Synthesis and crystal structure of a new aluminum-silicon-nitride phosphor containing boron, Ba₅B₂Al₄Si₃₂N₅₂: Eu

Single crystals of Ba₅B₂Al₄Si₃₂N₅₂:Eu were grown on the wall of a boron nitride crucible by heating a starting mixture of binary nitrides at 2050 °C and a N₂ pressure of 0.85 MPa. The fundamental reflections of X-ray diffraction (XRD) for the crystals were indexed with triclinic cell parameters, a=9.7879(11) Å, b=9.7920(11) Å, c=12.7226(15) Å, α=96.074(4)°, β=112.330(3)°, and γ=94.080(4)°. Streak lines were observed between the fundamental reflections in the direction of the c* axis in the oscillation XRD images and selected area electron diffraction (SAED) patterns, indicating stacking faults in the structure. The atomic images of stacking faults with a slip system of (0 0 1)[−1 1 0]/3, and displacement of a Ba atom layer with (0 0 1)[−1 −1 0]/6 were observed with a scanning transmission electron microscope (STEM). The models of the basic (normal-stacking) structure with space group P1 and local structures of the stacking faults are herein presented. The single crystals emitted blue light with a peak wavelength of 472 nm and a full width at half maximum of 78 nm under 365 nm excitation.