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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]

The oxonitridosilicate La7Sr[Si10N19O3] : Eu2+ and its substitutional variants RE8‐xAEx[Si10N20‐xO2+x] : Eu2+ with RE=La, Ce; AE=Ca, Sr, Ba and 0≤x≤2 were synthesized starting from REN, SrN/Ca3N2/Ba2N, SiO2, amorphous Si3N4 and Eu2O3 as doping agent at 1600 °C in a radiofrequency furnace. The crystal structure of La7Sr[Si10N19O3] was solved and refined based on single‐crystal X‐ray diffraction data. La7Sr[Si10N19O3] crystallizes in the orthorhombic space group Pmn21 (no. 31). The crystal structures of the isotypic compounds RE8‐xAEx[Si10N20‐xO2+x] were confirmed by Rietveld refinements based on powder X‐ray diffraction data using the single‐crystal data of La7Sr[Si10N19O3] as starting point. Crystal structure elucidation reveals a 3D network of vertex sharing SiN4 and SiN2(N1/2‐x/4O1/2+x/4)2 (0≤x≤2) tetrahedra. When excited with UV to blue light, La7Sr[Si10N19O3] : Eu2+ shows amber luminescence with λem=612 nm and fwhm=84 nm/2194 cm−1, which makes it interesting for application in amber phosphor‐converted light emitting diodes. [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]

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]

Recent developments in solid‐state lighting lead to a demand for new phosphors with excellent thermal stability, exhibiting large bandgaps for highly efficient emission. A detailed characterization of the luminescent material AELi2Be4O6:Eu2+ (AE = Ba, Sr) is presented using soft X‐ray absorption spectroscopy, X‐ray emission spectroscopy, X‐ray excited optical luminescence (XEOL) spectroscopy, and density functional theory (DFT) calculations. The experimental indirect bandgap for both BaLi2Be4O6:Eu2+ (BLBO:Eu) and SrLi2Be4O6:Eu2+ (SLBO:Eu) is found to be 6.5 ± 0.3 eV, which agrees well with the DFT calculations (6.8 eV for BLBO:Eu and 7.4 eV for SLBO:Eu). The crucial Eu2+ 5d to conduction band energy separation is determined to be 0.21 ± 0.10 and 0.25 ± 0.10 eV for BLBO:Eu and SLBO:Eu, respectively, using resonant inelastic X‐ray scattering. These measured values are in good agreement with the thermal quenching measurements (0.20 ± 0.03 eV for BLBO:Eu and 0.26 ± 0.03 eV for SLBO:Eu). Finally, the XEOL measurement confirms the Eu2+ 5d14f6 → 4f7 transition, which is responsible for the ultranarrow band (full width at half‐maximum: 25 nm) blue optical luminescence at 455–457 nm for both compounds. With these measurements and calculations, deep insights are gained into the key properties of those two phosphors. [ABSTRACT FROM AUTHOR]

Materials derived from renewable resources have great potential to replace fossil-based plastics in biomedical applications. In this study, the synthesis of cellulose-based photoresists by esterification with methacrylic acid anhydride and sorbic acid was investigated. These resists polymerize under UV irradiation in the range of λ = 254 nm to 365 nm, with or, in the case of the sorbic acid derivative, without using an additional photoinitiator. Usability for biomedical applications was demonstrated by investigating the adhesion and viability of a fibrosarcoma cell line (HT-1080). Compared to polystyrene, the material widely used for cell culture dishes, cell adhesion to the biomaterials tested was even stronger, as assessed by a centrifugation assay. Remarkably, chemical surface modifications of cellulose acetate with methacrylate and sorbic acid allow direct attachment of HT-1080 cells without adding protein modifiers or ligands. Furthermore, cells on both biomaterials show similar cell viability, not significantly different from polystyrene, indicating no significant impairment or enhancement, allowing the use of these cellulose derivatives as support structures for scaffolds or as a self-supporting coating for cell culture solely based on renewable resources. [ABSTRACT FROM AUTHOR]

Abstract: Beryllate structures are marginally investigated, but show intriguing structural relations to oxo‐ and nitridosilicates. A typical feature is the coordination of Be in both trigonal planar and tetrahedral coordination by O. A broad range of structures is accessible by variable combinations of both building units. Three novel ternary Sr‐oxoberyllates are characterized by single‐crystal X‐ray diffraction analysis, density functional theory calculations and investigations on luminescence properties: α‐SrBeO2, β‐SrBeO2 and Sr12Be17O29 are obtained with oxoberyllate substructures, made up of either BeO3 triangles or BeO4 tetrahedra. The compounds can be described as chain‐ and layer‐type beryllates. When excited with blue light of (In,Ga)N LED chips, β‐SrBeO2 and Sr12Be17O29 show visible emission in the yellow and orange spectral range, respectively, upon doping with Eu2+. Exceptional narrow‐band yellow emission (λem=564 nm, fwhm=55 nm) makes β‐SrBeO2:Eu2+ a promising phosphor for application in phosphor‐converted (pc‐)LEDs. [ABSTRACT FROM AUTHOR]

Beryllates show an interesting and diverse structural chemistry, resembling that of well‐investigated silicates. The coexistence of tetrahedral and trigonal coordination of Be by O atoms in oxoberyllates allows for an even broader variety of structural motives and implies a plurality of possible atomic ratios Be:O in ternary or higher compounds. We have now synthesized the novel strontium oxoberyllate Sr3Be2O5 via a high‐temperature high‐pressure reaction and have structurally characterized the ternary oxide by single‐crystal and powder X‐ray diffraction analysis. Sr3Be2O5, a low condensed oxoberyllate, contains unprecedented [Be2O5]6– double triangles and Sr atoms in both double‐capped trigonal‐prismatic and octahedral coordination. These motifs show striking resemblance to α‐SrBeO2 and SrO, combining their structural properties. Lattice energy (MAPLE) calculations corroborate found parallels to the known phases SrO and α‐SrBeO2. [ABSTRACT FROM AUTHOR]

Abstract: Highly efficient phosphor‐converted light‐emitting diodes (pc‐LEDs) are popular in lighting and high‐tech electronics applications. The main goals of present LED research are increasing light quality, preserving color point stability and reducing energy consumption. For those purposes excellent phosphors in all spectral regions are required. Here, we report on ultra‐narrow band blue emitting oxoberyllates AELi2[Be4O6]:Eu2+ (AE=Sr,Ba) exhibiting a rigid covalent network isotypic to the nitridoalumosilicate BaLi2[(Al2Si2)N6]:Eu2+. The oxoberyllates’ extremely small Stokes shift and unprecedented ultra‐narrow band blue emission with fwhm ≈25 nm (≈1200 cm−1) at λem=454–456 nm result from its rigid, highly condensed tetrahedra network. AELi2[Be4O6]:Eu2+ allows for using short‐wavelength blue LEDs (λem<440 nm) for efficient excitation of the ultra‐narrow band blue phosphor, for application in violet pumped white RGB phosphor LEDs with improved color point stability, excellent color rendering, and high energy efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Highly efficient phosphor‐converted light‐emitting diodes (pc‐LEDs) are popular in lighting and high‐tech electronics applications. The main goals of present LED research are increasing light quality, preserving color point stability and reducing energy consumption. For those purposes excellent phosphors in all spectral regions are required. Here, we report on ultra‐narrow band blue emitting oxoberyllates AELi2[Be4O6]:Eu2+ (AE=Sr,Ba) exhibiting a rigid covalent network isotypic to the nitridoalumosilicate BaLi2[(Al2Si2)N6]:Eu2+. The oxoberyllates’ extremely small Stokes shift and unprecedented ultra‐narrow band blue emission with fwhm ≈25 nm (≈1200 cm−1) at λem=454–456 nm result from its rigid, highly condensed tetrahedra network. AELi2[Be4O6]:Eu2+ allows for using short‐wavelength blue LEDs (λem<440 nm) for efficient excitation of the ultra‐narrow band blue phosphor, for application in violet pumped white RGB phosphor LEDs with improved color point stability, excellent color rendering, and high energy efficiency. [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]

Oxo- and (oxo)nitridoberyllates show exceptional potential as host lattices for application in illumination grade phosphor converted (pc)LEDs due to their remarkable electronic and structural characteristics, allowing highly efficient narrow-band emission upon doping with Eu2+. Sr[Be6ON4]:Eu2+, the first example of an oxonitridoberyllate phosphor, exhibits narrow-band cyan emission (λem = 495 nm; full width at half-maximum, fwhm = 35 nm; ≈1400 cm-1), comparable to the emission of the oxonitridosilicate BaSi2O2N2:Eu2+ (fwhm = 35 nm) or a cyan-emitting primary LED (fwhm = 27 nm). Sr[Be6ON4]:Eu2+ reveals a highly condensed rigid 3D network with a remarkably large degree of condensation [i.e., atomic ratio Be:(O,N)] of κ = 1.2 that is achieved by interconnection of highly condensed layers of BeN4 tetrahedra by Be2ON6 units via common edges. The crystal structure of Sr[Be6ON4]:Eu2+ was solved on the basis of single-crystal and powder XRD data (C2/c, no. 15, a = 13.9283(14), b = 5.7582(6), c = 4.9908(5) Å, β = 90.195(1)°, Z = 4, R1 = 0.033, wR2 = 0.065, GoF = 1.046). Sr[Be6ON4]:Eu2+ shows a close structural relationship to other nitride as well as oxide compounds, and therefore closes a structural gap helping to understand relations in Be-containing solid-state materials. The electronic structure of Sr[Be6ON4]:Eu2+ was characterized by X-ray spectroscopy measurements, supported by density functional theory (DFT) calculations. Due to its excellent emission properties, large band gap, rigid 3D network, as well as chemical and thermal stability, Sr[Be6ON4]:Eu2+ is a promising phosphor to close the cyan gap in efficient high-CRI pcLEDs (CRI, color rendering index). [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]

The nitridomagnesosilicates Li2Ca2[Mg2Si2N6]:Eu2+ and Li2(Ca1.88Sr0.12)[Mg2Si2N6]:Eu2+ show narrow-band red emission at 638 and 634 nm, respectively, with an emission bandwidth of 62 nm (∼1513 cm-1) after excitation in the blue spectral region. Ce3+-doped samples show luminescence in the green spectral range (λem = 540 nm). The compounds were synthesized via solid-state metathesis reaction in Li melts. Refinement of single-crystal X-ray diffraction data revealed that Li2(Ca1.88Sr0.12)[Mg2Si2N6] crystallizes isomorphic to Li2Ca2[Mg2Si2N6]: C2/m [Z = 2, a = 5.5744(2), b = 9.8439(3), c = 6.0170(2) Å, β = 97.2520(10)°, R1 = 0.021, wR2 = 0.047]. Crystal composition was checked by EDS and ICP-OES measurements and luminescence properties are compared to state of the art narrow-band red emitting luminophors. On the basis of its narrow-band emission, application of the novel red luminophor in high CRI white pcLEDs is promising. [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]

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 perfect transmission of chargecarriers through potential barriers in graphene (Klein tunneling)is a direct consequence of the Dirac equation that governs the low-energycarrier dynamics. As a result, localized states do not exist in unpatternedgraphene, but quasibound states canoccur for potentialswith closed integrable dynamics. Here, we report the observation ofresonance states in photoswitchable self-assembled molecular(SAM)-graphenehybrid. Conductive AFM measurements performed at room temperaturereveal strong current resonances, the strength of which can be reversiblygated on- and off- by opticallyswitching the molecular conformation of the mSAM. Comparisons of thevoltage separation between current resonances (∼70–120mV) with solutions of the Dirac equation indicate that the radiusof the gating potential is ∼7 ± 2 nm with a strength ≥0.5eV. Our results and methods might provide a route toward opticallyprogrammablecarrier dynamics and transport in graphene nanomaterials. [ABSTRACT FROM AUTHOR]

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]

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]

The nitridosilicate CaLu[Si4N7–2xCxOx] (x≈0.3) was synthesized by carbothermal reduction and nitridation starting from CaH2, Lu2O3, graphite and amorphous Si3N4 at 1550 °C in a radiofrequency furnace. CaLu[Si4N7–2xCxOx] (x≈0.3) crystallizes isotypically to many previously known MIIMIIISi4N7 compounds in the space group P63mc, as was confirmed by Rietveld refinement based on powder X‐ray diffraction data. Incorporation of carbon into the crystal structure as a result of the carbothermal synthesis route was confirmed by 13C and 29Si MAS NMR spectroscopy. For the first time in the MIIMIIISi4N7 compound class, complementary EDX measurements suggest that simultaneous incorporation of oxygen compensates for the negative charge excess induced by carbon, resulting in an adjusted sum formula, CaLu[Si4N7–2xCxOx] (x≈0.3). When excited with UV‐to‐blue light, CaLu[Si4N7–2xCxOx] (x≈0.3) shows an emission maximum in the blue spectral region (λem=484 nm; fwhm=4531 cm−1) upon doping with Ce3+, whereas Eu2+‐doped CaLu[Si4N7–2xCxOx] (x≈0.3) exhibits a yellow‐green emission (λem=546 nm; fwhm=3999 cm−1). [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 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]

(Oxo)Nitridophosphates have recently been identified as a promising compound class for application in the field of solid‐state lighting. Especially, the latest medium‐pressure syntheses under ammonothermal conditions draw attention of the semiconductor and lighting industry on nitridophosphates. In this contribution, we introduce hot isostatic presses as a new type of medium‐pressure synthetic tool, further simplifying nitridophosphate synthesis. In a second step, phosphorus nitride was replaced as starting material by red phosphorus, enabling the synthesis of Ca2PN3 as model compound, starting only from readily available compounds. Moreover, first luminescence investigations on Eu2+‐doped samples reveal Ca2PN3:Eu2+ as a promising broad‐band red‐emitter (λem=650 nm; fwhm=1972 cm−1). Besides simple handling, the presented synthetic method offers access to large sample volumes, and the underlying reaction conditions facilitate single‐crystal growth, required for excellent optical properties. [ABSTRACT FROM AUTHOR]

(Oxo)Nitridophosphates have recently been identified as a promising compound class for application in the field of solid‐state lighting. Especially, the latest medium‐pressure syntheses under ammonothermal conditions draw attention of the semiconductor and lighting industry on nitridophosphates. In this contribution, we introduce hot isostatic presses as a new type of medium‐pressure synthetic tool, further simplifying nitridophosphate synthesis. In a second step, phosphorus nitride was replaced as starting material by red phosphorus, enabling the synthesis of Ca2PN3 as model compound, starting only from readily available compounds. Moreover, first luminescence investigations on Eu2+‐doped samples reveal Ca2PN3:Eu2+ as a promising broad‐band red‐emitter (λem=650 nm; fwhm=1972 cm−1). Besides simple handling, the presented synthetic method offers access to large sample volumes, and the underlying reaction conditions facilitate single‐crystal growth, required for excellent optical properties. [ABSTRACT FROM AUTHOR]

The nitridophosphates AEP8N14 (AE=Ca, Sr, Ba) were synthesized at 4–5 GPa and 1050–1150 °C applying a 1000 t press with multianvil apparatus, following the azide route. The crystal structures of CaP8N14 and SrP8N14 are isotypic. The space group Cmcm was confirmed by powder X‐ray diffraction. The structure of BaP8N14 (space group Amm2) was elucidated by a combination of transmission electron microscopy and diffraction of microfocused synchrotron radiation. Phase purity was confirmed by Rietveld refinement. IR spectra are consistent with the structure models and the chemical compositions were confirmed by X‐ray spectroscopy. Luminescence properties of Eu2+‐doped samples were investigated upon excitation with UV to blue light. CaP8N14 (λem=470 nm; fwhm=1380 cm−1) and SrP8N14 (λem=440 nm; fwhm=1350 cm−1) can be classified as the first ultra‐narrow‐band blue‐emitting Eu2+‐doped nitridophosphates. BaP8N14 shows a notably broader blue emission (λem=417/457 nm; fwhm=2075/3550 cm−1). [ABSTRACT FROM AUTHOR]

Nitridophosphates exhibit an intriguing structural diversity with different structural motifs, for example, chains, layers or frameworks. In this contribution the novel nitridophosphate Sr3P3N7 with unprecedented dreier double chains is presented. Crystalline powders were synthesized using the ammonothermal method, while single crystals were obtained by a high‐pressure multianvil technique. The crystal structure of Sr3P3N7 was solved and refined from single‐crystal X‐ray diffraction and confirmed by powder X‐ray methods. Sr3P3N7 crystallizes in monoclinic space group P2/c. Energy‐dispersive X‐ray and Fourier‐transformed infrared spectroscopy were conducted to confirm the chemical composition, as well as the absence of NHx functionality. The optical band gap was estimated to be 4.4 eV using diffuse reflectance UV/Vis spectroscopy. Upon doping with Eu2+, Sr3P3N7 shows a broad deep‐red to infrared emission (λem=681 nm, fwhm≈3402 cm−1) with an internal quantum efficiency of 42 %. [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]

Recently, a number of different structurally related nitrides characterized by pairs of edge-sharing Si–N tetrahedra forming [Si2N6]10− units have emerged via different synthesis methods. Concurrently, upon doping with rare earth elements (e.g. Eu2+ and Ce3+), numerous applications in the field of luminescent materials were revealed, ranging from the visible spectrum to the near IR. This compound class in turn emphasizes the extraordinary large tuning range with respect to relative composition by formal cation exchange. In this contribution, we study the dynamical stabilities of the existing Si-based nitridotetrelates and hypothetical Ge analogues promising for future synthesis efforts of luminescent materials by means of extensive phonon calculations. Further calculations of electronic and mechanical properties corroborate the fundamental suitability of the predicted compounds for the applications of potential luminescent materials with regard to band gap (Eg) and Debye temperature (ΘD). Calculated enthalpies of the reaction provide further beneficial insights for future experimental attempts. Our study hence highlights a potential range of novel stable nitridogermanates with isotypic structures and suitable electronic properties for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Ba[Mg3SiN4]:Eux (x = 0.005-0.025) is prepared by a solid state metathesis reaction of BaF2, Mg3N2, Si(NH)2, LiN3 as N source, Li as flux, and EuF3 as dopant (Ta tube in evacuated silica tube, 1050 °C, 24 h; cooling to 500 °C within 250 h). [ABSTRACT FROM AUTHOR]