Silver nanoparticles were prepared by the reduction of silver salt (silver nitrate AgNO3) solution using three different methods. The main differences between these methods is by belong to the reducing agent. It is found that the prepared silver nanoparticle was pure and stable for long time. UV-VIS spectrometry indicated formation of spherical silver nano particles. The surface plasmon resonance peaks in absorption spectra for silver colloidal solution showed that the absorption maximum range was at 380- 420 nm. The structures are confirmed by X-ray diffraction (XRD) and the crystallite size was determined from X-ray line broadening using the Scherrer's equation and it was about 32 nm.AFM measurements show that silver nano particles have the average diameter of 69.39 nm and 81.91 nm.

تم تحضيردقائقالفضه النانوية باستخدام ثلاثة طرق مختلفه وذلك باختزال نترات الفضة ((AgNO3.ان الاختلاف الرئيسي بين هذه الطرق هو استخدام العامل المختزل. دقائق الفضه النانويه المحضرة وجدت نقيه ومستقرّة لوقت الطويل.جهاز قياس الطيف اشارإلى تشكيل الدقائق النانوية الفضية الكرويه . قمم طيف الامتصاص للمحلول الفضّي اظهرت بأنّ الإمتصاص الأعظم كان في مدى(nm420- 380).التركيب لدقائق الفضه النانويه والحجم البلوري مؤكّدة بوسطة قياس حيود الاشعة السينية (XRD ) و بإستعمال معادلة Scherrer's كان حوالي 32nm.

The energy electron distribution function at a particular reduced electric field E/p (where E is the electric field and p is the gas pressure) for SF6+He and SF6+Ar mixtures has been studied. The distribution function has been calculated as a function of percentage mixture ratio (k) ranging from zero (pure SF6) to 100% (for He or Ar) at (E/p)crt. On the other stage, these distribution functions are also studied as a function of (k) at a particular (E/p)crt. under which the breakdown occurs for the same gas mixtures. The (E/p)crt calculation is adopted to explain the discrepancy of the distribution function for gas mixtures. It is also found that the distribution function for gas mixtures at (E/p)crt. and for any value of (k) are identical.

Gas discharge --- Boltzmann equation --- Effective ionization coefficient

In this research, AuNPs prepared by laser ablation in liquid (PLAL) at 750 mJ energy and 90 pulses. They have been added to N719-dye to form (Au-N719) mixture. TiO2 paste was deposited on FTO substrates and immersion in a mixture dye and AuNPs. DSSC was fabricated and enhancement of the DSSC conversion efficiency was achieved. Scanning electron microscope, X-ray diffraction and UV-Visible spectrophotometer were used to characterize and study the DSSC components. The UV-Vis data show high absorbance of AuNPs+N719 dye compared to N719 dye only; that means the immersion of AuNPs in the N719-dye solution tend to increase the total absorbance of the dye. The XRD pattern of AuNPs has diffraction peaks at 38.2° and 44.4° which can be indexed by (111), (200) plane of Au in the cubic phase. The shape and size distribution shows spherical AuNPs with particle size about (50-60) nm. The relative increase of short circuit current density after the adding gold nanoparticles was about 76%. In the same way the relative increase of open circuit voltage after adding gold nanoparticles was about 6.7%. The total photon-to-current energy conversion efficiency for the standard DSSC is 1.75 while its 2.8 of the enhanced DSSC with gold NPs.The maximum enhancement is about 60 % under illumination (105 mW/cm2, (AM1.5).

في هذاالبحث،تمت إضافة جزيئات الذهب التي تم تحضيرها باستخدام الليزر(750ملي جول وعدد نبضات 90نبضه) للصبغة ليكون خليط. معجون التيتانيوم المرسب على قاعده فلورين اوكسيد القصديرغمس في الخليط المكون من الصبغه وجسيمات الذهب النانويه. بعد ذلك تم تصنيع خليه الصبغه وتحسين كفائتها.مجهر الماسح الالكتروني تشتت الاشعه السينيه ومطياف المرئي- فوق البنفسجي استخدم لتشخيص ودراسه خصائص خليه الصبغه. وجد ان امتصاص خليط الصبغه وجسيمات الذهب النانويه اعلى من الصبغه لوحدها مما ادى الى زياده الامتصاصيه الكليه للصبغه بعد اضافه جسيمات الذهب النانويه. تشخيص الاشعه السينيه لجسيمات الذهب النانويه كشفت عن مستووين (200) و (111) لزاوايا الحيود وهي (38.2 و44.4) وبطور المكعب. توزيع جسيمات الذهب النانويه كرويه الشكل وذات حجم يترواح بين (50 -60) نانوميتر . الزياده النسيبه في تيار الدائره القصيره بعد اضافه جسيمات الذهب النانويه كانت76%. بنفس الطريقه فولطيه الدائره المفتوحه بعد اضافه جسيمات الذهب النانويه كانت 6.7%. الكفاءه لخليه الصبغه النموذجيه هي 1.57 لكن خليه الصبغه المحسنه كانت 2.8 باستخدام ضوء الشمس كمصدر اضاءه بقدره 105ملي واط سم2 وكتله هواء 1.5 وحققت تحسين بلكفاءه بمقدار60%.

PLAL --- DSSC --- AuNps --- N719-dye

Nanocrystalline multiphase CaCu3Ti4O12 (CCTO) was prepared using CaNO2.6H2O , CuNO2.2H2O , TiO 2and oxalic acide. Effect of pH has been studied from the phase formation behavior of the CCTO powder wherein the pH was varied 3, 5, 6, 7, 8, and 11. It is found that the multiphase are content a TiO2, CuO, CaTiO3 and CCTO as shown on XRD result. The crystallite size was about 60 nm according to XRD result using Scherrer,s equation. The color of prepared (CCTO) powder was light blue at room temperature, then it changes to brown and dark brown when annealing at 800oC and 900oC respectively which can attributed to demerit second phase. Carbonate groups were observed in the prepared powder calcined 900oC at pH equals to 6 and 7 that showed at FTIR spectroscopy as a vibration peaks. These groups were not showed in powder calcined 900oC at pH equals to 5. FTIR and XRD results have confirmed that the pH value for preparing multi phases CCTO is 5.

Lithium doped Nickel-Zinc ferrite material with chemical formula Ni0.9−2x Zn0.1LixFe2+xO4, where x is the ratio of lithium ions Li+ (x = 0, 0.01, 0.02, 0.03 and 0.04) prepared by using sol-gel auto combustion technique. X-ray diffraction results showed that the material have pure cubic spinal structure with space group Fd-3m. The experimental values of the lattice constant (aexp) were decreased from 8.39 to 8.35 nm with doped Li ions. It was found that the decreasing of the crystallite size with addition of lithium ions concentration. The radius of tetrahedral (rtet) and octahedral (roct) site were computed from cation distribution. SEM images have been taken to show the morphology of compound. The dielectric parameters [dissipation factor (Df), the dielectric constant (Ԑ') and a.c. conductivity (σac)] of spinal ferrite nano-powder have been measured. The dielectric parameters as a function of concentration have been studied for ferrite synthesis. The saturation of magnetization (Ms), remiensis (Mr) and coersivity (Hc) were found from hysteresis loop. The Ms and Hc varied from 36.47 to 66.15 emu/gm and 103 to 133 Oe for ferrite synthesis, respectively.

تم تحضير نيكل-زنك فرايت المشوب بأيونات الليثيوم باستخدام تقنية الاحتراق التلقائي (sol-gel auto combustion). من طيف الاشعة السينية تم حساب القيم العملية لثابت الشبيكة (aexp) حيث وجد انه يقل مع إضافة ايونات الليثيوم بالإضافة الى النقصان في حجم البلورة. تم دراسة الخصائص الكهربائية كدالة للتردد ولقد وجد ان ثابت العزل والتوصيلية تقل مع زيادة التردد لكل العينات. لكن عند دراستها كدالة للتركيز فقد وجد ان هذه القيم تزداد مع اضافة الليثيوم. من حلقة الهسترة تم تحديد تمغنط الاشباع MS وحساب القيم العملية والنظرية لعزوم التمغنط.

Lithium ferrite --- dielectric constant --- magnetic moment.