Nanomateryallerin erime sürecindeki fiziksel özelliklerinin moleküler dinamik simülasyonu ile incelenmesi
Küçük Resim Yok
Tarih
2011
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Trakya Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu tezde, metalik nanomateryallerin (NM) erime sürecindeki fiziksel özelliklerinin ebat, şekil ve boyuta bağlılığı ile atomik, yapısal ve dinamik özelliklerindeki değişim moleküler dinamik simülasyon (MD) metodu kullanılarak incelenmiştir.Bu amaçla 0 boyutlu (0D) nanoparçacık, 1 boyutlu (1D) nanotel ve 2 boyutlu (2D) nanofilm olmak üzere üç farklı nanoyapı ile çalışılmıştır. Model olarak, 0D' lu küresel ve Truncated-octahedral (TO) nanoparçacıkları ile 1D' lu silindirik ve kare nanotelleri kullanılmıştır. İki bileşenli NM için alaşım düzeninde ve kor/kabuk (core/shell) yapısındaki nanoparçacıkları ile nanotelleri ele alınmış, erime noktası civarındaki bazı termodinamik, yapısal ve atomik dinamik özellikleri üzerine alaşım konsantrasyonunun etkisi araştırılmıştır. Tek bileşenli Au, Cu, Ag, Pt, V ve Sn NM ile çalışılmış, iki bileşenli Cu-Au ve Au-Pt sistemlerine odaklanılmıştır. MD simülasyon çalışmalarında atomlar-arası etkileşmeleri tanımlamak için çok cisimli gömülü atom model potansiyelleri ile modifiye analitik gömülü atom potansiyelleri kullanılmıştır.Hesaplanan erime sıcaklıklarının nanomateryalin ebadına, şekline ve boyutuna bağlı olarak değiştiği gözlenmiştir. Nanomateryalin ebadı artıkça erime sıcaklığı da artmaktadır. Küresel şekilli nanoparçacıkların erime sıcaklığı, TO şekilli nanoparçacıklara göre yüksektir. Nanomateryalin boyuta bağlı erime sıcaklığının, nanoyapının boyutu ile doğru orantılı olduğu bulunmuştur. Ayrıca, nanomateryallerin hesaplanan fiziksel özelliklerinin, nanomateryallerin ebat, boyut ve şekline bağlı erimesinin teorik model ve deney sonuçları ile uyum içerisinde olduğu gözlenmiştir.
In this thesis, size, shape and dimensionality effect on the physical properties of nanomaterials during melting processes and their atomic structural and dynamic properties have been investigated by molecular dynamics (MD) simulation method.For this purpose, it has been studied with three different nanostructures which known as zero dimension (0D) nanoparticles (NPs), one dimension (1D) nanowires (NWs), two dimensions (2D) nanofilms (NFs). The spherical and truncated-octahedron (TO) NPs have been chosen as a model for 0D nanostructures although cylindrical and square shaped NWs used for one dimensional systems. The binary nanomaterials have been handled as nanoparticles and nanowires in the order of alloying and core/shell form, and the alloy composition effect on some thermodynamic, structural and atomic dynamics properties at their near melting points have been also examined. It has been studied with pure Au, Cu, Ag, Pt, V, Sn systems and focused on binary Cu-Au, Au-Pt systems. In MD simulations, the many-body embedded atom model potentials and modified analytic embedded atom potentials have been applied to define an interactions between atomic species in the nanomaterials.It has been observed that the calculated melting temperatures are related with the size, shape and dimension of nanomaterials. As the size of nanomaterial increases, the melting temperature increases. The melting temperature of spherical nanoparticles is higher than that of TO shaped nanoparticles. It has been found that the melting temperature of nanomaterials show a linear behavior with the dimension of nanomaterials. Furthemore, it has been seen that the calculated physical properties are in good agreement with both experimental and theoretical model results which explain the size, shape and dimensionilty effects of nanomaterials.
In this thesis, size, shape and dimensionality effect on the physical properties of nanomaterials during melting processes and their atomic structural and dynamic properties have been investigated by molecular dynamics (MD) simulation method.For this purpose, it has been studied with three different nanostructures which known as zero dimension (0D) nanoparticles (NPs), one dimension (1D) nanowires (NWs), two dimensions (2D) nanofilms (NFs). The spherical and truncated-octahedron (TO) NPs have been chosen as a model for 0D nanostructures although cylindrical and square shaped NWs used for one dimensional systems. The binary nanomaterials have been handled as nanoparticles and nanowires in the order of alloying and core/shell form, and the alloy composition effect on some thermodynamic, structural and atomic dynamics properties at their near melting points have been also examined. It has been studied with pure Au, Cu, Ag, Pt, V, Sn systems and focused on binary Cu-Au, Au-Pt systems. In MD simulations, the many-body embedded atom model potentials and modified analytic embedded atom potentials have been applied to define an interactions between atomic species in the nanomaterials.It has been observed that the calculated melting temperatures are related with the size, shape and dimension of nanomaterials. As the size of nanomaterial increases, the melting temperature increases. The melting temperature of spherical nanoparticles is higher than that of TO shaped nanoparticles. It has been found that the melting temperature of nanomaterials show a linear behavior with the dimension of nanomaterials. Furthemore, it has been seen that the calculated physical properties are in good agreement with both experimental and theoretical model results which explain the size, shape and dimensionilty effects of nanomaterials.
Açıklama
Doktora
Anahtar Kelimeler
Fizik ve Fizik Mühendisliği, Physics and Physics Engineering
