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Tetrahedron‐based nitrides offer a wide range of properties and applications. Highly condensed nitridophosphates are examples of nitrides that exhibit fascinating luminescence properties when doped with Eu2+, making them appealing for industrial applications. Here, we present the first nitridomagnesophosphate solid solution series Ba3−xSrx[Mg2P10N20] : Eu2+ (x=0–3), synthesized by a high‐pressure high‐temperature approach using the multianvil technique (3 GPa, 1400 °C). Starting from the binary nitrides P3N5 and Mg3N2 and the respective alkaline earth azides, we incorporate Mg into the P/N framework to increase the degree of condensation κ to 0.6, the highest observed value for alkaline earth nitridophosphates. The crystal structure was elucidated by single‐crystal X‐ray diffraction, powder X‐ray diffraction, energy‐dispersive X‐ray spectroscopy (EDX), and solid‐state NMR. DFT calculations were performed on the title compounds and other related highly condensed nitridophosphates to investigate the influence of Mg in the P/N network. Eu2+‐doped samples of the solid solution series show a tunable narrow‐band emission from cyan to green (492–515 nm), which is attributed to the preferred doping of a single crystallographic site. Experimental confirmation of this assumption was provided by overdoping experiments and STEM‐HAADF studies on the series as well on the stoichiometric compound Ba2Eu[Mg2P10N20] with additional atomic resolution energy‐dispersive X‐ray spectroscopy (EDX) mapping. [ABSTRACT FROM AUTHOR]

In the field of nitride phosphors, which are crucial for phosphor‐converted light‐emitting diodes, mixed tetrahedral networks hold a significant position. With respect to the wide range of compositions, the largely unexplored (Si, P)–N networks are investigated as potential host structures. In this work, two highly condensed structures, namely Sr2SiP2N6 and Sr5Si2P6N16 are reported to address the challenges that arise from the similarities of the network‐forming cations Si4+ and P5+ in terms of charge, ionic radius, and atomic scattering factor, a multistep workflow is employed to elucidate their structure. Using single‐crystal X‐ray diffraction, energy‐dispersive X‐ray spectroscopy (EDX), atomic‐resolution scanning transmission electron microscopy (STEM)‐EDX maps, and straightforward crystallographic calculations, it is found that Sr2SiP2N6 is the first ordered, and Sr5Si2P6N16 the first disordered, anionic tetrahedral (Si, P)–N network. After doping with Eu2+, Sr2SiP2N6:Eu2+ shows narrow cyan emission (λmax = 506 nm, fwhm = 60 nm/2311 cm−1), while for Sr5Si2P6N16:Eu2+ a broad emission with three maxima at 534, 662, and 745 nm upon irradiation with ultraviolet light is observed. An assignment of Sr sites as probable positions for Eu2+ and their relation to the emission bands of Sr5Si2P6N16:Eu2+ is discussed. [ABSTRACT FROM AUTHOR]

Light‐emitting diodes (LEDs) producing pure, highly saturated colors are the industry standard for efficient backlighting of high‐color gamut displays. Vivid color reproduction, matching the eye's perception of nature, is the central paradigm in the design of narrow‐band emitting phosphors. To cover a wide range of naturally occurring color tones, expansion of the color gamut in the green spectral region, and therefore an advanced applicable green phosphor, is highly desired. Herein, the oxonitridoberyllosilicate Ba[BeSiON2]:Eu2+ showing outstanding narrow‐band green emission (λmax ≈526 nm with FWHM ≈1600 cm−1 (≈45 nm), x = 0.212, y = 0.715) when excited with InGaN‐based blue LEDs is presented. High quantum efficiency and low thermal quenching (>90% rel. quantum efficiency at 100 °C) as well as excellent scalability make the material suitable for industrial application in high color‐gamut LED displays. A prototype phosphor‐converted‐LED (pc‐LED), with green‐emitting Ba[BeSiON2]:Eu2+ and K2SiF6:Mn4+ as red phosphor shows an extraordinary coverage in the CIE 1931 color space of 109% compared to the DCI‐P3 standard, topping the widely applied β‐SiAlON:Eu2+ phosphor (104%), making it suitable for use in phone displays, monitors, and television screens. [ABSTRACT FROM AUTHOR]

Oxonitridophosphates exhibit the potential for broad structural diversity, making them promising host‐compounds in phosphor‐converted light‐emitting diode applications. The novel monophyllo‐oxonitridophosphate β‐MgSrP3N5O2 was obtained by using the high‐pressure multianvil technique. The crystal structure was solved and refined based on single‐crystal X‐ray diffraction data and confirmed by powder X‐ray diffraction. β‐MgSrP3N5O2 crystallizes in the orthorhombic space group Cmme (no. 67, a=8.8109(6), b=12.8096(6), c=4.9065(3) Å, Z=4) and has a structure related to that of Ba2CuSi2O7. DFT calculations were performed to investigate the phase transition from α‐ to β‐MgSrP3N5O2 and to confirm the latter as the corresponding high‐pressure polymorph. Furthermore, the luminescence properties of Eu2+ doped samples of both polymorphs were investigated and discussed, showing blue and cyan emission, respectively (α‐MgSrP3N5O2; λmax=438 nm, fwhm=46 nm/2396 cm−1; β‐MgSrP3N5O2; λmax=502 nm, fwhm=42 nm/1670 cm−1). [ABSTRACT FROM AUTHOR]

The nitridoberylloaluminate Ba2[BeAl3N5]:Eu2+ and solid solutions Sr2−xBax[BeAl3N5]:Eu2+ (x=0.5, 1.0, 1.5) were synthesized in a hot isostatic press (HIP) under 50 MPa N2 atmosphere at 1200 °C. Ba2[BeAl3N5]:Eu2+ crystallizes in triclinic space group P1‾ (no. 2) (Z=2, a=6.1869(10), b=7.1736(13), c=8.0391(14) Å, α=102.754(8), β=112.032(6), γ=104.765(7)°), which was determined from single‐crystal X‐ray diffraction data. The lattice parameters of the solid solution series have been obtained from Rietveld refinements and show a nearly linear dependence on the atomic ratio Sr : Ba. The electronic properties and the band gaps of M2[BeAl3N5] (M=Sr, Ba) have been investigated by a combination of soft X‐ray spectroscopy and density functional theory (DFT) calculations. Upon irradiation with blue light (440–450 nm), the nitridoberylloaluminates exhibit intense orange to red luminescence, which can be tuned between 610 and 656 nm (fwhm=1922–2025 cm−1 (72–87 nm)). In contrast to the usual trend, the substitution of the smaller Sr2+ by larger Ba2+ leads to an inverse‐tunable luminescence to higher wavelengths. Low‐temperature luminescence measurements have been performed to exclude anomalous emission. [ABSTRACT FROM AUTHOR]

We present the first nitridic analogs of micas, namely AESi3P4N10(NH)2 (AE=Mg, Mg0.94Ca0.06, Ca, Sr), which were synthesized under high‐pressure high‐temperature conditions at 1400 °C and 8 GPa from the refractory nitrides P3N5 and Si3N4, the respective alkaline earth amides, implementing NH4F as a mineralizer. The crystal structure was elucidated by single‐crystal diffraction with microfocused synchrotron radiation, energy‐dispersive X‐ray spectroscopic (EDX) mapping with atomic resolution, powder X‐ray diffraction, and solid‐state NMR. The structures consist of typical tetrahedra–octahedra–tetrahedra (T‐O‐T) layers with P occupying T and Si occupying O layers, realizing the rare motif of sixfold coordinated silicon atoms in nitrides. The presence of H, as an imide group forming the SiN4(NH)2 octahedra, is confirmed by SCXRD, MAS‐NMR, and IR spectroscopy. Eu2+‐doped samples show tunable narrow‐band emission from deep blue to cyan (451–492 nm). [ABSTRACT FROM AUTHOR]

The recently introduced nitridophosphate synthesis in a hot isostatic press (HIP) enabled simple access to large‐scale product quantities starting from exclusively commercially available starting materials. Herein, we show that this method is suitable for the synthesis of highly condensed functional nitridophosphates, as well. Hence, the syntheses of the nitridophosphate zeolites Ba3P5N10X (X=Cl, Br) are presented as proof of concept for this innovative access. Furthermore, samples of unprecedented Sr3P5N10X (X=Cl, Br) were prepared and characterized to demonstrate the advantages of this synthetic approach over commonly used methods. Luminescence investigations on Eu2+‐doped samples of AE3P5N10X (AE=Sr, Ba; X=Cl, Br) were carried out and characteristics of observed emission bands are discussed. [ABSTRACT FROM AUTHOR]

The ortho‐oxonitridophosphate Ba2PO3N was synthesized under ammonobasic conditions (T = 1070 K, p = 120 MPa) in custom‐built high‐temperature autoclaves, starting from red phosphorus, BaO, NaN3 and KOH. Thus, single crystals of up to several hundred µm were obtained, which were used for single‐crystal X‐ray diffraction. Ba2PO3N [Pnma (no. 62), a = 7.596(2), b = 5.796(1), c = 10.212(3) Å, Z = 4] crystallizes in the β‐K2SO4 structure type with non‐condensed [PO3N]4– ions and is isotypic to its lighter homologues EA2PO3N (EA = Ca, Sr). Powder X‐ray diffraction, energy dispersive X‐ray and Fourier Transformed Infrared spectroscopy corroborate the crystal structure. The optical band gap was determined by means of diffuse reflectance UV/Vis spectroscopy to be 4.3 eV. Eu2+ doped samples show green luminescence (λem = 534 nm, fwhm = 85 nm/2961 cm–1) when irradiated with UV light (λexc = 420 nm). However, Ba2PO3N:Eu2+ shows strong thermal quenching, even at room temperature. [ABSTRACT FROM AUTHOR]

M[BeSi2N4] (M=Sr,Eu), crystallizing in the hexagonal space group P 2c, was synthesized from Sr(NH2)2, Be3N2, and “Si(NH)2” in W crucibles under a N2 atmosphere in a radio‐frequency furnace. The crystal structure was solved from powder X‐ray diffraction data by the charge‐flipping method (Sr[BeSi2N4]: a=4.86082(2), c=9.42264(4) Å, Z=2; Eu[BeSi2N4]: a=4.85848(1), c=9.41615(4) Å). M[BeSi2N4] contains a highly condensed rigid network of trigonal planar [BeN3] units that are connected to Si2N7 double tetrahedra by common vertices. M[BeSi2N4] (M=Sr,Eu) are the first examples of nitridoberyllosilicates and are isotypic to the oxoberyllate Sr[Be3O4]. Eu2+‐doped Sr[BeSi2N4] and Eu[BeSi2N4] show orange‐trapped exciton emission (λem=605 nm, fwhm ≈126 nm), whereas Ce3+‐doped samples of Sr[BeSi2N4] show nontypical yellowish‐orange luminescence. Sr[BeSi2N4] has a large band gap of ≈4.4 eV and shows high chemical and thermal stability. Eu2+‐doped beryllates with regular 4f65d1→4f7‐emission could be interesting for future application in LEDs upon doping with Eu2+ or Ce3+ due to large band gaps, rigid networks, and chemical and thermal stability. [ABSTRACT FROM AUTHOR]

Highly efficient narrow-band red emitting (RE) phosphors are the most desired and requested materials for developing illumination grade phosphor-converted light emitting diodes (pcLEDs). This study presents direct measurements of RE energy levels, critical to the color and efficiency of LED phosphors. For the first time, we experimentally determine the energetic separation of the Eu 5d state and the conduction band, which is the key indicator of quantum efficiency. This was achieved for the next-generation pcLED phosphors Li2Ca2[Mg2Si2N6]:Eu2+, Ba[Li2(Al2Si2)N6]:Eu2+, and Sr[LiAl3N4]:Eu2+ using resonant inelastic X-ray scattering. Band to band and 4f to valence band transitions are directly observed in X-ray excited optical luminescence spectra of Sr[LiAl3N4]:Eu2+ and Sr[Mg3SiN4]:Eu2+. These techniques are widely applicable and create a comprehensive, experimental picture of the Eu2+ energy levels in these compounds, leading to a complete understanding of all pertinent electronic processes. This study forms the base needed for a detailed discussion of the structure-property relationships, such as specific atoms, coordination and density of states, underpinning phosphor color and efficiency. [ABSTRACT FROM AUTHOR]

In the search for materials for high‐efficiency lighting applications, the color‐point tuning of phosphors for inorganic phosphor converted LEDs (pcLEDs) is of special interest. We expand the recently explored phosphor class of SiBeONs (oxonitridoberyllosilicates) by the synthesis and characterization of SrBe1−xSi2+xO3−2xN2+2x:Eu2+. High temperature synthesis, starting from Sr2N, BeO, SiO2 and Si3N4, yields the target phase as the main product. Upon doping with Eu2+, the pale blue crystals exhibit blue luminescence with emission at 456 nm and a full width at half maximum (fwhm) of 66 nm/3108 cm−1. The structure is an ordered variant of the LaSi3N5 structure type and was elucidated by single‐crystal X‐ray diffraction data. The network in SrBe1−xSi2+xO3−2xN2+2x:Eu2+ is highly condensed with a condensation degree of κ=0.6 comprising corner‐sharing [MX4] (M=Be, Si; X=O, N) tetrahedra, with mixed occupancies on both the ligand and central metal sites. [ABSTRACT FROM AUTHOR]

In the field of nitride phosphors, which are crucial for phosphor‐converted light‐emitting diodes, mixed tetrahedral networks hold a significant position. With respect to the wide range of compositions, the largely unexplored (Si, P)–N networks are investigated as potential host structures. In this work, two highly condensed structures, namely Sr2SiP2N6 and Sr5Si2P6N16 are reported to address the challenges that arise from the similarities of the network‐forming cations Si4+ and P5+ in terms of charge, ionic radius, and atomic scattering factor, a multistep workflow is employed to elucidate their structure. Using single‐crystal X‐ray diffraction, energy‐dispersive X‐ray spectroscopy (EDX), atomic‐resolution scanning transmission electron microscopy (STEM)‐EDX maps, and straightforward crystallographic calculations, it is found that Sr2SiP2N6 is the first ordered, and Sr5Si2P6N16 the first disordered, anionic tetrahedral (Si, P)–N network. After doping with Eu2+, Sr2SiP2N6:Eu2+ shows narrow cyan emission (λmax = 506 nm, fwhm = 60 nm/2311 cm−1), while for Sr5Si2P6N16:Eu2+ a broad emission with three maxima at 534, 662, and 745 nm upon irradiation with ultraviolet light is observed. An assignment of Sr sites as probable positions for Eu2+ and their relation to the emission bands of Sr5Si2P6N16:Eu2+ is discussed. [ABSTRACT FROM AUTHOR]