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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]

A series of isostructural imidonitridophosphates AE2AlP8N15(NH) (AE=Ca, Sr, Ba) was synthesized at high‐pressure/high‐temperature conditions (1400 °C and 5–9 GPa) from alkaline‐earth metal nitrides or azides Ca3N2/Sr(N3)2/Ba(N3)2 and the binary nitrides AlN and P3N5. NH4F served as a hydrogen source and mineralizing agent. The crystal structures were determined by single‐crystal X‐ray diffraction and feature a three‐dimensional network of vertex‐sharing PN4‐tetrahedra forming diverse‐sized rings that are occupied by aluminum and alkaline earth ions. These structures represent another example of nitridophosphate‐based networks that simultaneously incorporate AlN6‐octahedra and alkaline‐earth‐centered polyhedra, with aluminum not participating in the tetrahedra network. They differ from previously reported ones by incorporating non‐condensed octahedra instead of strongly condensed octahedra units and contribute to the diversity of multicationic nitridophosphate network structures. The results are supported by atomic resolution EDX mapping, solid‐state NMR and FTIR measurements. Eu2+‐doped samples show strong luminescence with narrow emissions in the range of green to blue under UV excitation, marking another instance of Eu2+‐luminescence within imidonitridophosphates. [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]

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 first nitridic analog of an amphibole mineral, the quaternary nitridosilicate phosphate Cr5.7Si2.3P8N24 was synthesized under high‐pressure high‐temperature conditions at 1400 °C and 12 GPa from the binary nitrides Cr2N, Si3N4 and P3N5, using NH4N3 and NH4F as additional nitrogen source and mineralizing agent, respectively. The crystal structure was elucidated by single‐crystal X‐ray diffraction with microfocused synchrotron radiation (C2/m, a=9.6002(19), b=17.107(3), c=4.8530(10) Å, β=109.65(3)°). The elemental composition was analyzed by energy dispersive X‐ray spectroscopy. The structure consists of vertex‐sharing PN4‐tetrahedra forming zweier double chains and edge‐sharing (Si,Cr)‐centered octahedra forming separated ribbons. Atomic resolution scanning transmission electron microscopy shows ordered Si and Cr sites next to a disordered Si/Cr site. Optical spectroscopy indicates a band gap of 2.1 eV. Susceptibility measurements show paramagnetic behavior and support the oxidation state Cr+IV, which is confirmed by EPR. The comprehensive analysis expands the field of Cr−N chemistry and provides access to a nitride analog of one of the most prevalent silicate structures. [ABSTRACT FROM AUTHOR]

Introducing new elements into binary transition metal compounds can cause crystal distortion at the transition metal site. The newly synthesized high-temperature and high-pressure titanium oxonitridophosphate Ti5P12N24O2 is an example of such a compound. We analyze the structural distortion at the titanium sites by applying X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) techniques at the Ti L2,3-edge. We verify the two distinct titanium sites in the lattice, each exhibiting a specific valence state. We confirm that these are both Ti3+ and Ti4+ with a dominant presence of the Ti3+ cation. The degree of lattice distortion within the crystal is extracted and quantified by employing ligand field multiplet theory (LFMT) in a distorted octahedral crystal field (D4h). Using the calculated distortion values, we establish a correlation between the distorted parameters (Ds, Dt) and the crystallographic bond length of Ti–N at each titanium site. There is good agreement between the calculated and measured splitting energy (Δeg) of the eg orbitals and Ti4+ is identified as the more distorted titanium site, while the Ti3+ occupies the less distorted site in the polyhedral structure. [ABSTRACT FROM AUTHOR]

Tetrahedra‐based nitridophosphates show a rich structural chemistry, which can be further extended by incorporating cations in higher coordinated positions, for example, in octahedral voids or by substituting the nitrogen atoms in the network with other anions. Following this approach, SrAl5P4N10O2F3 was synthesized at high‐temperature and high‐pressure conditions using a multianvil press (1400 °C, 5 GPa) starting from Sr(N3)2, c‐PON, P3N5, AlN, and NH4F. SrAl5P4N10O2F3 crystallizes in space group I4‾m2 ${I\bar 4m2}$ with a=11.1685(2) and c=7.84850(10) Å. Atomic‐resolution EDX mapping with scanning transmission electron microscopy (STEM) indicates atom assignments, which are further corroborated by bond‐valence sum (BVS) calculations. Ten Al3+‐centered octahedra form a highly condensed tetra‐face‐capped octahedra‐based unit that is a novel structure motif in network compounds. A network of vertex‐sharing PN4 tetrahedra and chains of face‐sharing Sr2+‐centered cuboctahedra complement the structure. Eu2+‐doped SrAl5P4N10O2F3 shows blue emission (λem=469 nm, fwhm=98 nm; 4504 cm−1) when irradiated with UV light. [ABSTRACT FROM AUTHOR]

Tetrahedra‐based nitridophosphates show a rich structural chemistry, which can be further extended by incorporating cations in higher coordinated positions, for example, in octahedral voids or by substituting the nitrogen atoms in the network with other anions. Following this approach, SrAl5P4N10O2F3 was synthesized at high‐temperature and high‐pressure conditions using a multianvil press (1400 °C, 5 GPa) starting from Sr(N3)2, c‐PON, P3N5, AlN, and NH4F. SrAl5P4N10O2F3 crystallizes in space group I4‾m2 ${I\bar 4m2}$ with a=11.1685(2) and c=7.84850(10) Å. Atomic‐resolution EDX mapping with scanning transmission electron microscopy (STEM) indicates atom assignments, which are further corroborated by bond‐valence sum (BVS) calculations. Ten Al3+‐centered octahedra form a highly condensed tetra‐face‐capped octahedra‐based unit that is a novel structure motif in network compounds. A network of vertex‐sharing PN4 tetrahedra and chains of face‐sharing Sr2+‐centered cuboctahedra complement the structure. Eu2+‐doped SrAl5P4N10O2F3 shows blue emission (λem=469 nm, fwhm=98 nm; 4504 cm−1) when irradiated with UV light. [ABSTRACT FROM AUTHOR]