Zn1−xGax/2Fex/2O (x= 0, 0.0156, 0.0312) represents the polycrystalline hexagonal (wurtzite) phase with a space group P63mc synthesized using the sol–gel technique. A comparative study and investigation of structural, optical, and photo-sensing properties of these samples were performed. Structural and vibrational studies show enhancement in the crystallinity of the codoped samples. Optical band gap increases from ∼3.21 to 3.24 eV with substitution because of the improved crystallinity. The photoluminescence properties show modification from yellowish green for x= 0 to a more distinct green for x= 0.0156. The intensity of the luminescence decreases with doping, indicating an overall reduction of defects in the band gap helping the material to become more transparent to visible light. Photocurrent and photosensitivity are modified with the illumination wavelength (290, 450, 540 and 640 nm) with codoping. Sensitivity toward visible lights reduced with codoping. On the other hand, it is more sensitive to ultraviolet light. It indicates the material becomes more transparent for visible light and may be used as photostable device.

The recent observation of spectacular photocatalytic activity enhancements generated tremendous interest in the synthesis, properties, and potential applications of black titania. Most black titania are core–shell structures consisting of a perfect crystalline core surrounded by a defective surface shell. Because the properties are attributed to the defective shell, it is particularly important, but very challenging, to obtain atomic structure information of the core, the shell, and the core–shell relationship on a single particle level. While the role of various synthesis approaches for producing black titania with different properties has been extensively reviewed, this review focuses on understanding the structure–functionality relationship in black titania on a single particle level. We start by introducing the crystal and electronic band structure of different TiO2 phases, followed by the discussion of particle size effects, the origin of lattice distortions, and phase control by synthesis, and concluding with the discussion of crystalline order formation and evolution creating the defective shell.

In this work we study the interfaces between the Mott insulator LaMnO3 (LMO) and the band insulator SrTiO3 (STO) in epitaxially grown superlattices with different thickness ratios and different transport and magnetic behaviors. Using atomic resolution electron energy-loss spectral imaging, we analyze simultaneously the structural and chemical properties of these interfaces. We find changes in the oxygen octahedral tilts within the LaMnO3 layers when the thickness ratio between the manganite and the titanate layers is varied. Superlattices with thick LMO and ultrathin STO layers present unexpected octahedral tilts in the STO, along with a small amount of oxygen vacancies. On the other hand, thick STO layers exhibit undistorted octahedra while the LMO layers present reduced O octahedral distortions near the interfaces. These findings are discussed in view of the transport and magnetic differences found in previous studies.

In the present study, we report an activation and enhancement of room temperature ferromagnetism in pure ZnO and V-doped ZnO (Zn0.95V0.05O and Zn0.90V0.10O) thin films by trioctylphosphine (TOP) functionalization. X-ray diffraction patterns show a slight decrease in the intensity of the diffraction peak on TOP functionalization. Atomic force micrographs of pure and V-doped ZnO films reveal no disorder in the film surface on TOP functionalization. The chemical bond formation of TOP on ZnO film surface was examined by x-ray photoelectron spectroscopy measurements. Photoluminescence measurements of TOP-functionalized ZnO films show enhancements of UV emission and quenching of visible emission. TOP-functionalized ZnO films reveal enhanced ferromagnetic behavior as evidenced from vibrating sample magnetometer measurements.