Search results for "Electronic Propertie"

Engineering half-Heusler thermoelectric materials using Zintl chemistry

2016

In this Review, the structure, bonding and defects of half-Heusler compounds are explained in terms of the framework of Zintl (or valence-precise) chemistry. This deeper understanding of the structure and electronic properties of half-Heusler compounds should aid the design of improved thermoelectric materials.

Structure and Electronic Properties of an Expanded Terpyridine Complex of Nickel(II) [Ni(ddpd)2](BF4)2

2018

Pressure-dependent modifications in the optical and electronic properties of Fe(IO3)3: the role of Fe 3d and I 5p lone–pair electrons

2021

We have determined by means of optical-absorption experiments that Fe(IO3)3 is an indirect band-gap material with a band-gap energy of 2.1 eV. This makes this compound the iodate with the smallest band gap. We also found that under compression the band-gap energy has an unusual non-linear pressure dependence, which is followed by an abrupt and discontinuous decrease of the band gap at 24 GPa. The observed behavior is explained by means of density-functional calculations, which show that the behavior of the band gap is governed by the combined influence of Fe 4d and I 5p lone pair electrons. In addition, the abrupt decrease of the band-gap energy at 24 GPa is a consequence of a first-order s…

Electronic properties of carbon nanotubes under torsion

2012

A computationally-effective approach for calculating the electromechanical behavior of SWNTs and MWNTs of the dimensions used in nano-electronic devices has been developed. It is a mixed finite element-tight-binding code carefully designed to realize significant time saving in calculating deformation-induced changes in electrical transport properties of the nanotubes. The effect of the MWNT diameter and chirality on the conductance after mechanical deformation was investigated. In case of torsional deformation results revealed the conductance of MWNTs to depend strongly on the diameter, since bigger MWNTs reach much earlier the buckling load under torsion their electrical conductivity chang…

Straightforward Synthesis of Donor‐Stabilised Phosphenium Adducts from Imidazolium‐2‐carboxylate and Their Electronic Properties (Eur. J. Inorg. Chem…

2007

The cover picture shows one of donor-stabilized phosphenium compounds which have been obtained by direct addition of chlorophosphanes to the 1,3-dimethylimidazolium-2-carboxylate without any further purification step. Their stronger κ-acceptor character similar to phosphites and their ionic nature render these ligands very promising in the development of new continuous-flow catalytic processes. Details of phosphorylation mechanisms of imidazolium-2-carboxylate as well as the electronic and steric properties of these adducts are discussed in the article by J. Andrieu et al. on p. 4877 ff.

The Effect of Nb Incorporation on the Electronic Properties of Anodic HfO2

2017

Hafnium oxide and Nb doped HfO2 were grown by anodizing sputtering-deposited Hf and Hf-4at.%Nb. Photoelectrochemical characterization was carried out in order to estimate solid state properties such as band gap, flat band potential and electrons internal photoemission threshold energy as a function of thickness and composition of anodic oxides. Optical transitions at energy lower than the band gap value of the investigated anodic films were evidenced, and they are attributed to optical transitions involving localized states inside the band gap. Such states were located at 3.6 eV and 3.9 eV below the conduction band edge for the Nb free and Nb containing hafnium oxide, respectively. Impedanc…

Electron-Deficient Pyridylimines: Versatile Building Blocks for Functional Metallosupramolecular Chemistry

2017

Metallosupramolecular systems heavily rely on the correct choice of ligands to obtain materials with desired properties. Engaging this problem, we present three ligand systems and six of their mono- and dinuclear complexes, based on the subcomponent self-assembly approach using electron-deficient pyridylcarbaldehyde building blocks. The properties are examined in solution by NMR and UV-vis spectroscopy and CV measurements as well as in solid state by single crystal X-ray diffraction analysis. Ultimately, the choice of ligands allows for fine-tuning of the electronic properties of the metal centers, complex-to-complex transformations, as well as establishing distinct anion-π-interaction moti…

Optical contrast of 2D InSe on SiO2/Si and transparent substrates using bandpass filters

2017

The particular optical and electronic properties recently reported for 2D InSe depict this 2D material as being very versatile for future electronic and optoelectronic devices with tunable and optimized functionalities. For its fundamental study and the development of practical applications, rapid and accurate identification methods of atomically thin InSe are essential. Here, we demonstrate an enhancement of the optical contrast between InSe nanosheets and the underlying SiO2/Si substrate by illuminating with a 40 nm wide bandpass filter centered at 500 nm. Moreover, we study the optical contrast of 2D InSe on transparent substrates. Our results suggest that a good optical contrast is achi…

Recent progress on the characterization of the high-pressure behaviour of AVO4 orthovanadates

2018

AVO4 vanadates are materials of technological importance due to their variety of functional properties. They have applications as scintillators, thermophosphors, photocatalysts, cathodoluminescence, and laser-host materials. Studies at HP-HT are helpful for understanding the physical properties of the solid state, in special, the phase behavior of AVO4 materials. For instance, they have contributed to understand the macroscopic properties of vanadates in terms of microscopic mechanisms. A great progress has been made in the last decade towards the study of the pressure-effects on the structural, vibrational, and electronic properties of AVO4 compounds. Thanks to the combination of experimen…

Electronic Properties of Thermal Oxides on Ti and Their Influence on Impedance and Photoelectrochemical Behavior of TiO2 Nanotubes

2017

Thermal oxidation of titaniumwas carried out at 350◦C, 450◦C, and 550◦C for 2 h or 12 h.X-rayDiffraction and Raman Spectroscopy suggest that the thermal oxides are scarcely crystallinewhen the annealing temperature is low, while both anatase and rutile are present for high annealing temperature and time. Photoelectrochemical measurements allowed estimation of a bandgap decreasing from 3.35 eV to 3.15 eV with increasing annealing temperature. The impedance spectra confirmed the formation of n-type semiconductors, with an impedance strongly decreasing on going from a reverse bias toward a forward bias regime. TiO2 nanotubes grown by anodizing Ti in NH4F and water containing ethylene glycol so…