Sr₂OsO₅ and Sr₇Os₄O₁₉, Two Structurally Related, Mott Insulating Osmates(VI) Exhibiting Substantially Reduced Spin Paramagnetic Response

Abstract

The new osmates(VI), Sr2OsO5 and Sr7Os4O19, feature quasi-1-D polyoxo anions, consisting of corner sharing [OsO6] octahedra. In both compounds, the magnetic moment at T = 300 K is significantly lower (1.2-1.3 μB/Os-atom) than the value expected for S = 1. For neither of the new osmates(VI) is any evidence for long-range magnetic order found. For Sr7Os4O19, magnetic susceptibility suggests an antiferromagnetic ordering at TN = 43(3) K; however, no corresponding anomaly is visible in specific heat. Both compounds are semiconductors.

Sr5Os3O13: a mixed valence osmium(v,vi) layered perovskite variant exhibiting temperature dependent charge distribution

“…Moreover, the ionic radii 24 for Os 5+ and Os 6+ differ by just 0.03 Å for coordination number VI. Still, the average Os-O bond lengths (50 K data), amounting to 1.96, 1.95, and 1.92 Å for Os1, Os2A, and Os2B, respectively, are in the same range as reported in the literature, [6][7][8][9] and comply with the sum of the ionic radii. 24 However, based on atomic distances ( …”

New Sr9Os5O23, Made Up of Quasi 1D and 2D Fragments of the Perovskite Structure

“…The spread of bond distances in the Os2 octahedra are fairly narrow and do not show much deviation (1.95 to 1.99 Å) and are consistent with the bond distances reported for Os 5+/6+ . 12,[19][20][21]32,33 However, the bond distances in Os1 and Os3 show much larger spread (1.85 to 2.1 Å), which can be attributed to the different crystal chemical functions of the respective oxygen atoms: The longer bonds in Os1 and Os3 octahedra are formed with oxygen atoms bridging the neighboring Os octahedra, while the shorter ones contain oxygen atoms bridging to the neighboring Sr atoms. This crystal structure has striking similarities to the structures of both Sr 5 Os 3 O 13 and Sr 2 OsO 5 (Figure 4).…”

“…Interestingly, the crystal structure of this compound is built up of the exact excerpts from the Sr 5 Os 3 O 15 and Sr 2 OsO 5 structures. 10,21 The osmium here is in a mixed-valence state (+5/+6). Use of…”

Study of Polycrystalline Bulk Sr3OsO6 Double-Perovskite Insulator: Comparison with 1000 K Ferromagnetic Epitaxial Films

“…14 Moreover, a small anomaly is detected at ~12 K with thermal hysteresis, suggesting a glassy transition or FM transition. It should be noted that Sr5Os3O13, 31 Sr2Os3O5, 32 and Sr7Os4O19 32 have been synthesized in the ternary system Sr-Os-O, but none of them displays a magnetic anomaly at ~12 K. To conduct a quantitative analysis, the Curie-Weiss law 1/χ = (T-θW)/C was applied to fit to the curve above ~200 K, where θW is the Weiss temperature and C is the Curie constant. The estimated θW and C are -47.0(5) K and 0.638(2) emu mol -1 K, respectively.…”

“…14 Moreover, a small anomaly is detected at ∼12 K with thermal hysteresis, suggesting a glassy transition or FM transition. It should be noted that Sr 5 Os 3 O 13 , 31 Sr 2 Os 3 O 5 , 32 and Sr 7 Os 4 O 19 32 have been synthesized in the ternary system Sr−Os−O, but none of them displays a magnetic anomaly at ∼12 K.…”