# Ba2BP7N14 – A Quaternary Alkaline Earth Nitridoborophosphate with a Mixed 3D Network Structure

## TL;DR

Scientists synthesized a new quaternary alkaline earth nitridoborophosphate, Ba2BP7N14, with a 3D network structure and potential for luminescent applications.

## Contribution

The first synthesis and structural characterization of a quaternary alkaline earth nitridoborophosphate with a mixed 3D network of B and P tetrahedra.

## Key findings

- Ba2BP7N14 was synthesized under high-pressure and high-temperature conditions.
- The compound features a 3D network of PN4 and mixed (P0.75B0.25)N4 tetrahedra.
- Eu2+ doping leads to blue emission at 422 nm, suggesting potential for LED applications.

## Abstract

Highly condensed alkaline earth nitridophosphates have attracted increasing scientific interest, due to their high thermal and chemical stability, as well as their promising luminescence behavior upon doping with Eu2+ for pc‐LED applications. In particular, the barely explored mixed tetrahedra‐based nitridophosphates offer a wide range of structural and compositional diversity, enabling new insights into structure‐property relationships. Herein, we report on the first quaternary alkaline earth nitridoborophosphate Ba2BP7N14, synthesized at 8 GPa and 1600 °C in a multianvil press, starting from Ba(N3)2, h‐BN and P3N5. Ba2BP7N14 crystallizes in the barylite‐1O polytype and features a highly condensed mixed (B,P)–N anionic 3D network (κ≈0.57) built up of PN4 and mixed occupied (P0.75B0.25)N4 tetrahedra. The structure was characterized by a multi‐step process involving single‐crystal and powder X‐ray diffraction (SCXRD, PXRD), elemental analysis, electron microscopy (STEM, EELS), and solid‐state 31P and 11B MAS NMR spectroscopy. The plausibility of the structural model was corroborated by low‐cost crystallographic calculations. The optical band gap and the thermal behavior of an undoped sample of Ba2BP7N14, were determined from diffuse reflectance spectroscopy and temperature‐dependent powder X‐ray diffraction, respectively. Irradiation of a Eu2+‐doped sample with near‐UV light results in a blue emission peaking at λ
em=422 nm.

The alkaline earth nitridoborophosphate Ba2BP7N14 was synthesized under high‐pressure high‐temperature conditions. The crystal structure reveals a 3D‐network of PN4 and mixed occupied (P0.75B0.25)N4 tetrahedra and was determined using a multi‐step characterization process including SCXRD, PXRD, elemental analysis, electron microscopy and NMR spectroscopy. Furthermore, materials properties were investigated. This approach provides first insights into mixed quaternary AE–B–P–N systems.