scholarly journals Oxidation of nanocrystalline silicon at room temperature and various humidity

2019 ◽  
Author(s):  
Vadim M Popelensky ◽  
Sergey G Dorofeev ◽  
Nikolay N Kononov ◽  
Sergey S Bubenov ◽  
Alexander A Vinokurov

Oxidation of HF vapor-etched nanocrystalline silicon films, prepared by drop coating from nanocrystalline Si sol in acetonitrile, was studied. Oxidation of nc-Si at room temperature in air with 5% and 86% relative humidity was observed by means of IR spectroscopy for 2 days. The change in film mass after 15 hours of oxidation was determined using quartz crystal microbalance. In dry air, film mass and integral intensity of bands attributed to vibrations in Si3-x‒Si‒Hx and Si-O-Si groups changed linearly with time. In humid air, intensity of in Si3-x‒Si‒Hx band decays exponentially and intensity of Si-O-Si band increases as a square root of oxidation time. Film mass gain after 15 hours of oxidation corresponds to an average oxide layer thickness of 0.02 nm in dry air and 0.51 nm in wet air.

2001 ◽  
Vol 686 ◽  
Author(s):  
Shaoyun Huang ◽  
Souri Banerjee ◽  
Shunri Oda

AbstractWe prepared a SiO2/nanocrystalline Si (nc-Si)/SiO2 sandwich structure. A clear positive shift in C-V and G-V curves due to electrons trapped in nc-Si dots has been observed at room temperature. The peak in conductance around flat band condition indicates that a trap event had occurred where an electron is stored per nc-Si dot. A logarithmic charge loss function is found and this discharging process is independent of the thermal activation mechanism. The longer memory retention time and logarithmic charge loss in the dots are explained by a “built-in” electric field through the tunnel oxide, which varies with time, resulting in a variable tunneling probability. The electric repulsion induced by the built-in electric field hinders the discharging of electrons remained in the dots.


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3449
Author(s):  
Ireneusz Stefaniuk ◽  
Werner Obermayr ◽  
Volodymyr D. Popovych ◽  
Bogumił Cieniek ◽  
Iwona Rogalska

In this paper, we show a simple method of producing ferromagnetic materials with a Curie temperature above room temperature. The electron paramagnetic resonance (EPR) spectra of Cd1−xCrxTe (0.002 < x < 0.08) were measured with a dependence on temperature (82 K < T < 381 K). Obtained EPR lines were fitted to a Lorentz-shaped curve. The temperature dependencies of the parameters of the EPR lines, such as the peak-to-peak linewidth (Hpp), the intensity (A), as well as the resonance field (Hr), were studied. Ferromagnetism was noticed in samples at high temperatures (near room temperature). For a sample with a nominal concentration of chrome of x = 0.05, a very strong intrinsic magnetic field is observed. The value of the effective gyromagnetic factor for this sample is ge = 30 at T = 240 K. An increase of chrome concentration above x = 0.05 reduces the ferromagnetic properties considerably. Analysis of the temperature dependencies of the integral intensity of EPR spectra was carried out using the Curie–Weiss law and the paramagnetic Curie temperature was obtained.


2012 ◽  
Vol 66 (5) ◽  
pp. 591-594 ◽  
Author(s):  
Premkumar Sivasubramanian ◽  
Rana Mohtadi ◽  
Ragaiy Zidan ◽  
Kutty Pariyadath ◽  
Chad L. Leverette ◽  
...  

Raman and infrared vibrational spectroscopy were used to confirm the presence of aluminum borohydride dissolved in a commercial polydimethylsiloxane vacuum grease at room temperature. Spectroscopic evidence for an adduct between the aluminum borohydride and polydimethylsiloxane is also presented. Once dissolved in the polydimethylsiloxane grease, the aluminum borohydride was stabilized with respect to its usual pyrophoric reactivity in wet or dry air.


CORROSION ◽  
1968 ◽  
Vol 24 (12) ◽  
pp. 407-410 ◽  
Author(s):  
P. K. KRISHNAMOORTHY ◽  
S. C SIRCAR

Abstract The effect of plastic deformation and further annealing on the kinetics of growth of thin oxide films on copper at 30 C (86 F) has been investigated. Oxidation rate was found to decrease markedly with increasing deformation. Further annealing showed an increase in the rate, the most pronounced changes occurring during the recrystallization stage. Results are interpreted in the light of Cabrera-Mott theory of growth of very thin oxide films on metals. The change in rate has been related to the concentration of cation vacancies in the Cu2O semi-conductor, which is dependent on the lattice distortion and defect concentration of the substrate metal.


2000 ◽  
Vol 638 ◽  
Author(s):  
H. B. Kim ◽  
L. Montes ◽  
R. Krishnan ◽  
P. M. Fauchet ◽  
L. Tsybeskov

AbstractWe have studied carrier transport and lateral electrical properties of nanocrystalline Si layers containing size controlled Si nanocrystals. Using results from direct current (dc) and alternating current (ac) conductivity measurements, the charging of Si nanocrystals and Coulomb blockade effect are discussed.


2017 ◽  
Vol 61 (3) ◽  
pp. 91-94
Author(s):  
M. Lovíšek ◽  
T. Liptáková ◽  
J. Bronček ◽  
S. Dundeková

Abstract Tribological properties of Al-brass pipes of various producers were studied in different environments. The tested brasses have very similar chemical composition, but they differ in microstructure due to mainly by heat treatment after cold drawing. Microstructure as well as roughness of surface influence chemical and mechanical properties which are important in operating conditions. The experiments of tribological behavior were made in various environments, dry air, cooling treated water and 3.5 % solution of NaCl at room temperature 21 ± 2°C. The tribological tests were carried out on the Linear Tribometer at normal loading 5 N by the method ball on plate for the duration of 5500 s. The measured friction coefficients were evaluated by the program DIAdem and the diagrams were created from signal generated by software NSignal Express


2019 ◽  
Vol 23 (11n12) ◽  
pp. 1495-1504 ◽  
Author(s):  
Mariya V. Tesakova ◽  
Sergey M. Kuzmin ◽  
Vladimir I. Parfenyuk

The process of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization has been studied by the quartz crystal microbalance method in different electrodeposition conditions. The films were deposited in two modes: in potentiostatic conditions (at the potential of [Formula: see text]2 V) and in potentiodynamic conditions (CV with the potential scan rate of 20 mV/s). The effect of electrolysis parameters on 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization has been studied by obtaining films in two modes and using two supporting electrolytes: tetrabutylammonium perchlorate or tetrabutylammonium hexafluorophosphate. The biggest film mass gain was observed on a clean electrode surface. At further film deposition on the polyporphyrin-coated electrode, the film mass growth stopped. The electrodeposition effectiveness was somewhat higher in the potentiodynamic conditions, with the formation of a looser film. The nature of the supporting electrolyte did not have a significant effect on the electrodeposition process. A significant contribution to the deposition was made by the electrode material. The film thickness was 25–80 nm. The films possessed [Formula: see text]-type conductivity; and the flat-band potential for poly-H[Formula: see text]T(4-OHPh)P obtained in potentiodynamic conditions was 0.33 V, for poly-H[Formula: see text]T(4-OHPh)P obtained in potentiostatic conditions it was 0.16 V.


2004 ◽  
Vol 338-340 ◽  
pp. 318-321 ◽  
Author(s):  
Liangcai Wu ◽  
Min Dai ◽  
Xinfan Huang ◽  
Yongjun Zhang ◽  
Wei Li ◽  
...  

2019 ◽  
Vol 76 (Suppl 1) ◽  
pp. A85.2-A85
Author(s):  
Bojana Miladinovic ◽  
Maja Nikolic ◽  
Aleksandra Stankovic ◽  
Sci Visa Tasic

Sick Building Syndrome (SBS) is a diseases associated with indoor air quality accompanied with various nonspecific symptoms that occur in the occupants of a building. This syndrome has been the subject of serious scientific investigation in the past years, but there are not enough studies in transition countries.The aim of this study was to investigate the symptoms of the syndrome among employees in the commercial centers in Niš, Serbia.MethodsThe cross-sectional study was conducted amongst employees of two commercial centers in the city of Niš, Serbia. In this study the MM-040EA questionnaire was used with two additional questions and 1152 employed were interviewed during the period of three years. Data extracted from the questionnaires were analyzed using the chi-square test and binary logistic regression.ResultsThe prevalence of SBS was high. The most common symptoms reported by employees included high room temperature (74.9%), stuffy air (73.5%), and dry air (75.7%), while rare complaints were towards static electricity (47.3%) and low room temperature (45.2%). Binary logistic regression showed that too low room temperature (p=0.002), dry air (p=0.015), static electricity (p=0.007) and noise (p=0. 024) were the most important factors for the high symptoms score. A relatively small number of sick absence (13.4%) was found among subjects working in the investigated commercial centers.ConclusionThe high prevalence of SBS symptoms in the environment of commercial centers was almost associated with factors of unpleasant microclimate. So improvement of environmental conditions such as increasing the efficiency of the ventilation system, increasing fresh air flow in the sector and noise prevention , as well as enhancing the quality of working life will motivate the employees and increase productivity in the workplace. The occupational health care workers play an important role in educating of workers and their employers.


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