“…Phase and structural behaviour in the NdAlO 3 −GdAlO 3 pseudobinary system follows well the general trends observed in the related NdAlO 3 −RAlO 3 [24,31] and RAlO 3 −GdAlO 3 [15,32] [47], LaRuO 3 −SrRuO 3 [48] and PrCoO 3 −PrFeO 3 [49].…”
“…Phase and structural behaviour in the NdAlO 3 −GdAlO 3 pseudobinary system follows well the general trends observed in the related NdAlO 3 −RAlO 3 [24,31] and RAlO 3 −GdAlO 3 [15,32] [47], LaRuO 3 −SrRuO 3 [48] and PrCoO 3 −PrFeO 3 [49].…”
“…4). The reason for this phenomenon, which was earlier also observed in the related rare earth aluminates, gallates and titanates-chromites [21–26], is the different cell parameter ratios within the same orthorhombic GdFeO 3 type of structure observed for the end members of these series.Fig. 4Concentration dependencies of the normalized unit cell dimensions of PrCo 1 − x Fe x O 3 series.…”
Two series of nanocrystalline powders of PrCo1 − xFexO3 (x = 0.1, 0.3, 0.5, 0.7 and 0.9) of high purity were obtained by sol-gel citrate method at 700 and 800 °C. The formation of continuous solid solution with an orthorhombic perovskite structure (sp. group Pbnm) was observed. A peculiarity of the PrCo1 − xFexO3 solid solution is the lattice parameter crossovers, which occurred at certain compositions and revealed in the pseudo-tetragonal or pseudo-cubic metric. An average crystallite size of the PrCo1 − xFexO3 samples estimated from the analysis of the angular dependence of the X-ray diffraction (XRD) line broadening varies between 30 and 155 nm, depending on the composition and synthesis temperature.
“…1) [20]. Because of relatively small content of the doped 3d elements, only very small deviations of the lattice parameters were observed for separate compounds.…”
Six La 0:4 Ca 0:5 Ti 0:5 Cr 0:4 M 0:1 O 3Àδ (M=Cr, Mn, Fe, Co, Ni, Cu) and two La 0:4 Ca 0:4 Ti 0:4 Cr 0:4 M 0:2 O 3Àd (M= Ni, Cu) single-phase compositions were prepared by conventional solid-state reactions. Oxygen nonstoichiometry, electrical conductivity, phase transformations under reduction-reoxidation at high temperatures and catalytic activity for hydrocarbons oxidation of these compositions were investigated in a wide temperature and oxygen partial pressure range. The Cu-, Ni-, Co-, and Fe-containing compositions are decomposed in reducing Ar/H 2 O/H 2 atmosphere with pH 2 O/pH 2 =0.3 at 1,000°C, while the Cr-and Mn-containing ceramics remain stable at the same conditions. The metallic particles of the added 3d elements formed after decomposition were registered by X-ray diffraction method in case of Cu-and Nicontaining compositions. These formed composites can be completely reoxidized with formation of initial compositions by treatment in air at 1,000°C. The electrical conductivity of the ceramics investigated in air and Ar/ H 2 O/H 2 gas flow increases with rising M content. The highest catalytic activity for oxidation of CH 4 and C 3 H 6 , which was comparable with the activity of the La 0:4 Ca 0:5 Ti 0:5 Cr 0:5 O 3Àd þ 5%NiO composite, shows the Cu-containing powders.
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