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Smooth and dense preheated cerium (Ce) and manganese (Mn) codoped barium strontium titanate (CeMn-BST) films with various thicknesses have been prepared by improved sol-gel method. Capacitance-voltage curves show that with increasing film thickness, combination of dielectric properties are significantly improved with optimized values of about 1300 moderate permittivity, less than 0.007 dielectric loss, more than 58% tunability and hence near 180 figure of merit (FOM) for eight-layer CeMn-BST film. The objective of this paper is to study the improved mechanisms for such excellent dielectric properties. XRD shows that the films layered-grow mainly along (110) orientation and exhibit ABO3cubic perovskite structure. As film thickness increases, Ce3+and/or Mn2+ions are showing doping modes from donor doping to acceptor doping, the crystallization of films is enhancing, but the average grain sizes of the films show gradually decreased trend from about 45nm to 25nm in terms of the intensities of (110) diffraction peaks. AFM indicates that the films are getting smoother with smaller roughness with increasing thickness. XPS reveals that the films reveal decreased non-perovskite structure, element core levels and Fermi levels with increasing thickness. Leakage current densities are significantly decreased almost at two orders of magnitude with increasing thickness. Pure BST films are compared. [ABSTRACT FROM AUTHOR]

By adjusting film thickness, smooth and dense Mn and Y alternately doped Ba0.6Sr0.4TiO3(Mn/Y-BST) films have been designed and prepared by improved sol-gel method, and the structure and dielectric properties of the films have been studied. X-ray diffraction (XRD) reveals that all films grow along (110) orientation, doped Mn2+ions or Y3+ions show acceptor doping, and thicker film shows stronger crystallization. Atomic force microscope (AFM) shows the films are relatively smooth without obvious cracks or pinholes. Scanning electronic microscope (SEM) indicates that from substrate to surface the films show nodular microstructures to columnar ones without obvious interface among nodular microstructure layers. Compared to pure BST film or Mn or Y doped BST films, all alternately doped films show markedly improved structures and dielectric properties, which is strongly dependent on film thickness. 6-layer Mn/Y-BST film shows best structure and combination of dielectric properties with dielectric loss of 1.18%, tunability of 38% and figure of merit (FOM) of 32.2 at 100 kHz. [ABSTRACT FROM AUTHOR]

Manganese (Mn) and yttrium (Y) alternately doped Ba0.6Sr0.4TiO3(BST) films are novelly designed as MnBST/YBST/MnBST/YBST and prepared layer-after-layer on Pt wafer electrodes, and two films where one with the first layer preheated (1Mn/YBST) and the other with four layers preheated (4Mn/YBST) are focused on. XRD shows that two films grow along (110) orientation and reveal ABO3cubic perovskite structures and donor doping, but 4Mn/YBST film shows larger average grain size. SEM demonstrates that 1Mn/YBST film is composed of one 630nm-thick layer with nodular microstructure and the other 570nm-thick surface layer with columnar microstructure, whereas 4Mn/YBST film is 670 nm thick with nodular microstructure. AFM shows that two films are smooth with no cracks, but 4Mn/YBST film is denser with smaller roughness. Two films show more than 55% high tunabilities, but 4Mn/YBST film also reveals low losses of 0.0062∼0.0156 and high figure of merit (FOM) of near 90 at -35V and 100 kHz, fully meeting the needs of tunable microwave applications. [ABSTRACT FROM AUTHOR]

Cerium (Ce) and manganese (Mn) codoped Ba0.6Sr0.4TiO3(BST) films were prepared by improved sol-gel method and the effect of preheating on their dielectric properties was investigated. X-ray diffraction (XRD) reveals that the films grow principally along (110) orientations and show cubic perovskite structures. Preheating corresponds to smaller FWHMs, stronger crystallization and larger grain sizes, and preheating with codoping corresponds to the smallest FWHM, the strongest crystallization and the largest grain size. The prepared film can show tunability of 55.7%, dielectric loss of 0.0074∼0.0175 and approximately 75 FOM, meeting the needs of tunable microwave applications. [ABSTRACT FROM AUTHOR]

Vanadium oxide thin films have been deposited by reactive DC magnetron sputtering. The results showed that the sputtering voltage has a special change behavior in Ar condition and Ar/O2mixed conditions. With O2gas flow input instantaneously, the sputtering voltage climbs quickly, and then tends to be stable shortly. Also, the sputtering voltage evolution appears a hysteretic loop characteristics with O2gas supplied increasing and decreasing. The sputtering voltage behavior observed is related to the ion induced secondary electron emission (ISEE) coefficient of the target material. The ISEE coefficient of the oxidized vanadium on target surface is lower than the ISEE coefficient of the pure vanadium metal, which is not in agreement with the generally accepted idea that the ISEE coefficient of oxides is much larger than for metals. [ABSTRACT FROM AUTHOR]

In this article, a miniaturized bandpass filter with improved stopband using a short-circuit centered stepped impedance resonator is presented. An extra transmission zero can be provided near the passband for good frequency selectivity by introducing mixed electric/magnetic coupling in the proposed filter. Multiple transmission zeros are introduced in the upper stopband via, taking advantage of the harmonic effects of the distributed transmission line. Meanwhile, source-load coupling is introduced to improve the skirt selectivity via shifting the transmission zeros to the vicinity of the passband. The odd- and even-mode analytical method is used to design the filter. To verify the validity of the proposed technique, the new bandpass filter has been analyzed, simulated, and fabricated. The measurement results agree well with the full-wave electromagnetic designed responses. [ABSTRACT FROM PUBLISHER]

Presents a study that investigated the composition depth profiles, structure and ball-on-hard disk frictional characteristics of aluminum alloys 2024 plasma-based ion implanted with nitrogen, titanium and nitrogen then acetylene. Examination of the micro-hardness and nano-hardness of the layers; Observations on the graphitization phenomenon of a diamond-like carbon film; Discussion on the tribological morphology of sliding cycles dominated by rubbing and abrasive wear.