Effects of Surface Layer Defects and Adsorbed Oxygen on TiO2-Rutile Schottky Barriers

1981 ◽  
Vol 5 ◽  
Author(s):  
M. Levinson
Keyword(s):  
Surface Defects ◽  
Schottky Barriers ◽  
Adsorbed Oxygen ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Surface Conditions ◽  
Ohmic Behavior ◽  
Al Metallization ◽  
Tio2 Rutile

ABSTRACTThe electronic properties of TiO2 surfaces are of interest to further understanding of grain boundary effects in TiO2 and ZnO based varistor devices. Schottky barriers have been fabricated by Au or Al metallization on Nb doped TiO2-rutile [001] single crystal surfaces. Surface conditions included the presence or absence of either mechanical polishing induced surface defects and/or adsorbed oxygen. I­V measurements on Au samples indicate that surface defects yield ohmic behavior, but the defects may be electrically compensated by adsorbed oxygen to give non-ohmic I­V curves. All Al junctions show ohmic behavior which is interpreted in terms of reaction with surface oxygen. These results explain the necessity of firing varistor materials in an oxidizing atmosphere and suggest that the role of additives in these materials is to stabilize the oxygen concentration at the grain boundaries.

The interface between chloroaluminum phthalocyanine and titanium dioxide: The influence of surface defects and substrate termination

2021 ◽  
Author(s):  
Małgorzata Polek ◽  
Tamara Basova ◽  
Thomas Chassé ◽  
Heiko Peisert
Keyword(s):  
Titanium Dioxide ◽  
Surface Defects ◽  
Photoemission Spectroscopy ◽  
Interface Properties ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
X Ray ◽  
Ultraviolet Photoemission Spectroscopy ◽  
Chloroaluminum Phthalocyanine ◽  
Rutile Titanium Dioxide

Interface properties of chloroaluminum(III) phthalocyanine (AlClPc) on two different rutile titanium dioxide (TiO2) single crystal surfaces ((100) and (001)) have been studied using X-ray and ultraviolet photoemission spectroscopy (XPS and...

scholarly journals From single crystal surfaces to single atoms: investigating active sites in electrocatalysis

Nanoscale ◽  
2014 ◽  
Vol 6 (8) ◽  
pp. 4012-4026 ◽  
Author(s):  
Anthony P. O'Mullane
Keyword(s):  
Single Crystal ◽  
Active Sites ◽  
Critical Role ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Single Atoms

Electrocatalysis will be at the heart of energising future transportation and technology. This article discusses the critical role of active sites and the recent efforts in their characterisation and visualisation.

scholarly journals Elucidating the important role of surface-adsorbed oxygen for improving the sensing of formaldehyde by ZnO nanostructures

2021 ◽  
Author(s):  
Sherif Abdulkader Tawfik ◽  
Hang Tran ◽  
Michelle Jeanette Sapountzis Spencer
Keyword(s):  
Surface Defects ◽  
Health And Safety ◽  
Adsorbed Oxygen ◽  
Zno Nanostructures ◽  
High Importance ◽  
Surrounding Environment ◽  
Pollutant Gases ◽  
Effect Of Surface

Detection of pollutant gases, such as formaldehyde (HCHO), in our homes and surrounding environment is of high importance for our health and safety. The effect of surface defects and specifically...

scholarly journals In situ imaging of two-dimensional surface growth reveals the prevalence and role of defects in zeolite crystallization

2020 ◽  
Vol 117 (46) ◽  
pp. 28632-28639
Author(s):  
Madhuresh K. Choudhary ◽  
Rishabh Jain ◽  
Jeffrey D. Rimer
Keyword(s):  
Silica Nanoparticles ◽  
Rational Design ◽  
Surface Defects ◽  
Surface Growth ◽  
Two Dimensional ◽  
Crystal Surfaces ◽  
Structure Directing Agent ◽  
Layered Growth

Zeolite crystallization predominantly occurs by nonclassical pathways involving the attachment of complex (alumino)silicate precursors to crystal surfaces, yet recurrent images of fully crystalline materials with layered surfaces are evidence of classical growth by molecule attachment. Here we use in situ atomic force microscopy to monitor three distinct mechanisms of two-dimensional (2D) growth of zeolite A where we show that layer nucleation from surface defects is the most common pathway. Direct observation of defects was made possible by the identification of conditions promoting layered growth, which correlates to the use of sodium as an inorganic structure-directing agent, whereas its replacement with an organic results in a nonclassical mode of growth that obscures 2D layers and markedly slows the rate of crystallization. In situ measurements of layered growth reveal that undissolved silica nanoparticles in the synthesis medium can incorporate into advancing steps on crystal surfaces to generate defects (i.e., amorphous silica occlusions) that largely go undetected in literature. Nanoparticle occlusion in natural and synthetic crystals is a topic of wide-ranging interest owing to its relevance in fields spanning from biomineralization to the rational design of functional nanocomposites. In this study, we provide unprecedented insight into zeolite surface growth by molecule addition through time-resolved microscopy that directly captures the occlusion of silica nanoparticles and highlights the prevalent role of defects in zeolite crystallization.

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