Showing papers on "Erbium published in 1981"

Some characteristics of population inversion of the 4I13/2 level of erbium ions in ytterbium–erbium glasses

Abstract: A comparative investigation is made of phosphate, germanate, and lithium silicate glasses activated with Yb3+ and Er3+ ions in order to determine their potential usefulness for the development of laser-pumped (λ = 1.06 μ) amplifiers for short (10−8 sec) pulses at the λ = 1.54 μ wavelength. Some features of the spectral and luminescence charactenstics and the kinetics of energy transfer in these glasses are studied. It is shown that the increase in the population inversion of the 4I13/2 level of Er3+ ions in lithium silicate and germanate glasses is considerably slower than the increase in the absorbed pump energy. Possible mechanisms for this anomalous behavior are discussed. It is shown theoretically and experimentally that the main reason for this is reverse transfer of excitation energy from Er3+ to Yb3+ ions, which is almost absent in phosphate glasses.

The crystal structures of yttrium, holmium and erbium formate dihydrates

Abstract: Crystal structures of orthorhombic Ρ 212121 isomorphous Y, Ho and Er formate dihydrates [Y(HC02)3 · 2 H20] have been determined from X-ray diffraction data. The metal atom is coordinated by eight oxygens in a distorted Z)4d square antiprism. Two of the oxygens are associated with water, six with the three formate groups. The three formate groups link the metal polyhedra to a three dimensional framework structure. Lanthanide contraction is expressed in slightly shorter Μ — O distances in Er-formate dihydrate. Introduction The determination of the crystal structure of Y formate dihydrate is an extension of Pabst's (1978) work on synthesis and lattice geometry of various formates and formate dihydrates. The structure was used as a suitable example to illustrate the heavy atom technique in a crystallography course. In this way I became involved with these organometallic compounds whose structural results were found to be interesting and therefore warrant a brief report. In 1940 Zachariasen determined the structure of monoclinic Na-formate with sixfold coordination of sodium. Pabst (1943) followed with the ninecoordinated Gd-formate. More recently considerable work was done on the synthesis of rare earth formates. In these experiments, treating powdered sesquioxides with formic acid, Plyuschchev et al. (1966) observed in addition to the anhydrous formates of Y, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy and Ho which are all isostructural with rhombohedral Gd formate, crystals of Y, Er and Ho formate dihydrates. Pabst (1978) described the morphology of these * Dedicated to Professor A. Pabst on occasion of his 80th birthday 138 H.-R. Wenk: The crystal structures of Y. Ho and Er formate dihydrates crystals, as being dominated by prismatic forms ¡101 ,, ¡120 j and ¡021} and on the basis of Weissenberg photographs was able to assign these isomorphous dihydrated formates the orthorhombic space group Ρ 2 χ 2 χ 2 ν He noted that reflections hOl, h + k = odd were very weak, suggesting a pseudosymmetry with an η glide plane normal to y. Crystals from Pabst's (1978) study were available for this project. Methods of structure determination and refinements The crystal structure of yttrium formate dihydrate was first determined. Subsequently structures of the isomorphous rare-earth compounds were Table t . Information about data collection

The growth of crystals of erbium hydride

Abstract: Crystals of the rare-earth hydride ErH2 have been produced with face areas greater than a square millimetre and corresponding volumes exceeding those of earlier crystals by orders of magnitude. The hydride, which was produced in bulk polycrystalline form by hydriding erbium metal at 950° C, has been examined by optical and X-ray techniques. For material of composition ErH2 and ErH1.8 the size of the grains and their degree of strain appears to depend more on oxygen contamination during formation and on the subsequent cooling procedure, than on the size of erbium metal crystals in the starting material.

Magnetoelastic effects in erbium

Abstract: A new ultrasonic sing-around system has been used to measure the changes in the elastic moduli of single-crystal specimens of erbium to a much higher precision than has been achieved previously. The variations of the second-order elastic constants C33, C11, C44 and C66 have been measured as a function of temperature over the range 4.2-100K. The variations of the moduli C11 and C33 have also been investigated as a function of magnetic field applied along the c and b crystallographic axes respectively at a series of temperatures in the three magnetically ordered phases of erbium. The results have allowed critical magnetic fields and their dependence upon temperature to be determined.

Electrode for electriccdischarge lamp

Abstract: PURPOSE:To reduce the deterioration of a flux of light in a lighting action by using an electrode, which has an electron emitter which in turn contains a specific material, to increase the adherence of the electron emitter to constitutive elements of the electrode. CONSTITUTION:An electrode consists of an electrode core 15 which is made of a heat resisting metal, an inner coil 16, an outer coil 17 and an electron emitter 18. The electron emitter 18 contains dysprosium oxide and at least one rare earth metal oxide selected from the oxides of cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, holmium, erbium, thulium, ytterbium and lutetium.