Mehanical properties & strength of materials: The aim of this module is to introduce and train students on basic issues regarding the mechanical behaviour of materials and its description using continuum elasticity theory. Furthermore, the basic experimental methods for the determination of mechanical properties are also presented.
After the end of the course the students will have a unified picture of the optical properties of materials, how they are related with the structure of the materials (types of bonds, free carriers etc) and how they can be used for the study of the materials properties (e.g. relation of the electronic density of states with the absorption spectra) as well as for their applications.
Course Content (Syllabus)
- Mechanical Properties: 1. The concepts of stress and strain. Hooke’s law. 2. Poisson ratio, bulk modulus, strain energy, thermal strains. 3. The stress tensor. Normal and shear strain on an inclined plane. Two-dimensional stress state. Principal stresses in three dimensions. Analysis of the stress tensor. Graphical determination of the normal and shear stresses as a function of principal stresses using the Mohr approach. Inhomogeneous stress – Diffrential equations of equilibrium. 4. Description of the strain state at a point. Plane strain state. Compatibility of strains. 5. Stress-strain relation. 6. Elastic deformation energy in the 3D case. 7. Anisotropic elasticity. The generalized Ηοοke law. 8. Generalized plane stress and plane strain states. 9. Plastic deformation of materials. Plastic flow criteria. State equations in the plastic regime. 10. Torsion. 11. Ductile and brittle fracture. Griffith criterion. 12. Creep. 13. Hardness. 14. Experimental determination of mechanical properties (tension, bending, fracture toughness, creep, hardness).
- Electrical Properties: Electrical conductivity in metals, alloys, semiconductors and semiconductor devices. Superconductivity and superconductor devices. Dielectrics.
- Magnetic Properties: This module attempts to provide the necessary comprehension framework of magnetic materials and their properties both from fundamental and application point of view. Firstly, the different aspects of magnetism are discussed such as diamagnetism, paramagnetism, ferro(i)magnetism, superparmagnetism and superconductivity together with basic definitions of physical quantities in magnetism, magnetic units and conversions. What follows the introductory part is a brief introduction to micromagnetism and band magnetism in an effort for the students to become acquainted with standard magnetic theories. Then, material case studies are discussed based on their magnetic response. For example, this section includes hard magnetic materials, permanent magnets, amorphous, nanocrystalline, soft magnetic materials and also specific application materials such as giant magnetoresistance, giant magnetostriction and materials for magnetic and/or magneto-optic recording applications.
- Optical Properties and spectroscopy: General description of the optical properties of materials (semiconductors, metals, glasses) and optical coefficients. Light interaction with matter (Maxwell’s electromagnetic theory and semiclassical approach). Light absorption from materials (fundamental, excitonic, free carrier, lattice and defect related absorption). Light reflectivity from metals and semiconductors. Electro- and photoluminescence from semiconductors. Luminescence centers.
optical properties, absorption, luminescence, reflectivity, optical materials, semiconductors, glasses, metals
Course Bibliography (Eudoxus)
- «Οπτικός χαρακτηρισμός υλικών», Σημειώσεις, Σ. Βες
- Διαφάνειες μαθήματος, Μ. Κατσικίνη
- Μαγνητισμός και Μαγνητικά Υλικά (33074645), Μετάφραση, Μ. Αγγελακέρης, Κ. Γ. Ευθυμιάδης, Ο. Καλογήρου, COPY CITY ΕΠΕ
- Μηχανικές ιδιότητες υλικών (διαφάνειες), Γ. Δημητρακόπουλος.