CRYSTAL LATTICE AND UNIT CELL
Summary
TLDRThe video script delves into the fascinating world of crystal lattices, explaining their three-dimensional cubic arrangement as points in space. It introduces the concept of unit cells, which are the building blocks of crystals, and distinguishes between primitive and centered unit cells. The script further explores the seven crystal systems and 14 Bravais lattices, highlighting the importance of unit cell parameters and angles in understanding crystal structures.
Takeaways
- 🔬 Crystal lattices are three-dimensional arrangements of particles in space.
- 🌐 There are 14 different three-dimensional lattices known as Bravais lattices, named after French mathematician Auguste Bravais.
- 📏 Unit cells are the basic building blocks of crystals, with parameters a, b, c for edges and alpha, beta, gamma for angles between them.
- 🏠 Unit cells can be of two types: Primitive (particles only at corners) and Centered (particles also at other positions).
- 🔶 Primitive unit cells have particles only at the corners.
- 🔵 Centered unit cells have particles at additional positions besides the corners and are further divided into three types: body-centered, face-centered, and end-centered.
- 🔵 Body-centered unit cells have a particle at the center of the body in addition to the corners.
- 🔵 Face-centered unit cells have particles at the centers of all six faces plus the corners.
- 🔵 End-centered unit cells have particles at the centers of any two opposite faces along with the corners.
- 🌐 There are seven crystal systems that classify crystal forms based on symmetry and crystallographic parameters a, b, c, and angles alpha, beta, gamma.
- 📊 Crystal systems are further divided into 32 classes based on symmetry.
Q & A
What is a crystal lattice?
-A crystal lattice is a three-dimensional arrangement of particles as points in space, which forms the basis of a crystal's structure.
Who was Bravais?
-Bravais was a French mathematician who identified 14 different three-dimensional lattices that are possible in crystals.
What are the unit cell parameters?
-The unit cell parameters are 'a', 'b', and 'c', which are the lengths of the edges of the unit cell, and 'alpha', 'beta', and 'gamma', which are the angles between them.
What is a unit cell?
-A unit cell is the smallest part of a crystal lattice that, when repeated, generates the entire crystal structure.
What are the two types of unit cells?
-There are two types of unit cells: Primitive, where particles are only at the corners, and Centered, where particles are at additional positions along with corners.
What is a Primitive unit cell?
-A Primitive unit cell is one where the constituent particles are present only at the corners.
What are the three types of Centered unit cells?
-The three types of Centered unit cells are Body-centered, Face-centered, and End-centered.
Define a Body-centered unit cell.
-A Body-centered unit cell is one where a particle is present at the body center along with the particles at the corners.
What is a Face-centered unit cell?
-A Face-centered unit cell is one where particles are present at the centers of all six faces along with the particles at the corners.
Explain an End-centered unit cell.
-An End-centered unit cell is one where particles are present at the centers of any two opposite faces along with the particles at the corners.
What are crystal systems?
-Crystal systems are the classification of crystal forms based on symmetry, which are divided into seven categories depending on the crystallographic parameters a, b, c, and alpha, beta, gamma.
How many crystal systems are there?
-There are seven crystal systems.
How many classes are there in the classification of crystal systems?
-There are 32 classes in the classification of crystal systems based on symmetry.
Outlines
🔬 Crystal Lattices and Unit Cells
This paragraph introduces the concept of crystal lattices, which are three-dimensional arrangements of particles as points in space. It explains that there are 14 different three-dimensional lattices known as Bravais lattices, named after the French mathematician Auguste Bravais. The paragraph further discusses the unit cell, which is the smallest part of a crystal lattice that can be repeated to generate the entire crystal structure. It mentions that unit cells can be of two types: Primitive, where particles are only at the corners, and Centered, which includes particles at other positions besides the corners. Centered unit cells are further divided into three types: body-centered, face-centered, and end-centered, each defined by the presence of particles at specific locations within the unit cell.
Mindmap
Keywords
💡Crystal Lattice
💡Unit Cell
💡Bravais Lattices
💡Unit Cell Parameters
💡Primitive Unit Cell
💡Centered Unit Cell
💡Body-Centered Unit Cell
💡Face-Centered Unit Cell
💡End-Centered Unit Cell
💡Crystal Systems
💡Symmetry
Highlights
Crystal lattices are three-dimensional arrangements of particles as points in space.
There are 14 different three-dimensional lattices possible, known as Bravais lattices.
Bravais lattices are named after the French mathematician Auguste Bravais.
Unit cell parameters include a, b, c for edges and alpha, beta, gamma for angles between them.
A unit cell is the smallest part of a crystal lattice that repeats itself to generate the crystal.
Unit cells are of two types: Primitive and Centered.
Primitive unit cells have particles only at the corners.
Centered unit cells have particles at additional positions besides the corners.
Centered unit cells are further divided into body-centered, face-centered, and end-centered.
A body-centered unit cell has a particle at the center of the body in addition to the corners.
A face-centered unit cell has particles at the centers of all six faces.
An end-centered unit cell has particles at the centers of any two opposite faces.
There are seven crystal systems based on symmetry and crystallographic parameters.
Crystal systems are classified into 32 classes based on symmetry.
Crystallographic parameters a, b, c, and alpha, beta, gamma determine the crystal system.
The symmetry of a crystal system is crucial for its classification.
Understanding crystal systems is essential for material science and crystallography.
The arrangement of particles in a crystal lattice affects its physical properties.
Transcripts
Crystal ltis and unit
cell threedimensional cubic
ltis three dimensional arrangement of
particles as points in space is called
space ltis or Crystal
ltis these are 14 different
three-dimensional latices are possible
which are called bravis
latis bravis was a French mathematician
unit cell parameters a b c are three
edges as alpha beta and gamma are the
angles between
them unit cell is the simple part of
Crystal lce which repeats itself to
generate a crystal unit cell types of
unit cells it is of two types A
Primitive and B
centered when the constituent particles
are present only at the corners of the
unit cell then it is called primitive
unit cell when the constituent particles
are present at other positions along
with Corners then it is called centered
unit cell it's again of three types one
body centered two
face centered three end
centered one body
centered if the constituent particle is
present at the body centered along with
Corners called body centered unit cell
Two Face
centered if the constituent particles
are present at the six phase centers
along with Corners called face centered
unit
cell Three N
centered if the constituent particles
are present at the centers of any two
opposite faces along with Corners called
n centered unit
cell seven Crystal
systems Crystal
systems these are 230 Crystal forms
possible these are classified into 32
classes on the basis of symmetry which
are further divided into seven Crystal
systems depending on the
crystallographic parameters a b c and
Alpha Beta gamma
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