."
Date: June 30, 1953
Creator: Ewing, R. A. & Bearse, A. E.
Partner: UNT Libraries Government Documents Department

Radioactive Rare-Earth Deposit at Scrub Oaks Mine, Morris County, New Jersey

Description: From abstract: A deposit of rare-earth minerals in the Scrub Oaks iron mine, Morris County, N. J., was mapped and sampled in 1955. The rare-earth minerals are mainly in coarse-grained magnetite ore and in pegmatite adjacent to it. Discrete bodies of rare-earth-bearing magnetite ore apparently follow the plunge of the main magnetite ore body at the north end of the mine. Radioactivity of the ore containing rare earths is about 0.2 to 0.6 milliroentgens per hour.
Date: 1959
Creator: Klemic, Harry; Heyl, Allen V., Jr.; Taylor, A. R. & Stone, Jerome
Partner: UNT Libraries Government Documents Department

THE EFFECT OF MAGNETICALLY ALIGNED POWDER ON THE MAGNETOSTRICTION OF SINTERED RARE EARTH - IRON LAVES PHASE COMPOUNDS

Description: A powder metallurgical approach is utilized to prepare grain oriented Laves phase compounds of Tb{sub x}Dy{sub 1-x}Fe{sub 2}. The magnetostrains observed in the oriented compounds, though containing {approx}20% porosity as presently prepared, are far superior to those of arc cast and highly dense liquid phase sintered materials. Also, it is shown that the alignment achieved is strongly dependent on the Tb/Dy ratio.
Date: October 1, 1977
Creator: Malekzadeh, M. & Pickus, M.R.
Partner: UNT Libraries Government Documents Department

Effect of Temperature on the Protonation of the TALSPEAK Ligands: Lactic and Diethylenetrinitropentaacetic Acids

Description: The protonation reactions of two ligands that play important roles in the TALSPEAK process for the separation of trivalent actinides from lanthanides, lactic acid and diethylenetrinitropentaacetic acid (DTPA), have been studied at variable temperatures. The protonation constants at 10-70 C were determined by titration potentiometry and the protonation enthalpies were determined at 25 C by titration microcalorimetry. The protonation constants remain essentially unchanged (25-70 C) within the experimental uncertainties, indicating that the effect of temperature on the protonation of lactate is insignificant. In contrast, the protonation constants of DTPA (log {beta}H's) generally decrease as the temperature is increased. Results from this study indicate that the effect of temperature on the protonation of DTPA could alter the speciation of metal ions (actinides and lanthanides) in the TALSPEAK system, since lower values of log{beta}H at higher temperatures suggest that the hydrogen ions would compete less strongly with the metal ions for the complexation of DTPA at higher temperatures.
Date: October 20, 2009
Creator: Tian, Guoxin & Rao, Linfeng
Partner: UNT Libraries Government Documents Department