Structural and Optical Properties for TiO2 thin films Prepared by Screen Printing method

In this study, Structural and Optical Properties of titanium dioxide thin films are studied, TiO2 (Anatase) thin films were prepared by screen printing (SP) method. X-ray diffraction analysis showed that the structure of TiO2 films are polycrystalline and the lattice system is tetragonal. The main diffraction peak of TiO2 was (101) at 2θ=25ᵒ. The data of optical absorption indicated that TiO2 thin films prepared by SP have a direct optical band gap (about 3.1eV). The data of reflectivity was also used to calculate the band gap and was around 2.95 eV http://dx.doi.org/10.25130/tjps.24.2019.093

Magnetic and dielectric properties of Ca-substituted BiFeO3 nanoferrites by the sol-gel method

Background: A multiferroic material can simultaneously show two or more basic magnetic properties, including ferromagnetism, antiferromagnetism, and ferroelectricity. BiFeO3 is a multiferroic material with a rhombohedral distorted perovskite structure. Doping can reduce the volatility of Bi and greatly improve the magnetoelectric properties of BiFeO3. Methods: To investigate the influence of the doping content we used the following analytical methods: X-ray powder diffraction (XRD), scanning electron microscopy (SEM), microwave network analysis (PNA-N5244A), and the Superconducting Quantum Interference Device (Quantum Design MPMS) test. Results: With the increase of Ca2+ concentration in the solution, the grain size of Bi1- xCa xFeO3 becomes smaller, showing the role of Ca2+ ions as the dopant for fine grains. The calcination temperatures are the major causes for the saturated magnetization. The residual magnetization ( Mr) and the coercive force ( Hc) decrease linearly with the increase of x value, and due to the effect of Ca2+ substitution at Bi3+ sites, which causes the valence change of Fe and/or the oxygen vacancies. Conclusions: The XRD result indicates that the diffraction peak emerges with the increase of Ca2+ and the main diffraction peak achieves a high angle. The best calcining temperature is 600 °C, and the morphology is very dependent on the calcining temperature.

The Structure and Adhesion of Zr/TiAlN Coatings on High-Speed Steel and Cemented Carbide Substrates

Zr/TiAlN coatings as well as single TiAlN coatings were deposited on high-speed steel and cemented carbide substrates by medium frequency magnetron sputtering. The crystal structure and cross-sectional morphology of coatings were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The adhesion of coatings to substrate was measured by Rockwell indention tests. These investigations show that the main diffraction peak of Zr/TiAlN and TiAlN coatings are corresponding to the TiN phase. The preferred orientation of out TiAlN coatings is obviously affected by Zr interlayer and substrate materials. The TiAlN coatings both on HSS and cemented carbide substrates exhibit a columnar structure. But, the columnar morphology of Zr/TiAlN on cemented carbide substrate becomes ambiguous and this structure of Zr/TiAlN coatings on HSS substrate even changes to isometric. The Rockwell indention results indicate that the adhesion of TiAlN coatings is significantly improved by adding Zr interlayer both on HSS substrate and cemented carbide substrate.

Effect of Sputtering Pressure on the Formation of Semiconducting Mg2Si Films

Semiconducting Mg2Si films were fabricated on Si (111) substrates by magnetron sputtering and subsequent annealing, and the effects of sputtering pressure on the Mg2Si film growth were studied. The structural and morphological properties of Mg2Si films were investigated by the means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the Mg2Si (220) main diffraction peak intensity increased and then decreased with the increasing of sputtering pressure. The (220) diffraction peak got its maximum at 3.0 Pa sputtering pressure. The intensity of Mg2Si (200) and (400) diffraction peaks increased rapidly as the sputtering pressure decreased when the pressure was lower than 1.5 Pa. The films prepared at higher sputtering pressure had very irregular microstructures, and the surface of semiconducting Mg2Si films became smoother with the decreasing of the sputtering pressure.

Coherent and diffuse X-ray scattering in crystals modulated by a surface acoustic wave

Equations describing the coherent and diffuse scattering in a crystal modulated by a surface acoustic wave (SAW) are derived using the dynamical X-ray diffraction theory. The effect of depth attenuation of the Rayleigh surface wave amplitude on the crystal rocking curve profiles is investigated. Results of the numerical simulation of the dynamical diffraction in a mosaic crystal modulated by a SAW, taking into account a block size distribution, are presented. It is shown that the diffuse scattering is distributed in the reciprocal space not only in the vicinity of the main diffraction peak but also about the satellite diffraction peaks, and this distribution depends on the size fluctuations of the crystal defects. Theoretical reciprocal space maps and rocking curves are compared with the corresponding experimental results.