Ceramics Exam 1 Review

Piezeolectric Behavior

A material that functions as an electrical to mechanical displacement transformer. A force on the material can shift the extent of the offset of an ion, altering the potential difference across the material, thus acting as a force transducer. An applied electrical potential will cause a slight shift in the position of an ion in the unit cell, resulting in a mechanical distortion.

Paulings Electronegativity Scale

The extent to which + and - charges are separated (measured via capacitance) and is an indicator of percent ionic character.

Most common elements in Earth’s crust (in descending order)

O, Si, Al, Fe, Ca, Na, K, Mg

Tectonic Plate Divergence

A trench forms between the plates reducing pressure on mantle rock. The reduced pressure allows the rock to melt forming a magma pool at a lower density than the surrounding rock. The magma pool then rises to fill the trench. If an ocean is above it, then additional ocean floor is formed. If two landmasses diverge then it forms a new span of ocean between them.

Tectonic Plate Convergence

Ocean plates subduct beneath a landmass due to the land mass being a lower density. This draws ocean water into the mantle and the supercritical fluid mixes with the rock compositions forming molten compounds. The buoyant liquid can yield an arc of volcanoes. When two ocean plates converge, one of them subducts and forms an arc of volcanic islands in the ocean over the subducted plate. When two landmasses converge, neither plates subducts instead material piles up to higher elevations and forms a mountain range.

Igneous Rock

Rock formed from the solidification of magma from its origins in the upper mantle.

Extrusive Igneous Rock

Igneous rock formed from quickly cooling magma that has risen to the surface via volcanic action. Individual phases are of microscopic size.

Intrusive/Plutonic Igneous Rock

Igneous rock formed from magma that buoyantly percolates through existing rock above it, solidifies slowly, and yields course-sized mineral phases visible to the eye.

Periodite

MgO-FeO-SiO₂

Olivine

Binary solid solution between 2MgO•SiO₂ and 2FeO•SiO₂

Pyroxene

(Mg,Fe)O•SiO₂

Malfic

Magnesium and iron rich. Makes up the ocean floor.

Basalt

The composition of the sea floor. Has a composition closer to original periodite (malfic).

Felsic

Rich in feldspar and silica. Makes up landmasses.

Granite

Rock formed from the liquid phase of the MgO, FeO, SiO₂ phase diagram and is relatively deficient in MgO and FeO (felsic). Less dense than basalt.

Albite

NaAlSi₃O₈

Anorthite

CaAl₂Si₂O₈

Plagioclase Feldspars

A continuous solid solution between albite and anorthite. Tend to co-precipitate in malfic deposits.

Calcium-Rich Plagioclase

Crystallizes at higher temperatures and is typically found with malfic deposits.

Sodium-Rich Plagioclase

Crystallizes with more felsic compounds.

Potassium

Tends to remain in the liquid phase as more malfic phases precipitate. Ultimately crystallizes into more felsic phases in granite, orthoclause, quartz, and mica.

Orthoclause

Potassium feldspar: KAlSi₃O₈

Quartz

SiO₂

Island Silicates

Isolate tetrahedra separated by cations. Minerals with isolated tetrahedral pairs or rings also occur.

Zircon

ZrSiO₄

Chain Silicates

Can be single-chain (pyroxenes) or double-chain (amphiboles). These chains are connected by other cations to form a 3-dimensional chain structure.

Enstatite

MgSiO₃

Sheet Silicates

Three or four oxygen in a silica tetrahedron attached to Si⁴⁺ ions in other tetrahedra. Examples: kaolinite, mica, and talc.

Framework Silicates

Consist of a three-dimensional network of SiO₄^4- tetrahedra. Example: alpha quartz

Feldspar Minerals

Based on substituting Al³⁺ for ¼ to ½ of the Si⁴⁺, and positioning K⁺, Na⁺, or Ca²⁺ cations between SiO₄^4- tetrahedra to maintain space charge neutrality.

Zeolites

Framework silicates that which sustain wide channels through the centers of the unit cells. Used for molecular sieves, can function as a desiccant, and can facilitate water softening.

Modenite

NaAlSi₅O₁₂•3H₂O

Pegmatites

Large natural single crystals, usually associated with granites. As plutonic magma crystallizes, the remaining fluid becomes rich in insoluable or volatile rare elements and high pressure steam. When injected into fissures and veins, depressurization causes precipitation forming large single crystals.

Gemstones

Valuable, rare crystals with a hardness of at least 7.

Moh’s Hardness Scale

From a scale of 1-10, it measures the hardness (how easily it will scratch or plastically deform on a fine scale) of minerals.

Beryl

Al₂Be₃Si₆O₁₈. Pegmatite minerals

Emeralds

Green or blue-green beryl gemstones containing Cr³⁺ or V⁵⁺ dopants.

Aquamarines

Green-blue or light blue beryl gemstones containing Fe²⁺ dopants.

Heliodors

Green-blue or light blue beryl gemstones containing Fe³⁺ dopants.

Amethyst

Alpha quartz doped with Fe³⁺ and Al³⁺. Nuclear radiation then converts Fe³⁺ to Fe⁴⁺

Opal

A collection of microscopic cristiobalite dispersed in hydrates silica glass

Sapphire

Synthetic clear transparent single crystal Al₂O₃

Rubies

Red sapphires due to Cr³⁺ impurities

Muscovite

KAl₂(AlSi₃O₁₀)(OH)₂

Bauxite

Formed via weathering of igneous silicate rocks in well-drained tropical climates

Gibbsite

Al(OH)₃

Diaspore

αAlO(OH)

Boehmite

γAlO(OH)

LImestone

CaCO₃

Dolomite

CaMg(CO₃)₂

Sediments

Sedimentary minerals are formed from the weathering of igneous rock. They are then transported downslope by erosional agents to form sediments.

Lithification

Compaction and cementation

Sedimentary Rock

The overburden of weight as sediments build up can result in lithification to form sedimentary rock

Silt

Finely divided quartz and feldspar.

Shale

Lithified clay and silt. Relatively weak. Liquid-impermeable

Sandstone

Lithified silica and feldspar. It undergoes less extensive compaction, but more extensive cementation in which particles are bonded together through aqueous solution and precipitation.

Slate and Shist

Metamorphized shale

Marble

Metamorphized limestone and/or dolomite

Metamorphism of Sedimentary rock and minerals

Sedimentary rock can be metamorphized through the action of elevated temperature and pressure into rock of altered composition, structure, and microstructure. 3 way to metamorphize sedimentary minerals: 1. Sedimentary rocks heated in the vicinity of buoyant magma pools. 2. Converging tectonic plates causing sedimentary minerals in an oceanic plate to subduct to high temperature high pressure depths with the inclusion of supercritical fluid. 3. Mountain-building tectonic plates within a landmass. Within the deep roots of those mountains, sedimentary minerals metamorphize under elevated temperature and pressure.

Kaolinite

The most abundant of the known kaolin minerals. Sheets of silica bonded to modified gibbsite. Layers cohere via hydrogen bonds. Layers are superimposed with a slight distortion causing strain to build up over multiple layers which limits the thickness of a kaolinite particle to about 200 sheets. This yields particles in the form of platelets, thin in the direction perpendicular to the sheets. Defined by two layer structures

Halloysite

Kaolin where the stacking is random. Water molecules lodge between the sheets. Stacking stress cuases platelets to roll up into fibers.

Chrysotile/Asbestos

Mg₃Si₂O₅(OH)₂. Behaves similarly to halloysite.

Montmorillonite

Structures based on a repeating stacking sequence of three layers. They can be described based on pyrophillite or talc.

Pyrophillite

Al₂Si₂O₁₀(OH)₂. Based on a modified gibbsite sheet sandwiched between silica sheets. Results in adjacent silica sheets.

Talc

Mg₃Si₄O₁₀(OH)₂. moisture-absorbing, friction-reducing, and thickening-inducing powder. Shears extremely easily.

Montmorillonites (clay structure family)

Form via lattice substitutions

Illites

Clays based on the structure of micas. Result from the replacement of non-exchangeable cations in mica.

China Clays

Residual clays: they reide at the location at which they are formed. Also called kaolins.

Sodium Silicate

NaSiO₃. Additions facilitate clay particles forming charged surface so that they mutually repel.

Ball Clays

Sedimentary clays: they are transported from where they form to settling points at the bottoms of lakes and rivers. Finer particle size than China clays. Typically composed of disordered kaolinite with minor amounts of montmorillonite and illite.

Bentonites

75% montmorillonite clays. Undergo substantial swelling in response to water,

Metakaolin

Al₂O₃•2SiO₂. Formed from an endothermic phase transition of kaolinite at 450-500 C where the kaolinite loses its structural water

Metastable Spinel Structure

2Al₂O₃•3SiO₂ + SiO₂. Exothermic phase transformation of metakaolin at 980 C

Psuedo-Mullite

Al₂O₃•SiO₂ + SiO₂. Transformed from metastable spinel with increasing temperature

Mullite

3Al₂O₃•2SiO₂ + SiO₂. Transforms from psuedo-mullite