Glossary

Accuracy
How close the result of an analytical measurement comes to the true value. To determine accuracy the method of analysis usually needs to be calibrated with a known standard.
Adhesion
The joining of two different materials.
Angstrom Unit
Length unit equal to 1 x 10-10 meter or 1 x 10-8 centimeter used for atomic measurements and radiation wavelengths.
Astronomical Unit (AU
A measurement unit used in astronomy equal to the mean distance between the earth and the sun (149.6 x 109 m).
AstronomyThe science of studying the nature, magnitude, motions, distances, periods of revolution, etc. of celestial bodies (e.g., planets, stars, meteors, etc.).
Atomic Force Microscope (AFM)
One of several scanning probe microscopes used to determine the length scale and size of very small structures.
Atomic packing factor (APF)
The volume of atoms in a unit cell divided by the volume of the unit cell.
Base SI Units
See SI Units.
Blackbody
Description of a perfect radiator that only emits its own light and does not reflect outside light.
Body Centered Cubic (BCC)
Atomic packing structure in which one atom is in the center of the unit cell, the simple cubic. The center atom is in contact with eight identical corner atoms.
Brittle fracture
Failure of a material due to an applied stress in which there is no indication of material elongation prior to breaking.
Celsius
A scale used to measure temperature. The size of the degree increments is the same for both Celsius and Kelvin. Zero degrees Celsius corresponds to 273.15 K and/or the freezing temperature of water at 1 atmosphere.
Centimeter
1 x 10-2 meter.
Close-Packed Direction
Crystallographic direction in a unit cell in which atoms are co-linear.
Close-Packed Planes
Crystallographic planes that have the highest atomic packing factor.
Convective heat loss
Heat transfer that occurs when a fluid, such as air or water, is contacted with an object whose temperature is higher than that of the surroundings. The temperature of the fluid touching the object increases as thermal energy is removed from the object's surface.
Cross-sectional area/s
The cross-sectional area of the filament region locally (cm2).
Crystal structure
An atomic arrangement that has a repeated pattern over distance.
Crystallographic Equivalent Planes
Planes of atoms that have the same atomic packing number.
Crystalline
Atoms arranged in a periodic array over atomic distances.
Crystallinity of the filament
The amount of the filament's structure that has returned to crystal (repeated patterns) due to increased temperature.
Current flow
The measure of positive (hole) and negative (electron) charge movement. By convention, current flow is indicated with an arrow in the direction of positive charge flow.
Decimal Scale
A scale pertaining to multiples of tens.
Derived SI Units
See SI Units.
Drawn tungsten filaments
Tungsten ingot are pulled/stretched through a series of diamond dies until a desired cross sectional area is attained.
Ductile tungsten
Tungsten characterized by its ability to yield (stretch) at normal temperatures when a load is applied.
Electric current (i)
The measure of charge movement (i.e. dq=i dt), where i denotes current in units of amperes ( 1 ampere = 1 A = 1 coulomb/sec = 1 C/s).
Electric power (P)
Rate of conversion of electrical energy to another form, such as heat. For a resistor, such as a tungsten lightbulb filament, the power may be expressed as: P = i2R = V2/R.
Electrical resistance (R)
A measure of how easily charge flows through a material (i.e. we determine the resistance of a conductor between any two points by applying a potential difference volts, V, between those points and measuring the current, i, that results). 1 ohm = 1W = 1 volt/ampere = 1 V/A
Electromagnetic spectrum
A scale of various forms of radiation (e.g., visible light, microwaves, radio waves, x-rays, etc.) described in terms of the propagating energy's frequency and wavelength.
Electron
An elementary subatomic, negatively charged particle that orbits the nucleus of an atom and has a mass of 9.1096 x 10-28 grams.
Electron Microscope (EM)
A type of microscope that uses electromagnetic lenses to focus electrons on a material surface to make enlarged or magnified images of minute objects residing at relatively close distances from the imaging source of the microscope.
Energy state
The magnitude of energy of an electron.
Engineering applications
The use to which engineering concepts are applied.
Etch
A chemical process that removes surface atoms, usually by a strong acid.
Evacuated chamber
An enclosure pumped below atmospheric pressure. Molecules such as Nitrogen, Oxygen, and other gases have been removed via a purging mechanism.
Evaporation point
The point at which a material changes form from a liquid to a gas, usually denoted in units of temperature.
Face Centered Cubic (FCC)
An atomic packing structure in which an atom is present at the center of each face of the cubic cell and in contact with four identical corner atoms. The layered stacking sequences are ABCABC…. Each atom is surrounded by 12 neighboring atoms.
Fahrenheit
The English unit temperature scale used in the US and England. A scale smaller than the Celsius scale is used and zero is set to a different temperature.
Fluorescent light
Lighting produced by exciting gas atoms into higher energy states and then allowing them to release the gained energy as photons to create light. The gas is contained inside a glass tube with two metal caps/ends.
Grain boundaries
The interface between two similar crystals with different orientations. Atoms at grain boundaries have weaker bonds than atoms inside the matrix.
Ground energy
The lowest energy stationary state.
High impedance
A material's high electrical resistance makes the flow of current difficult. This results in giving off energy at the surface as heat.
Hybridization
A combination of two different entities to render the resulting hybrid material.
Instrument
A device used to measure or characterize one or more properties of an object.
Incandescence
The process by which a hot body emits visible light.
Inert chamber
An enclosure that has been filled with inert gases.
Inert gases
Gases that do not chemically react with other chemicals. Inert gases are typically used to flush/blanket materials in order to prevent oxygen or any other reactive gas from interacting with the material in a controlled environment. Column 8A of the periodic table includes the inert gases. Examples: Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rd).
Interstellar
Situated among the stars.
Isometrically
1) Characterized by equality of measure. 2) Crystallization system with three axes of equal length at right angles (90 degrees). There are nine planes of symmetry that are singly refracting.
Kelvin (K)
An absolute SI temperature scale used by physicists in which the degree scale increments are the same as Celsius. Zero K is known as absolute zero and 290 K is considered typical room temperature.
Lattice
A three-dimensional arrangement of atoms.
Lattice Coordinates
Numerical coordinates that describe a position of a point on or within a unit cell. They are usually fractions of the unit length of the axes a, b and c having the origin at a cell corner. For example, the center atom of a BCC structure has x, y and z coordinates all equal to ½. (½,½, ½)
Lattice parameter (a)
The edge length of a unit cell.
Lens
A transparent substance to some propagating medium (e.g., light rays, electrons, etc.) which has one or both surfaces curved to redirect or focus the propagating medium onto a surface.
Light Year
The distance light (electromagnetic radiation) can travel in one year. For light traveling in a vacuum, a light year is 9.4605 x 1015 meters or 0.33 parsecs.
Light Year Scale
An astronomical length scale based on the light year.
Local reactivity
The concentrated/focused reaction at a fixed point. Local reactivity usually occurs at grain boundaries because activation energies are lower there than in the bulk crystal.
London Dispersion Forces
A form of weak, secondary chemical bond (dipole-dipole) energy.
Materials
The matter or substances of which something is composed.
Mega-Parsec
1 x 106 Parsec.
Melting point
The point at which a material changes forms from a solid to a liquid, usually denoted in units of temperature.
Mesoscale
A nano-length scale ranging from 2 to 50 nm.
Meter (m)
1 x 102 of a centimeter; also defined as a multiple of the wavelength of light. 
Micrometer (µm)
1 x 10-6 meter (see micron).
Micron (µm)
1 x 10-6 meter or 0.000001 meter.
Microstructure
The structure of a material having a length scale ranging between 1 µm - 1 mm.
Microscope
An instrument consisting of a lens or combination of lenses and used to make enlarged or magnified images of minute objects residing at close distance away from the microscope.
Millimeter (mm)
1 x 103 meter.
Morphology
The science of form and arrangement of material structures.
Nanometer (nm)
1 x 10-9 meter or 0.000000001 meter.
Nanoscale
A length scale that covers the nanometer size of objects.
Ohm's Law
A derived model that outlines the relationship of voltage to current and resistance (V = iR).
Optical Microsope
A type of microscope that uses light and glass lenses to enlarge or magnify images of minute objects or features of an object.
Oxidation
The loss of an electron by an atom, ion or molecule, which leads to an increase in the oxidation number.
Oxidation number
A number assigned to each element in a compound in order to keep track of the electrons during a reaction. This is defined as the apparent electrical charge of an atom according to a set of rules.
Parsec (pc)
A unit for stellar distance equal to 3.26 light years or 206,265 astronomical units (AU).
Planck's Law
In 1900 Max Planck proposed a formula for the spectral radiancy that fit his experimental data perfectly for all wavelengths and temperatures.
Polycrystalline
A material that does not have any long-range repeated crystalline patterns.
Powers of Ten Scale
A succession of ascending and descending steps in multiples of ten.
Precision
The reproducibility of multiple measurements, regardless of accuracy. Precision is usually described by standard deviation, standard error or confidence interval.
Pressure
The force exerted on an object divided by the area over which the force is exerted. Common units are: 1 atmosphere (atm) = 6.805 x10-2 pounds per square inch = 1.316 x 10-2centimeters of mercury (cmHg) at 0°C, 1 torr = 1 millimeter of mercury (mmHg).
Properties
The physical and chemical characteristics of a material.
Refractive Index (RI)
The ratio of the speed of light in a vacuum and by the speed of light in the medium or material of interest. RI is determined by Snell's Law.
Residual air
Air remaining after a system/bulb has been pumped down via vacuum pump. Residual air inside a bulb usually shortens a bulb's lifetime.
Resolution
The smallest distance two points can be separated and yet be observed as two distinct entities. For example, the length scale limit in determining two distinct features of an object using the optical microscope is 0.2 micron, also known as the resolving power.
Resolving power
The ability of an optical device to produce separate images of two close objects.
Scale
A succession of ascending and descending steps (e.g., relative dimensions) used to assess the absolute or relative size of some property (e.g., length, surface area, volume) of an object.
Scanning Electron Microscope (SEM)
An analytical tool (microscope) that uses electrons for resolving media. The SEM is capable of greatly extending the limited magnification range of the optical microscope, which is only about 1500X to over 50,000X. The SEM makes it possible to obtain useful images of specimens that have a great deal of surface characteristics, such as those found on deeply etched specimens or fractured surfaces. The depth of field of the SEM can be as great as 300 times grated than the optical microscope.
Scanning Probe Microscope (SPM)
A scanning probe instrument used to make enlarged or magnified two and three-dimensional images of very minute objects residing at extremely close distances to the microscope probe. It allows one to determine the scale and size of various two and three-dimensional features on a material surface over the length scale ranging from microns to angstroms, and thus is able to provide information on the surface morphology.
Scanning Tunneling Microscope (STM)
A type of scanning probe instrument that uses electron current between probe and sample to make enlarged or magnified two and three-dimensional images of very minute objects residing at extremely close distances to the microscope probe.
Scientific notation
The representation of a number in the form A X 10n. The coefficient, A, is a number with a single nonzero digit to the left of the decimal point and n is an integer, or whole number.
SI Units
Standard international (SI) units of measurement (centimeter, gram, second or 'cgs' units).
Simple Cubic
The unit cell with one atom at each of the four corners. Each atom is in contact with six identical neighboring atoms.
Sinter
The process of heating a powdered material into a solid ingot, reducing the voids and/or porosity.
Size
Extent of length, surface, or volume of a material system.
Snell's Law
Relates the RI to the sine of the angle of incidence to the angle of refraction.
Speed of Light
2.9979 x 108 meters/second.
Sublimation
A process by which a solid changes state to a gas. The most common example of this is dry ice.
Surface
The extent of an outermost face or exterior boundary of an object.
Surface Area
The area of a material that represents its surface, usually measured in squared length units. For example, mm2 or ft2.
Telescope
An optical instrument consisting of a lens or combination of lenses used for making enlarged or magnified images of very large objects that reside at astronomical distances away from the telescope.
Tensile strength
A material property that measures a material's ability to resist breaking under applied strain.
Torr
SI unit for pressure (1 torr = 1 millimeter of mercury, mmHg).
Transmission Electron Microscope (TEM)
A type of electron microscope used to createenlarged or magnified images of the interior ultrastructure of very thin samples of material objects.
Tungsten crystal structure
The defining arrangement of tungsten atoms in a periodic array over atomic distances. Tungsten has a BCC structure.
Ultraviolet (UV) Light
Light outside the visible light spectrum of humans.
Unit cell
The fundamental structural unit of a crystal lattice which defines the crystal structure in terms of geometry and atom position.
Vacuum systems
Systems designed to generate pressures less then 1 atmosphere.
Volume
1) The amount of space occupied by an object or substance, usually measured in cubic length units. For example, cm3. The derived SI unit is liter (L), which is the capacity equal to the volume of 1 kg of water at 4 degrees Celsius. 2) The three-dimensional size or quantity of an object at a given length scale.
Wavelength (l)
The length or distance between the crest of one wave and the crest of the next or adjacent wave.
Wien's Law
Derived from Planck's Law, Wien's Law correlates temperature and wavelength.

 


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