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Register a new userPreparation Films from Nano Tungsten Oxide Powders and Studying Their Sensing Properties for Ethanol Vapor
تحضير أغشية من مساحيق أكسيد التنغستين النانوية, ودراسة خصائصها التحسسية تجاه بخار الإيثانول
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Tishreen University ورقة بحثية
Publication date
2014
fields
Physics
and research's language is
العربية
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Shamra Editor
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حُضّرت أغشية سميكة بطريقة الطلاء الكيميائي من مساحيق أكسيد التنغستين النانوية مركب مصدر, بالطحن في مطحنة الكرات عالية الطاقة لفترات زمنية متعددة (1-18h) ، على ركائز زجاجية نظيفة تحتشر وطحرارية معينة (تم تغيير درجة الحرارة من 25°C إلى(350°C . دُرست الأغشية من حيث خصائصها التحسسية تجاه 100 ppm من بخار الإيثانول , باستخدام مميزات تيار-جهد (I-V) . تم استنتاج طاقة التنشيط Ea للأغشية المحضّرة من معادلة أرينيوس. وُثق تأثير الحجم الحبيبي والشروط الحرارية في الخصائص التحسسية للأغشية تجاه بخار الإيثانولو , كذلك الترابط بين الناقلية الكهربائية والحجم الحبيبي لمادة الأغشية. وأخيراً حُدد زمن الاستجابة للأغشية ذات الحجم الحبيبي 70.54 nm عند الدرجة 300°C.
Thick Films have been prepared by the chemical painting method from Tungsten Oxide nanopowdersas the source compound, which are prepared by milling in a high energy ball mill for variousspans of time (1-18h) on cleanedglasssubstratesunder limited thermal conditions. The temperature of the films have been changed from 25°C to 350°C. The films have been investigated for their sensing properties relating to 100 ppm ethanol vapor adsorption, using the (I–V) characteristics.The activation energy Ea for deposition films is deduced from the Arrhenius equation. The effect of the grain size and the thermal conditions on the sensing properties of the WO3thick films to ethanol vapor adsorption, as well as the correlations between The electrical conductivity of the WO3 thick films and the grain size of the material films are reported.The response time for films which have particle size about 70.54nm is defined at 300°C.
References used
GIL-SU K, YOUNG JUNG L, DAE-GUN K, YOUNG DO K; Consolidation Behavior Of Mo Powder Fabricated From Milled MO Oxide By Hydrogen-Reduction. Journal of Alloys and Compounds, Vol.454, 2008, 327–330
SAFAEI A, ATTARIAN SHANDIZ M, SANJABI S, BARBER Z H; Modelling The Size Effect On The Melting Temperature Of Nanoparticles, Nanowires And Nanofilms. J. Phys.: Condens. Matter, Vol. 19, 2007, 1-9
Dae-Gun Kim, Kyung Ho Min, Si-Young Chang, Sung-Tag Oh, Chang-Hee Lee, Young Do KimaEffect of pre-reduced Cu particles on hydrogen-reduction of W-oxide in WO3–CuO powder mixtures. Materials Science and Engineering A, Vol. 399, 2005, 326–331
C. V. Ramana, S. Utsunomiya, R. C. Ewing, C. M. Julien, and U. Becker; Structural Stability and Phase Transitions in WO3 Thin Films. J. Phys. Chem. B, Vol. 110, 2006, 10430-10435
S. Saloum and B. Alkhaled; Growth Rate and Sensing Properties of Plasma Deposited Silicon Organic Thin Films from HexamethyldisilazaneCompound.ActaPhysicaPolonica A. Vol. 117, No. 3, 2010, 484- 489
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There are wide uses of tin oxide thin films, especially in the field of
transparent conductors, solar cells, gas sensors and piezoelectric materials.
Laser deposition is considered one of the most important techniques followed to
obtain these film
s. In this research, we develop a technique to obtain
homogeneous thin films of tin oxide depending on vaporization of pile targets of
this oxide by continuous CO2 laser in the atmosphere, with a fan which
guarantees obtaining homogenous films. Some of these films were annealed in
different conditions. The optical microscope images revealed the presence of
high degree of homogeneity, while the X-Ray study showed different
crystallization grain orientations which depend on the preparation conditions.
The preferred direction is (110). The optical absorption gives information
about the value of the effective band gal for the samples before and after
thermal annealing. We have found that some films have Eg = 3.2 ev. before
annealing, and after long annealing they have Eg=1.3ev. In addition, the hard
annealed thin films reveal anisotropy in the optical and electrical.
Characteristics, they have different absorption coefficients in two
perpendicular directions, also there is an electrical resistance anisotropy along
these two directions especially after hard annealing. The Eb was 0.73 ev before
annealing, it became 0.37 ev for one direction and 0.32 ev for the other
direction.
Mn doped tin oxide transparent conducting thin films were deposited at a
substrate temperature of 450°C by spray pyrolysis method. Structural
properties of the films were investigated as a function of various Mn-doping
levels (0, 1, 3, 5, 7 wt%) w
hile all other deposition parameters such as
substrate temperature, spray rate, carrier gas pressure and distance between
spray nozzle to substrate were kept constant.
This study has been performed in Agriculture Research Directorated Labs, Ministry of
Science and Technology/Iraq, aimed to use different formulations of weaning food
contained different concentrations of black rice flour, brown rice, peas and oat c
hips. Some
physical treatments like cleaning, peeling and milling to rice and and germination, chard,
peeling, drying and milling to peas were used to make these four formulations, which were
chosed depended on chemical analysis (moisture, protein, ash, fiber, carbohydrate, fat and
energy) in addition the estimation of some minerals (Ca, Fe and Zn) comparing with
recommendation of FAO weaning food and functional properties; like bulk density (BD),
foam capacity (FC) and swelling power (SP). Sensory evaluation was also conducted.
يعد الميتانول و الإيتانول من أكثر المحلات شيوعاً، و بما أن درجة غليانها أقل من مئة
درجة مئوية فإنها تتطاير بشكل سريع. و على سبيل المثال، يستعمل الميتانول في تصنيع
الأصبغة و العقاقير و العطور.. و هو شديد السمية، لذلك من الضروري تطوير محسات لكشفه.
أ
ما غاز الأمونيا فهو من ملوثات الهواء و له مصادر كثيرة مثل صناعة الأسمدة و أنظمة
التبريد.. و من هنا أهمية كشفه.
In this work, multi-layer thin films (insulator - metal - insulator) were prepared on glass substrates. Where we deposited the following order of (zinc oxide - silver - zinc oxide) by magnetron sputtering of zinc oxide and vacuum thermal evaporation technique for silver.
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