Synthesis and characterization of Zr2Al3C4 thin films

Zr2Al3C4 is an inherently nanolaminated carbide where layers of ZrC alternatewith layers of Al3C2. Characterization of bulk samples has shown it has improved damage tolerance and oxidation resistance compared to its binary counterpart ZrC. Though a potential candidate for coatings applied for use in harsh environments, thin films of Zr2Al3C4 have not been reported.We have synthesized epitaxial Zr2Al3C4 thin films by pulsed cathodic arc deposition from three elemental cathodes, and have studied the effect of incident atomic flux ratio, deposition temperature, and choice of substrate on material quality. X-ray diffraction analysis showed that Zr2Al3C4 of the highest structural quality was obtained for growth on 4 H-SiC(001) substrate at 800 ^deg;C. Also, suppression of competing phases could be achieved on á-Al2O3(001) at elevated substrate temperatures. Very similar growth behavior to that of the well-known Mn+1AXn phases - Al supersaturation, binary carbide intergrowth and high sensitivity to choice of substrate - indicates a strong connection between the two families ofmaterials, despite their differences in structure and in chemistry

Synthesis and DFT investigation of new bismuth-containing MAX phases

The M(n + 1)AX(n) phases (M = early transition metal; A = group A element and X = C and N) are materials exhibiting many important metallic and ceramic properties. In the present study powder processing experiments and density functional theory calculations are employed in parallel to examine formation of Zr(2)(Al(1−x)Bi(x))C (0 ≤ x ≤ 1). Here we show that Zr(2)(Al(1−x)Bi(x))C, and particularly with x ≈ 0.58, can be formed from powders even though the end members Zr(2)BiC and Zr(2)AlC seemingly cannot. This represents a significant extension of the MAX phase family, as this is the first report of a bismuth-based MAX phase

Assessment of the Efficiency of a Nanospherical Gallic Acid Dendrimer for Long\u2010Term Preservation of Essential Oils: An Integrated Chemometric\u2010Assisted FTIR Study

Essential oils (EOs) are volatile chemicals very popular in the food, cosmetic and pharmaceutical industry as aromas, fragrances and alternative therapeutic devices. EOs are susceptible to oxidative degradation, loss of quality and alterations of sensory and pharmacological properties with production of smelly or harmful compounds, responsible for allergic reactions. For preventing EOs\u2019 spoilage, synthetic preservatives are adopted, but with poor efficiency and danger of health diseases. Natural polyphenols as gallic acid (GA) are proposed as safer alternatives, but the low compatibility with oils limits their efficacy. In this study, a hydrophobic, GA\u2010enriched antioxidant dendrimer (GAD), is advised as an innovative preservative, after due evaluations. Besides oxidation chemical indexes, the desired information was obtained by FTIR spectroscopy assisted by multivariate analysis. For further confirmation, FTIR data were interpreted by considering the area of some selected bands. Iodometric titration, was performed to determine peroxide value (PV), selected as chemical index. GAD showed a preservative power extraordinary better than that of GA and no pro\u2010oxidant action