نتایج جستجو برای: band gap

تعداد نتایج: 261994  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده علوم پایه 1390

در این تحقیق اتصال پپتیدی نانولوله به صفحات گرافن مورد بررسی قرار گرفته است. از میان جنبه های مختلف قابل بررسی برای این ساختارها، مطالعات ساختاری، مطالعات مربوط به انرژی تشکیل پیوند، مطالعاتnmr) )neuclear magnetic resonance و nuclear quadrupole resonance (nqr)و molecular electrostatic potential (mep)، مطالعات مربوط به شکاف انرژی (band gap)هریک از این هیبریدهای نانولوله - گرافن و همچنین بررسی ان...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - دانشکده علوم 1387

boron nitride semiconducting zigzag swcnt, $b_{cb}$$n_{cn}$$c_{1-cb-cn}$, as a potential candidate for making nanoelectronic devices was examined. in contrast to the previous dft calculations, wherein just one boron and nitrogen doping configuration have been considered, here for the average over all possible configurations, density of states (dos) was calculated in terms of boron and nitrogen ...

Journal: :journal of optoelectronical nano structures 0
khojasteh zarei 1department of electronic engineering, sepidan branch,islamic azad university, sepidan, iran. ghahraman solookinejad department of physics, marvdashtbranch,islamic azad university, marvdasht, iran. masoud jabbari department of electrical engineering, marvdasht branch, islamic azad university, marvdasht, iran.

in this paper, a photonic crystal waveguide with point defects and lattice constant perturbations of +5%, -5% are being investigated. firstly waveguide structures with constant and specific parameters are being studied and photonic band gap diagrams for te/tm modes are depicted; then pulse propagation in the frequencies available in the band gap are shown. after that, effects of parameters like...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده علوم 1393

in this thesis, structural, electronical, and optical properties of inverse pervskite(ca3pbo) in cubic phase have been investigated.the calculation have been done based on density functional theory and according to generalized gradiant approximate (gga) as correlating potential. in order to calculate the configurations, implementing in the wien2k code have been used from 2013 version. first of ...

Journal: :journal of nanostructures 2012
sh. khaleghi

by means of first principles calculations we show that both rutile and anatase phases of bulk tio2 doped by s, se or pb can display substantial decreasing in the band gap (up to 50%), while doping by zr does not sizably affect the band-gap value. moreover, the absorption edge is shifted (up to 1 ev) to the lower energy range in the case of tio2 doped by s or pb that opens a way to enhancing of ...

پایان نامه :دانشگاه تربیت معلم - تبریز - دانشکده علوم 1389

فیلتری باساختارپریودیک سه گانه یک بعدی مطرح شده وروابط پراکندگی در ان بررسی میشود.با انالیز ریاضی می توان باندهای ممنوعه و مجاز طول موجها را با تغییرات زاویه فرودی پیش بینی کرد.با استفاده از روابط پراکندگی و با انتخاب مقادیر مناسب پارامترهای کنترلی میتوان طرح یک فیلتر اپتیکی را داد که می تواند در همه رنجهای طیف الکترومغناطیسی بکار گرفته شود.این مطالعه میتواند برای بهبود کارایی و دقت pbg(photoni...

Journal: :international journal of nano dimension 0
j. nouri department of chemistry, mahabad branch, islamic azad university, mahabad, iran t. khoshravesh department of chemistry, mahabad branch, islamic azad university, mahabad, iran s. khanahmadzadeh department of chemistry, mahabad branch, islamic azad university, mahabad, iran a. salehabadi department of chemistry, naragh branch ,islamic azad university, naragh, iran m. enhessari department of chemistry, naragh branch ,islamic azad university, naragh, iran

li2ni8o10 and limn2o4 nanoparticles as cathode materials of lithium ion battery, were successfully synthesized using lithium acetate, nickel and manganese acetate as li, ni and mn sources and stearic acid as a complexing reagent. the structure of the obtained products were characterized by ft-ir and xrd. the shape, size and distribution of the li2ni8o10 and limn2o4 nanoparticles were observed b...

A. Gaur, B.P. Malik, D. Sharma, N. Singh, P. Gaur,

The Photoexcited carrier lifetime (τ) and peak to valley transmission difference (ΔTp-v) in direct and indirect band gap crystals has been investigated by the use of single beam open and closed aperture z-scan technique using frequency doubled Nd:YAG laser. The peak to valley transmission difference (ΔTp-v) is found to be of the order of 10-2 in case of direct band gap crystals and of the order...

Journal: :international journal of nano dimension 0
s. janitabar darzi nuclear science and technology research institute, 11365/8486 tehran, iran. a. mahjoub department of chemistry, tarbiat modares university, 14115-175 tehran, iran. a. bayat department of chemistry, tarbiat modares university, 14115-175 tehran, iran.

sol-gel derived sulfur modified and pure zno nanorod were prepared using zinc chloride and thiocarbamide as raw materials. prepared nanorods were characterized by means of x-ray diffraction (xrd), thermogravimetry- differential scanning calorimetry (tg–dsc), uv- vis absorption spectroscopy, brunauer emmett teller (bet) specific surface area and barrett joyner halenda (bjh) pore size distributio...

In this paper, a photonic crystal waveguide with point defects and lattice constant perturbations of +5%, -5% are being investigated. Firstly waveguide structures with constant and specific parameters are being studied and photonic band gap diagrams for TE/TM modes are depicted; then pulse propagation in the frequencies available in the band gap are shown. After that, effects of parameters like...

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