Structure of Crystalline Solids Flashcards
It is a material in which its atoms area arranged in a repeating or periodic array
Crystalline Material
Material wherein long range order is absent
Non-Crystalline
What is another term for non-crystalline?
Amorphous
It refers to the manner in which atoms, ions or molecules are spatially arranged
Crystal Structure
It means a three dimensional array of points coinciding with atom positions
Lattice
It is the basic structural unit or building block of the crystal structure
Unit Cell
It is the smallest entity which is repeated in three dimensions.
Unit Cell
Most unit cells are called ____
Parallelepipeds
Structures that tend to have lower energies
Dense, ordered packing
Has atoms that are periodically packed
Crystalline Materials
Has atoms that have no periodic packing
Non Crystalline Materials
The atomic bonding in this group of materials is nondirectional in nature
Metallic Crystal Structures
It refers to the nearest neighbor or touching atoms
Coordination Number
It is the volume of atoms per unit cell/volume of unit cell
Atomic Packing Factor
It is the sum of the sphere volumes of all atoms within a unit cell divided by the unit cell volume
Atomic Packing Factor
It is rare due to its low packing density
Simple Cubic Structure
A unit cell that consists of atoms situated only at the corners of the cube
Simple Cubic Structure
Coordination Number of Simple Cubic
6
APF of Simple Cubic
0.52
How many atoms are there in a unit cell of simple cubic?
1 atom
The only element with a simple cubic structure
Polonium
It has a cubic unit cell with atoms located at all eight corners and a single atom at the cube center
Body-Centered Cubic Structure
How many atoms are there in a unit cell of body-centered cubic?
2 atoms
Coordination Number of BCC
8
AFP of BCC
0.68
Elements that have a BCC structure
Cr, W, Fe, Ta, Mo
It has a unit cell with atoms located at each of the corners and the centers of all the cube faces
Face-Centered Cubic Structure
How many atoms in an FCC?
4 atoms
Coordination Number of FCC
12
APF of FCC
0.74
Stacking sequence of FCC
ABCABC
Elements that have the FCC structure
AL, Cu, Au, Pb
It has a hexagonal cubic cell
Hexagonal Close-Packed Structure
How many atoms in HCP
6
Coordination Number of HCP
12
APF of HCP
0.74
Stacking sequence of HCP
ABAB
Elements with the HCP structure
Cd, Mg, Ti, Zn
It is mass over volume
Density
Occurs when a metal or a nonmetal possess more than one crystal structure
Polymorphism
Is the term used for a metal that is an elemental solid
Allotropy
What are a, b, and c called in unit cell geometry?
Edge Lengths
What are 𝛼, 𝛽, and 𝛾 called in unit cell geometry?
Interaxial Angles
What are the 6 parameters of unit cell geometry collectively called?
Lattice Parameters
The representation of the combinations of the lattice parameters
Crystal System
What are the 7 crystal systems?
cubic,
tetragonal,
hexagonal,
orthorhombic,
rhombohedral,
monoclinic,
triclinic
The directionality of properties
Anisotropic
Substances in which measured properties are independent of the direction of measurement
Isotropic
They have properties vary with direction
Single Crystals
They have properties that may/may not vary with direction
Polycrystals
Smallest repetitive volume which contains the complete lattice pattern of a crystal
Unit Cell
Is defined as a line between two points, or a vector
Crystallographic Direction
A collection of many small crystals
Grains
Crystallographic planes in hexagonal crystal systems are specified by three ____
Miller Indices
Also known as the four-axis system
Miller-Bravais
