Evolution of transition metal charge states in correlation with the structural and magnetic properties in disordered double perovskites Ca_2−xLa_xFeRuO₆ (0.5 ≤ x ≤ 2)

Abstract

A series of disordered Ca1.5La0.5FeRuO6, CaLaFeRuO6 and La2FeRuO6 double perovskites was prepared by solid-state method and investigated by neutron powder diffraction, x-ray absorption near edge structure (XANES) analysis at the...

Evolution of the valence state of Ru metal ions in correlation with the structural and electronic properties of double perovskite ruthenates; A2SmRuO6 (where A = Ba & Sr)

“…11), where Ru ions are in the +4-oxidation state. The M 3 edge peak of Ru ions in the “RO” compound appears at ∼464.5 eV, where the Ru ion is clearly in the +4-oxidation state, 47 while the M 3 edge peak of Ru ions is observed at 464.8 eV and 465.6 eV for the SSRO and BSRO compounds, respectively. The M 3 edge of the Ru ion in the SSRO compound (464.8 eV) is found to be nearly at the same position as that of the RO compound (∼464.5 eV), which indicates that Ru ions in the SSRO compound are also possibly in the +4-oxidation state.…”

Magnetic structure of the swedenborgite compound CaBaMn2Fe2O7 derived by powder neutron diffraction and Mössbauer spectroscopy

“…Here, for CaBaMn 2 Fe 2 O 7 , a close inspection of the residual diffuse scattering at the tails of the strongest magnetic Bragg reflection suggests that the system is almost fully ordered, which is furthermore supported by the equally sized amplitudes of kagome and trigonal spins of almost 4 µ B in comparison to the theoretical 5 µ B for a mixture of Fe 3+ and Mn 2+ S = 5 2 spins. Full magnetic order is also supported by the uniform evolution of the magnetic hyperfine pattern in the Mössbauer spectra, while magnetic disorder effects typically lead to paramagnetic signals even below T N [33]. With respect to the expected charge states, the Mössbauer spectra do not show any signals pointing toward the presence of Fe 2+ , which should have clearly different hyperfine parameters.…”

Structure‐property Relationship of Double Perovskite Oxide towards Trifunctional Electrocatalytic Activity: Strategy for Designing and Development

“…Both the octahedral factor as well as the chemical nature of A‐ and B ‐site cations are playing a significant role for the formation and predictive of the stability for the DP structure [47,50] . Such factors can further influences to local symmetry and related essential properties like as electronegativity, valence state of the DP structure [51–56,80] . On the basis of structural flexibility and compositional variability, perovskite compound can be classified into three main types as shown in Table 1 [81] .…”

“…Among various precious (Pt‐group metals) and non‐precious metal based electrocatalysts including metal hydroxides, [33–34] sulfides, [35–36] phosphides, [37–38] phosphates, [39–41] phosphonate [42–44] and their composite materials, [45–46] currently multinary oxides associated to perovskite ( AB O 3 ) and double perovskite structures ( AA′BB′ O 6 ) with disparate combinations of A and B metal cations have been attracted intensive research attention because of their huge variability of structural skeleton and different functional properties [47–50] . Of particular, double perovskites (DPs) that governed by the several possibilities including variable oxidation state at A ‐ and B ‐site cations as well as inherent electronic conductivity and high stability in different pH mediums that makes the DPs as one of the prominent and effective electrocatalyst compared to simple perovskites and other mixed metal oxides such as spinel and Ruddlesden−Popper oxides [51–57] …”