ChemInform Abstract: New Antiferromagnetic Perovskite CaCo₃V₄O₁₂ Prepared at High‐Pressure and High‐Temperature Conditions.

Abstract

The new title perovskite is synthesized from mixtures of Ca(VO3)2, Co(VO3)2, and Co (14-18 GPa, 900-1300°C, 0.5-8 h). The product is characterized by powder and single crystal XRD, SEM, magnetic susceptibility, and electrical resistivity measurements. CaCo3V4O12 crystallizes in the cubic space group Im3 with Z = 2 and is the first double perovskite with Co 2+ ions at the A' sites. The compound orders antiferromagnetically around 100 K and exhibits semimetallic conductivity in the temperature range 1.6-370 K. -(OVSYANNIKOV*, S. V.; ZAINULIN, Y. G.; KADYROVA, N. I.; TYUTYUNNIK, A. P.; SEMENOVA, A. S.; KASINATHAN, D.; TSIRLIN, A. A.; MIYAJIMA, N.; KARKIN, A. E.; Inorg. Chem. 52 (2013) 20, 11703-11710, http://dx.doi.org/10.1021/ic400649h ; Inst. Solid State Chem., Ural Branch Russ.

Structural and Magnetic Transitions in CaCo3V4O12 Perovskite at Extreme Conditions

“…13 However, there are only a few cases of perovskites reported to date with the A′ sites occupied by other transition-metal ions, e.g., by Fe 2+ in CaFe 3 Ti 4 O 12 14 and Ca(Cu 2 Fe)V 4 O 12 , 15 by Ti 4+ ions in Na(Cu 2.5 Ti 4+ 0.5 )Ti 4 O 12 16 and Sr 0.946 (Cu 2.946 Ti 0.054 )-Ti 4 O 12 , 17 by Pd 2+ in CaPd 3 (Ti,V) 4 O 12 , 18 and by Co 2+ ions in CaCo 3 V 4 O 12 . 19 These unusual square-planar-coordinated positions for Fe and Co ions that are linked to unconventional electronic configurations of these ions were also observed in other compounds, e.g., in CaFeO 2 20 and Sr 3 Co 2 O 4 C l2 . 21 Among different families of the above A-site ordered AA′ 3 B 4 O 12 double perovskites, the most studied to date are compounds with B = Fe because of their nontrivial magnetic properties and charge disproportionation reactions, which can lead to spectacular phenomena.…”

“…A sample with a volume of about 1.5 mm 3 was placed inside a CCR-based cryostat. We collected neutron powder diffraction patterns at scattering angles of 2θ = 45.5 and 90°from room temperature and down to 10 K, across the antiferromagnetic ordering transition around 100 K. 19 We analyzed the neutron diffraction patterns by the Rietveld refinement method using the Fullprof program. 51 We considered possible models of the lowtemperature magnetic structure of CaCo 3 V 4 O 12 taking into account a symmetry analysis performed in the framework of BasIreps program (https://www.ill.eu/sites/fullprof/).…”

“…39−44 Recently, a novel and unique perovskite material, CaCo 3 V 4 O 12 with the Co 2+ ions occupying the crystallographic sites with the square-planar oxygen coordination (Figure 1) and simultaneously adopting the high-spin (HS) state, was synthesized. 19 Magnetic susceptibility measurements established that below 100 K CaCo 3 V 4 O 12 undergoes an antiferromagnetic ordering transition and indicated that a sizable orbital moment may be present on Co 2+ . 19 Subsequent band-structure calculations confirmed an orbital moment on the order of 1 μ B , 45 but remained uncertain about the exact size of this moment and its orientation.…”

“…19 Magnetic susceptibility measurements established that below 100 K CaCo 3 V 4 O 12 undergoes an antiferromagnetic ordering transition and indicated that a sizable orbital moment may be present on Co 2+ . 19 Subsequent band-structure calculations confirmed an orbital moment on the order of 1 μ B , 45 but remained uncertain about the exact size of this moment and its orientation. CaCo 3 V 4 O 12 features a combination of several dissimilar and potentially competing electronic effects, including strong Coulomb correlations, spin− orbit coupling, and orbital polarization, thus posing a daunting challenge for ab initio calculations 45 and making this compound an interesting system for experimental studies.…”

Synthesis of Ilmenite-type ε-Mn2O3 and Its Properties

“…The synthesis procedure was similar to those described in previous publications. 69,70 Selected samples were examined by scanning electron microscopy (SEM) using a Zeiss Leo-1530 instrument. A phase analysis of the samples was performed using X-ray diffraction (XRD) studies using a high-brilliance Rigaku diffractometer.…”