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AlB4O6N, Al0.97Cr0.03B4O6N, and Al0.83Cr0.17B4O6N are the first representatives of the recently established structure‐family of oxonitridoborates containing Al3+. These compounds are isotypic to CrB4O6N and are synthesized in a multi‐anvil press under high‐pressure/high‐temperature conditions of 7.0 GPa/1350 °C. Structural refinement by single‐crystal X‐ray diffraction shows that they crystallize in the space group P63mc (no. 186) with two formula units per cell. Detailed characterization including high‐temperature X‐ray powder diffraction (HT‐XRD), electron probe microanalysis (EPMA), measurements of second harmonic generation (SHG), hardness, photoluminescence properties, vibrational spectroscopy, and band structure calculations reveal intriguing physicochemical properties that strongly resemble the famous material ruby. [ABSTRACT FROM AUTHOR]

The orthorhombic phases LaB3.6O7 and PrB3.6O7 were obtained by high‐pressure/high‐temperature syntheses at 11 GPa and temperatures of 1130 °C (LaB3.6O7) as well as 850 °C (PrB3.6O7) using a modified Walker‐type multianvil apparatus. The title compounds crystallize in the space group Pmn21 (no. 31) exhibiting a defective α‐SrB4O7 structure variant with the unit cell parameters a=10.4551(3) Å, b=4.4562(1) Å, c=4.2973(1) Å for LaB3.6O7 and a=10.4305(3) Å, b=4.4257(1) Å, c=4.2815(1) Å for PrB3.6O7. Both compounds were characterized by powder/single‐crystal X‐ray diffraction, vibrational spectroscopy, second harmonic generation, and electron dispersive X‐ray spectroscopy measurements. [ABSTRACT FROM AUTHOR]

Five transition metal borates were synthesized in a Walker-type module under high-pressure/high-temperature conditions of 8–9 GPa and 800–1200 °C. They all exhibit the same interpenetrating, anionic borate network B12O2616−, crystallizing in the space group I41/acd, and therefore show high similarities to the borates Ti5B12O26 and Ga5B12O25(OH). Cr5B12O25(OH) and V5B12O25(OH) are isotypic to Ga5B12O25(OH), whereas Mn5Mn0.83B12O26 and Fe5Fe0.14B12O24.3(OH)1.7 feature the partial occupation of an additional, cuboctahedral cavity in the structure. This is due to a partial reduction of the cations to the oxidation state +2, as presented with the novel compound Mn5MnB12O22(OH)4, which only features Mn2+ for charge compensation. These structures feature a twelvefold coordination of manganese and iron. [ABSTRACT FROM AUTHOR]

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 ‾ (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. [ABSTRACT FROM AUTHOR]

In an article published in Advanced Functional Materials, Markus Suta, Hubert Huppertz, and their colleagues introduce a new oxonitridoborate compound called AlB4O6N:Cr3+. This compound exhibits a highly efficient red line emission and has the potential to serve as an alternative luminescent pressure sensor. The researchers suggest that AlB4O6N:Cr3+ could offer more precise pressure calibration in diamond anvil cells compared to the current standard, ruby. The authors express gratitude to Abraham Siedler and Marie-Theres Wildauer for their contributions to the design of the inside back cover. [Extracted from the article]

By high-pressure/high-temperature multianvil synthesis a new high-pressure (HP) phase of Co3TeO6 was obtained. The compound crystallizes in the acentric trigonal crystal system of the Ni3TeO6-type structure with space group R3 and the following unit cell parameters and refinement results: a = 519.37(6) pm, c = 1382.4(2) pm, V = 322.93 Å3, R1 = 0.0150, wR2 = 0.0374, GooF = 1.114 and a Flack parameter of 0.04(5). High-temperature powder X-ray diffraction (PXRD) measurements showed an exceptionally high-temperature stability of the HP-modification up to 1070 K. Magnetic measurements revealed an antiferromagnetic ordering below TN = 58.2(1) K and a spin-flop-type transition at T = 3 K with a critical magnetic field of Hcrit = 10.8(1) kOe. Magnetic and magnetoelectric (ME) transition temperatures were determined by specific heat measurements and exhibited a non-hysteretic behavior of the magnetoelectric coupling. Additionally, from the UV-Vis reflectance spectra a direct and an indirect band gap of Eg = 1.88 eV and Eg = 1.91 eV were calculated, underlining the semiconducting nature of HP-Co3TeO6. [ABSTRACT FROM AUTHOR]

The crystal structure of bentorite, ideally Ca6Cr2(SO4)3(OH)12·26H2O, a Cr3+ analogue of ettringite, is for the first time investigated using X-ray single crystal diffraction. Bentorite crystals of suitable quality were found in the Arad Stone Quarry within the pyrometamorphic rock of the Hatrurim Complex (Mottled Zone). The preliminary semi-quantitative data on the bentorite composition obtained by SEM-EDS show that the average Cr/(Cr + Al) ratio of this sample is >0.8. Bentorite crystallizes in space group P31c, with a = b = 11.1927(5) Å, c =21.7121(10) Å, V = 2355.60(18) Å3, and Z = 2. The crystal structure is refined, including the hydrogen atom positions, to an agreement index R1 = 3.88%. The bentorite crystal chemical formula is Ca6(Cr1.613Al0.387)Σ2[(SO4)2.750(CO3)0.499]Σ3.249(OH)11.502·~25.75H2O. The Raman spectra of bentorite from two different localities exhibit the presence of the main stretching and bending vibrations related to the sulfate group at 983 cm-1 (ν1), 1109 cm-1 (ν3), 442 cm-1 (ν2), and 601 cm-1 (ν4). Moreover, the presence of bands assigned to the symmetric Cr(OH)63' stretching mode and hydroxyl deformation vibrations of Cr-OH units at ~540 cm-1 and ~757 cm-1, respectively, may be used to distinguish between ettringite and bentorite. In situ high temperature single crystal XRD experiments show that the decomposition of bentorite starts at ca. 45 °C and that a dehydroxylation product similar to metaettringite is formed. [ABSTRACT FROM AUTHOR]

Mg3TeO6 can be synthesized at ambient pressure conditions and temperatures of 920–1070 K in a centrosymmetric, rhombohedral structure‐type (R3). By means of high‐pressure/high‐temperature synthesis at 12.5 GPa and 1570 K a new, colorless, non‐centrosymmetric high‐pressure (HP) phase of Mg3TeO6 is formed, crystallizing in the Ni3TeO6‐type structure with the following unit cell parameters and refinement results: R3, a = 513.82(7) pm, c = 1380.7(2) pm, V = 31.57(1) nm3, R1 = 0.0283, wR2 = 0.0732, and GooF = 1.096. High‐temperature PXRD measurements on HP‐Mg3TeO6 revealed exceptionally high temperature stability for a metastable high‐pressure compound of up to 1220 K. Additionally, vibrational spectra (IR/Raman) were recorded and compared to theoretical calculations obtained by Density Functional Theory. Due to the acentric crystal structure, SHG measurements on a powdery sample exhibited an SHG efficiency of 0.83 times KH2PO4 (KDP) and a wide transparency range up to an absorption edge of 260 nm was determined by UV/Vis measurements. Overall, HP‐Mg3TeO6 is therefore interesting for UV‐laser applications. [ABSTRACT FROM AUTHOR]

In a sequence of temperature‐dependent solid‐state reactions in the system CaO–Al2O3–MgO the formation of the ternary phase Ca3Al4MgO10 or C3A2M has been studied. Whereas the compound could not be prepared at 1200°C, a yield of 85 wt.‐% of Ca3Al4MgO10 was obtained at 1320°C (incongruent melting point: 1330°C). Powder diffraction data compare well with results of previous investigations from the 1960s. Single crystals of Ca3Al4MgO10 could be retrieved from the sinter‐pellets. Basic crystallographic data are as follows: orthorhombic symmetry, space group Pbcm, a = 5.14073(8), b = 16.7576(2), c = 10.70977(16) Å, V = 922.61(2) Å3, Z = 4. Using synchrotron diffraction data it was possible to solve the crystal structure. Least‐squares refinements resulted in a residual of R(|F|) = 0.021 for 1000 independent observed reflections with I > 2σ(I) and 97 parameters. The structure contains [TO4]‐tetrahedra (T=Al,Mg) forming a three‐dimensional (3‐D) framework whose topological characteristics have been determined. Al‐Mg distributions on the different T‐sites have been studied. The calcium cations are located in voids of the network. More than 50 years after its first observation our investigation clarifies the crystal structure of a compound belonging to a system that is of relevance for several fields of materials science. [ABSTRACT FROM AUTHOR]