Pyrolyzed Iron-based precious group metal (PGM)-free nitrogen-doped single site carbon catalysts (Fe-NC) are possible alternatives to Platinum-based carbon catalysts for the oxygen reduction reaction (ORR). Bimetallic PGM-free M1M2-NC catalysts and...

Analytical electron microscopy revealed the structure and growth of hard coating Cr(Al)N/SiOx nanocomposite films prepared in a differential pumping cosputtering (DPCS) system, which has two chambers to sputter different materials and a rotating substrate holder. The substrate holder was heated at 250 °C and rotated at a speed as low as 1 rpm. In order to promote the adhesion between the substrate and composite film, transition layers were deposited on a (001) Si substrate by sputtering from the CrAl target with an Ar flow and a mixture flow of Ar and N2 (Ar/N2) gases, subsequently, prior to the composite film deposition. Then, the Cr(Al)N/SiOx nanocomposite film was fabricated on the transition layers by cosputtering from the CrAl target with the Ar/N2 gas flow and from the SiO2 target with the Ar gas flow. The film had a multilayer structure of ∼1.6 nm thick crystallite layers of Cr(Al)N similar to NaCl-type CrN and ∼1 nm thick amorphous silicon oxide layers. The structure of the transition layers was also elucidated. These results can help with the fabrication of new hard nanocomposite films by DPCS.

For elemental analysis with energy dispersive X-ray spectroscopy (EDS) in transmission electron microscopy (TEM), the demand for the improved efficiency of X-ray detection, a higher counting rate, is very strong, because the improvement not only results in high throughput, but also extends the method to the specimens fairly susceptible to electron beam damage. We have already developed and introduced into the market an advanced commercial EDS system with a large area silicon drift type detector (SDD). The sensor area of this SDD is as large as 100 mm 2 . The detection efficiency of X-ray in this system increases by approximately four times with respect to the one with a conventional Si (Li) type detector.This time, a new system for analysis with EDS has been developed which is about twice as efficient as the former high efficiency system. The new system consists of the two large area SDDs (SDD1 and SDD2). This paper describes the characteristic features of this system. Figure 1 shows a schematic diagram of the system for a field emission TEM (JEM-2800). The SDD1 was located on the right side of the specimen holder rod in the same way as the former single SDD system whereas the SDD2 was located in the direction between the opposite side of the SDD1 and the axis of the specimen holder rod as shown in the figure. For the second detector of SDD2, a new port was added to the JEM-2800. Besides, a new specimen holder for the analysis was developed to make shorter the distance between a specimen and the detectors. All the following experiments were carried out at 200 kV.Observed features of this system are as follows: 1. High acquisition efficiency, counting rate of the X-ray The acquisition efficiency of the X-ray in this system was expected to almost double with the addition of one more detector, SDD2, without any increase in the probe current. Besides the addition of SDD2 the shape of the specimen holder and the geometry of the SDD was redesigned to improve the efficiency. In this system, the peak intensity of Al-K acquired from an aluminum foil with the SDD1 and SDD2 double detectors was about 1.7 times as high as that acquired with the SDD1 single detector, as shown in figure 2.2. Acquisition of X-ray intensities independent of insensitive to specimen tilt angle In the conventional single SDD system, the counting rate is highest at a certain optimum tilt angle of the specimen holder. In the present double SDD system, however, the counting rate was expected to be rather insensitive to the specimen tilt angle, because the second detector, SDD2, is located nearly opposite to the first detector, SDD1. The measured dependence of the intensity of Ni K acquired from a nickel deposited film with a uniform thickness is shown figure 3. The intensity variation due to the specimen tilt angle was substantially smaller in the double SDD system than in either single SDD1 or SDD2 system. In fact, the intensity variation in each single system largely canceled out each other. The double SDD system assures that specimen tilting does...

Structure and mechanical properties of nanoscale multilayered CrN/ZrSiN coatings J. Vac. Sci. Technol. A 27, 672 (2009); 10.1116/1.3136856Ti-Al-Si-N films for superhard coatings deposited by reactive cosputtering using Ti, Al, and Si targets

Nanocomposite films of metal nitrides such as TiN/Si 3 N 4 , TiN/BN, and CrN/AlN have attracted substantial attention as new hard coating materials. It is difficult to prepare composite films consisting of nitride and oxide by conventional reactive sputtering methods. Nose et al. developed a differential pumping cosputtering (DPCS) system with two chambers A and B, which can fabricate different nanocomposite films [1]. We elucidated the process and mechanism of film growth in the DPCS system, using Cr(Al)N/SiO x nanocomposite layer deposited on the under buffer layers grown on a Si substrate [2-4]. Here, we report the mechanical property and structure of Cr(Al)N/Al 2 O 3 layers prepared at various conditions in the DPCS system, to demonstrate its usefulness for fabricating superhard coatings. Cr 50 Al 50 and Al 2 O 3 targets were set in chambers A and B respectively, and a (001) Si wafer was used as the substrate. The substrate was heated at 250 o C. First, three depositions were successively performed on the Si substrate for making the transition or buffer layers to promote adhesion between the composite layer and substrate. Except for a substrate rotational speed of ω =12 rpm, the preparation conditions of the gas flow and RF power for these transition layers were the same as that used for the previous Cr(Al)N/SiOx nanocomposite coating [2-4]. Next, the main deposition was carried out for 810 min by operating both the CrAl chamber A and the Al 2 O 3 chamber B, on the transition layers rotated at the same speed ω. The CrAl sputtering and the Al 2 O 3 sputtering were performed with flows of Ar (10 sccm)+N 2 (20 sccm) and Ar (20 sccm) respectively, at different RF powers for preparing composite layers with different compositions: e.g. 200 W and 100 W, respectively so as to obtain a nominal composition of Cr(Al)N/17 vol.％Al 2 O 3. The structure was observed by analytical electron microscopy using JEOL JEM-2800 and ARM200F microscopes, and the indentation hardness H IT and Young's modulus E* of the films were measured using a nanoindentation system (Fischerscope, H100C-XYp) at room temperature. We got the following conclusion from the experiments such as shown in Figures 1-4. (1) The transition or buffer layers prepared successively on the Si substrate by sputtering from the CrAl target with flows of (i) Ar (10 sccm), (ii) Ar (10 sccm)+N 2 (10 sccm), and (iii) Ar (10 sccm)+N 2 (20 sccm) were layers of composed of bcc Cr crystallites and a-Al 2 O 3 particles (layer C), Cr crystallites, NaCl-type CrN crystallites, and a-Al 2 O 3 particles (D), and Cr(Al)N crystallites and a-Al 2 O 3 particles (E), respectively. These layers, where the composition gradually changes from metal (Cr) to nitride (CrN), are appropriate to the adhesion between the metal substrate and the composite nitride layer. The multilayered structure composed of Cr (or CrN) layers and oxide layers, which were found in the layers prepared at ω =1 rpm, was not observed in the present layers prepared at first rotational speeds. (2) The main layer (F) grew ...