Nano yapılı manyetik şeritlerin ve tozların yapısal ve manyetik özelliklerinin incelenmesi

Abstract

Bu tez calismasinda, ustun manyetik ozellik gosteren Nd13.4Fe68.6Co11.4B6.4Zr0.2 serit ve HDDR islemi uygulanmis toz orneklerinin, yapisal ve manyetik ozellikleri incelenmistir. Serit ornekler eriyik egirme sisteminde uretilmistir ve HDDR islemi ise Vaksis marka HDDR cihazinda yapilmistir. Orneklerin yapisal karakterizasyonlari Zeiss EVO-40 marka Taramali Elektron Mikroskobu (SEM) ve NT-MDT marka Atomik Kuvvet Mikroskobu (AKM) kullanilarak yapilmistir. Manyetik karakterizasyonlar ise NT-MDT marka Manyetik Kuvvet Mikroskobu (MKM), Quantum Design Fiziksel Ozellikler Olcum Sistemi (PPMS) ve LakeShore marka Gaussmetre ile yapilmistir. X-isini kirinim deneylerinden, serit orneginde tetragonal Nd2Fe14B ve rombohedral Nd2Fe17 fazinin bulundugu gozlenmistir. Serit orneginin x-isini toz kirinimi deseni kullanilarak William-Hall esitligi yardimi ile parcacik buyuklukleri 48.91 nm olarak hesaplanmistir. Serit ornegi AKM’de incelendiginde ise, parcacik buyuklugunun ortalama 51 nm oldugu gozlenmistir. Serit orneginin sicakliga bagli MKM olcumlerinde Nd2Fe14B fazi icin Curie sicakligi belirlenmis ve manyetik alan altindaki olcumlerde ise manyetik bolmelerdeki degisimler gozlenmistir. HDDR islemi uygulanmis toz orneklerin karakterizasyonlari sonucunda, HDDR isleminin en onemli parametrelerinin sicaklik ve DR zamani oldugu anlasilmistir. 580 °C’de DR zamani bir saat oldugunda neodmiyum (Nd) birikmesinin ve buna bagli olarak da miknatislanmanin arttigi gozlenmistir. Bu calismada elde edilen sonuclar; literaturdeki sonuclarla karsilastirmali olarak verilmistir.Abstract The aim of this study is to examine structural and magnetic properties of Nd13.4Fe68.6Co11.4B6.4Zr0.2 ribbon and applied HDDR process powder samples which show superior magnetic property. Ribbon samples were produced in melt spinner system and Vaksis Furnace was used for HDDR process. Structural characterization of samples was performed by using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray diffractometer. Magnetic characterization of samples was performed by using Magnetic Force Microscopy (MFM), Physical Properties Measurement System (PPMS) and Gaussmeter. Tetragonal Nd2Fe14B and rhombohedral Nd2Fe17 phases were observed in x-ray diffraction studies. By using x-ray powder diffraction pattern of ribbons, particle size was calculated about 48.91 nm with William-Hall equation. From AFM investigation a particle size of approximately 51 nm was obtained. The Curie temperature of Nd2Fe14B phase was determined by temperature dependent MFM measurements and the variations of magnetic domains structure were also observed in magnetic field dependent MFM measurements. According to characterizations of HDDR powder samples, it was noticed that temperature and DR time are the most important parameters for HDDR process. For the DR time of one hour at 580 °C, neodymium was accumulated in samples and because of that, magnetization increased. In this study, all obtained results were given by comparing with literature values.