Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPressure-induced amorphization and polyamorphism in one-dimensional single crystal TiO2 nanomaterials
152
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The structural phase transitions of single crystal TiO2-B nanoribbons were investigated in-situ at high-pressure using the synchrotron X-ray diffraction and the Raman scattering. Our results have shown a pressure-induced amorphization (PIA) occurred in TiO2-B nanoribbons upon compression, resulting in a high density amorphous (HDA) form related to the baddeleyite structure. Upon decompression, the HDA form transforms to a low density amorphous (LDA) form while the samples still maintain their pristine nanoribbon shape. HRTEM imaging reveals that the LDA phase has an {alpha}-PbO2 structure with short range order. We propose a homogeneous nucleation mechanism to explain the pressure-induced amorphous phase transitions in the TiO2-B nanoribbons. Our study demonstrates for the first time that PIA and polyamorphism occurred in the one-dimensional (1D) TiO2 nanomaterials and provides a new method for preparing 1D amorphous nanomaterials from crystalline nanomaterials.
rate research
Read More
It has recently been shown that amorphization and melting of ice were intimately linked. In this letter, we infer from molecular dynamics simulations on the SiO2 system that the extension of the quartz melting line in the metastable pressure-temperature domain is the pressure-induced amorphization line. It seems therefore likely that melting is the physical phenomenon responsible for pressure induced amorphization. Moreover, we show that the structure of a pressure glass is similar to that of a very rapidly (1e+13 to 1e+14 kelvins per second) quenched thermal glass.
We study the valence band structure of ReSe$_{2}$ crystals with varying thickness down to a single layer using nanoscale angle-resolved photoemission spectroscopy and density functional theory. The width of the top valence band in the direction perpendicular to the rhenium chains decreases with decreasing number of layers, from 280 meV for the bulk to 61 meV for monolayer. This demonstrates increase of in-plane anisotropy induced by changes in the interlayer coupling and suggests progressively more one-dimensional character of electronic states in few-layer rhenium dichalcogenides.
In one-dimensional quantum systems with strong long-range repulsion particles arrange in a quasi-periodic chain, the Wigner crystal. We demonstrate that besides the familiar phonons, such one-dimensional Wigner crystal supports an additional mode of elementary excitations, which can be identified with solitons in the classical limit. We compute the corresponding excitation spectrum and argue that the solitons have a parametrically small decay rate at low energies. We discuss implications of our results for the behavior of the dynamic structure factor.
Transition metals, Fe, Co and Ni, are the canonical systems for studying the effect of external perturbations on ferromagnetism. Among these, Ni stands out as it undergoes no structural phase transition under pressure. Here we have investigated the long-debated issue of pressure-induced magnetisation drop in Ni from first-principles. Our calculations confirm an abrupt quenching of magnetisation at high pressures, not associated with any structural phase transition. We find that the pressure substantially enhances the crystal field splitting of Ni-$3d$ orbitals, driving the system towards a new metallic phase violating the Stoner Criterion for ferromagnetic ordering. Analysing the charge populations in each spin channel, we show that the next nearest neighbour interactions play a crucial role in quenching ferromagnetic ordering in Ni and materials alike.
In this paper, the effect of Ar+ bombardment of SrTiO3:Nb surface layers is investigated on the macro- and nanoscale using surface-sensitive methods. After bombardment, the stoichiometry and electronic structure are changed distinctly leading to an insulator-to-metal transition related to the change of the Ti d electron from d0 to d1 and d2. During bombardment, conducting islands are formed on the surface. The induced metallic state is not stable and can be reversed due to a redox process by external oxidation and even by self-reoxidation upon heating the sample to temperatures of 300{deg}C.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
