The Structure of the Ordered Phase in Rocksalt Type Titanium Carbide, Carbidenitride, and Carbidehydride

Abstract

It is shown that on the basis of the disordered &phase (space group Fm3m) two ordered equilib rium phases with cubic (b'-phase, space group Fd3m) and trigonal (6"-phase, space group R3m or P3121) unit cells can be formed in titanium carbide TiCo.62 and carbidenitrides TiC,N, (z + y M 0.63), whereas only a cubic &'-phase has been observed in TiCO.BaHy. With increasing temperature the low temperature trigonal 6"-phase transforms at about 1053 K to the cubic 6'-phase which experiences disordering. The formation of the cubic 6'-phase at temperatures lower than 1053 K is explained by the difference between the order of 6 -+ 6' and 8 + 6" phase transitions. YCTaHOBJIeHO C y l l p X B O B a H U e Ky6IIWCKOk (IIpOCTpaHCTBeHHaH rpynnaFd3m

Exfoliation of Ti2C and Ti3C2 Mxenes from bulk trigonal phases of titanium carbide: A theoretical prediction

“…We begin by noting that amongst the many polytypes of bulk Ti 2 C, the two most stable ones are the trigonal (Figure 1(a)) and the cubic ( Figure S1(a)) phases. [29][30][31][32][33] Depending on the experimental conditions, both these phases have been successfully synthesized. 29,31,33 From our calculations we find that, in agreement with previous literature report, 30 the cubic phase is about 0.02 eV/atom more stable than the trigonal phase (Table S1).…”

“…[29][30][31][32][33] Depending on the experimental conditions, both these phases have been successfully synthesized. 29,31,33 From our calculations we find that, in agreement with previous literature report, 30 the cubic phase is about 0.02 eV/atom more stable than the trigonal phase (Table S1). While the cubic phase of Ti 2 C have a sodium chloride structure with the C atoms or vacancy surrounded by the distorted octahedra of Ti atoms, the trigonal phase forms a layered structure of the form Ti-C-Ti, where the Ti atoms in the two hexagonal planes are separated by a plane of C atoms.…”

Nonmetal ordering inTiC1−xNx: Ground-state structure and the effects of finite temperature

“…Few experiments have been performed on TiC 1−x N x to detect long-or short-range order on the nonmetal sublattice, either with or without nonmetal vacancies. X-ray 11 and neutron 12 diffraction experiments have produced results rejecting particular atomic configurations, but have not ruled out the possibility of other ordering schemes or the existence of short-range order. Ordering of structural vacancies is known to exist in both substoichiometric TiC ͑Refs.…”

Reaction of titanium with carbon in a laser heated diamond anvil cell and reevaluation of a proposed pressure-induced structural phase transition of TiC

“…* Corresponding author. For low carbon concentrations (up to TiC 0.71 ), a cubic phase with space group symmetry Fd3m and twice the lattice parameter of the ı-phase has been reported [5] to be the stable phase at high temperatures above T ≈ 1050 K. An ordered rhombohedral structure ı -phase has been suggested to be stable at lower temperatures [6]. A trigonal structure with space group P31 or P3 1 21 has been discussed by [3] and [2], respectively.…”