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Structure and cation distribution in perovskites with small cations at the A site: the case of ScCoO 3

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ABSTRACT

We synthesize ScCoO3 perovskite and its solid solutions, ScCo1−xFexO3 and ScCo1−xCrxO3, under high pressure (6 GPa) and high temperature (1570 K) conditions. We find noticeable shifts from the stoichiometric compositions, expressed as (Sc1−xMx)MO3 with x = 0.05–0.11 and M = Co, (Co, Fe) and (Co, Cr). The crystal structure of (Sc0.95Co0.05)CoO3 is refined using synchrotron x-ray powder diffraction data: space group Pnma (No. 62), Z = 4 and lattice parameters a = 5.26766(1) Å, b = 7.14027(2) Å and c = 4.92231(1) Å. (Sc0.95Co0.05)CoO3 crystallizes in the GdFeO3-type structure similar to other members of the perovskite cobaltite family, ACoO3 (A3+ = Y and Pr-Lu). There is evidence that (Sc0.95Co0.05)CoO3 has non-magnetic low-spin Co3+ ions at the B site and paramagnetic high-spin Co3+ ions at the A site. In the iron-doped samples (Sc1−xMx)MO3 with M = (Co, Fe), Fe3+ ions have a strong preference to occupy the A site of such perovskites at small doping levels.

No MeSH data available.


Uncorrected inverse FCC magnetic susceptibility curves (χ−1 versus T) of (Sc0.95M0.05)MO3 (M = Co1−xCrx with x = 0.25 and 0.5) at 100 Oe and 10 kOe. Parameters (μeff and θ) of the Curie–Weiss fits (lines) are given.
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Figure 9: Uncorrected inverse FCC magnetic susceptibility curves (χ−1 versus T) of (Sc0.95M0.05)MO3 (M = Co1−xCrx with x = 0.25 and 0.5) at 100 Oe and 10 kOe. Parameters (μeff and θ) of the Curie–Weiss fits (lines) are given.

Mentions: We also prepared solid solutions with the total composition of Sc0.9Co1−xCrxO2.85 (x = 0.25 and 0.5). The structural parameters of (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) are given in tables 1 and 2; and the compositional dependence of the lattice parameters is shown on figure 8. Almost linear changes of the lattice parameters suggest that the solid solutions are formed in the whole compositional range. Inverse magnetic susceptibilities of (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25 and Co0.5Cr0.5) are given on figure 9. The χ−1 values were almost field-independent above 70 K for (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) and above 100 K for (Sc0.95M0.05)MO3 (M = Co0.5Cr0.5) suggesting an impurity-free paramagnetic behaviour. The Curie–Weiss fits of the data corrected for diamagnetic contributions gave μeff = 2.47μB/f.u. and θ = −144 K for (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) with the expected μeff = 2.20μB/f.u and μeff = 2.99μB/f.u. and θ = −107 K for (Sc0.95M0.05)BO3 (M = Co0.5Cr0.5) with the expected μeff = 2.91μB/f.u. The anomalies at 100 Oe below 70 K in (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) and below 100 K in (Sc0.95M0.05)MO3 (M = Co0.5Cr0.5) could originate from the onset of short-range or long-range magnetic interactions.


Structure and cation distribution in perovskites with small cations at the A site: the case of ScCoO 3
Uncorrected inverse FCC magnetic susceptibility curves (χ−1 versus T) of (Sc0.95M0.05)MO3 (M = Co1−xCrx with x = 0.25 and 0.5) at 100 Oe and 10 kOe. Parameters (μeff and θ) of the Curie–Weiss fits (lines) are given.
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Figure 9: Uncorrected inverse FCC magnetic susceptibility curves (χ−1 versus T) of (Sc0.95M0.05)MO3 (M = Co1−xCrx with x = 0.25 and 0.5) at 100 Oe and 10 kOe. Parameters (μeff and θ) of the Curie–Weiss fits (lines) are given.
Mentions: We also prepared solid solutions with the total composition of Sc0.9Co1−xCrxO2.85 (x = 0.25 and 0.5). The structural parameters of (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) are given in tables 1 and 2; and the compositional dependence of the lattice parameters is shown on figure 8. Almost linear changes of the lattice parameters suggest that the solid solutions are formed in the whole compositional range. Inverse magnetic susceptibilities of (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25 and Co0.5Cr0.5) are given on figure 9. The χ−1 values were almost field-independent above 70 K for (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) and above 100 K for (Sc0.95M0.05)MO3 (M = Co0.5Cr0.5) suggesting an impurity-free paramagnetic behaviour. The Curie–Weiss fits of the data corrected for diamagnetic contributions gave μeff = 2.47μB/f.u. and θ = −144 K for (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) with the expected μeff = 2.20μB/f.u and μeff = 2.99μB/f.u. and θ = −107 K for (Sc0.95M0.05)BO3 (M = Co0.5Cr0.5) with the expected μeff = 2.91μB/f.u. The anomalies at 100 Oe below 70 K in (Sc0.95M0.05)MO3 (M = Co0.75Cr0.25) and below 100 K in (Sc0.95M0.05)MO3 (M = Co0.5Cr0.5) could originate from the onset of short-range or long-range magnetic interactions.

View Article: PubMed Central - PubMed

ABSTRACT

We synthesize ScCoO3 perovskite and its solid solutions, ScCo1−xFexO3 and ScCo1−xCrxO3, under high pressure (6 GPa) and high temperature (1570 K) conditions. We find noticeable shifts from the stoichiometric compositions, expressed as (Sc1−xMx)MO3 with x = 0.05–0.11 and M = Co, (Co, Fe) and (Co, Cr). The crystal structure of (Sc0.95Co0.05)CoO3 is refined using synchrotron x-ray powder diffraction data: space group Pnma (No. 62), Z = 4 and lattice parameters a = 5.26766(1) Å, b = 7.14027(2) Å and c = 4.92231(1) Å. (Sc0.95Co0.05)CoO3 crystallizes in the GdFeO3-type structure similar to other members of the perovskite cobaltite family, ACoO3 (A3+ = Y and Pr-Lu). There is evidence that (Sc0.95Co0.05)CoO3 has non-magnetic low-spin Co3+ ions at the B site and paramagnetic high-spin Co3+ ions at the A site. In the iron-doped samples (Sc1−xMx)MO3 with M = (Co, Fe), Fe3+ ions have a strong preference to occupy the A site of such perovskites at small doping levels.

No MeSH data available.