Doğal Ve Yapay Mezokristaller Üzerine Bir Çalışma: Sentez, Yapısal Karakterizasyon ve Fiziksel Özellik Araştırmaları

Abstract

Crystallization and crystal growth processes are scientifically and technologically important. Because the feature of many solid materials depend on crystal structure, crystal shape and crystallite quality. Crystallization stages that occur by self-orientation of atomic and molecular bonding starting from atomic structure to macroscopic structure, are easily affected from external physical parameters. The mesocrystal structures which are defined as the new and up-to-date material class for the scientific and technological studies include many parallel or vertically oriented / different crystal and amorfous structure layers over curvature surfaces. These structures and layers which have different features than crystal and amorfous give superior capabilities to materials. In the content of this thesis, the investigations were focused on the natural and newly synthesized artificial mesocrystals. Sea urchins as natural mesocrystals and, Azurith and Malahit crystals which grow on rocks in the form of mesocrystal structures were studied. The samples that are tried to be synthesized artificially are: the polymer composite covered sea urchin spine/shell (biologic structure + membrane layer) and the hydroxyapatite formation growth on the surface of the sea urchin shell. In another important section of the thesis, growing ability of the antibacterial organic crystal (2,2'-[(1E,2E)-hydrazine-1,2-diylidenedi(1E)eth-1-yl-1-ylidene] diphenol) on silver, zirconium oxide, cobalt and titanium nanopowders were also examined. It was obtained that, the studied crystal structure which has magnetic property can form a mesocrystal structure with the silver nanopowder which has diamagnetic property. At this stage, the studies were focused on the sea urchines as the best natural mesocrystals, because of their perfect mesocrystal models. Structures are tried to be examined by using Small Angle X-ray Scattering (SAXS), X-ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) experimental methods. At the end of the study, it is concluded that organic compound which have bioactive and magnetic features can form mesocrystal structure with silver (Ag) nanoparticles; sea urchin spines and shell structures can be examined more detailed by using complementary modern experimental methods; polymer and hydroxyapatite materials can be also used in the formation of mesocrystals. Additionally, electric current and voltage characteristic of the new prepared mesocrystal form (including sea urchin spine and original membrane polymer) was measured as evidence of electrical conductivity. It is also found that these type mesocrystals prepared on the biological substrate may be used as new coaxial cylindrical conductor.