Search results for " Zirconia"

Escaping scaling relationships for water dissociation at interfacial sites of zirconia-supported Rh and Pt clusters

2019

<p>Water dissociation is an important reaction involved in many industrial processes and a good model reaction for probing the activity of catalytic sites. In this computational study, the dissociation of water at interfacial sites of globally optimized ZrO2 sup- ported Pt and Rh clusters is investigated under the framework of density functional theory. Our findings demonstrate that the perimeter sites of these small clusters can activate water, but the dissociation behavior varies considerably between sites. It is shown that the studied clusters break scaling relationships for water dissociation, suggesting these catalysts may achieve activities beyond the maximum imposed by such rel…

Tungsten -catalysts supported on ZrO2 nanopowder

2009

Investigation on the stability of dispersion of zirconia nanoparticles prepared by microwave- hydrothermal synthesis

2005

Difficulties in reproducing the performances of nanoparticles dispersions are obstructive for the progress of the nanotechnology. A plausible reason for this variability is the lack of the control of the stability as well as the dimensions of the nanoparticles in the dispersions. In this work we report results of investigations on the stability of zirconia nanoparticles in aqueous medium, monitoring nanoparticles sizes by means of Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS). Nanocrystalline zirconia powders, prepared by microwave-hydrothermal synthesis, were determined to be 6-8 nm in size by TEM observations. By using DLS technique the as-prepared dispersions wit…

Effect of nanoparticles on the morphology, mechanical properties and thermal degradation kinetics of polymetylmetacrylate and polycarbonate

2013

As the filler influences morphology, mechanical properties and thermal degradation of a polymer

2013

Luminescence properties of neodymium-doped yttrium aluminium garnet obtained by the co-precipitation method combined with the mechanical process

2005

Nanopowders of yttrium aluminium garnet Y3Al5O12 (YAG) doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium and yttrium nitrate and neodymium oxide with ammonia. After washing and drying the hydroxide precursors were calcined at 500, 700, 800 and 900 °C for 1 hour and at 1000 °C for 3 hours. This product was treated by ball milling in a zirconia vial for 0.5, 1.5 and 10 h in order to achieve smaller nanoparticles. The structure, microstructure, morphology and optical properties were investigated by means of diffractometric, microscopic and spectroscopic techniques. The course of the amorphous-to-crystalline transformation was complete after c…

DFT Prediction of Enhanced Reducibility of Monoclinic Zirconia upon Rhodium Deposition.

2018

Oxides are an important class of materials and are widely used, for example, as supports in heterogeneous catalysis. In a number of industrial catalytic processes, oxide supports actively participate in chemical transformations by releasing lattice oxygen anions. While this is intuitively understood for reducible oxides, the reducibility of irreducible oxides may be modified via nanoengineering or upon inclusion of foreign species. Our calculations predict that the ability of irreducible monoclinic zirconia to release oxygen improves substantially upon deposition of rhodium. Through a comprehensive screening of Rh/ZrO2 with different size of the rhodium species, we find that a Rh adatom and…

Resistive switching in memristors based on yttria-stabilized zirconia

2021

Effect of pulse amplitude on depression and potentiation of ZrO2(Y)-based memristive synaptic device

2022

The effect of the amplitude of depressing and potentiating pulses on the synaptic plasticity (potentiation and depression) of a memristive device based on the Ta/ZrO2(Y)/Pt stack has been experimentally studied. It is shown that the amplitude of depressing and potentiating pulses affects the synaptic plasticity, namely, the value of current passing through the memristive device. The presented results demonstrate the prospects of using the ZrO2(Y)-based memristive devices as stable and low-power elements of neuromorphic systems.