absorbers, optical sensing devices, and flexible electronics.  

   In this thesis, we intend the the electronic properties of boron - phosphide monolayer under applying perpendicular electric and magnetic fields. We study the beharier of electronic density of states of the thestruclure and temperature beharier of tra  ort preperties such as electrical and thermal conduetivities. We have found the results based on Green's function and many body approaches. Tight binding model in the presence of bias voltage and Zeeman effects due to external magnetic field has been applied to study electron dynamics. Using electronic band structure in the context of Green's function and linear respense theory, the mentioued physical preperties have been analysed. Moreover, the effects of electric and megnetic fields intensities and electron doping on the temperature behavior of conductivities and density of states of states have been investigated.

  Electromagnetic waves consist of two components, electric and magnetic, so it is necessary that composite coatings absorbing electromagnetic waves have simultaneous magnetic and electric absorption. The electromagnetic properties of magnetic nanoparticles are different from their aggregated state due to surface effects. Because the particles are close to each other, there will be a possibility of dipole-dipole interactions between them, which usually causes magnetic particles to aggregate. These interactions can have a negative impact on their use in electromagnetic wave absorbers. Therefore, to reduce these interactions, the particles can usually be coated with various non-magnetic compounds. Cobalt ferrite is a hard magnetic material with an inverted spinel structure, has properties of magnetic anisotropy, saturation magnetization (MS) and high coercivity (HC), mechanical hardness and high chemical stability, which is used for magnetization loss in this thesis, and activated carbon and carbon nanotubes are also used for dielectric loss in this thesis, and the role of PVA is to stabilize nanoparticles in the composition, which prevents their agglomeration and clumping. In this thesis, cobalt ferrite nanorods and carbon nanotubes are immobilized in the pores of activated carbon by PVA using a sol-gel method, forming a new compound called polyvinyl alcohol/cobalt ferrite/carbon nanotube/activated carbon. These materials are measured by scanning electron microscopy (SEM) and X-ray diffraction (XRD), visible-ultraviolet spectroscopy, LCR meter, and analyzed by cyclic voltammetry (CV) and electrochemical charge/discharge (GCD).

Abstract Transition metal sulfides (TMDs) possess exceptional dielectric properties and a narrow band gap, rendering them highly efficient as electromagnetic absorbing materials. Among these TMDs, the two-dimensional MoS2 nanosheet has received significant attention in research. However, the quest for new absorbers no longer finds satisfaction in solitary absorption mechanisms. This article introduces a successful method for creating PVA/NiFe2O4/(MoS2)x nanocomposites via a straightforward sol-gel technique, wherein porous amorphous NiFe2O4 microspheres are integrated into MoS2 nanosheets. The investigation uncovers that the incorporation of MoS2 results in an enhanced complex permittivity, facilitating the attainment of a desirable permittivity level. The PVA/NiFe2O4/(MoS2)x nanocomposites absorber exhibits an incredibly low reflection loss (RL) of -16.75 dB at a mere thickness of 1 mm, achieved through the cooperative interaction of dielectric and magnetic loss, along with the advantages of the structure and composition. Consequently, the PVA/NiFe2O4/(MoS2)x nanocomposites effectively absorb electromagnetic waves. Therefore, it is posited that MoS2-based composites hold great promise as highly effective microwave absorbers, boasting strong absorption intensity and a wide absorption frequency range, given the exceptional performance of the as-fabricated PVA/NiFe2O4/(MoS2)x nanocomposites.  

Abstract The presence of electromagnetic pollution not only poses a threat to human health but also disrupts the proper functioning of large-scale machinery. In light of this,a novel method involving sol-gel technique   was utilized to synthesize PVA/Mn Ferrite/(MoS2)x nanocomposites, which exhibit remarkable electromagnetic wave absorption roperties. By intelligently combining MoS2 with PVA/Mn Ferrite, the composite's electromagnetic parameters were optimized, leading to enhanced impedance matching. A   a   result,   the PVA/Mn Ferrite/(MoS2)x nanocomposites showcased an exceptional minimum reflection loss of -15.971dB at a thickness of 1 mm.The remarkable capability of absorbing substances can primarily be attributed to the outstanding synergistic interaction between PVA/Mn Ferrite and MoS2. Additionally, MoS2 also plays a significant role in generating dielectric loss and achieving ideal impedance matching. As a result, the potential applications of PVA/Mn Ferrite/(MoS2)x nanocomposites extend to serving as both absorption materials and light dependent resistance (LDR) sensors. These nanocomposites exhibit not only high efficiency but also possess the added advantages of flexibility and lightweight properties, further enhancing their desirability. Keywords: Absorbing material, Electrical and magnetic properties, Impedance matching, LDR sensor   

  Investigating the magnetic, electrical and structural behaviors of Au/MoS2@(NiFe2O4)x nanostructures as electromagnetic absorbers

Two-dimensional T-graphene is one of the allotropes of carbon, which is made of carbon tetragonal and octagonal rings alternately, and it is expected to have distinctive and interesting properties due to its different band structure compared to graphene. The electronic properties of nanostructures are a function of their geometry and type of atoms. In this thesis, an attempt is made to investigate the electronic properties of zigzag and armchair T-graphene nanotubes with different diameters. The theoretical approaches used are tight-binding approximation, nearest neighbor approximation and Green's function approach. For this purpose, we first write the Hamiltonian of the studied nanostructures in the tight-binding approximation and the second quantization for Bloch electrons without interaction, and then we obtain the equation of motion of the valence electrons of the considered system. In the next step, using the obtained Green's function, the density of energy states and band structure are calculated, and at the end, the graphs of band structure and density of energy states for zigzag and armchair T-graphene nanotubes has been drawn using coding in MATLAB programming language and we analyze the resulting graphs  

   In today's world, the need for flexible, light, small and at the same time energy storage devices with high energy storage density for use in the manufacture and design of electronic devices is very much felt. Preparing capacitors in the shortest possible time with high energy storage capacity based on cheap and environmentally friendly materials is one of the challenges of today's human progress in using energy storage tools. Therefore, in this thesis, the design and construction of flexible microsupercapacitor based on the active materials of graphene nanocomposites was put on the agenda. In this research, by emphasizing the use of environmentally friendly materials and in the shortest possible time, a tool is designed and built to store as much energy as possible in small and portable dimensions. The morphology of the surface and the crystal structure of the manufactured electrodes are evaluated by different analyses. Also, the capacity and energy density of the prepared microsupercapacitor is investigated by electrochemical analysis. In this research, by making two different electrodes, RGO and RGO/CuO, and examining the electrochemical characteristics of each, we achieved a compatible and useful material for increasing energy density and power density. By performing cyclic voltammetry on these two electrode materials, we obtained a capacity of 2.73 mF.cm-2 and 9.02 mF.cm-2 at a scan rate of 10 mV.s-1 for RGO and RGO/CuO electrodes. The capacity of the composite supercapacitor after 1000 cycles has been maintained at 87%, which is an acceptable number compared to valid articles.   

   In order to realize low cost and high-performance energy storage, it is very important to develop a doped cathode material for high capacity and long cycle lithium ion batteries. LiMn1.977(Ce, Cu, Ti, CeCuTi)0.023O4 nanoparticles are considered a promising cathode material due to incomparable high structural stability, high capacity and safety during the charge/discharge cycles. Here we report on the LiMn2O4 cathode doped with Ce, Cu, Ti, CeCuTi and CNT contamination. Among the pure LiMn2O4 and different doped LiMn2O4 samples, the Ti-doped LiMn2O4 cathode calcined at 700 ?C shows the highest capacity of 144.701 mAh.g-1 after 20 cycles with a high current density of 0.1 C which reaches 186.413 mAh.g-1with CNT doping (capacity retention=98.924 %). This is due to the small size of the Ti atom, resulting in high porosity for reversible storage of lithium, and also the presence of titanium in the lattice increases the dielectric constant. This study provides a reliable and easy way to fabricate and analyze LiMn1.977(Ce, Cu, Ti, CeCuTi)0.023O4 nanoparticle-based cathodes with excellent performance.

   In this thesis morphology, structural and optical properties of three layers of ITO / Metal / NiO were investigated. NiO thin films were prepared by sputtering method in power of 100 w on the glass substrate which has thin films of ITO and metal on it. Metal thin films include two metals, silver and copper, which were deposited by thermal evaporation method. Two samples of ITO / Ag / NiO and ITO / Cu / NiO thin films were prepared which showed a weak crystaline peak on the Bragg plate (200) for Ag thin film and Bragg plate (111) for Cu thin film. The surface morphology of thin films displaied that the average size of NiO nanoparticles were about 14 nm and they had a uniform and regular growth. Also, optical studies indicate that the prepared three layers of ITO / Metal / NiO had good tra  arency of about 65% in the visible and infrared regions and absorption severely occurred in the ultraviolet region.

   In this work, we investigate optical nonlinear phenomena up to ninth order of hybrid molecule composed of a semiconductor quantum dot near a spherical metallic nanoparticle (SQD-MNP),and a hybrid nanosystem consisting of   two metallic nanoparticles and a semiconductor quantum dot (MNP-SQD-MNP) in the presence of an external field because for some applications higher-order nonlinearities are desired. On the other hand, by using the density matrix approach, the higher order nonlinear susceptibilities such as third, fifth, seventh and ninth order are obtained. We found that the non-linear optical response of these hybrid systems dependent on the interparticle distance, the size of particle, material of the nanoparticle and the dielectric constant of the inviroment. Also, the higher-order nonlinear refractive indices and absorption coefficient related to the nonlinear susceptibilities are derived and numerically discussed.   

   In this thesis we intend to investigate the optical absorption of bilayer   graphene with both simple and bernal stacking due to Hubbard model. the effects of electronic concentration and electronic interaction strength on optical absorption behavior have been analyzed. also bias voltage as an electric field perpendicular to the plane has bee   applied.   firstly density of states behavior has been studied and frequency behavior of electromagnetic absorption rate by bilayer   graphene based on electronic Green’s function is addressed.   Moreover, the Drude weight situation on frequency behavior of optical absorption is investigated. the effects of stacking type and electronic concentration on frequency behavior optical absorption are studied. firstly the situation of finite frequency peak of optical absorption curves service and variation of position and highest of peaks due to bias voltage, electronic concentration and electronic interaction has bee   discussed.

اين مطالعه با هدف بررسي غلظت گرد و غبار در جو و واداشت تابشي هواويز­هاانجام گرفته است. براي اين منظور دو رويداد طوفان گرد و غبار رخ داده در 12 الي 14آوريل سال 2011 (23 الي 25 فروردين سال 1390) و 16 الي 18 ژوئن 2016 (27 الي 30خرداد 1395) با بررسي داده­هاي ديد افقي 18 ايستگاه همديدي در سه استان كردستان،كرمانشاه و ايلام واقع در غرب كشور ايران انتخاب شده است. براي انجام محاسبات وشبيه سازي­ها از مدل عددي WRF-Chem و طرحواره GOCART استفاده شده است. براي شرايط آغازين و شرايط مرزي در اين شبيهسازي، از داده­هاي باز تحليل GFS مراكز مليپيش بيني محيطي (NCEP) استفاده گرديده است. مدل تحت دو شرايط با درنظر گرفتن اثر گرد وغبار بر تابش و بدون در نظر گرفتن اين اثر اجرا شده است. براي ارزيابي نتايج حاصلاز مدل، داده­هاي ديد افقي گزارش شده از چهار ايستگاه از سازمان هواشناسي كشور، باغلظت شبيه سازي شده توسط مدل مقايسه شده و همچنين غلظت                                       اندازه­گيريشده در سازمان محيط زيست كرمانشاه با غلظت گرد و غبار شبيه سازي شده توسط مدلمقايسه شده است. نتايج نشان مي­دهد كهاين مدل در شبيه سازي طوفان­هاي گرد و غبار داراي عملكرد قابل قبولي است. نتايجحاصل از شبيه سازي با مدل WRF-Chem در دوحالت مدل سازي حاكي از آن است كه ذرات گرد و غبار با جذب و پخش تابش سبب كاهش تابشموج كوتاه و كاهش شار گرماي محسوس و نهان در سطح زمين در مناطق تحت تاثير گرد وغبار شده است. از ديگر اثرات اين ذرات، افزايش تابش موج بلند در سطح زمين و كاهشتابش زمين تاب در بخش فوقاني جو است.