Luminescent Nitridophosphates CaP₂N₄:Eu²⁺, SrP₂N₄:Eu²⁺, BaP₂N₄:Eu²⁺, and BaSr₂P₆N₁₂:Eu²⁺

Abstract

Abstract Nitridophosphates MP 2 N 4 :Eu 2+ (M=Ca, Sr, Ba) and BaSr 2 P 6 N 12 :Eu 2+ have been synthesized at elevated pressures and 1100–1300 °C starting from the corresponding azides and P 3 N 5 with EuCl 2 as dopant. Addition of NH 4 Cl as mineralizer allowed for the growth of single crystals. This led to the successful structure elucidation of a highly condensed nitridophosphate from single‐crystal X‐ray diffraction data (CaP 2 N 4 :Eu 2+ ( P 6 3 , no. 173), a =16.847(2), c =7.8592(16) Å, V =1931.7(6) Å 3 , Z =24, 2033 observed reflections, 176 refined parameters, wR 2 =0.096). Upon excitation by UV light, luminescence due to parity‐allowed 4f 6 ( 7 F)5d 1 →4f 7 ( 8 S 7/2 ) transition was observed in the orange (CaP 2 N 4 :Eu 2+ , λ max =575 nm), green (SrP 2 N 4 :Eu 2+ , λ max =529 nm), and blue regions of the visible spectrum (BaSr 2 P 6 N 12 :Eu 2+ and BaP 2 N 4 :Eu 2+ , λ max =450 and 460 nm, respectively). Thus, the emission wavelength decreases with increasing ionic radius of the alkaline‐earth ions. The corresponding full width at half maximum values (2240–2460 cm −1 ) are comparable to those of other known Eu 2+ ‐doped (oxo)nitrides emitting in the same region of the visible spectrum. Following recently described quaternary Ba 3 P 5 N 10 Br:Eu 2+ , this investigation represents the first report on the luminescence of Eu 2+ ‐doped ternary nitridophosphates. Similarly to nitridosilicates and related oxonitrides, Eu 2+ ‐doped nitridophosphates may have the potential to be further developed into efficient light‐emitting diode phosphors.