Nitridophosphate-Based Ultra-Narrow-Band Blue-Emitters: Luminescence Properties of AEP8 N14 :Eu2+ (AE=Ca, Sr, Ba).

The nitridophosphates AEP8 N14 (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 CaP8 N14 and SrP8 N14 are isotypic. The space group Cmcm was confirmed by powder X-ray diffraction. The structure of BaP8 N14 (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. CaP8 N14 (λem =470 nm; fwhm=1380 cm-1 ) and SrP8 N14 (λem =440 nm; fwhm=1350 cm-1 ) can be classified as the first ultra-narrow-band blue-emitting Eu2+ -doped nitridophosphates. BaP8 N14 shows a notably broader blue emission (λem =417/457 nm; fwhm=2075/3550 cm-1 ).