Synthesis of New MAX-Phases (Ti0.5,Ta0.5)3AlC2, (Ti0.5,Nb0.5)3AlC2, (Ti0.5,V0.5)3AlC2 and MXenes Based on Them

The previously unknown aluminum-containing solid solution 312 Mn + 1AXn phases (Ti0.5,V0.5)3AlC2, (Ti0.5,Ta0.5)3AlC2 and (Ti0.5,Nb0.5)3AlC2 were successfully synthesized by the standard non-pressure sintering method. The composition of the MAX-phase was confirmed by complementary methods: XRD, SEM and EDS. Rietveld analysis of the powder X-ray diffractograms was used to calculate the lattice parameters and phase compositions. Heating of pure Ti, Al, C powders with Ta, Nb added in 1.5 : 1.5 : 1.1 : 2 molar ratio up to 1450°C for 8 h under dynamic vacuum resulted in samples with dominant MAX phase volume fraction. All new MAX phases were then successfully converted to MXenes using the standard MILD protocol-chemical etching of aluminum layers in a mixture of HCl acid and LiF. The obtained MXenes were characterized using several techniques, including: XRD, SEM, TEM, EDS, AFM, and Raman spectroscopy.