Effects of parameters on titanium nitride formation at atomic level

The effects of parameters on nanoscale titanium nitride during the formation process in ferrite were studied via the molecular dynamics (MD) simulation. The formation of titanium nitride was executed by employing a dislocation-motivated formation model in which the atomic diffusion has a significant contribution. The roles of N/Ti atom ratio, temperature and matrix defect were identified and the according nitride formation property was analyzed.

Can Empirical Biplots Predict High Entropy Oxide Phases?

High entropy oxides are entropy-stabilised oxides that adopt specific disordered structures due to entropy stabilisation. They are a new class of materials that utilises the high-entropy concept first discovered in metallic alloys. They can have interesting properties due to the interactions at the electronic level and can be combined with other materials to make composite structures. The design of new meta-materials that utilise this concept to solve real-world problems may be a possibility but further understanding of how their phase stabilisation is required. In this work, biplots of the composition’s mean electronegativity are plotted against the electron-per-atom ratio of the compounds. The test dataset accuracy in the resulting biplots improves from 78% to 100% when using atomic-number-per-atom Z/a ratios as a biplot parameter. Phase stability maps were constructed using a Voronoi tessellation. This can be of use in determining stability at composite material interfaces.

Effect of Steam on the Homogeneous Conversion of Tar Contained from the Co-Pyrolysis of Biomass and Plastics

The co-pyrolysis tar formed from microcrystalline cellulose (MCC) and polyethylene (PE) was used to study their further conversion path under the effect of steam. This paper addressed the yield and transformation of tar with different steam/feedstock mass ratios (S/F= 0.8, 1.6) in a two-stage fixed-bed when the two stages furnace temperature was set at 600℃ and 800℃, separately. Compared with pyrolysis, steam promoted tar cracking effectively, the tar yield decreased at least 1/3. However, with the addition of steam, the cracking effect of tar is not further improved. The tar yield depended more on the PE content in the mixture, which was enhanced with PE increment. Besides, the H/C atom ratio was related to the conversion path of tar. Steam was beneficial to the cracking of compounds, but the generated hydrogen radicals affected the direction of the subsequent reaction. The steam mainly promotes the cracking of long-chain hydrocarbons, accompanied by cyclization and aromatization when the steam was limited. Nevertheless, these reactions were hindered when the steam was excessive due to the apparent effect of hydrogenation. In this process, the short-chain hydrocarbons come to recombine instead of cyclization and aromatization.

Surface evolution of Janus Cu-Ag nanoparticles: Influence of atom arrangements and interface structures

In this paper, the effect of the atom ratio and interface structure on the surface evolution of Janus Cu–Ag Nanoparticles (NPs) were studied by molecular dynamics (MDs) simulation during sintering process. The results show that Cu/Ag alloys tend to form the Cu-core@Ag-shell NPs with stable configuration in the case of excessive Ag. However, the different arrangements of atoms and interface lead to Janus Cu–Ag NPs exhibiting unique coalescence during the contact stage of sintering process, and the interface with Cu/Ag two-type atoms is more likely to diffuse. Moreover, the systems gradually change from separate NPs to a uniform Cu/Ag alloy as the temperature rising, meanwhile the shrinkage ratio of the Janus Cu–Ag NPs is stable at 80%.

Activated Carbon Production by Co-Pyrolysis of Vacuum Residue and Gum Rosin

Vacuum residue (VR) is potential to be used as a feedstock for mesophase pitch (MP) production because of its low cost and aromatic content. MP, which is a liquid-crystalline state of VR, may be used as precursor of activated carbon (AC). Gum rosin containing conjugated double bonds may be added to and can improve crystallinity and pore surface area in further processes of carbonisation and activation. In the present study, co-pyrolysis was carried out in a stirred tank reactor at 450°C with holding time for 120 minutes. The amount of gum rosin mixed with VR was varied 0, 5, 10 and 15% wt of VR. The precursor products had C/H mole ratio of about 2.43, 2.37, 2.28, and 2.01 by increasing gum rosin added. Subsequently, this precursor underwent carbonization at 700°C with holding time for 120 minutes under N2 flow and activation. KOH solution was used as activating agent to the precursor of activated carbon. Activated carbon gave higher surface area and lower C/H atom ratio with increasing gum rosin added during co-pyrolysis. With gum rosin addition, surface areas of ACs were 120.81, 194.56, 312.36, dan 462.19 m2/g, respectively, and crystallite sizes increased from 8 to 22 Å.

The Effect of Carbon Content on Methanol Oxidation and Photo-Oxidation at Pt-TiO2-C Electrodes

The oxidation of methanol is studied at TiO2-supported Pt electrodes of varied high surface area carbon content (in the 30-5% w/w range) and C÷Ti atom ratio (in the 3.0-0.4 ratio). The Pt-TiO2 catalyst is prepared by a photo-deposition process and C nanoparticles (Vulcan XC72R) are added by simple ultrasonic mixing. The optimum C÷Ti atom ratio of the prepared catalyst for methanol electro-oxidation is found to be 1.5, resulting from the interplay of C properties (increased electronic conductivity and methanol adsorption), those of TiO2 (synergistic effect on Pt and photo-activity), as well as the catalyst film thickness. The intrinsic catalytic activity of the best Pt-TiO2/C catalyst is better than that of a commercial Pt/C catalyst and could be further improved by nearly 25% upon UV illumination, whose periodic application can also limit current deterioration.