Showing papers by "Colin Greaves published in 1990"
TL;DR: Sr2CuO3 (orthorhombic, Immm) is converted at about 400°C under oxygen at 160 bar to Sr2cuO3 as mentioned in this paper, which is structurally related to La2 CuO4, and powder neutron diffraction data provide no evidence for O2−2 or O−2 ions.
44 citations
TL;DR: The partial replacement of Li + ions in Li 7 MO 6 (M=Sb, Bi) by Zn 2+ ions has been investigated in this article, where powder neutron diffraction is used to obtain the structure of the new compounds.
42 citations
TL;DR: A phase of composition Ba4CaCu3O8.61 has been synthesised and its structure determined using time-of-flight powder neutron diffraction as mentioned in this paper, which is closely related to the recently reported compound, Ba4YCu3O 8.61.
25 citations
TL;DR: In this article, it was shown that the change in structure from a B82 type to a more ordered variant, which occurs with increasing gallium content at x ≈ 085, is consistent with an ordering process associated with vacant iron sites.
Abstract: X-ray diffraction and Mossbauer studies have been used to identify precisely the crystal structure of recently discovered ferromagnetic alloys based on a series of Fe3Ga2−xAsx (021 ⩽ x ⩽ 1125) alloys In particular, it is shown that the change in structure from a B82 type to a more ordered variant which occurs with increasing gallium content at x ≈ 085, is consistent with an ordering process associated with vacant iron sites Comparison is also made between the lattice spacing data of as-cast and homogenized alloys
21 citations
TL;DR: In this article, powder neutron diffraction was used to examine the oxygen vacancy ordering in YBa2Cu3O7-x using sealed tube techniques to maintain stoichiometry.
12 citations
TL;DR: The structural properties of the perovskite system Ba(Bi1−xLix)O3−y have been investigated for 0.0 < x < 0.25 as mentioned in this paper.
12 citations
01 Jan 1990
2 citations
TL;DR: In this article, an orthorhombic to tetragonal structural transformation occurs in lanthanum-europium-copper oxides with compositions between 0.5 and 0.8.
Abstract: Lanthanum-europium-copper oxides of composition La2−x
Eu
x
CuO4 with structures related to those of the high temperature superconducting oxides have been prepared by solid state reactions between the component oxides in air. The X-ray powder diffraction data demonstrate that an orthorhombic to tetragonal structural transformation occurs at compositions betweenx=0.5 andx=0.8. The151Eu Mossbauer spectra show that europium is present in all phases as Eu3+. Thermal analysis studies in hydrogen show that a two-step reduction process occurs in the lanthanum-europium-copper oxides with the orthorhombic type structure.151Eu Mossbauer spectroscopy shows that the process does not involve the reduction of the lanthanide ion.
1 citations
TL;DR: In this paper, it was shown that the change in structure from a B82 type to a more ordered variant, which occurs with increasing gallium content at x ≈ 0.85, is consistent with an ordering process associated with vacant iron sites.
Abstract: X-ray diffraction and Mossbauer studies have been used to identify precisely the crystal structure of recently discovered ferromagnetic alloys based on a series of Fe3Ga2−xAsx (0.21 ⩽ x ⩽ 1.125) alloys. In particular, it is shown that the change in structure from a B82 type to a more ordered variant which occurs with increasing gallium content at x ≈ 0.85, is consistent with an ordering process associated with vacant iron sites. Comparison is also made between the lattice spacing data of as-cast and homogenized alloys.