Structure and luminescence properties study of Eu2+ doped Ca2Al2−xSi1+xO7−xNx phosphors based on size-mismatch model

Eu
²⁺
doped Ca
₂
Al
_2-x
Si
_1+x
O
_7-x
N
_x
(CASON) green-emitting phosphors were prepared by the high temperature solid state reaction method. The crystal structure and luminescence properties were systematically investigated by X-ray powder diffraction and fluorescence spectrophotometer. It was found that Al-O bond could be substituted by Si-N bond in the Ca
₂
Al
₂
SiO
₇
lattice with the maximum solubility of about x =0.4. Under the excitation of 360nm, the photoluminescence (PL) spectra of Ca
₂
Al
_2-x
Si
_1+x
O
_7-x
N
_x
: Eu
²⁺
phosphors presents a blue shift with the increase of x values. The mechanism was discussed in detail by Size-Mismatch model.