Crystallite size 20 X ray diffraction 11 Scanning electron microscopy 7 Energy gap 6 Nanoparticles 5 Oxide minerals 5 Nanostructured materials 4 Titanium dioxide 4 Zinc oxide 4 Magnesia 3 Morphology 3 Nanorods 3 Nanostructures 3 Optical properties 3 Particle size analysis 3 Self-propagating combustion 3 Semiconductor doping 3 Sol-gels 3 Substrates 3 Band gap narrowing 2 Catalyst activity 2 Cathode materials 2 Cathode structure 2 Coated glass substrates 2 Combustion method 2 Crystallinity 2 Dislocation densities 2 Doping 2 Electrochemical performance 2 Field emission microscopes 2