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The impact of the surrounding ligand field is successfully exploited in the case of Eu2+ to tune the emission characteristics of inorganic photoactive materials with potential application in, e.g. phosphor‐converted white light‐emitting diodes (pc‐wLEDs). However, the photoluminescence of Mn2+ related to intraconfigurational 3d5–3d5 transitions is also strongly dependent on local ligand field effects and has been underestimated in this regard so far. In this work, we want to revive the idea how to electronically tune the emission color of a transition metal ion in inorganic hosts by unusual electronic effects in the metal‐ligand bond. The concept is explicitly demonstrated for the weakly coordinating layer‐like borosulfate ligand in the Mn2+‐containing solid solutions Zn1‐xMnx[B2(SO4)4] (x = 0, 0.03, 0.04, 0.05, 0.10). Zn[B2(SO4)4]:Mn2+ shows orange narrow‐band luminescence at 590 nm, which is an unusually short wavelength for octahedrally coordinated Mn2+ and indicates an uncommonly weak ligand field. On the other hand, the analysis of the interelectronic Racah repulsion parameters reveals ionic Mn−O bonds with values close to the Racah parameters of the free Mn2+ ion. Overall, this strategy demonstrates that electronic control of the metal‐ligand bond can be a tool to make Mn2+ a potent alternative emitter to Eu2+ for inorganic phosphors. [ABSTRACT FROM AUTHOR]

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The synthesis and crystal structure of Zn6B22O39·H2O are described. This new zinc borate was synthesized at 7 GPa and 1523 K in a multianvil device. It crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 818.77(4), b = 768.42(3), c = 1744.82(9) pm, V = 1.09777(9) nm3, and two formula units per unit cell (Z = 2). The structure is closely related to those of M6B22O39·H2O (M = Fe, Co, Ni, Cd) and features non-planar (BO3) units as demonstrated by single-crystal and powder X-ray diffraction techniques. [ABSTRACT FROM AUTHOR]

The compounds Li6MoN4 and Li6WN4 were prepared from the reactants M (M = Mo, W) and Li3N in a radiofrequency furnace at 1000 °C. The lithonitridometallates crystallize in the tetragonal system with the lattice parameters: a = 6.6844(1), c = 4.9294(1) Å for Li6WN4 based on single-crystal X-ray diffraction data and a = 6.6611(3), c = 4.9338(3) Å for Li6MoN4 taken from powder X-ray diffraction data. Colorless to slightly reddish single-crystals of the tungsten compound were isolated and the crystal structure was refined in the space group P42/nmc (no. 137) with Z = 2 and the powder X-ray data of the molybdenum compound were analyzed by a Rietveld refinement. Both structures belong to the Li6[ZnO4] type published by Hoppe et al. in 1987 (Untenecker H., Hoppe R. Z. Anorg. Allg. Chem. 1987, 551, 147–150) and could be doped with Ce3+ for the first time. The investigated compounds show a reddish color impression upon UV to blue irradiation and exhibit a broad emission band with a maximum at λmax = 693 nm (fwhm 97 nm) for Li6MoN4 and at λmax = 653 nm (fwhm 133 nm) for Li6WN4. [ABSTRACT FROM AUTHOR]

The two compounds Fe2B3O7 (a = 663.61(4), c = 438.39(3) pm, space group: P 4 ‾ 21m) and Mn4(B6O13(OH)) (a = 445.14(1), b = 683.56(2), c = 1330.34(3) pm, β = 90.42(1)°, space group: P21/c) were synthesized under high-pressure/high-temperature conditions of 9 GPa and 800 °C. Their crystal structures have been determined via single-crystal X-ray diffraction and the occurring side-phases have been identified. Fe2B3O7 crystallizes in the melilite structure type, whereas the novel structure of Mn4(B6O13(OH)) can be derived from the structures of the minerals melilite or johachidolite. [ABSTRACT FROM AUTHOR]

With Li7Si2NO6, a new member of the family of lithium oxonitridosilicates with a so far unseen structure type could be synthesized. Using a high‐temperature solid‐state reaction in open nickel crucibles under nitrogen flow, it was possible to obtain single crystals from the starting materials SiO2, Li3N, and Li2O at temperatures of 900 °C. Single crystal X‐ray diffraction data yielded lattice parameters of a=5.0934(2), b=7.4128(2), c=8.5918(2) Å, α=75.16(1)°, β=87.36(1)°, γ=73.01(1)° and a cell volume of V=299.75(2) Å3. The compound, crystallizing in the triclinic space group P1‾ ${\bar{1}}$ (no. 2), consists of a highly condensed anionic network built up by [SiNO3]‐, [LiO4]‐, and [LiN2O2]‐tetrahedra as well as lithium in octahedral coordination as completing cation. With an activation barrier of 695 meV for lithium migration, Li7Si2NO6 is a potential lithium‐ion conductor. The structure allows a classification not only as a sorosilicate but also as a tecto‐lithosilicate and most precisely as a lithium oxonitridolithosilicate, when the different coordinations of the lithium ions are taken into account. Interestingly, the new compound is none of the several proposed representatives of the lithium oxonitridosilicates, thus expanding this substance class unexpectedly. [ABSTRACT FROM AUTHOR]

The new quaternary lithogallate Sr2LiGaO4 was prepared by conventional solid-state synthesis in a welded tantalum ampoule at T = 850 °C. Single-crystal X-ray diffraction was used to elucidate the crystal structure of the compound, which crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 11.2434(4), b = 5.6879(2), and c = 6.6983(2) Å. The phase composition of the powder sample was determined by Rietveld refinement based on X-ray diffraction data. The crystal structure is composed of layers of corner-sharing LiO4 and GaO4 tetrahedra with alternating orientation parallel to the crystallographic bc plane. The eightfold coordinated strontium atoms are arranged in a zigzag manner between the layers forming two types of double-capped trigonal prismatic SrO8 units with common faces. The crystal structure of Sr2LiGaO4 is isotypic to that of the lithoaluminate derivate Sr1.85Ba0.15LiAlO4. [ABSTRACT FROM AUTHOR]

In1.4B3O5.6(OH)1.4, tetragonal, P4̄21m (no. 113), a = 6.6969(9) Å, c = 4.4865(9) Å, V = 201.21(7) Å3, Z = 2, Rgt(F) = 0.0117, wRref(F2) = 0.0297, T = 293(2) K.

Two new Dion–Jacobson layered perovskite polymorphs of the known oxyfluoride compound KWO3F are reported. A high‐pressure modification was synthesized using a multianvil setup and subsequently transformed into a high‐temperature 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|F anion positions, and Rietveld refinements as well as MAPLE calculations support the structure models. [ABSTRACT FROM AUTHOR]

The novel zinc borate Zn2B10O17 was synthesized under high‐pressure/high‐temperature conditions of 8 GPa and 1573 K in a multianvil apparatus. Single‐crystal X‐ray diffraction revealed a unique crystal structure that crystallizes in the orthorhombic non‐centrosymmetric space group Pmc21 (no. 26) with a=769.15(2), b=711.14(2), c=822.14(2) pm, V=0.450(1) nm3 and two formula units (Z=2) per unit cell. The crystal structure is discussed, SHG measurements, and theoretical calculations at HSEsol level of theory were carried out. Herein, we reported about the novel zinc borate Zn2B10O17. It is synthesizable via high‐pressure/high‐temperature solid state reactions and features a unique crystal structure in the non‐centrosymmetric space group Pmc21 (no. 26), which was confirmed by a SHG‐measurement. The structure of Zn2B10O17 consists of an anionic borate framework, that is formed solely by (BO4) units. The zinc atoms are located in channels along the a‐axis and are tetrahedrally and octahedrally coordinated by oxygen atoms. The crystal structure was confirmed by MAPLE, CHARDI, and BL/BS calculations. Furthermore, theoretical calculations at HSEsol level were performed to obtain insight into the band structure properties and the DOS of the zinc borate. Zn2B10O17 is a colourless, ionic compound with a wide band gap of 8.4 eV and is therefore categorized as insulator. [ABSTRACT FROM AUTHOR]

The new zinc borate Zn3B4O9 was synthesized at high‐pressure/high‐temperature conditions of 10 GPa and 1173 K in a Walker‐type multianvil pressure device. It crystallizes in the space group P1‾ ${\bar{1}}$ (no. 2) with a=5.5028(2) Å, b=6.7150(3) Å, c=7.8887(3) Å, α=83.99(1)°, β=73.38(1)°, γ=74.75(1)°, V=269.35(2) Å3, and two formula units (Z=2) per unit cell. The structure was confirmed via single‐crystal X‐ray diffraction. Zn3B4O9 can be synthesized phase pure, which is shown with a Rietveld refinement. IR‐spectroscopic data of a powder sample were collected. [ABSTRACT FROM AUTHOR]

Using high-pressure/high-temperature synthesis methods, it was possible to increase the number of known borates with a crystal structure derived from gadolinite. Syntheses of Tb2Co(B2O5)2 (8 GPa, 1000 °C) and Tb2Cu(B2O5)2 (11 GPa, 650 °C) were carried out in a Walker-type multianvil device. The crystal structures were determined by single-crystal X-ray diffraction methods and Rietveld refinements of the powder patterns. The new compounds were further characterized by their infrared spectra. The lanthanoid cobalt and copper borates Tb2Co(B2O5)2 and Tb2Cu(B2O5)2 crystallize in the monoclinic space group P21/c (no. 14) with the unit cell parameters a = 4.5630(1), b = 7.2991(2), c = 9.4161(2) Å, and β = 91.14(1)° for the cobalt and a = 4.5757(1), b = 7.3078(2), c = 9.3771(3) Å, β = 90.73(1)° for the copper compound. [ABSTRACT FROM AUTHOR]

The high-pressure/high-temperature synthesis of β-MgB4O7 at 9 GPa and 1200 °C is presented. The determination of its crystal structure by single-crystal X-ray diffraction has shown that the compound is isotypic to the transition metal borates with the structure type of β-MB4O7 (M = Mn–Zn). β-MgB4O7 crystallizes in the orthorhombic space group Cmcm with the lattice parameters a = 10.848(2), b = 6.513(2), and c = 5.144(1) Å. The structural relation between the normal-pressure phase α-MgB4O7 to the here presented high-pressure phase β-MgB4O7 and to other reference compounds is discussed. [ABSTRACT FROM AUTHOR]

Red‐emitting narrow‐band phosphors are of utmost importance for next‐generation white‐light phosphor‐converted light‐emitting diodes (pc‐wLEDs) for improved efficacy and optimized correlated color temperatures. A promising representative crystallizing in an ordered variant of the UCr4C4 structure type is Sr[Li2Al2O2N2]:Eu2+ (SALON:Eu2+) emitting at a desirable wavelength of 614 nm. Despite an expected eightfold coordination of the Eu2+ ions by four N3− and O2− ions, respectively, the exact local coordination symmetry and a 1:1 ratio between the two types of ligands is not straightforwardly proven by X‐ray diffraction. Low‐temperature luminescence spectroscopy in conjunction with ligand field theory are powerful alternatives to resolve local features of Eu2+ as its excited 4f65d1 configuration reacts sensitively to the polarity of the ligands. The dominant emission at 614 nm shows pronounced vibronic fine structure at 10 K. In addition, weak emission bands can be resolved at 570 and 650 nm even at a low doping concentration of 0.5 mol% and are assigned to Eu2+ ions being eightfold coordinated by N3− and O2− ions in a ratio different from 1:1. Due to the feature of vierer ring‐type channels in SALON:Eu2+, those Eu2+ centers are sufficiently close for mutual energy transfer, which is characterized by time‐resolved luminescence at 10 K. [ABSTRACT FROM AUTHOR]

The high-pressure/high-temperature synthesis of β-MgB4O7 at 9 GPa and 1200 °C is presented. The determination of its crystal structure by single-crystal X-ray diffraction has shown that the compound is isotypic to the transition metal borates with the structure type of β-MB4O7 (M = Mn–Zn). β-MgB4O7 crystallizes in the orthorhombic space group Cmcm with the lattice parameters a = 10.848(2), b = 6.513(2), and c = 5.144(1) Å. The structural relation between the normal-pressure phase α-MgB4O7 to the here presented high-pressure phase β-MgB4O7 and to other reference compounds is discussed. [ABSTRACT FROM AUTHOR]

Building on studies of monoclinic Li3SiNO2, a polymorph, β-Li3SiNO2, with a previously unknown structure type was synthesized. The β-phase crystallizes in the orthorhombic space group Pbca (no. 61) with lattice parameters of a = 18.736(2), b = 11.1267(5), c = 5.0897(3) Å, and a cell volume of V = 1057.2(1) Å3. Using high-temperature solid-state reactions in sealed tantalum tubes, it was possible to obtain high purity samples (<5 wt% of side phase LiSi2N3 according to Rietveld analysis) containing exclusively one or the other polymorph, depending solely on the cooling rate. In contrast to the monoclinic phase, orthorhombic β-Li3SiNO2 additionally contains a third layer and shows a layer-sequence of the type ABCB. Doped with the activator ion Eu2+, the new polymorph exhibits an intense yellow emission (λmax = 586 nm, fwhm = 89 nm, 0.33 eV, 2650 cm−1) under irradiation with UV to blue light. Hence, the structural difference between the two polymorphs goes along with a significant blue-shift of 16 nm. The results from single-crystal diffraction and single-grain luminescence measurements were confirmed by Rietveld analysis of bulk samples and powder luminescence data. [ABSTRACT FROM AUTHOR]

In this paper, we present the high‐pressure/high‐temperature synthesis and characterization of the potassium fluoridooxidoniobate K3Nb2O4F5. Single‐crystal analysis revealed that the phase crystallizes in the trigonal space group R3‾ ${R\bar{3}}$ m (hR18) with a=5.799(2), c=21.371(4) Å, V=622.4(4) Å3 and Z=3 at T=299 K exhibiting a structure type closely related to that of Ba2RbFe2F9. 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 Mn4+ 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 λmax=630 nm. [ABSTRACT FROM AUTHOR]

The praseodymium metaborate molybdate(VI) PrBO2MoO4 was synthesized by solid-state reaction methods at 850 °C under an argon atmosphere and identified by its powder X-ray diffraction pattern. The polycrystalline sample was placed in a Walker-type multianvil press, where pressure-induced crystal growth at 1 GPa and 850 °C was successful, yielding single crystals suitable for structure determination. PrBO2MoO4 crystallizes monoclinically in the space group P21/c (no. 14) with the unit cell parameters a = 10.1735(2), b = 4.1479(1), c = 11.9090(3) Å, β = 116.52(1)°, and four formula units per cell. [ABSTRACT FROM AUTHOR]

The praseodymium metaborate molybdate(VI) PrBO2MoO4 was synthesized by solid-state reaction methods at 850 °C under an argon atmosphere and identified by its powder X-ray diffraction pattern. The polycrystalline sample was placed in a Walker-type multianvil press, where pressure-induced crystal growth at 1 GPa and 850 °C was successful, yielding single crystals suitable for structure determination. PrBO2MoO4 crystallizes monoclinically in the space group P21/c (no. 14) with the unit cell parameters a = 10.1735(2), b = 4.1479(1), c = 11.9090(3) Å, β = 116.52(1)°, and four formula units per cell. [ABSTRACT FROM AUTHOR]