Bengt-Olov Marinder

Structure of UMoO5 studied by single-crystal X-ray diffraction and high-resolution transmission electron microscopy

A combination of X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) has been used to study the crystal structure of molybdenum uranium pentoxide, UMoO 5 , obtained by hydrothermal and ceramic methods. Crystal data: M r = 414.0, orthorhombic, Pbaa (number 54), a=12.746(1), b = 7.3494 (7), c = 4.1252 (2) A, V = 386.4 (1) A 3 , Z = 4, D x = 7.116 Mgm -3 , R = 0.037 for 723 reflections. The structure of UMoO 5 is related to that of UVO 5 . Both are built up by slabs of pentagonal UO 7 bipyramids with slabs of MO 6 octahedra in-between. They differ in symmetry due to different types of displacement of the M atoms from the ab plane. The HRTEM study revealed a few defect regions in the UMoO 5 crystals prepared by ceramic methods. Energy-dispersive spectroscopy (EDS) analyses indicate a slight excess of uranium in such crystals. Hypothetical models of defect regions are given.

A simple apparatus for determining the density of solids

A gas volumenometer for solid material is described. Using helium as a pressure medium an accuracy of about 1% or better is achieved for sample volumes of . The relative standard deviations range from 0.2 to 0.3%. A novel feature of the method is that a set of pressure and volume readings are collected and used in Boyles law in the form . Plotting these data gives a straight line whose slope is used to calculate . A standard volume is used for calibration of the apparatus. Sources of experimental error are discussed, and an error analysis of the obtained sample volume is performed. Air, argon, and helium have been used and are compared as pressure media. Mass and volume measurements have been obtained for six substances, and their observed densities are compared with x-ray densities taken from the literature.

On the phase relations in the VxMo1−xO2 system (0 ≤ x ≤ 0.55)

Abstract The pseudo-binary system V x Mo 1−x O 2 (0 ≤ x ≤ 0.55) has been studied by X-ray examination of samples quenched after prolonged heat-treatment at temperatures between 400°C and 1190°C. The phase diagram is complicated, with several rutile-related phases. The approach to equilibrium is sluggish in some areas.

Structural studies on Li1−xTa3O8−xFx solid solutions by full-profile refinements of guinier-hägg X-ray film data

Three compositions of solid solutions Li1−xTa3O8−xFx (x = 0) 0.25 and 0.5) have been studied by full-profile analysis of microdensitometer-measured Guinier-Hagg powder diffraction data. From sequential changes in disorder and interatomic distances within this series, the preferred lithium position is proposed to be approximately (0.11, 12, 0.03). The results obtained for the high temperature modification of LiTa3O8 by A.G. Nord and J.O. Thomas from X-ray single crystal and neutron powder diffraction data [Nord, A.G. and Thomas, J.O., Acta Chem. Scand., in press] are discussed in view of the present investigation.

Structure and ionic conductivity of Lix(MeO)4Me30O90 (Me = NbV, WVI)

Abstract The compound Lix(MeO)4Me30O90 (Me = NbV, WVI) has been prepared and investigated by X-ray powder and electron diffraction techniques as well as by measurements of complex impedance. The structure is of the tripled tetragonal tungsten bronze type with one third of the pentagonal tunnels filled with equal numbers of Me and 0 atoms. The conductivity at 300°C is 0.20 and 0.25 ohm−1m−1 for sintered samples with x equal to 2 and 4, respectively. The location and probable routes of transport of the lithium ions are discussed.