Structure, Morphology, Heat Capacity, and Electrical Transport Properties of Ti3(Al,Si)C2 Materials

Abstract

A study of Ti3Al1−xSixC2 (x = 0 to x = 1) MAX-phase alloys is reported. The materials were obtained from mixtures of Ti3AlC2 and Ti3SiC2 powders with hot pressing sintering technique. They were characterised with X-ray diffraction, heat capacity, electrical resistivity, and magnetoresistance measurements. The results show a good quality crystal structure and metallic properties with high residual resistivity. The resistivity weakly varies with Si doping and shows a small, positive magnetoresistance effect. The magnetoresistance exhibits a quadratic dependence on the magnetic field, which indicates a dominant contribution from open electronic orbits. The Debye temperatures and Sommerfeld coefficient values derived from specific heat data show slight variations with Si content, with decreasing tendency for the former and an increase for the latter. Experimental results were supported by band structure calculations whose results are consistent with the experiment concerning specific heat, resistivity, and magnetoresistance measurements. In particular, they reveal that of the s-electrons at the Fermi level, those of Al and Si have prevailing density of states and, thus predominantly contribute to the metallic conductivity. This also shows that the high residual resistivity of the materials studied is an intrinsic effect, not due to defects of the crystal structure.

Temperature Evolution of Composition, Thermal, Electrical and Magnetic Properties of Ti3C2Tx-MXene

“…This confirms its metallic nature, as predicted theoretically in [32], but the surface termination will affect its properties, and this in turn is dependent on the synthesis and processing methods employed [33]. The values of ΘD and γ parameters, namely ΘD = 160.1(3) K and γ = 2.62(4) J/(mol•K 2 ) obtained in our study, are compared to those determined for Ti3AlC2-MAX compound, ΘD = 484.2(1.6) K and γ = 4.848(6) J/(mol•K 2 ) [34], respectively. The much lower Debye temperature of Ti3C2Tx-MXene indicates a much softer lattice structure of this 2D nanomaterial than that of the parent MAX phase compound.…”

Effects of TiC, Si, and Al on Combustion Synthesis of Ti3SiC2/TiC/Ti5Si3 Composites

“…), and X is C or N [ 1 ]. Typical MAX phases such as Ti 2 AlC, Cr 2 AlC, Ti 3 SiC 2 , Ti 3 AlC 2 , Nb 4 AlC 3 , and Ti 4 AlN 3 as well as their associated solid solutions have been broadly investigated [ 1 , 2 , 3 , 4 , 5 ]. Properties of the MAX phases combine merits of both metals and ceramics.…”

The Electrical Resistivity of Multiphase Systems Based on the Ti3AlC2 Hexagonal Phase at Low Temperatures

“…The compound Ti 3 AlC 2 is one of the so-called MAX phases M nþ1 AX n (where M is the transition metal, A is the element of the III-or IV-subgroup of the periodic system, and X is carbon or nitrogen). [1,2] It has high hardness and anticorrosion properties, which are characteristics for a ceramic material as well as low electrical resistivity, which is a characteristic for a metal. [3][4][5][6] Due to these properties, Ti 3 AlC 2 can be used in the wide range of applications, such as for the electromagnetic interference shielding, [7] for electrical contact applications, [8] as an absorber for the laser technique, [9] as materials with resistance of corrosion and oxidation, [3,4] and due to high mechanical damage tolerance and stability under the neutron irradiation.…”