Ph.D student in material chemistry.
sali@inorg.su.se
Qulification:
M.Sc Engineering in Material Processing Technology (KTH).
My C.V
This project presents a new group of glass materials based on nitrido-silicates, silicates where all of oxygen is replaced by nitrogen. They are non-existent in nature and historically the incentive to study crystalline nitrido-silicates was to make new materials with improved properties. Oxynitride glasses are special types of silicate glasses which occur in XSiON and XSiAlON systems where X is a modifying cation such as one of the alkali metals (Li,Na,K) the alkaline earths metals (Mg, Ca, Ba, Sr) or the rear earth lanthanides. Oxynitride glasses were originally discovered in the late 1960s.
Scientific and Engineering Principles:
Because of the folllowing reason research on new nitrido-silicate is important.
1. Their structures are different from those of oxysilicates and exhibit unique features.
The structure chemistry of nitrido-silicates is similar to that of oxy-silicates in that the structures exhibit various linkages of SiN4 tetrahedra, but a min significant difference is that N atoms in nitrido-silicate structure are also found to be bonded to three, or even four, Si atoms. Because of this, frameworks of linked SiN4 tetrahedra have in general a higher connectivity and are often more condensed.Unique features found in nitrido-silicate structures include edge-sharing SiN4 tetrahedra and Si atoms that are coordinated by an octahedron of N atoms. The atomic orderign of nitrido-silicates is thus a significant extension to that of oxo-silicates.
2. Nitrido-silicate compositions are, for a given connectivity of the Si tetrahedra, different from those of corresponding oxo-silicates.
This is simply due to the higher formal negative charge of -3 for N compared with -2 for O, but it has the important consequence that more, or higher valent, cations can be incorporated within a fixed framework.
3. Properties of nitrido-silicates are, for fundamental reasons, different from those of similar oxosilicates.
The properties are determined by the compounds chemical compositions and atomic structures. Nitrido-silicate frameworks are comparatively more connected, resulting in not only higher hardness and strength but also a higher rigidity of the framework.
Project aim:
The aim of this project is to synthesis and characterise new amorphous nitridosilicate towards magneto-optical applications
Project objectives:
1. Synthesis of new glasses in oxynitride systems.
2. To study the chemical composition of the oxynitride glass systems.
3. To evaluate the mechanical, optical and magnetical properties of the oxynitride glass systems.
4. To get rid of the black colour and to have a transparent glass in the oxynitride glass systems.
Methodology:
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