|SCIENTIFIC DISCIPLINARY SECTOR||CHIM/03|
AIMS AND CONTENT
Attainment of competences in the fields of crystal structure of solids (identification of symmetry elements, space group, etc. of a crystal structure; use of the International Tables of Crystallography, etc.) and correlation between crystal structure and bonding characteristics. Attainment of competences in the field of thermodynamic stability of solids, with reference to the crystal structure (thermodynamic modelling of the phases in mono- and multi-component systems), and use of software packages for the thermodynamic calculation of phase equilibria and phase diagrams of complex materials.
Lectures and practical exercises
Part 1 – Structure and bonding in crystalline solids (4 CFU)
Crystal structure, elementary cell, lattice planes, etc.; point symmetry elements and operations; crystallographic point groups in 2D and 3D; stereographic representation; space symmetry elements and operations; Bravais lattices in 2D and 3D; space groups in 2D and 3D; use of the “International Tables for Crystallography”; standard description of a crystal structure according to the “Pearson's Handbook”; coordination, coordination histogram and polyhedra, atomic environments; close packed crystal structures described as stacking of close packed planes (triangular, hexagonal and Kagomé, etc.); interstitial sites and their coordination; detailed description of selected intermetallic structures (hcp, fcc, bcc, dhcp and related ordered structures, Laves phases, further structures such as -Mn, CrFe, Fe7W6, CaCu5, etc.; Laves principles, theories of Engel-Brewer and Altmann-Coulson-Hume-Rothery.
Detailed description of selected tipically ionic structures (rock salt, sphalerite, wurtzite, fluorite, rutile, cristobalite, cuprite, spinel, perowskites, silicates, etc.); rationale of the ionic structures: ionic radii and Pauling rules; stability (Madelung energy, Born-Mayer and Kapustinskii equations, diagrams of Mooser-Pearson and Phillips-van Vechten, etc.).
Description of selected covalent structures (diamond, graphite, etc.).
Exercises: 1) Symmetry and space groups; 2) Closed packed structures and coordination; 3) Structure/bonding relations. The Ball&Sticks software and the “Pauling Files” database will be used.
Parte 2 – Stabilità termodinamica dei sistemi eterogenei (2 CFU)
Short overview on thermodynamics of heterogeneous systems (state variables and functions, extensive and intensive quantities, potentials, types of energy, characteristic equations, Gibbs-Duhem equation, phase rule, topology of the phase diagrams, ZPF lines, etc.)
Thermodynamic modelling of the solid phases: a) pure elements (thermodynamic functions, temperature and pressure dependence, magnetic contribution, etc.); b) stoichiometric compounds (functions of formation, etc.); c) disordered solutions (ideal solutions, regular and subregular solutions, Bragg-William approximation, Redlich-Kister polynomials, etc.); d) ordered solutions (compound energy formalism, sublattice models for different phases and constituents, extrapolations to third- and higher-order systems, etc.). Thermodynamic modelling and crystal structure.
The CALPHAD method for the calculation and prediction of phase equilibria and thermodynamic functions in multi-component systems: a) critical analysis of literature data; b) calculations based on existing databases; c) optimisation methodologies; d) extrapolation and prediction methodologies; e) application to alloy systems of technological interest.
Exercises: 1) calculation of binary and ternary phase diagrams; 2) calculation of thermodynamic properties in binary and ternary systems; 3) application of the thermodynamic calculations to systems of technological interest. The Thermo-Calc software package will be used.
Antony R. West, Basic Solid State Chemistry, Wiley
Ulrich Muller, Inorganic Structural Chemistry, Wiley
Hans Lukas, Suzana G. Fries, Bo Sundman, Computational Thermodynamics - The Calphad Method, Cambridge University Press
TEACHERS AND EXAM BOARD
GABRIELE CACCIAMANI (President)
SERENA DE NEGRI (President Substitute)
From October 16, 2023
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Evaluation of the exercise reports and final oral examination. Reports about the practical activity individually prepared by each student are assessed by the teacher. The average of the evaluations is considered in view of the final assessment. The oral examination is conducted by two teachers and it lasts not less than 30 minutes.
With the methods described above, given that at least one of the two teachers has many years of exams experience in the discipline, the commission is able to verify with high accuracy the achievement of the educational objectives of the teaching. When these are not reached, the student is invited to deepen the study and to make use of further explanations by the lecturer. The CCS guarantees the correspondence between the topics of the exam and those actually carried out during the course. To this end, the teacher in charge makes the detailed program public at the beginning of the lessons (on a site called the web room reserved for teachers and students of the University). Furthermore, at the end of the course, the register of lessons is published on a site reserved for CCS members and student representatives. In this way the students themselves can verify compliance with this rule.