Fabrication of metallic Cd multifarious prismatic microcrystals (CMPMCs) under NH₃ gas ambient

We report here highly dense and pure metallic cadmium (Cd) multifarious prismatic microcrystals (CMPMCs) fabricated by thermal decomposition of cadmium oxide (CdO) powder at 700 °C for 60 min under NH₃ gas ambient inside horizontal tube furnace. CMPMCs were observed to be 1-1.5 μm in size with interesting morphologies of various cross sections such as triangular, trapezoidal, pentagonal and hexagonal etc. having solid, hollow/semi-hollow appearances. The as-synthesized CMPMCS were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Room temperature photoluminescence (PL) spectrum for Cd metal microcrystals exhibited a prominent emission band at 365 along with a shoulder peak at 404 nm. The UV main emission band is ascribed to radiative recombination of the electrons in the s, p conduction band near the Fermi surface and holes in the d bands generated under xenon light excitation whereas shoulder peak may be owing to surface oxidation effects or induced defects. This study shows the potential of CMPMCs for applications in optical devices. Based on vapour-solid (VS) process, growth mechanism for the formation of CMPMCs is also proposed and discussed briefly.