Hierarchical Assembly of CaMoO4Nano-Octahedrons and Their Photoluminescence Properties

Hierarchical assemblies of CaMoO4 (CM) nano-octahedrons were obtained by microwave-assisted hydrothermal synthesis at 120 °C for different times. These structures were structurally, morphologically and optically characterized by X-ray diffraction, micro-Raman spectroscopy, field-emission gun scanning electron microscopy, ultraviolet−visible absorption spectroscopy and photoluminescence measurements. First-principle calculations have been carried out to understand the structural and electronic order−disorder effects as a function of the particle/region size. Supercells of different dimensions were constructed to simulate the geometric distortions along both the yand zplanes of the scheelite structure. Based on these experimental results and with the help of detailed structural simulations, we were able to model the nature of the order−disorder in this important class of materials and discuss the consequent implications on its physical properties, in particular, the photoluminescence properties of CM nanocrystals.