سنتز پودرهای نانوکامپوزیت نقره-اکسید قلع از روش هم رسوبی شیمیایی

Synthesis  of  silver  tin  oxide  nanocomposite  powders

 via  chemical coprecipitation method

سنتز پودرهای نانوکامپوزیت نقره-اکسید قلع از روش هم رسوبی شیمیایی

ABSTRACT

Introduction : Silver-metal  oxide  composite  contact  materials  have  a variety  of  applications  in  low  voltage  switches  such  as relays,  contactors  and  circuit  breakers . Until  three decades  ago,  Ag-CdO  composite  was  the  preferred material  for  these  usages  due  to  excellent  functional and  technological  properties.  However,  because  of  toxic nature  of  Cd,  especially  when  it  is  evaporated,  consider- able  efforts  have  been  made  to  replace  it  with  environ-ment-friendly  substances  such  as  Ag-SnO2. Ag-SnO2 materials,  in  addition,  have  higher  hardness,  contact resistance  and  temperature  rise  than  Ag-CdO  substances. Besides  their  arc  erosion  and  anti-welding  properties  are excellent.

 

تولید، خواص و قابلیت‌های گرافن Production, properties and potential of graphene

Production, properties and potential of graphene

تولید، خواص و قابلیت‌های گرافن

ABSTRACT

This review on graphene, a one-atom thick, two-dimensional sheet of carbon atoms, starts with a general description of the graphene electronic structure as well as a basic experimental toolkit for identifying and handling this material. Owing to the versatility of graphene properties and projected applications, several production techniques are summarized, ranging from the mechanical exfoliation of high-quality graphene to the direct growth on carbides or metal substrates and from the chemical routes using graphene oxide to the newly developed approach at the molecular level. The most promising and appealing properties of graphene are summarized from an exponentially growing literature, with a particular attention to matching production methods to characteristics and to applications. In particular, we report on the high carrier mobility value in suspended and annealed samples for electronic devices, on the thickness-dependent optical transparency and, in the mechanical section, on the high robustness and full integration of graphene in sensing device applications. Finally, we emphasize on the high potential of graphene not only as a post-silicon materials for CMOS device application but more ambitiously as a platform for post-CMOS molecular architecture in electronic information processing.

 

شناسایی ساختار و انتقال بار لایه های گرافن

Structural and charge transport characteristics of graphene layers

obtained from CVD thin film and bulk graphite materials

شناسایی ساختار و انتقال بار لایه های گرافن حاصل از لایه نازک CVD و مواد گرافیتی

ABSTRACT

We report an experimental comparative study of graphene layers produced by micromechanical cleavage of bulk graphite materials of different origins and graphite films obtained by plasma enhanced chemical vapor deposition (PECVD). Structural characteristics of these materials were evaluated using Raman spectroscopy and electron microscopy. Field effect transistors (FETs) based on the PECVD graphene were produced using electron beam lithography. Conductivity, carrier mobility and other characteristics of the PECVD graphene obtained from Raman and FET tests were similar to the properties of graphene flakes obtained from bulk graphite materials. Taking into account the scalability of the CVD fabrication, these results confirm the possible industrial use of graphene films obtained by this method.

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