Optical and gas sensing studies of transparent ZnO thin film deposited from a new precursor by ultrasonic aerosol assisted chemical vapor deposition

Transparent semi-conducting ZnO thin films with low resistivity and high transmittance in the visible optical region were deposited by the decomposition of bis(2,4-pentanedionate)-bis(aminoethanol) zinc(II) under an atmosphere of oxygen on ceramic, metal and quartz substrates by ultrasonic aerosol assisted chemical vapor deposition. The precursor was synthesized from bis(2,4-pentanedionate) zinc(II) and aminoethanol by sonication in acetonitrile and was characterized by melting point, infrared spectroscopy, CHNS-O elemental, atomic absorption, and single crystal X-ray diffraction analysis. TGA-FTIR was used to identify the cause of the weight losses and evolved gases formed during the breakup of the molecules. Electrical and optical measurements showed that the ZnO film has a band gap of 3.02 eV and typical semiconductor properties with a resistivity that depends on the thickness of the film. Powder XRD, SEM and EDX show that films are uniform, smooth and crystalline in nature, giving particle sizes in the range of 30-60 nm and exhibit a (002) orientation with the c-axis perpendicular to the substrate surface

Near Edge Fine Structures on Electron Energy Loss Spectroscopy Core Loss Edges

Core edges recorded in Electron Energy Loss Spectroscopy (EELS) display a large variety of profiles. We have investigated several specific aspects concerning Energy Loss Near Edge Structures (ELNES) and emphasize the interest in a careful edge shape analysis to obtain refined microanalytical information, such as local symmetry. After indicating the general impact of EELS fine structures as compared to EDX and Auger spectroscopies we discuss the instrumental conditions required for recording satisfactory spectra and consider the theoretical problems which are involved in data interpretation. The major portion of this paper presents results for selected K, L23, M45 and N45 core excitations in compounds (mainly oxides). In each case the phenomena governing the ELNES distribution are pointed out. In conclusion, we summarize the potential of a careful analysis of ELNES for studying the chemical state of the absorbing atom and the symmetry of it s first coordination shell (molecular description) or longer range effects (projections of solid state density of states as seen by the ejected atom)

Structural effect of heavy ion irradiation on GdBaCuO ceramics

The influence of twin boundaries as sinks on defects induced by 480 keV Kr ion irradiation in GdBaCuO crystals was observed in situ at 40 and 300 K. The interaction of the dislocations with the twin boundaries followed on a video recording. A crystalline to amorphous transition was observed above a total fluence of ∼ 4 - 5 x 10^12 Kr/cm2. A comparison between orthorhombic (Os) crystals and a monoclinic structure (Ms) (close to Os and whose parameters were calculated) shows that the behaviour of irradiation-induced extended defects does not depend on a small initial deformation of the orthorhombic cell. In both case, an occasional orthorhombic (or monoclinic) to tetragonal phase transition only occurs when the amorphization process has begun