LEARNING OUTCOMES

The course will introduce students to the knowledge of the structural chemistry of inorganic solids and of the structural (X-ray Diffraction), microstructural (optical and electronic microscopy), thermoanalytical (differential thermal analysis, thermogravimetry) and calorimetric characterization techniques for inorganic materials. The educational path has the aim of developing the ability to analyze critically experimental results in real cases.

AIMS AND LEARNING OUTCOMES

The educational path of the course will lead to the knowledge of different aspects of the chemistry of inorganic crystalline solids (i.e oxides and alloys) starting from the structure up to their characterization. In addition to the crystalline structure, microstructural features will be discussed in relation to the knowledge of two-component phase diagrams. Some concepts introduced in the course of Inorganic Chemistry 1 which will be studied, expanded and discussed in the classroom.

During the lectures, both Power Point and video presentations will be employed to increase the students’ engagement and improve their learning process. There will also be some practical activity in the classroom and visits to research laboratories to deepen the knowledge of the characterization techniques addressed during the theoretical lessons. In particular we will discuss X-ray diffraction techniques (Debye-Scherrer method, Bragg-Brentano automatic diffractometer), optical and electronic microscopy techniques with microprobe analysis, thermoanalytical (TA, DTA, TG) and calorimetric techniques (DSC , direct and indirect calorimetry). At the end of the course, the student will have to demonstrate the ability to analyze critically different experimental data concerning a "model" binary system such as the Mg-Cu, using the research material provided by the teacher.

TEACHING METHODS

Lectures (power point presentations, videos, discussion); classroom exercises in groups led by the teacher; visits to research laboratories in small groups with practical exercises guided by the teacher.

SYLLABUS/CONTENT

- Crystalline and amorphous solids. Bravais lattices. Pearson’ symbols. Miller Indices. Compact structures. Allotropy and Polymorphism. Symmetry elements and related symmetry operations, point groups, translational symmetry, spatial symmetry elements and related symmetry operations, space groups. Wychoff positions.

- Features of X-Rays. Thermionic effect. X-Ray production. Kα and Kβ radiation. Interaction X-Rays and matter. X-Ray Diffraction. Bragg's law. Description of the Debye-Scherrer method. Determination of the lattice parameters of a crystalline solid. Nelson-Riley equation. Bragg-Brentano automatic Diffractometer.

- Synthesis of NaxWO3 by ceramic method. Structure and properties of tungsten bronzes. Electrochromism.

- Phase diagrams. Gibbs Phase Rule. Solubility limits. Substitutional and interstitial solid solutions. Extension of one-phase fields. Intermetallic compounds and intermetallic phases. Correlation between Gibbs free energy curves and phase diagram. Lever rule. Tie-lines. Isomorphous phase diagram. Eutectic, monotectic, eutectoidal, peritectic and peritectoidal equilibria. Microstructure evolution on cooling. Coring phenomenon. Real examples of binary diagrams with eutectic equilibria. Description of eutectic phase diagrams for solvents. Fe-C system: description of perlite microstructures on cooling.

- Synthesis methods for alloys: arc furnace, induction furnace; crucibles. Preparation of Mg-Cu binary alloys: strategy and problems. Specimen preparation for metallographic observation.

- Optical microscopy: scheme. Rayleigh criterion: resolution limit, field depth. Bright-Field, Dark-Field and Polarized Light modes.

- Electron microscopy: scheme of the microscope. Primary beam: thermionic sources (W and LaB6 filament) and field emission gun. Interaction volume between primary beam and samples. Elastic and inelastic interactions: BSE and SE signals. Microanalysis by X-Ray: WDX and EDS detectors. Qualitative analysis via EDS detector. "ZAF" correction. Compositional maps in microanalysis.

- Thermoanalytical techniques. Thermocouples and Seebeck effect. Thermal analysis (TA) and Differential Thermal Analysis (DTA): principle and thermogram interpretation. Thermogravimetry (TGA): measurement parameters, instrument diagram, thermobalances. TGA and DTG curves. TGA applications. EGA-TGA and TGA-DTA analysis.

- Adiabatic, isothermal, isoperibolic, heat flow calorimeter. Measurement methods of thermal effects. Differential Scanning Calorimetry (DSC): power compensation DSC. Heat flow DSC (Calvet-type, 1D and 3D). Continuous and step-by-step method of measuring specific heat by DSC. Determination of phase transitions: examples of applications. Cp expression and Kopp-Neumann law.

- Calorimetric determination of formation enthalpy and mixing enthalpy. Direct and indirect calorimetry. Calvet-type dissolution calorimeter. High temperature drop calorimeter. Experimental variables and measurement reliability. Examples and applications.

RECOMMENDED READING/BIBLIOGRAPHY

J. Goldstein et al. “Scanning Electron Microscopy and X-Ray Microanalysis”, Kluwer Academic.

H. Rhines, "Phase Diagrams in Metallurgy", Mc Graw-Hill Book Company, p. 1-170.

W.D. Callister: Materials Science and Engineering, 6th ed.  Wiley.