60/69/27 - SOLID STATE PHYSICAL CHEMISTRY

Academic Year 2021/2022

Free text for the University

Objectives

Knowledge: At the end course the student will acquire the fundamental and advanced concepts of the Physical Chemistry of the solid state, both regarding 1) the structure of crystalline solids (crystallography and crystallochemistry) and structural defects. 2) the chemical-physical technique of structural investigation (also through laboratory practice) X-ray diffractometry for powders and its applications.
Skills: Through the acquired knowledge the student will be able to 1) understand the symbolism of space groups 2) index a powder X-ray diffraction pattern 3) identify the crystalline phases in a X-ray diffraction pattern 4) calculate the constant of cell from experimental data and the theoretical density 5) visualize the crystals using appropriate software 6) calculate the structure factor 7) perform a structural refinement and semi-quantitative analysis of an X-ray pattern
Behavior: The student will have to acquire 1) familiarity with the instrumentation and the acquisition of experimental data 2) the processing and interpretation of the experimental data 3) intellectual and practical autonomy in preparing and conducting the experiments 3) ability to report data with scientific rigor.

Prerequisites

Knowledge of chemistry, physics and mathematics acquired in the B.A. in Chemistry, Physics or Materials Science

Contents

Course contents

Theoretical part:
1) Introduction to the Course. The physical chemistry of the solid state.
2) Classification of crystalline solids. Classification of crystalline and non-crystalline solids. Glass state. Characterization of crystalline and amorphous solids. Monocrystals, polycrystals and nanocrystals, grain boundaries. Polymorphism and isomorphism. Classification based on the type of bond and Laing tetrahedron. Molecular and non-molecular solids.

3) crystallography. Unit cell, the 7 crystal systems, concept of crystal lattice, lattice planes, Miller indices and crystal shape. Lattice planes, directions, Bravais lattices, interplanar distances and relationships between Miller indices, interplanar distances and reciprocal lattice. Equivalent lattice planes, systematic absences in X-ray diffractograms, fractional coordinates, density in crystals.
Hermann-Mauguin nomenclature compared to Schonflies, crystalline classes, space groups and elements of translational symmetry. Space groups, international tables of crystallography, symbolism of space groups, representation of space groups.

4) Description of the crystal structure in real systems: close packing and space filling polyhedra.
Atomic packing factor. Eutactic structures. Interstitial sites, determination of the size of the interstices. Structures that can be described by dense packing: metals, alloys, ionic solids, reticular coving isolides, molecular solids.
Description of the structure by means of polyhedra that fill the space.

5) Reference structures: CCP (rock salt, zinc blende, antifluorite), HCP (Wurtzite, NiAs), CsCl, TiO2 (rutile), CdI2, CdCl2, ternary systems (perovskites and spinel oxides).
6) Visualization of 3D crystalline structures from .cif files (crystallographic Information file) using appropriate software (VESTA, Mercury) .
7) Characterization techniques of crystalline solids. Discovery of X-rays. Generation of X-rays. Interaction between matter and X-rays. Diffraction of X-rays. Bragg's law. Diffractometers and XRD pattern. Atomic scattering factor, structure factor.
8) Defects.

Laboratory (24 hours):
1. Sample preparation, collection and interpretation of powder X-ray diffraction data;
2. Visualization of a structure with an appropriate software;
3. Indexing of two unknown XRD patterns;
4. Qualitative analysis of a diffraction pattern;
5. Calculation of the structure factor;
6. Structural refinement and quantitative analysis of a mixture of compounds.

Teaching Methods

The lectures 4 CFU (32 hrs) will be accompanied by practical sessions (24 hrs).

Verification of learning

The exam for the Solid State Physics-Chemistry course includes:
1) two in itinere tests, each with multiple choice questions and exercises. The first test will concern the part of the program relating to crystallography; the second test will concern the part of the program relating to X-ray diffraction and the structure factor.
2) oral exam which will consist of a presentation on power point of about 25 minutes on the laboratory/calcultation part and on the description of an assigned scientific article and in questions on the presentation and on the theoretical part.

Texts

1) P. Atkins, De Paula, - Chimica FIsica- Eds. Zanichelli
2) A. West: Solid State Chemistry and its applications (Wiley)
3) Massimo Simonetta. Chimica Fisica. VOlume 2. Strutturistica Diffrattometrica. A. Mugnoli.
4) Walter Borchardt-Ott. Crystallography. An Introduction. Third edition

More Information

Lectures slides and further files will be provided.