پديد آورنده :
اصلي بيكي، باقر
عنوان :
مطالعه ي ويژگيهاي مغناطيسي نانو ذرات فريت MnFe2O4 و بررسي تاثير آلايش نقره و كبالت بر روي آن
محل تحصيل :
اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك
صفحه شمار :
دوازده،165ص.: مصور،جدول،نمودار
يادداشت :
ص.ع.به فارسي و انگليسي
استاد راهنما :
پرويز كاملي
استاد مشاور :
هادي سلامتي
توصيفگر ها :
فريت اسپيلني , ابر پارامغناطيس , شيشه ي ابر اسپيني , پذير رفتاري متناوب , توان اتلافي گرمايي
تاريخ نمايه سازي :
11/10/92
استاد داور :
مرتضي مظفري، علي قاسمي، فرهاد شهبازي
كد ايرانداك :
ID588 دكتري
چكيده فارسي :
به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي
چكيده انگليسي :
167 Studying the magnetic properties of MnFe2O4 nanoparticles and the effect of Ag and Co doping on its properties Student name Bagher Aslibeiki Email address b aslibeiki@ph iut ac ir Date of submission 2013 11 06 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree Ph D Language Farsi Supervisor Dr Parviz Kameli kameli@cc iut ac ir Abstract In this project the structural and magnetic properties of manganese ferrite nanoparticles MnFe2O4 have been investigated Large scale synthesis method was one of the aims of this study In the first part of this work the nanoparticles were prepared successfully by using thermal decomposition of metal nitrates in presence of citric acid Although the XRD analysis confirmed crystalline structure of samples without noticeable trace of impurity phases the saturation magnetization Ms was smaller than that for bulk Mn Ferrite Such a decrease in Ms is mainly arised from the presence of dead layer in the shell of nanoparticle Because of agglomeration and direct contact of nanoparticles these samples are highly interacting At low temperature these interactions lead to frustrated super spin galss SSG state AC magnetic susceptibility at different frequencies and memory experiments confirmed SSG behavior of these samples In the following by grinding the aggregates compaction of nanoparticles was decreased and SSG behavior almost diminished In the next section of this project the effect of Ag and Co doping on the structural and magnetic properties of MnFe2O4 nanoparticles have been investigated Because of non magnetic nature of Ag1 cations doping of silver in spinel structure leads to reduction in magnetic response of sample to external applied fields Decrease in crystallite s size with increase in Ag doping level and consequently increase in surface volume ratio is the main reason of decrease in Ms Also in this section we showed that there is a solubility limit in substitution of Ag1 in iron and manganese sites because of larger ionic radius of Ag1 cations than Fe3 and Mn2 Metallic silver phase was formed at higher doping level On the other hand by doping the highly anisotropic Co2 in manganese sites we found that Ms of samples is not influenced while the coersivity showed a remarkable increase by increasing the Co content in the samples In the last section we focused on improving the quality of samples by change in sample preparation method We used Tri ethylene glycol TEG as a solvent of metal nitrates in order to increase the saturation magnetization and decrease the contribution of disordered surface spins It was found that molecular coating of nanoparticles decreases the surface spins canting by improving the metal oxygen metal bond in the interface of nanoparticles As same as thermal decomposition this method can be applied for large scale syntheses of PDF created with pdfFactory trial version www pdffactory com
استاد راهنما :
پرويز كاملي
استاد مشاور :
هادي سلامتي
استاد داور :
مرتضي مظفري، علي قاسمي، فرهاد شهبازي
