Sol–gel based synthesis and enhanced processability of MAX phase Cr₂GaC

Abstract

New and facile wet chemistry based synthesis method for the preparation and processing of MAX phase Cr2GaC.

Towards a mechanistic understanding of the sol–gel syntheses of ternary carbides

“…Now, more than 150 years later, the underlaying processes – hydrolysis and condensation – have been widely studied and applied to a plethora of systems. Initially developed for the synthesis of oxides, 2 carbides, 3,4 nitrides, 5 and borides 6 are nowadays also accessible through sol–gel chemistry. 7 Furthermore, the number of possible sol–gel starting materials knows almost no limit and has been vastly diversified from the original alkoxide-based chemistry and includes, for instance, small molecule routes as well as polymer-based gels.…”

Experimental and theoretical investigation of the chemical exfoliation of Cr-based MAX phase particles

“…The precursor MAX phase particles were prepared by a sol-gel based (solution combustion) method that is described in detail elsewhere. 12 These highly crystalline and anisotropic particles were treated with aqueous hydrofluoric acid (HF) in order to assess the possibility to synthesize a Cr-based MXene. Briefly, 100 mg of the Cr2GaC particles were carefully added to 10 mL 40% HF in a PTFE beaker and stirred for 24 hours.…”

“…However, some peaks of very low intensities are also observed, that correspond to binary chromium carbide, Cr3C2, and chromium oxide, Cr2O3, as reported earlier. 12 After HF treatment, the peak intensities of the crystalline components have decreased significantly and a large amorphous background at lower angles is observed. The reflections of Cr2GaC are still visible, yet ten times less intense than before HF-treatment, and further peaks are clearly visible.…”

“…We have recently developed a wet chemical-based synthesis method to prepare Cr2GaC particles. 12 In short, an aqueous gel is prepared that contains intimately mixed metal ions that are coordinated with citric acid. Upon heating oxide particles form that are reduced by carbon (from citric acid) and subsequently react with the excess in carbon to form the target MAX phase.…”

312 MAX Phases: Elastic Properties and Lithiation

“…There are also experimental reports on stable forms of Zr3SnC2 and Hf3AlC2 from Lapauw et al [34]. There are also some trends in thin film MAX phases [35], as well as in sol-gel methods of creating the MAX phases compounds [36], that are examined by experimentalists for the synthesis of new MAX phases. To conclude, of the four 312 materials that we propose should be examined for potential lithiation, two of them have already been synthesized in stable forms (Zr3SnC2 and Hf3AlC2) and one has been synthesized as part of a mixed structure (Zr3SiC2); accordingly, we believe that their lithiation abilities could be investigated both experimentally and theoretically.…”