Crystal structure and semiconductor-metal transition of the quasi-two-dimensional transition metal oxide, La2NiO4

Structural study of lanthanum nickelate thin films deposited on different single crystal substrates

“…8(b)). At room temperature, the resistivity value is of 0:54 O cm and is coherent with results reported in the literature for La 2 NiO 4þd compounds [23][24][25]. However, down to 30 K, the behavior of the resistivity is best described by a variable-range hopping mechanism which is coherent with the observed disorder of plane structural faults [26].…”

Properties of La2CuO4 and related compounds

“…We note that La2NiO4 adopts the K2NiF4 structure at room temperature; however, it undergoes a tetragonal-to-orthorhombic transition [5 ] K. La2CoO4 [6] and YCaCrO 4 [7 ] have the same structure as that of La2CuO4 at room temperature. La2CoO4 undergoes an antiferromagnetic transition [ 13] at ~275 K and its structure changes to an unknown tetragonal phase at ~ t35 K. Some of the compounds with tetragonal or distorted K2NiF4 structure are listed in table I.…”

“…Large single crystals have been grown variously from CuO, PbO and Li20-B203 fluxes; the last two fluxes incorporate some Pb and Li, respectively, into the structure. As regards the La and Cu sites, various measurements (X-ray refinement, electron microprobe, classical density and recently neutron diffraction ) on samples prepared differently [ 7 ] Orthorhombic II Sm2CoO4 [ 9 ] Monoclinic Pr2NiO4 [ 5 ] Nd_,NiO, [ 5 ] La2NiO4 undergoes a structural transition from T(I) to O(I) at ~240 K [5] LazCoO4 undergoes a structural transition from O(I) to an unknown tetragonal structure at ~135K [13] 9…”

“…The tetragonal-to-orthorhombic transition [3,4 ] for La2CuO4 occurs at To= 530 K and involves a tilting of the elongated CuO6-octahedra. (This distortion is sometimes ascribed to a Jahn-Teller distortion of Cudg; however, the presence of a similar distortion in La~NiO4 [5], La2CoO4 [6], and YCaCrO4 [7] would argue against it being the only cause of the distortion.) The elongation of these octahedra is such that the Cu-O distance in the layers (1.907 ~) is considerably shorter than the Cu-O distance out-ofthe layers (2.459 ~).…”

Magnetism Within the Limitations of the LDA Band Structure Calculations

“…At low temperatures La2CuO4 and La2NiO4 are similar with respect to both their crystal structure (tetragonal/orthorhombic) and their magnetic properties (antiferromagnetism). However, in high temperature paramagnetic state La 2 NiO4 becomes metallic [44] in contrast to La2CuO4 and indicates that these compounds are Slater's and Mott's insulators respectively, because the first becomes metallic at high temperature while the second stays insulating. As we demonstrated in our previous paper [45], antiferromagnetic ordering can be obtained easily in nickel perovskites.…”