scholarly journals High-Temperature Oxidation of Heavy Boron-Doped Diamond Electrodes: Microstructural and Electrochemical Performance Modification

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 964 ◽  
Author(s):  
Jacek Ryl ◽  
Mateusz Cieslik ◽  
Artur Zielinski ◽  
Mateusz Ficek ◽  
Bartlomiej Dec ◽  
...  

In this work, we reveal in detail the effects of high-temperature treatment in air at 600 °C on the microstructure as well as the physico-chemical and electrochemical properties of boron-doped diamond (BDD) electrodes. The thermal treatment of freshly grown BDD electrodes was applied, resulting in permanent structural modifications of surface depending on the exposure time. High temperature affects material corrosion, inducing crystal defects. The oxidized BDD surfaces were studied by means of cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM), revealing a significant decrease in the electrode activity and local heterogeneity of areas owing to various standard rate constants. This effect was correlated with a resultant increase of surface resistance heterogeneity by scanning spreading resistance microscopy (SSRM). The X-ray photoelectron spectroscopy (XPS) confirmed the rate and heterogeneity of the oxidation process, revealing hydroxyl species to be dominant on the electrode surface. Morphological tests using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that prolonged durations of high-temperature treatment lead not only to surface oxidation but also to irreversible structural defects in the form of etch pits. Our results show that even subsequent electrode rehydrogenation in plasma is not sufficient to reverse this surface oxidation in terms of electrochemical and physico-chemical properties, and the nature of high-temperature corrosion of BDD electrodes should be considered irreversible.

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 666 ◽  
Author(s):  
Nikolay Ivanovich Polushin ◽  
Alexander Ivanovich Laptev ◽  
Boris Vladimirovich Spitsyn ◽  
Alexander Evgenievich Alexenko ◽  
Alexander Mihailovich Polyansky ◽  
...  

Boron-doped diamond is a promising semiconductor material that can be used as a sensor and in power electronics. Currently, researchers have obtained thin boron-doped diamond layers due to low film growth rates (2–10 μm/h), with polycrystalline diamond growth on the front and edge planes of thicker crystals, inhomogeneous properties in the growing crystal’s volume, and the presence of different structural defects. One way to reduce structural imperfection is the specification of optimal synthesis conditions, as well as surface etching, to remove diamond polycrystals. Etching can be carried out using various gas compositions, but this operation is conducted with the interruption of the diamond deposition process; therefore, inhomogeneity in the diamond structure appears. The solution to this problem is etching in the process of diamond deposition. To realize this in the present work, we used triethyl borate as a boron-containing substance in the process of boron-doped diamond chemical vapor deposition. Due to the oxygen atoms in the triethyl borate molecule, it became possible to carry out an experiment on simultaneous boron-doped diamond deposition and growing surface etching without the requirement of process interruption for other operations. As a result of the experiments, we obtain highly boron-doped monocrystalline diamond layers with a thickness of about 8 μm and a boron content of 2.9%. Defects in the form of diamond polycrystals were not detected on the surface and around the periphery of the plate.


2020 ◽  
Vol 225 ◽  
pp. 106862 ◽  
Author(s):  
Qingzhen Guo ◽  
Haijian Su ◽  
Jiawei Liu ◽  
Qian Yin ◽  
Hongwen Jing ◽  
...  

Plant Disease ◽  
2008 ◽  
Vol 92 (12) ◽  
pp. 1695-1700 ◽  
Author(s):  
A. Murillo-Williams ◽  
G. P. Munkvold

Fusarium verticillioides causes seedling decay, stalk rot, ear rot, and mycotoxin contamination (primarily fumonisins) in maize. Systemic infection of maize plants by F. verticillioides can lead to kernel infection, but the frequency of this phenomenon has varied widely among experiments. Variation in the incidence of systemic infection has been attributed to environmental factors. In order to better understand the influence of environment, we investigated the effect of temperature on systemic development of F. verticillioides during vegetative and reproductive stages of plant development. Maize seeds were inoculated with a green fluorescent protein-expressing strain of F. verticillioides, and grown in growth chambers under three different temperature regimes. In the vegetative-stage and reproductive-stage experiments, plants were evaluated at tasseling (VT stage), and at physiological maturity (R6 stage), respectively. Independently of the temperature treatment, F. verticillioides was reisolated from nearly 100% of belowground plant tissues. Frequency of reisolation of the inoculated strain declined acropetally in aboveground internodes at all temperature regimes. At VT, the high-temperature treatment had the highest systemic development of F. verticillioides in aboveground tissues. At R6, incidence of systemic infection was greater at both the high- and low-temperature regimes than at the average-temperature regime. F. verticillioides was isolated from higher internodes in plants at R6, compared to stage VT. The seed-inoculated strain was recovered from kernels of mature plants, although incidence of kernel infection did not differ significantly among treatments. During the vegetative growth stages, temperature had a significant effect on systemic development of F. verticillioides in stalks. At R6, the fungus reached higher internodes in the high-temperature treatment, but temperature did not have an effect on the incidence of kernels (either symptomatic or asymptomatic) or ear peduncles infected with the inoculated strain. These results support the role of high temperatures in promoting systemic infection of maize by F. verticillioides, but plant-to-seed transmission may be limited by other environmental factors that interact with temperature during the reproductive stages.


1981 ◽  
Vol 23 (4) ◽  
pp. 265-267
Author(s):  
O. V. Abramov ◽  
A. I. Il'in ◽  
V. M. Kardonskii

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