We obtained single crystals of the binary mixed-valent fluorides Mn2F5 and Mn3F8 using a high-pressure/high-temperature approach. Mn2F5 crystallizes isotypic to CaCrF5 in the monoclinic space group C2/c (No. 15), with a = 8.7078(8) Å, b = 6.1473(6) Å, c = 7.7817(7) Å, β = 117.41(1)°, V = 369.80(6) Å3, Z = 4, and mC28 at T = 173 K. Mn3F8 crystallizes in the monoclinic space group P21 (No. 4) with a = 5.5253(2) Å, b = 4.8786(2) Å, c = 9.9124(4) Å, β = 92.608(2)°, V = 266.92(2) Å3, Z = 2, and mP22 at T = 183 K and presents a new structure type. Crystal-chemical reasoning, CHARDI calculations, and quantum-chemical calculations allowed for the assignment of the oxidation states of the Mn atoms. In both bulk compounds, MnF2 was present as an impurity, as evidenced by powder X-ray diffraction and IR and Raman spectroscopy.
In this paper, we present the high-pressure/high-temperature synthesis and characterization of the potassium fluoridooxidoniobate K 3 Nb 2 O 4 F 5 . Single-crystal analysis revealed that the phase crystallizes in the trigonal space group R � 3m (hR18) with a = 5.799(2), c = 21.371(4) Å, V = 622.4(4) Å 3 and Z = 3 at T = 299 K exhibiting a structure type closely related to that of Ba 2 RbFe 2 F 9 . The assignment of the anion positions to oxygen and fluorine is based on crystallographic data and BLBS/CHARDI calculations. Further characterization via EDX spectroscopy was carried out, corroborating the ratio of K to Nb. Doping of the title compound with Mn 4 + was achieved in a secondary step using a ball-mill, resulting in a red phosphor material, which was additionally analyzed by luminescence spectroscopy. The emission maximum is located at λ max = 630 nm.
In this work, the development of a novel class of ecofriendly red pigments based on doped Li 2 MnO 3 is reported. These new compounds offer red color values of a* Ͼ 34, which are recognizably higher than the red value provided by the commonly used red pigment iron oxide Bayferrox 4130. However, the real outstanding attribute of these novel substances is their strikingly high NIR-reflectance that gives promise for a new class of materials for the practical utilization as cool pigments in building components and ceramics. We have syn
In this paper, we present the crystal structure of the novel compound Sm3SiO5F3. Single crystals were obtained using a high-pressure/high-temperature approach. Sm3SiO5F3 crystallizes in the triclinic space group P 1 ‾ $\bar{1}$ (aP24) with a = 6.1894(2), b = 7.1315(2), c = 7.3997(3) Å, α = 103.66(1), β = 98.06(1), γ = 90.16(1)°, V = 314.03(2) Å3, Z = 2 at T = 300 K and, to the best of our knowledge, presents a new structure type. BLBS and CHARDI calculations were used to assign oxidation states to the atoms, thus allowing us to differentiate between fluorine and oxygen atoms within the crystal structure. MAPLE calculations were carried out to support the structure solution. Electron microprobe measurements corroborate the ratio of Sm to Si and unequivocally prove the presence of Si within the compound. Despite various attempts, bulk synthesis of the compound could not be realized.
Two new Dion-Jacobson layered perovskite polymorphs of the known oxyfluoride compound KWO 3 F are reported. A high-pressure modification was synthesized using a multianvil setup and subsequently transformed into a hightemperature phase at ~311 °C. The crystal structures of both polymorphs were determined by use of single-crystal X-ray diffraction and are described in detail herein. Differential thermal analyses and thermogravimetric analyses were carried out to further investigate the phase transition characteristics. Bond valence (BV) and charge distribution (CHARDI) calculations confirm the occupancy of mixed O j F anion positions, and Rietveld refinements as well as MAPLE calculations support the structure models.
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