Synthesis, crystal structure and photoluminescence of a new Eu-doped Sr containing sialon (Sr _0.94Eu _0.06)(Al _0.3Si _0.7) ₄(N _0.8O _0.2) ₆

Colorless transparent platelet single crystals of a novel Eu ²-doped strontium silicon aluminum oxynitride, (Sr _0.94Eu _0.06)(Al _0.3Si _0.7) ₄(N _0.8O _0.2) ₆, were prepared at 1800 °C and 0.92 MPa of N ₂. Fundamental reflections of electron and X-ray diffraction of the crystals were indexed with a face-centered orthorhombic unit cell (a=5.8061(5) Å, b=37.762(3) Å, c=9.5936(9) Å). Diffuse streaks elongated in the b-axis direction were observed around the fundamental reflections hkl with h=2n1 of the electron and X-ray diffraction, indicating stacking faults of (0 1 0)[1 0 0]/2. A crystal structure model without the stacking faults was obtained using the X-ray diffraction data of the fundamental reflections with the space group Fdd2. A SiN ₄- tetrahedron double layer of [SiN ₂] ₂ and a Sr/Eu double layer of [(Sr _0.94Eu _0.06)Al _1.2Si _0.8N _0.8 O _1.2] ₂ are stacked alternately along the b-axis direction. The title compound showed an emission with a peak wavelength of 490 nm under 334 nm excitation at room temperature.