First-principles study on solid solution systems of(Ti1-xNbx)5AIC4(x=0.4,0.75,1)
First-principles calculations were used to study the multi-proportion doping of Nb substituting for M in the ternary layered compound(MAX)Ti5AlC4 by Projector Augmented Wave(PAW)and Generalized Gradi-ent Approximation(GGA).By calculating the phonon spectrum,formation enthalpy and elastic constant of the solid solution systems,the stabilities of the(Ti1-xNbx)5 AlC4 solid solution systems were discussed,and three stable structures were obtained:(Ti0,6Nb0.4)5AlC4,(Ti0.25Nb0.75)5AlC4 and Nb5AlC4,namely(Ti1-xNbx)5AlC4(x=0.4,0.75,1)solid solution systems.Bader charge,electron localization function,and density of states indicate that the solid solution systems exhibit metallic properties,and with the increase of the doping ratio,the charge is continuously transferred and the conductivity is enhanced.The mechanical properties of the solid solution systems were discussed by calculating the elastic moduli and Vickers hardnesses of different doping ratios.
MAX phaseElectronic propertiesElastic propertiesPhonon propertiesFirst-principles calcu-lations
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