This document summarizes a seminar on quasicrystals. It begins with an introduction distinguishing crystals and amorphous solids. It then discusses the discovery of quasicrystals by Dan Shechtman in 1984 in an alloy exhibiting forbidden 5-fold symmetry. Quasicrystals have long-range atomic order like crystals but lack 3D translational symmetry. They exhibit properties intermediate between crystals and amorphous solids. Methods to prepare quasicrystals include rapid solidification. Potential applications include non-stick coatings, surgical instruments, and hydrogen storage.

1. A Seminar On
“Quasicrystals”
Presented By: Premananda Marndi
B.Sc. Chemistry 3rd yr.
Class Roll No: BS19-808
Exam Roll No: IB2219066
Under the supervision of: Dr. Gobinda Ch. Behera
MPC Auto. College Takhatpur, Bpd., Mbj.

2. Contents
Introduction
Discovery
Structure
Properties
Preparation
Application

3. Introduction
• Classical view of solid-state
Two types of solid states
I. Crystalline
II. Amorphous
Structure

4. According to Crystallography
Crystals occur with
Long range order
Holding a lattice which contains the atoms, ions
or molecules with translational periodicity
 1,2,3,4 and 6-fold rotational symmetries
5 ,7 and higher fold symmetries are forbidden

5. Discovery of quasicrystal
 Dan Shechtman, Philip Tobias Prof.
Nobel prize, Chemistry 2011
 In 1984, he first discovered a regular
dodecahedron pattern, but was not allowed
in crystallography and many
crystallographers were not convinced.
 Prof. Psai prepared an alloy of Al and Mn ;
(Al6Mn) with this pattern.

6. ‘Quasi’- resembling /pretending to be
Quasicrystal: resembling or pretending to be
crystal
Quasicrystals are materials with long range
order, but with no 3D translation symmetry
They are typically binary or tertiary metallic
aloys
Some of their properties are similar to crystal
and some have similarities with amorphous
It is also called quasiperiodic crystal.

7. Structure
Prof. Dan Shechtman claimed that he has observed an
dodecahedron single grain with 5-fold symmetry
The ratio of distances between the central and other
spots is the Fibonacci no. known as golden mean
Atomic positions are ordered, but with rotational
symmetries e.g. 5,8,10 or 12-fold which are forbidden in
crystal

8. Physical properties
• Properties are intermediate between
crystalline and amorphous alloys.
• The alloys are harder than the individual
components, are brittle.
• Have a very low co-efficient of friction
(non-stick)
->They have a very low surface tension
• Low electrical and thermal conductivity
• Resistant to oxidation and corrosion

9. Preparation
• Rapid solidification (Melt spinning)
• Conventional Casting
• Multi-layer deposition
• Mechanical alloying (Ball milling)
• Laser and electron melting method

10. Applications
Surface non-stick
coating and thin film
->Coatings of AlCuFe is deposited
at high tempr.
Surgical instruments
Hydrogen storage
->TiZrNi can store a prodigious amount
of hydgen.
Heat insulation
Protection against corrosion
and oxidation
Catalysis

11. New definition for crystal
“…….By crystal we mean any solid having an
essentially discrete diffraction diagram, and by
aperiodic crystal we mean any crystal in which
three-dimentional lattice periodicity can be
considered to be absent.”
Solid state:
1. Crystalline
2. Quasicrystal
3. Amorphous
Material Ordered Periodic
Crystal  
Quasicrystal  ꭓ
Amorphous ꭓ ꭓ