Crystal structure and luminescence properties of SrxCa1-xAlSiN3:Eu2+ mixed nitride phosphors

Abstract This study was performed to characterize the crystal structure and luminescence properties of Eu 2+ -doped Sr x Ca 1 −  x AlSiN 3 (0.2 ≤  x  ≤ 1) red phosphor. Structural refinement was carried out using the Rietveld method. The unit cell volumes were shown to expand linearly with increasing Sr content throughout the whole solid solution range. As an end member, SrAlSiN 3 :Eu 2+ phosphor was synthesized under a high pressure of 190 MPa and high temperature of 2173 K. The phosphor crystallizes with an isotypic structure of CaAlSiN 3 in the orthorhombic space group Cmc2 1 with lattice parameters of a  = 9.8087(1) A, b  = 5.75600(8) A, c  = 5.16614(7) A, and unit cell volume = 291.674(7) A 3 . This unit cell volume was larger than that of CaAlSiN 3 :Eu 2+ by 4%. The phosphor showed intense orange–red emission by 5d → 4f transition of Eu 2+ at around 610 nm. Through the whole range of solid solution, Eu 2+ -doped Sr x Ca 1 −  x AlSiN 3 red phosphors showed a broad excitation band ranging from UV to visible light, and temperature characteristics comparable to those of CaAlSiN 3 :Eu 2+ at the Eu concentration of 0.8 mol%.