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Cutout of the crystal structure of Sr 5 Os 3 O 13 , emphasizing the connectivity pattern of the OsO 6 octahedra. Same color code as Figure 3.
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New Sr5Os3O13, as synthesized from binary constituents, exhibits several uncommon features. Its crystal structure is dominated by quasi-2D poly-oxoanions that correspond to unprecedented cutouts of the perovskite type of structure, where corner sharing (OsO6) octahedra aggregate to form terraced slabs. The Os5+/Os6+ mixed valence oxide displays a p...
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Context 1
... primary building units OsO 6 are linked via common vertices, engaging three each from the Os2A and Os2B, and four from the Os1 centered coordination polyhedra, to form plate-like poly-oxoanions of composition Os 3 O 13 , extending parallel to (001), see Figures 2 and 3. The local connectivity pattern is visualized in Figure 4. Interestingly, the resulting anionic partial structure corresponds to a slab excised from the perovskite structure, however, in contrast to known perovskite related layered structures, as represented by e.g. ...
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Variable valence oxides of the perovskite crystal structure have emerged as promising candidates for solar hydrogen production via two-step thermochemical cycling. Here, we report the exceptional efficacy of the perovskite CaTi0.5Mn0.5O3–δ (CTM55) for this process. The combination of intermediate enthalpy, ranging between 200 and 280 kJ (mol-O)⁻¹,...
Citations
... It should be noted, that the following strontium oxido-osmates have so far been reported in the ternary Sr-Os-O system: SrOsO3 [16], SrOsO4 [17], Sr2OsO5 [18], Sr2Os3O5 [18], Sr2Os2O6.4 [19], Sr3OsO6 [14], Sr5Os3O13 [20], Sr7Os4O19 [18], Sr8Os6.3O24 [21], Sr9Os5O23 [22], and Sr11Os4O24 [23]. ...
... Ba3MOs2O9 (M = , Li, Na, Cu and Zn) and Ba3MRu2O9 (M = Li, Na, Cu and rare-earth). [13][14][15][16][17][18][19][20][21] In continuation to our expedition to find compounds containing osmium and featuring magnetic ordering transitions at high temperature, [22][23][24][25] we report the new compound Sr3CaOs2O9, crystallizing in a conventional monoclinic triple-perovskite structure. Sr3CaOs2O9 orders antiferromagnetically at TN 385 K. ...
Synthesis, crystal structure and magnetic properties of a new 2:1 ordered triple perovskite Sr3CaOs2O9 are reported. The compound crystallizes in P21/c space group and features a unique buckled honeycomb lattice of osmium. It exhibits long-range antiferromagnetic ordering with a high Neel temperature of 385 K as confirmed by susceptibility, heat capacity and neutron diffraction measurements and is electrically insulating. This compound is also the first example of a 2:1 ordered osmate perovskite. Theoretical investigations indicate that Sr3CaOs2O9 features a sizeable antiferromagnetic exchange between the puckered planes resulting in a high TN. The magnetic properties of the known compound Sr3CaRu2O9 are elucidated in comparison. It shows antiferromagnetic order below TN = 200 K.
Spin-orbit coupling is a quantum effect that can give rise to exotic electronic and magnetic states in the compounds of the 4 d and 5 d transition metals. Exploratory synthesis, chemical tuning...
Polycrystalline Sr$_3$OsO$_6$, which is an ordered double-perovskite insulator, is synthesized via solid-state reaction under high-temperature and high-pressure conditions of 1200 $^\circ$C and 6 GPa. The synthesis enables us to conduct a comparative study of the bulk form of Sr$_3$OsO$_6$ toward revealing the driving mechanism of 1000 K ferromagnetism, which has recently been discovered for epitaxially grown Sr$_3$OsO$_6$ films. Unlike the film, the bulk is dominated by antiferromagnetism rather than ferromagnetism. Therefore, robust ferromagnetic order appears only when Sr$_3$OsO$_6$ is under the influence of interfaces. A specific heat capacity of 39.6(9) 10$^{-3}$ J mol$^{-1}$ K$^{-2}$ is found at low temperatures ($<$17 K). This value is remarkably high, suggesting the presence of possible fermionic-like excitations at the magnetic ground state. Although the bulk and film forms of Sr$_3$OsO$_6$ share the same lattice basis and electrically insulating state, the magnetism is entirely different between them.
Crystalline orthorhombic rare earth carbonate hydroxides Ln [CO 3 ][OH] ( Ln =La, Pr, Nd, Sm, Eu, Gd) were synthesised as phase pure powders via a simple hydrothermal reaction. CO 2 from air acted as natural carbonate source and cetyltrimethylammonium bromide was added as templating agent to an aqueous rare earth nitrate solution. Single-crystal X-ray structure determination was performed on La[CO 3 ][OH] ( Pnma , a =7.4106(5), b =5.0502(3), c =8.5901(6) Å, 563 independent reflections, 38 refined parameters, wR 2=0.037), Pr[CO 3 ][OH] ( Pnma , a =7.2755(4), b =4.9918(3), c =8.5207(5) Å, 744 independent reflections, 38 refined parameters, wR 2=0.04), Eu[CO 3 ][OH] ( Pnma , a =7.1040(4), b =4.8940(3), c =8.4577(5) Å, 1649 independent reflections, 38 refined parameters, wR 2=0.05) and Gd[CO 3 ][OH] ( Pnma , a =7.069(7), b =4.874(5), c =8.464(9) Å, 431 independent reflections, 38 refined parameters, wR 2=0.051). These findings are supported by powder XRD, infrared spectroscopy, UV/Vis spectroscopy and, for Pr[CO 3 ][OH] and Eu[CO 3 ][OH], by measurements of the non-linear optical properties. Thermal analysis could demonstrate the possible use of the Ln [CO 3 ][OH] phases as precursors for rare earth carbonate dioxides Ln2 [CO 3 ]O 2 and rare earth oxides Ln2 O 3 . The decomposition products inherit the precursor’s morphology. The lattice parameters of Pr 2 [CO 3 ]O 2 were refined from high-temperature powder XRD data.
