Two novel oxonitridophosphates M2PO3N with M = Ca and Sr were synthesized under high-pressure high-temperature (7 GPa and 1100 °C) using the multianvil technique or by solid-state reaction in the silica ampules (1100 °C) from amorphous phosphorus oxonitride (PON) and the respective alkaline earth oxides MO (M = Ca, Sr). The products represent the first examples of alkaline earth ortho-oxonitridophosphates containing noncondensed [PO3N](4-) ions. The crystal structures were elucidated by single-crystal X-ray diffraction. Sr2PO3N [space group Pnma (No. 62), Z = 4, a = 7.1519(5) Å, b = 5.5778(3) Å, c = 9.8132(7) Å, R1 = 0.020, wR2 = 0.047] crystallizes in the β-K2SO4 structure type. The structure of Ca2PO3N was solved and refined in the (3 + 1)D superspace group Pnma(α00)0ss [Z = 4, a = 6.7942(7) Å, b = 5.4392(6) Å, c = 9.4158(11) Å, R1 = 0.041, wR2 = 0.067]. It exhibits an incommensurate modulation along [100] with a modulation vector q = [0.287(5), 0, 0]. Rietveld refinements support the structural models as well as the phase purity of the products. Upon doping with Eu(2+), Ca2PO3N exhibits luminescence in the green range (λem = 525 nm) of the visible spectrum if excited by near-UV light (λexc = 400 nm).
was synthesized by metathesis reaction starting from LaCl 3 , BaH 2 , CeF 3 and the product of the ammonolysis of Si 2 Cl 6 . The title compound is stable towards air and moisture. Diffraction data of a microcrystal were recorded using microfocused synchrotron radiation. Xray spectroscopy confirms the chemical composition of the crystal. IR spectra corroborate absence of N-H bonds. The compound is homeotypic to Ba 2 Nd 7 Si 11 N 23 and crystallizes in space group Cmmm with a
Three quasi-binary phase systems, BiSX(1 - x)Y(x) (X, Y = Cl, Br, I; 0 < x < 1), have been investigated by X-ray powder diffraction. All three systems show unlimited solubility. For BiSCl(1 - x)Br(x) and BiSCl(1 - x)I(x), strong positive and negative deviations from Vegard's rule are observed with respect to the lattice parameters a and c. They are qualitatively explained by the asymmetry of the X coordination polyhedron and by anion-anion repulsions. For x < 0.32 [x > 0.32] the BiSCl(1 - x)I(x) system mimics the behaviour of the BiSCl(1 - y)Br(y) [BiSBr(1 - y)I(y)] system (0 < y < 1).
, an adduct compound that can be obtained from dicyandiamide in autoclave reactions at 450 8Ca nd elevateda mmonia pressure, had previously been describedbased on mass spectrometry and NMR spectroscopy,b ut only incompletelyc haracterized. The crystal structure of this compound has now been elucidated by means of synchrotron microfocus diffraction and subsequent quantum-chemical structure optimization applying DFT methods. The structure was refinedi nt riclinic space group P1 based on X-ray data. Cell parameters of a = 4.56(2), b = 19.34(8), c = 21.58(11) , a = 73.34(11)8, b = 89.1(2)8,a nd g = 88.4(2)8 were experimentally obtained. The resulting cell volumes agree with the DFT optimized value to within 7%.M olecular units in the structure form stacks that are interconnectedb yavastarray of hydrogen bridge interactions. Remarkably large melam dihedral angles of 48.48 were found that allow melam to interact with melem molecules from differents tack layers,t hus forming a3 Dn etwork. p-stacking interactions appear to play no major role in this structure.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.
Microcrystals of the oxonitridosilicate oxide La(11)Si(13)N(27.636)O(1.046):Ce(3+) were obtained by exploratory high-temperature synthesis starting from La, La(NH2)3, Si(NH)2, BaH2, and CeF3. Owing to the small size of the crystals, microfocused synchrotron radiation was used for structure investigations (space group Cmc21 (No. 36), a = 9.5074(4) Å, b = 32.0626(9) Å, c = 18.5076(8) Å, Z = 8, R1(all) = 0.0267). The crystal structure consists of an unprecedented interrupted three-dimensional network of vertex-sharing SiN(4-x)O(x) tetrahedra that form channels of siebener rings along [100]. Moreover, the structure is characterized by layers of condensed sechser rings in a boat conformation and vierer rings, which are alternatingly stacked with layers of vierer and dreier rings. Several split positions indicate two different local structure variants. Infrared spectroscopy confirms the absence of N-H bonds. Powder X-ray diffraction data show that bulk samples contain only a small amount of La(11)Si(13)N(27.636)O1.046:Ce(3+). However, once the exact composition was determined from structure analysis, it was possible to optimize the synthesis using fluorides as starting materials. Thereby, bulk samples of the homeotypic compound La(11)Si(13)N(27.376)O(0.936)F were obtained and investigated.
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