Crystal Structure and Luminescence Investigations of the Nitridomagnesoaluminates Mg3AlnNn+2 with n=1, 2, 3

Mg3Al3N5, Mg3Al2N4, and Mg3AlN3 were synthesized at 1100 degrees C in a closed system by utilizing weld-shut niobium ampoules. Their crystal structures were solved and refined on the basis of powder XRD data in space group P6(3)/mmc [a = b = 3.2422(1), c = 26.340(1) angstrom, Z = 2] for Mg3Al3N5, P (3) over bar m1 [a = b = 3.2860(1), c = 10.7461(1) angstrom, Z = 1] for Mg3Al2N4, and R (3) over barm [a = b = 3.3683(0), c = 25.4835(1) angstrom, Z = 3] for Mg3AlN3. Their crystal structures are characterized by wurtzite-type [AlN] and [MgN] block layers alternating with octahedral [MgN] layers along the c-axis direction. Europium(III)-doped samples of Mg3Al3N5 show characteristic emission in the visible region of the spectrum on excitation with UV radiation at lambda(ex) = 370 nm. Mg3AlN3 doped with europium(II) shows yellow luminescence on excitation with UV radiation at lambda(ex) = 365 nm.