CrTiAlN/TiAlN composite coatings were deposited on cemented carbide by using a home-made industrial scale multi-arc ion plating system. The samples were studied by X-ray diffraction, scanning electron microscopy （SEM）, microhardness and ball-on-disk testing. The properties of the CrTiAlN/TiAlN coatings were significantly influenced by the microstructure and the deposition time ratio of TiAlN over CrTiAlN layers. With the increase of deposition time ratio, the microhardness of CrTiAlN/TiAlN increased from 28.6 GPa to 37.5 GPa, much higher than that of CrTiAlN coatings. The friction coefficients of the CrTiAlN/TiAlN coatings were higher than those of CrTiAlN coatings against a cemented carbide ball. The microhardness of the CrTiAlN/TiAlN coatings was changed after annealing at 800 ℃, and the friction coefficients of the annealed coatings were increased against the cemented carbide ball.
CrN microspheres were synthesized by using a cathodic arc plasma source system. The obtained samples were annealed in air at temperatures of 300-800 ℃ for 60 min. The influence of annealing temperature on the microstructure and surface morphology of the CrN microspheres was investigated. The CrN microspheres were characterized by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. The results show that the CrN nanoparticles arranged into leaf-like structures before annealing. With the rising of the annealing temperature, the size of CrN crystal nanoparticals became larger. When the annealing temperature exceeded the oxidation point（500 ℃）, the CrN was oxidized and the leaf-like structure was broken. With further increase of the annealing temperature（700 ℃）, the arrangement of CrN nanoparticles was changed from leaf-like structure to be discrete.
Crystalline BiFeO3 （BFO） films each with a crystal structure of a distorted rhombohedral perovskite are characterized by X-ray diffraction （XRD） and high-resolution electron microscopy （HRTEM）. The diffusion of silicon atoms from the substrate into the BiFeO3 film is detected by Rutherford backscattering spectrometry （RBS）. The element analysis is per- formed by energy dispersive X-ray spectroscopy （EDS）. Simulation results of RBS spectrum show a visualized distribution of silicon. X-ray photoelectron spectroscopy （XPS） indicates that a portion of silica is formed in the diffusion process of silicon atoms. Ferroelectric and weak ferromagnetic properties of the BFO films are degraded due to the diffusion of silicon atoms. The saturation magnetization decreases from 6.11 down to 0.75 emu/g, and the leakage current density increases from 3.8 × 10^-4 upto7.1 × 10^-4 A/cm-2.
Soil samples taken from Xilamuren Grassland,Resonant Sand Bay,Inner Mongolia,and Yichang,western Hubei Province were investigated by Mssbauer spectroscopy at room temperature and 20 K.This was supplemented with phase identification and elemental analysis to obtain information about the composition and structure types of Fe-containing compounds.The samples collected from both Xilamuren Grassland and Resonant Sand Bay,Inner Mongolia were found to have small amount of iron 1%-2%.The main phases were determined as silica,albite,and microcline.Two or three dominant doublets were observed in the Mssbauer spectra of these samples,respectively and identified as corresponding to the valence states of Fe2＋and Fe3＋.A sextet observed in all the spectra is attributed to the hematite phase.Low temperature Mssbauer measurements have revealed Morin transition.
Pelenovich V OCHEN YilongXIAO RenzhengLIU ShouyinFU Dejun
Multilayered TiAlN/CrN coatings have been synthesized on stainless steel substrates by cathodic arc plasma deposition using TiAl and Cr targets.Influences of the bias voltage,cathode current ratio ITiAl/ICr,and deposition pressure on the hardness and friction coefficient of the coatings were investigated.The measurement revealed existence of two cubic phases,face-centercubic （Cr,Al）N and（Ti,Al）N,in the coatings deposited under various bias voltages except for the coating deposited at -400 V,which is amorphous.The hardness of the coatings was strongly dependent on the Itial/Icr ratio and deposition pressure,and reached a maximum of 33 GPa at an ITiAI/ICr ratio of 1.0 and a pressure of 1.0 Pa.The incorporation of the element chromium can reduce the density of pinholes in the coatings and assist the optimization of deposition conditions for high quality TiAlN/CrN coatings.
Spectra of absorption, luminescence, magnetic circular dichroism （MCD）, and magnetic circular polarization of lumines- cence （MCPL） in Gd3Ga5O12：Eu3＋ and Eu3Ga3O12 garnets were studied within the visible spectral range at 300 K. Analysis of the spectral and temperature dependences of the magnetooptical and optical spectra made it possible to identify the magneto-dipole （MD） and electro-dipole （ED） 4f→4f transitions occurring between Stark sublevels of the 7FJ （J=1, 2） and 5D0 multiplets in Eua＋-containing garnet structures. Quantum mechanical ＂mixing＂ had significant influence on quasi-degenerate states of the non-Kramers rare-earth Eu3＋ ion for Eu3GasOl2 in MCD due to forbidden MD transition 7F1→SD0 and for GdaGasOiE：EU3＋ in MCPL due to MD 4f→4f transition 5Do→7F1 and forced ED-transition 5Do→7F2. A parameterized Hamiltonian defined to operate within the entire 4f（6） ground electronic configuration of Eu3＋ ion was used to model the experimental Stark levels, including their irreducible rep- resentations and wavefunctions. The crystal-field parameters were determined through a Monte-Carlo method in which nine in- dependent crystal-field parameters, Bkq, were given random starting values and optimized using standard least-squares fitting between calculated and experimental levels. The final fitting standard deviation between 57 calculated-to-experimental levels was 0.73 meV.
Uygun V.ValievJohn B.GruberAnvar K.MukhammadievVasiliy O.Pelenovich付德君Gary W.Burdick
