Structural transformations of the La_2−xPr_xNiO_4+δ system probed by high-resolution synchrotron and neutron powder diffraction

Abstract

Subtle structural distortions in the La2−xPrxNiO4+δ system are investigated using high resolution X-ray powder diffraction and neutron powder diffraction, analyzed by combined Rietveld refinements.

Structure, electrical conductivity and oxygen transport properties of Ruddlesden–Popper phases Lnn+1NinO3n+1 (Ln = La, Pr and Nd; n = 1, 2 and 3)

“…The X-ray diffractograms of La 2 NiO 4+d and Nd 2 NiO 4+d can be tted in the orthorhombic space group Fmmm, which is in good agreement with previous analyses of data from synchrotron Xray powder diffraction (SXRPD) and neutron powder diffraction (NPD) of both materials. 10,44,45 The XRD pattern of La 3 Ni 2 -O 7Àd can be tted in the orthorhombic space group Cmmm, consistent with the results from Mössbauer spectroscopy and XRD by Kiselev et al 46 The XRD patterns of the n ¼ 3 RP S1-S5. † All compositions are found to be phase-pure, i.e., no impurity peaks are observed up to 1000 C. Fig.…”

“…The cell parameters for all compositions are in good agreement with those reported previously in the literature. 5,10,41,[43][44][45][46][47] The crystallographic parameters obtained from the Rietveld renements are listed in Table S1. † The corresponding structures of the RP nickelates are shown in Fig.…”

Deep eutectic solvent route synthesis of zinc and copper vanadate n-type semiconductors – mapping oxygen vacancies and their effect on photovoltage

“…The relatively high ADP value for the O1 site (Table 2) is not from signicant thermal motion of oxygen but likely from disordered oxygen ion displacements. 47,48 All oxygen positions are corner-shared sites of either vanadium or copper centered polyhedra, such as two VO 4 tetrahedra sharing O1 sites. Both O2 and O3 are shared between a VO 4 tetrahedron and a CuO 5 distorted square pyramid.…”

Using applied pressure to guide materials design: a neutron diffraction study of La2NiO4+δand Pr2NiO4+δ

“…Previous studies have shown a reasonably linear decrease in unit-cell volume with increasing chemical doping (x) in the solid solutions La 2−x Pr x NiO 4 and Pr 2−x Nd x NiO 4 (see Figure 5). 32,33 This is expected, as the ionic radii of the lanthanides decrease with increasing Z across the lanthanide series La (1.216 Å) > Pr (1.179 Å) > Nd (1.163 Å) (with ninefold coordination in 3+ oxidation state). It is possible to determine the equivalent pressure required to compress the parent (undoped) material to the same unit-cell volume using the EoS parameters determined for the end member.…”