This document discusses the atomic arrangement and properties of crystalline solids such as metals. It begins by describing the long-range order in crystalline solids compared to the short-range order in amorphous solids. It then discusses various crystal structures including cubic, hexagonal, and body-centered cubic. It provides examples of calculating properties like atomic packing factor and theoretical density based on crystal structure. Finally, it discusses using X-ray diffraction to determine crystal structure by measuring spacing between crystal planes.
NANO106 is UCSD Department of NanoEngineering's core course on crystallography of materials taught by Prof Shyue Ping Ong. For more information, visit the course wiki at http://nano106.wikispaces.com.
NANO106 is UCSD Department of NanoEngineering's core course on crystallography of materials taught by Prof Shyue Ping Ong. For more information, visit the course wiki at http://nano106.wikispaces.com.
The crystal structure notes gives the basic understanding about the different structures crystalline materials and their properties and physics of crystals. It also throw light on the basics of crystal diffraction
Crystal Material, Non-Crystalline Material, Crystal Structure, Space Lattice, Unit Cell, Crystal Systems, and Bravais Lattices, Simple Cubic Lattice, Body-Centered Cubic Structure, Face centered cubic structure, No of Atoms per Unit Cell, Atomic Radius, Atomic Packing Factor, Coordination Number, Crystal Defects, Point Defects, Line Defects, Planar Defects, Volume Defects.
The crystal structure notes gives the basic understanding about the different structures crystalline materials and their properties and physics of crystals. It also throw light on the basics of crystal diffraction
Crystal Material, Non-Crystalline Material, Crystal Structure, Space Lattice, Unit Cell, Crystal Systems, and Bravais Lattices, Simple Cubic Lattice, Body-Centered Cubic Structure, Face centered cubic structure, No of Atoms per Unit Cell, Atomic Radius, Atomic Packing Factor, Coordination Number, Crystal Defects, Point Defects, Line Defects, Planar Defects, Volume Defects.
Dear aspirants,
This presentation includes basic terms of crystallography, a brief note on unit cell and its type With derivation of its properties: APF, Coordination no., No. of atoms per unit cell and also its atomic radius. I also added 7 Crystal System, Bravais Lattice and finally Miller Indices concept.
Hope this presentation is helpful.
Any questions or clarifications are welcomed.
Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. Crystallography is a fundamental subject in the fields of materials science and solid-state physics (condensed matter physics). The word crystallography is derived from the Ancient Greek word κρύσταλλος (krústallos; "clear ice, rock-crystal"), with its meaning extending to all solids with some degree of transparency, and γράφειν (gráphein; "to write"). In July 2012, the United Nations recognised the importance of the science of crystallography by proclaiming that 2014 would be the International Year of Crystallography.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
2. 2
Atomic arrangement of solids
Source: The Principles of Engineering Materials [Craig R. Barrett, Alan S. Tetelman, William D. Nix
Solids
Crystalline solids
Amorphous solids
Long range order
Repetitive pattern
Periodic arrangement
of atoms
Bricks on a wall
Random arrangement
Short range order
-metals
-ceramics
-some polymers
3. 3
The basic principles of many materials characterization
techniques such as X-ray diffraction (XRD), are based
on crystallography.
Crystalline cristoballite
Silica glass
4. Energy of Crystalline and Amorphous
Structures
• Non-dense, random packing
• Dense, ordered packing
Dense, ordered packed structures tend to have lower energies.
Energy
r
typical neighbor
bond length
typical neighbor
bond energy
Energy
r
typical neighbor
bond length
typical neighbor
bond energy
4
5. Energy
r
typical neighbor
bond length
typical neighbor
bond energy
5
• Atomic radii of metallic atoms do not differ
dramatically
• Metallic bonding is non-directional
• Nearest neighbor distances tend to be small
• Electron cloud shields cores from each other
Smallest
repeating
structure as
unit cell
Dense ordered packing in metallic structures.
6. 6
Space Lattice
It is a three-dimensional array of points.
Also defined as periodic configuration of points in space, defines 3D shapes that fill
space
Bravais Lattice
14 different ways of arranging lattice points so that each lattice point has
identical surrounding.
14 different lattices are called ‘Bravais lattices’
7. 7
14 different unit cells which are grouped to form 7 crystal systems.
7 systems of Crystal symmetry--- Crystal Systems
Crystal Systems Bravais Lattices
Cubic 3 Bravais Lattice
Tetragonal 2 Bravais Lattice
Orthorhombic 4 Bravais Lattice
Monoclinic 2 Bravais Lattice
Triclinic 1 Bravais Lattice
Hexagonal 1 Bravais Lattice
Rhomdohedral 1 Bravais Lattice
8. 7 systems of crystal symmetry
Source: R.E. Smallman, Ch1, F1.7
8
10. 10
Cubic Crystal Systems – 3 Bravais Lattice arrangement
Source: Solid-State Physics: Introduction to the Theory ; By James Patterson, Bernard Baile
Simple Cubic Lattice
Body Centered Cubic Lattice
Face Centered Cubic Lattice
11. Enforcing Terminology
Unit Cell of Crystal Structure: Describes the smallest repetitive pattern and
explains the complete lattice pattern of the crystal.
• a, b, and c are the lattice parameters
• α, β, γ are the angles between axes
11
12. Using Crystal Structure to Predict
Properties
For each of the cubic based crystal structures, we will now identify the:
Closed packed directions (where the hard spheres can touch)
Identify the number of nearest neighbors to each atom
Calculate the atomic packing factor
Atomic coordination number
Calculate the theoretical density
APF =
Volume of atoms in unit cell*
Volume of unit cell
12
14. • Rare due to low packing density (only Po has this structure)
• Close-packed directions are cube edges.
(Courtesy P.M. Anderson)
Simple Cubic Structure (SC)
14
Atomic coordination number = ?
15. Atomic Packing Factor (APF) for SC
close-packed directions
a
R=0.5a
15
Step 1: Volume of Atoms in the unit cell :
Given Atomic radii is ‘R’
Information required ->
Number of atoms in the unit cell
Each corner contains 1/8th of the atom
So, total number of atoms in the unit cell =
8 x 1/8 = 1 atom per unit cell
Volume of atoms =1 atom x ( 4/3 𝝅𝑹 𝟑)
Step 2: Identify the close-packed direction in SC unit cell i.e, ‘a’ = 2R
Volume of unit cell = a3=(2R)3 = 8R3
Atomic Packing Factor =
4
3
𝜋𝑅3
8𝑅3 = 0.52
16. Body Centered Cubic
Source: R.E. Smallman, Ch1, F1.15
16
• Atoms touch each other along cube diagonals.
--Note: All atoms are identical; the center atom is shaded differently only for ease of viewing.
ex: Cr, W, Tantalum, Molybdenum
Atomic coordination number = 8
17. Atomic Packing Factor (APF) for BCC
a
aR
Adapted from
Fig. 3.2(a), Callister 7e.
a2
a3
17
Step 1: Number of atoms per unit cell =
1 atom at center + 1/8 th of 8 corner atoms = 2 atoms
Step 2: Identify close packed direction
3 𝑎 = 4𝑅
Step 3: Volume of unit cell =𝑎3=(
4𝑅
3
)3
Atomic Packing Factor =
𝑽𝒐𝒍𝒖𝒎𝒆 𝒐𝒇 𝒂𝒕𝒐𝒎𝒔
𝑽𝒐𝒍𝒖𝒎𝒆 𝒐𝒇 𝒖𝒏𝒊𝒕 𝒄𝒆𝒍𝒍
=
𝟐𝒙
𝟒
𝟑
𝝅𝑹 𝟑
𝒂 𝟑 = 0.68
18. • Coordination # = 12
Adapted from Fig. 3.1, Callister 7e.
(Courtesy P.M. Anderson)
• Atoms touch each other along face diagonals.
--Note: All atoms are identical; the face-centered atoms are shaded
differently only for ease of viewing.
Face Centered Cubic Structure (FCC)
ex: Al, Cu, Au, Pb, Ni, Pt, Ag
4 atoms/unit cell: 6 face x 1/2 + 8 corners x 1/8
18
19. Atomic Packing Factor (APF) for FCC
19
Close packed direction length, 4R= a. 2 => a=
4𝑅
√2
Atomic Packing Factor=
𝑽𝒐𝒍𝒖𝒎𝒆 𝒐𝒇 𝒂𝒕𝒐𝒎𝒔
𝑽𝒐𝒍𝒖𝒎𝒆 𝒐𝒇 𝒖𝒏𝒊𝒕 𝒄𝒆𝒍𝒍
=
𝟒𝒙
𝟒
𝟑
𝝅𝑹 𝟑
𝒂 𝟑 = 0.74
Step 1: Number of atoms per unit cell = 6 x ½ + 8 x 1
8
= 4 atoms per unit cell
Step 2: Close packed direction in FCC are along the
face diagonals.
20. Hexagonal Close Packed
For ideally packed hcp, c/a=1.633 c/a(Zn)=1.856, c/a(Ti)=1.587
Source: R.E. Smallman, Ch1, F1.15
20
Coordination number =12
APF=0.74 with 6 atoms/unit cell
ABAB… stacking
sequence
21. 21
• The face-centered atom and the three
mid-layer atoms form a tetrahedron
MNOP which has sides equal to a (as
atoms at vertices touch each other) and
height of c/2.
• Using this tetrahedron it can be shown
that for an ideal hexagonal crystal c/a
ratio = 1.633
Hexagonal Lattice
22. Stacking: Difference between HCP
(0.74) and FCC (0.74)
FCC: ABCABCABC
HCP: ABABAB
Source: R.E. Smallman, Ch1, F1.16
22
24. Two or more distinct crystal structures for the same material
(allotropy/polymorphism)
Each structure is stable under
different conditions such
as temperature or pressure
the crystal structure with the
lowest free energy will be
stable
BCC
FCC
BCC
1538ºC
1394ºC
912ºC
Fe
Gamma -Fe
alpha-Fe
liquid
iron system
24
Carbon
Diamond
(high pressure)
Graphite
(stable at
normal
conditions)
25. 25
Where,
n= number of atoms/unit cell
A=atomic weight (g/mol)
Vc= Volume of unit cell = a3 for cubic
NA= Avogadro’s number= 6.023 x 1023atoms/mol
Density = =
VC NA
n A
=
CellUnitofVolumeTotal
CellUnitinAtomsofMass
Theoretical Density
Example: Chromium - with BCC crystal structure.
A=52 g/mol and atomic radius R=0.125 nm
a=4R/ 3 𝜌 =
2×52.0
6.023×1023
×𝑎3
26. Examples of Metallic Crystal Structure Unit Cells:
SC, BCC, FCC, HCP
z
x
y
1/19/2017 26
27. Point Coordinates: Determining where atoms sit.
Point coordinates for unit cell center are
(½ , ½, ½)
Point coordinates for unit cell corner are
(1, 1, 1)
Translation: integer multiple of lattice
constants identical position in
another unit cell
Notation for point coordinates -> (a,b,c)
z
x
y
a b
c
000
111
y
z
·
2c
·
·
·
b
b
1/19/2017 27
28. Crystallographic Directions: Moving Between Atomic
Positions
1. Vector repositioned (if necessary) to pass
through origin.
2. Read off projections in terms of
unit cell dimensions a, b, and c
3. Adjust to smallest integer values
z
x
Algorithm
y
1/19/2017 28
Example
1, 0, ½ => 2,0,1 => [201]
-1,1,1 => [111] , the overbar represents negative index.
Notation for crystallographic direction
Enclose in square brackets, no commas
[uvw]
29. 29
Example 2: The vector is obtained by subtracting the coordinates
of the tip of the vector from the coordinates of tail
-4, 1, 2
families of directions <uvw>
z
x
where the overbar represents a
negative index
[412]=>
y
Step 1:
pt. 1 x1 = a, y1 = b/2, z1 = 0
pt. 2 x2 = -a, y2 = b, z2 = c
=> -2, 1/2, 1
pt. 2
head
pt. 1:
tail
Step 2: Multiplying by 2 to eliminate the fraction
1/19/2017
30. 1/19/2017 30
Example 3: In a cubic unit cell find the vector with indices [123]
Step 1: Divide all indices with the largest integer.
X component = 1/3
Y component = 2/3
Z component = 3/3
Step 2: Note the coordinates (1/3, 2/3, 1)
Step 3: Draw the vector
33. 33
Example 1 z
x
y
a b
c
Read off
intercepts of
plane with X, Y
and Z axes in
terms of a, b, c
Intercepts a b c
1 1 1
Take reciprocals
of intercepts
Reciprocals 1/1 1/1 1/ꝏ
Reduce to
smallest integer
values
Reduction 1 1 0
Enclose in
parentheses, no
commas (hkl)
Miller indices (110)
1/19/2017
34. 34
Identify the Miller indices of given plane
z
x
y
a b
c
·
·
·
4. Miller Indices (634)
example
1. Intercepts 1/2 1 3/4
a b c
2. Reciprocals 1/½ 1/1 1/¾
2 1 4/3
3. Reduction 6 3 4
1/19/2017
35. a b c
z
x
y
a b
c
4. Miller Indices (100)
1. Intercepts 1/2
2. Reciprocals 1/½ 1/ 1/
2 0 0
3. Reduction 2 0 0
Example 2
1/19/2017 35
37. Properties vary with direction:
anisotropic.
-Example: the modulus
of elasticity (E) in BCC iron:
Importance of Linear/ Planar Densities
E (diagonal) = 273 GPa
E (edge) = 125 GPa
1/19/2017 37
38. Examples of Linear Density
a
[110]
1/19/2017 38
Linear density of Al in [110] direction
a = 0.405 nm
# atoms
length
1
3.5 nm
a2
2
LD -
==
39. Planar Density of (100) Iron
At T < 912 C iron has the BCC structure.
(100)
R
3
34
a =
Adapted from Fig. 3.2(c), Callister 7e.
2D repeat unit
1/19/2017 39
=Planar Density =
a2
1
atoms
2D repeat unit
=
nm2
atoms
12.1
m2
atoms
= 1.2 x 1019
1
2
R
3
34
area
2D repeat unit
40. 40
Planar Density of (111) Iron-BCC
Solution (cont): (111) plane 1 atom in plane/ unit surface cell
atoms in plane
atoms above plane
atoms below plane
ah
2
3
=
a2
1/2
= =
nm2
atoms
7.0
m2
atoms
0.70 x 1019
3
2
R
8
Planar Density =
atoms
2D repeat unit
area
2D repeat unit
1/19/2017
41. Spacing between equivalent planes
dhkl =
a
h2
+ k2
+ l2
What is the spacing between (111) planes in
FCC Nickel? The atomic radius is 0.124 nm.
a) 0.20 nm
b) 0.35 nm
c) 0.30 nm
1/19/2017 41
42. 42
X-Rays to Determine Crystal Structure
X-ray
intensity
(from
detector)
θ
θc
d =
nλ
2 sinθc
Measurement of
critical angle, c,
allows computation of
planar spacing, d.
• Incoming X-rays diffract from crystal planes.
Adapted from Fig. 3.22,
Callister & Rethwisch 9e.
reflections must
be in phase for
a detectable signal
spacing
between
planes
d
θ
λ
θ
extra
distance
travelled
by wave “2”
1/19/2017
43. 43
X-Ray Diffraction Pattern
Adapted from Fig. 3.22, Callister 8e.
(110)
(200)
(211)
z
x
y
a b
c
Diffraction angle 2θ
Diffraction pattern for polycrystalline α-iron (BCC)
Intensity(relative)
z
x
y
a b
c
z
x
y
a b
c
dhkl-spacing increases
1/19/2017