Photoluminescence: A probe for short, medium and long-range self-organization order in image oxide

Photoluminescent disordered image powders were obtained by the polymeric precursor soft-chemical method. This oxide system (ordered and disordered) was characterized by photoluminescence, Raman spectroscopy, X-ray diffraction, differential scanning calorimetry and UV–vis absorption experiments. The UV absorption tail formation in the disordered oxides was related to the diminution of optical band gap. In the disordered phase, this oxide displayed broad band photoluminescence caused by change in coordination number of titanium and zirconium with oxygen atoms. The gap decreased from 3.09 eV in crystalline oxide to 2.16 eV in disordered oxide. The crystalline oxide presented an orthorhombic image-image-type structure in which image and image were randomly distributed in octahedral coordination polyhedra with oxygen atoms. The amorphous–crystalline transition occurred at almost image, at which point the photoluminescence vanished. The Raman peak at close to 80–image indicated the presence of locally ordered Ti–image and Zr–image polyhedra in disordered photoluminescent oxides.