Powder X-ray diffraction and Rietveld analysis of La_1−xCa_xMnO₃(0<X<1)

Abstract

Single-phase samples of La1−xCaxMnO3compounds have been synthesized by solid-state reaction. Detailed Rietveld analysis of powder X-ray diffraction data showed that La1−xCaxMnO3undergoes a structural phase transformation fromR-3ctoPnmaatX=0.05–0.075. There is a linear variation of lattice parameters as a function of calcium concentration. The slope of this linear variation changes atX=0.6. A correlation between observed Mn-O bond lengths, corresponding to different compositions, and possible magnetic phases is discussed.

Thickness dependence of substrate-induced strain in La0.9Ca0.1MnO3 thin films

“…3. The b value for the thinnest film is considerably lower than the literature value, which is consistent with the tensile in-plane epitaxial strain (approximately 0.14%) between the bulk LCMO and (1 0 0) STO [12,13]. With increasing film thickness, b increases and converges to the bulk value, which can be explained by the relaxation of the epitaxial strain for the thicker films.…”

“…A stoichiometric La 0.9 Ca 0.1 MnO 3 polycrystalline ceramic disc (diameter is 10 mm) was used as a target. The lattice parameters of the bulk ceramic target are [13]. Prior to the deposition, the STO substrate was cleaned in acetone using an ultrasonic bath followed by ethanol rinsing for 10 min.…”

Strain-induced first-order orbital flip transition and coexistence of charge-orbital ordered phases inPr0.5Ca0.5MnO3

“…22 The as-prepared pellet of Pr 0.5 Ca 0.5 MnO 3 was cut across the thickness 3 in two parts. XRD measurements at room temperature ͑RT͒ and low temperature, down to 90 K, were done on the cut surface of one of the pieces of the cut pellet and also on the powder.…”

Mn(I) in an Extended Oxide: The Synthesis and Characterization of La1–xCaxMnO2+δ(0.6 ≤x≤ 1)

“…Similar disordered Ca 0.5 Mn 0.5 O rocksalt phases can be prepared by sintering CaO and MnO at high temperature, indicating these are thermodynamically stable phases. 25,26 In contrast to the calcium-rich La 1Àx Ca x MnO 2+δ phases, the lanthanum-rich reduced materials (0.6 e x e 0.7) adopt aniondeficient tetragonal structures which retain the ordered cation lattices of the parent perovskite phases. The anion deficiency in these tetragonal phases is accommodated within equatorial layers of composition MnO.…”

“…35 As described above, the transformation from CaMnO 3 perovskite to Ca 0.5 Mn 0.5 O rocksalt is kinetically facilitated by the common cation lattice shared by the two structures (Figure 10a and b); thus, no longrange cation diffusion is required during the transformation, and the reaction is driven by the thermodynamic stability of the rocksalt phase which is formed. 25,26 Reduction of the analogous La 1Àx Ca x MnO 3 perovskite phases follows a similar path to form materials with structures based on that of rocksalt. However, as the reduction reactions are performed at low temperature, there is insufficient energy to expel the lanthanum cations from the ternary oxide phase and form mixtures of Ca 0.5Àx Mn 0.5+x O and x / 2 La 2 O 3 in reactions analogous to the decomposition of LaMnO 3 .…”