Neutron diffraction, synchrotron radiation and EXAFS spectroscopy study of crystal structure peculiarities of the lanthanum nickelates Lan+1NinOy (n=1,2,3)

Thermodynamic analysis of the ternary La–Ni–O system

“…First structure refinements resulted in Fmmm space group [44,45]. Recently, the crystal structure of the lanthanum nickelates La n+1 Ni n O y (n = 1, 2, 3) has been re-investigated by means of neutron and X-ray powder diffraction, synchrotron radiation and EX-AFS spectroscopy [20,46]. The lattice symmetry was found to be orthorhombic.…”

Thermodynamic properties of complex oxides in the La–Ni–O system

“…Four complex oxides belonging to this homologous series: La 2 NiO 4 (n ¼ 1), La 3 Ni 2 O 7 (n ¼ 2), La 4 Ni 3 O 10 (n ¼ 3) and LaNiO 3 (n ¼ N) were described in the La-Ni-O system. La 2 NiO 4+d possesses either tetragonal [1][2][3][4][5][6] or orthorhombically distorted [7][8][9][10][11] K 2 NiF 4 -type crystal structure. The type of crystal structure depends on the temperature and oxygen content.…”

“…X-ray diffraction pattern of La 3 Ni 2 O 7 allowed describing it in an orthorhombic structure in either Fmmm [15][16][17] or Cmcm [7,18,19] space group. Same discrepancy appears in the description of crystal structure of La 4 Ni 3 O 10 .…”

“…Same discrepancy appears in the description of crystal structure of La 4 Ni 3 O 10 . Orthorhombic symmetry of La 4 Ni 3 O 10 unit cell described within Fmmm space group [20,21], or lower symmetry Cmca space group [7,18,19]. Both phases can possess oxygen nonstoichiometry to some extent.…”

Phase Equilibria and Crystal Structures of Mixed Oxides in the La-Mn-Ni-O System

“…5). Therefore, La 4 Ni 3 O 10 contains layers of oxygen octahedra sandwiched between similar, slightly distorted layers [34], while La 2 NiO 4 and La 3 Ni 2 O 7 contain no such layers. In view of this, one would expect an appreciable manganese substitution for nickel in LaNiO 3 within its thermodynamic stability region (T, -100 20 30 Intensity, arb.…”