Search results for "ZrO"

ZrO2 Based materials as photocatalysts for 2-propanol oxidation by using UV and solar light irradiation and tests for CO2 reduction

2018

Abstract Bare ZrO2, Ce doped ZrO2 and Er doped ZrO2 samples have been prepared by a hydrothermal process and have been used as photocatalysts for 2-propanol oxidation reaction in gas solid regime. Moreover, some preliminary tests have been carried out for CO2 reduction. The samples were physico-chemically characterized and both bare and doped ZrO2 based materials resulted active for oxidation and reduction reactions by using UV and solar irradiation. The reactivity results have been correlated with the compositional, structural and morphological features of the photocatalysts.

Systematic Trends in Hybrid-DFT Computations of BaTiO3/SrTiO3, PbTiO3/SrTiO3 and PbZrO3/SrZrO3 (001) Hetero Structures

2022

We acknowledge the financial support from the funder—Latvian Council of Science. The funding number is: Grant No. LZP-2020/1-0345. The Institute of Solid State Physics, University of Latvia (Latvia), as the Centre of Excellence, has received funding from the European Unions Horizon 2020 Framework Programme H2020-WIDESPREAD01-2016-2017-Teaming Phase2 under Grant Agreement No. 739508, project CAMART-2.

Phase formation in mixed TiO2-ZrO2 oxides prepared by sol-gel method

2011

Pure titania, zirconia, and mixed oxides (3—37 mol.% of ZrO2) are prepared using the sol-gel method and calcined at different temperatures. The calcined samples are characterized by Raman spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption porosimetry. Measurements reveal a thermal stability of the titania anatase phase that slightly increases in the presence of 3—13 mol.% of zirconia. Practically, the titania anatase-rutile phase transformation is hindered during the temperature increase above 700 C. The mixed oxide with 37 mol.% of ZrO2 treated at 550 C shows a new single amorphous phase with a surface area of the…

Computational Studies on BaCeO3 and BaZrO3 Derivatives.

2011

First principles calculations of SrZrO3 bulk and ZrO2-terminated (001) surface F centers

2016

Abstract Using a supercell model and B3PW hybrid exchange-correlation functional in the framework of the density functional theory (DFT), as it is implemented in the CRYSTAL computer code, we performed ab initio calculations for the F -center located in the SrZrO 3 bulk and on the ZrO 2 -terminated (001) surface. According to the results of performed relaxation of atoms around the defect, two nearest Zr and four Sr atoms are repulsed, but all oxygen atoms are attracted towards both, the bulk and (001) surface F -center. The displacement magnitudes of atoms surrounding the bulk F -center are smaller than around the (001) surface F -center. The B3PW calculated SrZrO 3 bulk optical band gap (5…

ZrO2 Acting as a Redox Catalyst

2016

Surface defects are discussed and reviewed with regards to the use of ZrO2 in applications involving interactions with CO, H2, CH4, CO2, water and hydrocarbons. Studies of catalytic partial oxidation of methane reveal that part of the surface lattice oxygen in terraces can be removed by methane at high temperatures (e.g. 900 °C). The reaction proceeds via a surface confined redox mechanism. The studies presented here also highlight that defects play a decisive role in the water–gas-shift reaction, since the reaction is likely carried out via OH groups present at defect sites, which are regenerated by dissociating water. Hydroxyl chemistry on ZrO2 is briefly reviewed related to the studies p…

MoSi2 laser cladding—A new experimental procedure: double-sided injection of MoSi2 and ZrO2

2003

International audience; In the last decade, development of low density advanced material systems for service at temperatures up to 1300 °C was one of the goals of many researches. This kind of material should mainly have moderate fracture toughness and should exhibit oxidation resistant behaviour at low and intermediate temperature. One of the most studied materials continues to be the intermetallic compound MoSi2. The molybdenum disilicide has been considered as an attractive candidate due to its melting point (2030 °C) and excellent oxidation resistance at high temperatures. The main problem associated with the MoSi2 layer synthesized using laser beam is the layer fragility. To avoid this…

The Role of Pluriactivity for Continuity and Survival in Family Farm Firms

2014

Our study focuses on family farm firms as an important and yet under-researched type of family firms. We explore the entrepreneurial growth behavior in the context of family farm firms by focusing on the role of pluriactivity. By integrating the literature of family business strategies, EO, and growth intentions, this study of 1618 Finnish family farms seeks to understand the idea of pluriactivity as a strategic orientation of family farm firms leading towards the growth and renewal of their prevailing and future domains. Our study revealed that pluriactivity is associated with growthorientation and perceived strengths of the family farm firms. We identified four types of growth groups (Est…

Large scale synthesis of nanostructured zirconia-based compounds from freeze-dried precursors

2013

Nanocrystalline zirconia powders have been obtained at the multigram scale by thermal decomposition of precursors resulting from the freeze-drying of aqueous acetic solutions. This technique has equally made possible to synthesize a variety of nanostructured yttria or scandia doped zirconia compositions. SEM images, as well as the analysis of the XRD patterns, show the nanoparticulated character of those solids obtained at low temperature, with typical particle size in the 10–15 nm range when prepared at 673 K. The presence of the monoclinic, the tetragonal or both phases depends on the temperature of the thermal treatment, the doping concentration and the nature of the dopant. In addition,…

Continuous hydrothermal synthesis of nanometric BaZrO3 in supercritical water

2007

Abstract Nanocrystalline barium zirconate (BaZrO 3 ) was synthesized using a hydrothermal synthesis process working in supercritical conditions and in a continuous way. By this method, we succeeded in the continuous and rapid production of nanopowders. As a preliminary work three barium precursors have been investigated: barium hydroxide (Ba(OH) 2 ), barium acetate (Ba(CH 3 COO) 2 ) and barium nitrate (Ba(NO 3 ) 2 ). Two of them (Ba(CH 3 COO) 2 and Ba(NO 3 ) 2 ) led to the pure perovskite phase. Then an experimental design has been conducted in order to determine the influence of the experimental parameters on the crystallinity and the grain size of the final product.