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

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.


Related in: MedlinePlus

(a) A portion of the experimental synchrotron XRPD pattern of ScCoO3. The bars show possible Bragg reflection positions for the perovskite phase and Sc2O3 impurity (from top to bottom); hkl indexes for some reflections are given. A star marks a reflection from Au (a contamination from an Au capsule). (b) Portions of experimental (black crosses), calculated (red line) and difference (black line) synchrotron XRPD patterns for (Sc0.95Co0.05)CoO3. The bars show possible Bragg reflection positions for the perovskite phase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC5036463&req=5

Figure 1: (a) A portion of the experimental synchrotron XRPD pattern of ScCoO3. The bars show possible Bragg reflection positions for the perovskite phase and Sc2O3 impurity (from top to bottom); hkl indexes for some reflections are given. A star marks a reflection from Au (a contamination from an Au capsule). (b) Portions of experimental (black crosses), calculated (red line) and difference (black line) synchrotron XRPD patterns for (Sc0.95Co0.05)CoO3. The bars show possible Bragg reflection positions for the perovskite phase.

Mentions: The stoichiometric ScCoO3 sample contained Sc2O3 impurity (figure 1(a)) suggesting that the composition of the main perovskite phase is shifted according to the scheme:1


Structure and cation distribution in perovskites with small cations at the A site: the case of ScCoO 3
(a) A portion of the experimental synchrotron XRPD pattern of ScCoO3. The bars show possible Bragg reflection positions for the perovskite phase and Sc2O3 impurity (from top to bottom); hkl indexes for some reflections are given. A star marks a reflection from Au (a contamination from an Au capsule). (b) Portions of experimental (black crosses), calculated (red line) and difference (black line) synchrotron XRPD patterns for (Sc0.95Co0.05)CoO3. The bars show possible Bragg reflection positions for the perovskite phase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036463&req=5

Figure 1: (a) A portion of the experimental synchrotron XRPD pattern of ScCoO3. The bars show possible Bragg reflection positions for the perovskite phase and Sc2O3 impurity (from top to bottom); hkl indexes for some reflections are given. A star marks a reflection from Au (a contamination from an Au capsule). (b) Portions of experimental (black crosses), calculated (red line) and difference (black line) synchrotron XRPD patterns for (Sc0.95Co0.05)CoO3. The bars show possible Bragg reflection positions for the perovskite phase.
Mentions: The stoichiometric ScCoO3 sample contained Sc2O3 impurity (figure 1(a)) suggesting that the composition of the main perovskite phase is shifted according to the scheme:1

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.


Related in: MedlinePlus