Temperature, strain and charge mediated multiple and dynamical phase changes of selenium and tellurium

Abstract

Trigonal-Se and -Te change to a metallic or a simple cubic structure under thermal excitation, compressive strain and excess positive charge, or to metallic, body-centered tetragonal and body-centered orthorhombic structures under negative charging.

Bonding, structure, and mechanical stability of 2D materials: the predictive power of the periodic table

“…For the trigonal Se bulk structure, the length of covalent intrachain bonds is 0.243 nm and for interchain interaction between neighboring chains it is 0.334 nm with a cohesive energy of À2.88 eV per atom. 250 In the case of the trigonal Te bulk structure, the difference of the two bond lengths of 0.290 nm and 0.342 nm is much smaller and the cohesive energy is À2.71 eV per atom. 250 For a single layer of the trigonal Te phase, the theoretical bond lengths are 0.278 nm and 0.304 nm.…”

“…250 In the case of the trigonal Te bulk structure, the difference of the two bond lengths of 0.290 nm and 0.342 nm is much smaller and the cohesive energy is À2.71 eV per atom. 250 For a single layer of the trigonal Te phase, the theoretical bond lengths are 0.278 nm and 0.304 nm. 256 In the layered covalently bonded tetragonal and square phases, these large differences in the bond lengths are reduced, and in the layered rhombic phase, the difference reduces to zero, leaving just a single bond length.…”

“…[246][247][248] In the following, the thickness direction is defined as the z-direction, and the chain direction is defined as the y-direction for the chain-like and tetragonal phases, whereas for the rhombic phase the y-direction extends along the armchair direction, due to the loss of the original chain structure by reconstruction. 247 The space group, cohesive energy, lattice constants, bond length, corrugation, and layer thickness of the trigonal, 246,[248][249][250] tetragonal, 246,251,252 rhombic, 245,248,[252][253][254] and monoclinic 224,249 structures of selenene are presented in Table 12, along with the bonding information and structural properties of the trigonal, 247,250,255,256 tetragonal, 247,255 rhombic, [252][253][254][255] and monoclinic 249 structures of tellurene. This data makes possible a discussion of bonding-structure-performance relationships for these recently discovered 2D materials with novel structures deviating from previous hexagonal 2D materials.…”

Vanishing‐Harmonicity and Phase‐Change Materials

“…In addition, Coulombic interactions may play some role in the stabilization of the distortion, [ 17 ] even a moderate excess charge of trigonal Se or Te closes the gap and the crystal goes back to a metallic state. [ 18 ]…”

Phase transformations in the nickel phosphide system induced by transition-metal doping and their electro-catalytic study

“…27–30 The thermal route as a mediator of phase transformations in Se, Te and Ni chalcogenides has also been studied. 31,32 There are, however, limited reports on this kind of phase transformation within the metal phosphide system. For example, secondary phase transformations of preformed Ni 12 P 5 nanoparticles to Ni 2 P, by employing TOP as the phosphorus source, have been reported.…”