Electronic and thermal properties of Ti3Al(C0.5,N0.5)2, Ti2Al(C0.5,N0.5) and Ti2AlN

Abstract

In this paper we report on the electronic, magnetotransport, thermoelectric, and thermal properties of Ti3Al(C0.5,N0.5)2, Ti2Al(C0.5,N0.5), and Ti2AlN. The electrical conductivities, Hall coefficients, and magnetoresistances are analyzed within a two-band framework and compared with the end members, Ti2AlC and Ti3AlC2. The analysis shows that all compounds are compensated conductors with hole and electron carrier densities of about 1.5×1027 m−3. The room temperature thermal conductivities of the carbonitrides are both over ≈50 W/mK, with the phonon contribution of Ti3Al(C0.5,N0.5)2 particularly large at over 35 W/mK. The low-temperature specific heat of Ti3Al(C0.5,N0.5)2 and Ti2Al(C0.5,N0.5) yield Debye temperatures of 685 and 724 K, respectively, comparable to those of the end members.

Spectroscopic ellipsometry study on the dielectric function of bulk Ti2AlN, Ti2AlC, Nb2AlC, (Ti0.5,Nb0.5)2AlC, and Ti3GeC2 MAX-phases

“…Carrier concentrations are of the order of 10 27 m −3 with equal contributions of electrons and holes, i.e., they are compensated conductors. 2,4,6 As seen in Table I, the resistivity values obtained in this work, through the Drude term, are within a factor of 2 to 3.5 of those reported for bulk materials measured using a four-probe technique. When the two sets of FIG.…”

“…In brief, both the Ti 2 AlN and Ti 2 AlC samples were fabricated by pressureless sintering of prereacted powders ͑3-ONE-2, Vorhees, NJ͒ at 1500°C for 1 h under Ar. 6 Bulk polycrystalline Ti 3 GeC 2 samples were prepared by hot pressing the appropriate stoichiometric composition of Ti, graphite, and Ge powders at 1500°C for 6 h under an applied pressure of 45 MPa. The samples were then annealed at 1500°C for 48 h in an Ar atmosphere.…”

“…In the scientific literature there are many reports on the processing of bulk MAX-phases as well as on their physical properties such as electrical, thermal, and elastic. [1][2][3][4][5][6] Also, the electronic properties of these materials have been studied both theoretically and experimentally. [4][5][6][7][8][9] For MAX-phases in thin film form, the processing and physical properties have been recently reviewed.…”

“…[1][2][3][4][5][6] Also, the electronic properties of these materials have been studied both theoretically and experimentally. [4][5][6][7][8][9] For MAX-phases in thin film form, the processing and physical properties have been recently reviewed. 10 Because the MAX-phases crystallize in a hexagonal structure the anisotropy of its conductivity is of great interest but it has been difficult to experimentally resolve this issue.…”

Phase stability ofTi2AlCupon oxygen incorporation: A first-principles investigation

“…Correspondingly, substitution of N on the C site, as investigated by use of hot isostatic pressing, resulting in a harder and more brittle material. 9,28 Theoretical studies based on ab initio calculations concern partial substitution of elements in Ti 2 AlC.…”