UEET 102 Lecture 1 Introduction to Geologic Materials and Nanotechnology Review of terminology Nanotechnology and Geosciences Mineral formation and properties Crystal Growth Concept of a lattice Lecture 2 – Asbestos Form Minerals What is asbestos? Comparing and contrasting silicate structures Phyllosilicates and double chain silicates Asbestos health hazards Lecture 3 – Clays and Nanotechnology Crystal structure Crystal Morphology Properties due to morphology and crystal structure Use and case study
UEET 102 Lecture 1 – Introduction Review of terminology Nanotechnology and Geosciences Mineral formation and properties Crystal Growth Concept of a lattice
Nanotechnology in Geology • What are some applications of nanotechnology in geology (or: How can nanotechnology benefit from geology?). • Nanotechnology goes underground to boost oil production. • http://www.nanowerk.com/news/newsid=4084.php • Typically 60 percent of oil remains underground after primary, secondary and in some cases even tertiary recovery methods. • Will develop intelligent subsurface micro and nanosensors that can be injected into oil and gas reservoirs to help characterize the space (chemical and physical characteristics of existing oil and gas reservoirs) in three dimensions and improve the recovery of existing and new hydrocarbon resources.
Nanotechnology in Geology • Nanotechnology goes underground to boost oil production. • http://www.nanowerk.com/news/newsid=4084.php • Typically 60 percent of oil remains underground after primary, secondary and in some cases even tertiary recovery methods. • Will develop intelligent subsurface micro and nanosensors that can be injected into oil and gas reservoirs to help characterize the space (chemical and physical characteristics of existing oil and gas reservoirs) in three dimensions and improve the recovery of existing and new hydrocarbon resources.
Nanotechnology in Geology • Future nanotech tools made from clay • Rochester, N.Y.-based company has found a way to use Halloysite, a naturally occurring tubular clay, as an unobtrusive carrier in metals, perfumes and other substances (http://news.cnet.com/Future-nanotech-tools-made-from-clay/2100-11390_3-5914034.html). • Halloysite - Al2Si2O5(OH)4 • Nanotech clay armor creates fire resistant hard wearing latex emulsion paints (http://www.physorg.com/news104666616.html) • Laponite clays • Discs are 1 nm thick by 25 nm in diameter
Minerals • A mineralis a crystalline solid, formed by natural geological processes, with a specific chemical composition. • Form in the geosphere (most minerals), hydrosphere (e.g., halite), biosphere (e.g., calcite), and even the atmosphere (e.g., water ice, as snow) • Consistent and recognizable physical and chemical properties
Minerals • A mineral must meet the following criteria: • Crystalline solid • Atoms are arranged in a consistent and orderly geometric pattern • Forms through natural geological processes • Has a specific chemical composition • Rock-forming minerals • Although over 4000 minerals have been identified, only a few hundred are common enough to be generally important to geology (rock-forming minerals) • Over 90% of Earth’s crust is composed of minerals from only 5 groups (feldspars, pyroxenes, amphiboles, micas, quartz)
Important ions in minerals • When an atom loses or gains an electron to or from another atom it is called an ion. • Positively charged ions (loss of electron) are cations. • Negatively charged ions (gain of electron) are anions. anions charge cations charge Si +4 K +1 Ca +2 Na +1 Al +3 Mg +2 Fe +2 or +3 O −2
Bonding and Atomic Arrangement Atomic structure of diamond (C) Atomic structure of graphite (C)
Composition of Earth’s Crust • Minerals have crystalline structures • Regular 3-D arrangement of atoms • d-spacings range from 0.7 to 24 Å (0.07 to 2.4 nm).
Crystal Structure • Anions are generally larger than cations • Structure of mineral determined largely by how the anions are arranged and how the cations fit between them.
Silicate Structures • The Silicon-Oxygen tetrahedron • Strongly bonded silicate ion • Four oxygens surrounding a silicon ion • Basic structure (tetrahedra) for silicate minerals
Atomic Packing schemes 0.225
Silicate Structures • Sharing of O atoms in tetrahedra • The more shared O atoms per tetrahedron, the more complex the silicate structure
Silicate Structures • Sharing of O atoms in tetrahedra • Isolated tetrahedra (none shared) • Chain silicates (2 shared) • Double-chain silicates (alternating 2 and 3 shared) • Sheet silicates (3 shared) • Framework silicates (4 shared)
Non-silicate Minerals • Carbonates • Contain CO3 in their structures (e.g., calcite - CaCO3) • Sulfates • Contain SO4 in their structures (e.g., gypsum - CaSO4.2H2O) • Sulfides • Contain S (but no O) in their structures (e.g., pyrite - FeS2) • Oxides • Contain O, but not bonded to Si, C or S (e.g., hematite - Fe2O3) • Hydroxides • Contain OH, but not bonded to Si, C or S (e.g., brucite – Mg(OH)2) • Native elements • Composed entirely of one element (e.g., diamond - C; gold - Au)
Polymorphs • Minerals with the same chemical composition, but different structure. • diamond and graphite – C • andalusite, kyanite, and sillimanite – Al2SiO5
Mineral Properties • Color • Visible hue of a mineral • Streak • Color left behind when mineral is scraped on unglazed porcelain • Luster • Manner in which light reflects off surface of a mineral • Hardness • Scratch-resistance • Crystal form • External geometric form • Cleavage • Breakage along flat planes • Fracture • Irregular breakage • Specific gravity • Density relative to that of water • Magnetism • Attracted to magnet • Chemical reaction • Calcite fizzes in dilute HCl
Thought Exercise • Diamond and graphite are polymorphs of C, why are their properties so different? • What are the uses of diamond and graphite and why do they differ?
Lattice and Unit Cell Concepts • Are these Lego blocks the same? • Would a structure made of yellow blocks look the same as one made of yellow and white? • Can we define a large structure by looking at a smaller subset of the structure?
Lattice and Unit Cell Concepts • In 1784 René Haüy came up with an explanation for growth morphology and regular cleavage planes. • He proposed that crystals are built up from elementary parallelepipeds (a polyhedron consisting of three pairs of parallel faces) filling up spaces without gaps. • Parallelepipeds are idealized unit cells (the basic repeating unit that can generate an entire crystal structure). SEM image of europium-tellurium alloy
Crystal Morphology and Symmetry The symmetry of crystal faces is due to the ordered internal arrangement of atoms, this is called a lattice. In 2-dimensions a plane lattice consists of an orderly array of points defined by the spacing and angles between points. The array can be reproduced by specifying the distance and angle from point to point. This is referred to as translational symmetry. 3-dimensional arrays are called space lattices.
Let’s start at the beginning! • Nucleation – The onset of a phase transition in a small but chemically stable domain. • Bubbles of carbon dioxide nucleate shortly after the pressure is released from a container of carbonated liquid. Nucleation
Nucleation can occur in the interior of a uniform substance, by a process called homogeneous nucleation. • This requires a lot of energy and is fairly difficult. • Nucleation often occurs more easily at a pre-existing interface (heterogeneous nucleation), as happens on boiling chips and prexisting mineral phases. Nucleation
What is crystal growth and crystallization? • Crystal growth is part of the crystallization process and represents changing chemical stability. Crystal Growth
What is crystal growth and crystallization? • What factors can influence crystal growth? Crystal Growth • Pressure • +differential P • Temperature • ° of undercooling • Time/Growth Rate • Solution dynamics • Interface controls • All of this relative to equilibrium of a phase
What is crystal growth? Crystal Growth • Sketch to illustrate the effect of relative growth rates on the dominance of faces. Faces with the slowest growth rate dominate the morphology. (a) Slower growing faces p and s begin to dominate face m. (b) Faces p and s are dominate by slower growing face m.
Crystal Morphology and Symmetry Crystal faces develop along planes defined by the points in the lattice. All crystal faces must intersect atoms or molecules that make up the points. Observation: The frequency with which a given face in a crystal is observed is proportional to the density of lattice nodes along that plane A face is more commonly developed in a crystal if it intersects a larger number of lattice points. This is known as the Bravais Law.
Crystal Morphology • Because faces have a direct relationship to the internal structure, they must have a direct and consistent angular relationship to each other • Nicholas Steno (1669): Law of Constancy of Interfacial Angles Quartz
Thought Exercise • In what ways can we emphasize favorable nanotechnology properties through controls on crystal formation? • What can Geology teach us?