Anode: The electrode of an electrochemical cell at which oxidation occurs; the positive terminal of an electrolytic cell.

Catalysis: A chemical reaction involving a material which promotes or increases the rate of the reaction without itself undergoing any permanent chemical change.

Cathode: The electrode of an electrochemical cell at which reduction occurs; the negative terminal of an electrolytic cell.

Co-firing: Simultaneous heat processing of multiple ceramics.

Doping: To treat with an impurity added in minute amounts to a pure substance to alter its properties.

Electrolyte: A nonmetallic electric conductor in which current is carried by the movement of ions.

Grain boundary resistance: The resistance which occurs at the interface between grains in a polycrystalline material.

Hybrid system: Power generating system which combines standard engines or gas turbines with solid oxide fuel cells.

Interconnect: The link between individual fuel cells.

Nanoscale: Of the order of 10^-9 meters in size.

N-type: A material in which electric charge which is carried by surplus electrons.

Oxidizing atmosphere: Gaseous environment in which an element or ion changes from a lower to a higher positive oxidation state (i.e., removes one or more electrons from an atom, ion, or molecule).

P-type: Material in which electric charge which is carried by a deficit of electrons, or holes.

Perovskite: An oxide having the same crystalline structure as the mineral, CaTiO₃, which is usually expressed as ABO₃. An ideal perovskite has a structure in which A (cation) is located at the center of the cubic unit cell, B (cation) is located at each corner and O (anion) is located at the center of each side.

Plasma spraying: A thermal spraying process in which the heat source is a jet of highly ionized gas (plasma). The coating material is melted in the plasma and propelled onto the substrate.

Reducing atmosphere: Gaseous environment in which an element or ion changes from a higher to a lower oxidation state (i.e., adds one or more electrons to an atom, ion or molecule).

Sinter: To densify by heating without complete melting.

Solid oxide: A hard ceramic compound of oxygen. In the case of fuel cells, the term refers to the electrolyte material, typically ZrO₂, the compound of zirconium metal and oxygen.

Tape casting: A ceramic forming process where a slurry is spread evenly onto a flat horizontal surface. After drying, the flexible, unfired tape can be cut, laminated, or shaped and then sintered.