Solid State Chemistry
Instructor: Jihoon Choi
Welcome to
Solid State Chemistry
1st week
Course Goal:
composition
atomic arrangement +
performance = f (design, construction) choice of materials
properties
workmanship
Wiley, Materials Science and Engineering, 9th Ed.
Bonding, Structure, and Properties
The bonding and structure of substances determine their properties.
Bonding is the way the atoms are held together.
Structure is the way the atoms are arranged relative to each other.
1. The type of basic particles it contains.
The substance could contain atoms, ions or molecules. For example, if it
contains ions (such as sodium chloride), then it will conduct electricity
when molten or dissolved in water. To be soluble in water, the substance
must contain either ions or polar molecules.
2. The way the basic particles are bonded together.
The bonding may be ionic, covalent, metallic or weak intermolecular
forces. The stronger the bonds, the higher the melting/boiling point and the hardness of the substance.
1) silica (SiO 2 ) has strong covalent bonds linking every atom to several others forming a giant covalent structure. The atoms in silica are very hard to separate, and therefore it is very hard and difficult to melt.
2) Carbon dioxide on the other hand has strong covalent bonds between the C and O atoms, but only weak intermolecular forces between each CO 2
molecule. The molecules are therefore easily separated and so CO 2 has a
low melting/boiling point.
3. The way the particles are arranged relative to one another.
The particles may be arranged in 1-dimensional plains (such as in
polymers), 2-dimensional sheets (like clays) or in many different kind of 3-dimensional arrangements. Graphite is arranged in 2- dimesnional sheets, and so its layers can move past each other (think of writing
using a graphite pencil). Diamond, on the other hand, has a giant 3-
dimensional structure and is the hardest natural substance.
1. Crystal Structures and Crystal Chemistry
2. Crystal Defects, Non-stoichiometry and Solid Solutions 3. Synthesis, Processing and Fabrication Methods
4. Characterization Technique 5. Bonding in Solids
Table of Contents
Overview
• Materials Science and Engineering
• Processing and Fabrication
• Characterization
• Optimization of Properties and Testing
• Improved/ New Materials for Engineering Applications in Products and Devices
• Materials Chemistry
• Synthesis
• Structure Determination
• Physical Properties
• New Materials
Matter
Occupies space and possesses mass:
may exist as solid, liquid, or gas
Pure substance
Matter having an invariant chemical composition and distinct properties
Mixture
Matter consisting of two or more pure substances that retain their individual identities and can be separated by physical methods
Element
Fundamental substances; cannot be separated into simpler
Compound
Substance composed of two or more elements in fixed proportions;
Homogeneous
Mixture having a uniform composition and properties throughout (also called a
Heterogeneous
Mixture not uniform in composition and properties throughout
Molecular vs. Non-molecular
Characteristic
Comparison of the chemistries of molecular and non-molecular materials
Water Aluminium oxide
Formula
Are defects present?
Doping possibilities
Structure and its
determination Properties and
applications
Fixed, H2O Usually fixed, Al2O3, but for other oxides may be
variable, e.g. Fe1-xO Not allowed: missing or mis-placed
atoms give rise to different molecules Not possible without producing a different molecule
Molecular structure can be determined Usually structural information is complete
Controlled by molecular formula and configuration;
cannot be modified by doping.
Some properties may depend on molecular packing arrangements in crystals.
Unavoidable: small concentration of vacancies, interstitials and dislocations are always present Doping or solid solution formation allows control and optimization of properties, e.g.
ruby is Cr-doped Al2O3
Full characterization of a solid requires structural and compositional information across the length scales from local, to unit cell, nano and microscopes.
Properties/applications depend on crystal structure, defects, dopants, surface structure, particle size and whether the material is a powder, single crystal, film, etc. Consider the diverse applications of Al2O3
(films - insulators, powders - abrasive, porous solids - catalyst supports, with Cr3+ dopants (Ruby) - laser)
origins of chemistry
* ancient Egyptian hieroglyphs refer to khemeia:
chemical processes for embalming the dead
* khemeia expanded to other chemical processes,
especially, metals extraction
origins of chemistry
chemistry astronomy
gold silver copper
iron tin lead mercury
the sun the moon
Venus Mars Jupiter
Saturn
Mercury
John Dalton
1803
Other classifications:
* “triads” 1829, Dovereiner (Jena)
* “octaves” 1864, Newlands (London)
* “periodic table”
1869, Mendeleef (St. Petersburg)
1870, Meyer (Tubingen)
1834-1907
