Note: Times Cited: 875 Reference EPFL-ARTICLE-206025doi:10.1021/cr0501846View record in Web of Science URL: ://WOS:000249839900009 Record created on 2015-03-03, modified on 2017-05-12

Complex Hydrides for Hydrogen Storage

Leu-M

In the past few decades, there has been a wide research interest in titanium dioxide (TiO2) nanomaterials due to their applications in photocatalytic hydrogen generation and environmental pollution removal. Improving the optical absorption properties of TiO2 nanomaterials has been successfully demonstrated to enhance their photocatalytic activities, especially in the report of black TiO2 nanoparticles. The recent progress in the investigation of black TiO2 nanomaterials has been reviewed here, and special emphasis has been given on their fabrication methods along with their various chemical/physical properties and applications.

Black titanium dioxide (TiO2) nanomaterials

In the paragraph following eq 28, the average bond valence was incorrectly referred to as V/R. It has been corrected to V/N. The paper originally posted to the web on September 3, 2009, and was reposted on September 24, 2009.

http://pubs.acs.org/doi/pdf/10.1021/cr900053k

Recent developments in the methods and applications of the bond valence model.

https://iris.unipa.it/bitstream/10447/74239/1/Di%20Paola-J%20hzardous%20mater%202012-survey.pdf

A survey of photocatalytic materials for environmental remediation.

Elastic and thermal properties of the TiO2 lattice in anatase and rutile phases were studied in the framework of density functional perturbation theory within the local density approximation (LDA) and generalized-gradient approximation (GGA) The full elastic constant tensors of the polymorphs were calculated by linear fits to the acoustic branches of the phonon band structure near the center of the first Brillouin zone in symmetry directions of the crystals It was observed that the elastic constants within the GGA are in better agreement with experiment In addition, the Born effective charges, dielectric tensor, heat capacity, mean sound velocity and Debye temperature were calculated The heat capacity at room temperature and the Debye temperature within the LDA are in better agreement with the experimental results Therefore, using the phonon band structure and the density of states, one can obtain the important mechanical and thermal properties of materials

http://iopscience.iop.org/article/10.1088/0953-8984/22/1/015401/pdf

First-principles elastic and thermal properties of TiO2: a phonon approach

Superhydrophilicity of TiO2 thin films using TiCl4 as a precursor

The effect of TiO2 doping on the structure and magnetic and magnetotransport properties of La0.75Sr0.25MnO3 (LSMO)∕xTiO2 has been investigated. These studies show that at low doping level (x⩽2) TiO2 mainly goes into the grain-boundary region, but at high doping level (x⩾3), some part of the TiO2 goes into the perovskite lattice substituting Mn in LSMO and the remainder segregates as a separate phase at the grain boundaries. Results also show that the TiO2 doping has an important effect on a low-field magnetoresistance. In the magnetic field of 8000Oe and at 77K a magnetoresistance value of ∼20% was observed for the composite with a TiO2 doping level of x=2.

The effect of TiO2 doping on the structure and magnetic and magnetotransport properties of La0.75Sr0.25MnO3 composite

The magnetoresistance measurements of single phase polycrystalline Gd(Ba 2− x Pr x )Cu 3 O 7+ δ and (Gd 1− x Pr x )Ba 2 Cu 3 O 7− δ samples have been compared and analyzed by the Ambegaokar and Halperin phase slip model. The derived power law dependences of pinning energy to applied magnetic field and temperature have been studied for different amounts of Pr doping. The power factors depend on the Pr doping. Moreover, in both systems, the magnetic field dependence of the pinning energy power factor increases for small amounts of Pr doping, while for larger amount of Pr doping, it decreases. The derived critical magnetic field at zero temperature limit is in good agreement with other model-based and experimentally measured values. The critical current power law dependence to magnetic field decreases with increasing Pr doping. Pr substitution at Ba or rare earth site, decreases the pinning energy and the critical current density, playing the role of weak links.

Magnetoresistance in Gd(Ba2−xPrx)Cu3O7+δ system

The zone-center phonons and dielectric properties of orthorhombic brookite and cotunnite structures ${\mathrm{TiO}}_{2}$ were studied in the framework of density functional perturbative theory. The dielectric properties of brookite and anatase structures are similar. The calculated static dielectric permittivity of brookite is found to be slightly higher than that of anatase, but far lower than that of the rutile structure. This is in contrast with the recent experimental report on brookite flowers. Our study suggests that the static dielectric constant of cotunnite structure is smaller than those of rutile and brookite structures. We obtained the full phonon band structure and elastic properties of these structures. The bulk modulus and Debye temperature of brookite are intermediate between those of the anatase and rutile structures. The obtained value of 301 GPa for the bulk modulus of cotunnite is in good agreement with the stiffness of the material reported experimentally. Because of the similarity in $z$-direction packing of the ${\mathrm{TiO}}_{6}$ tetrahedron between brookite and rutile structures, the elastic constants associated with the $z$-polarized movement of atoms in brookite are similar to those of the rutile structure. The elastic constants of brookite associated with the movement of the atoms in $x$-$y$ plane, are similar to the corresponding constants in anatase and rutile structures. This demonstrates the similarity between the packing character of the brookite structure with both anatase and rutile structures. So, the lattice dynamics of brookite is intermediate between those of anatase and rutile polymorphs. The calculated phonon density of states of cotunnite shows that it is stable at ambient pressure.

Mohammad Reza Mohammadizadeh

Papers

First-principles elastic and thermal properties of TiO2: a phonon approach

Superhydrophilicity of TiO2 thin films using TiCl4 as a precursor

The effect of TiO2 doping on the structure and magnetic and magnetotransport properties of La0.75Sr0.25MnO3 composite

Magnetoresistance in Gd(Ba2−xPrx)Cu3O7+δ system

First-principles study of lattice dynamics of TiO 2 in brookite and cotunnite structures