Cr3+ doped nanoporous anodic alumina: Facile microwave assisted doping to realize nanoporous ruby and phase dependent photoluminescence

Microwave-assisted solution technique (MAST) was used for the homogeneous doping of Cr3+ in nanoporous anodic alumina (NAA) which when heat-treated transforms into nanoporous ruby. The rise in annealing temperature led to the phase transition in the sequence: amorphous- δ- θ- α-alumina as evidenced by XRD. The dopant was homogenously distributed as seen from the elemental mapping and the Cr3+ content was 0.5 at%. Diffuse reflectance spectroscopy...