crystallography

50 %
50 %
Information about crystallography
Education

Published on January 12, 2011

Author: sudharani.kuram

Source: authorstream.com

Slide 1: SPACE LATTICE A space lattice is defined as an infinite array of points in three dimensions in which every point has surroundings identical to that of every other point in the array. Slide 2: A space lattice, two possible unit cells, and the environment of a point Slide 3: UNIT CELL The unit cell is the smallest unit which, when repeated in space indefinitely, generates the space lattice. BASIS A group of atoms or molecules identical in composition is called the basis. Lattice + basis crystal structure Slide 4: LATTICE + BASIS = CRYSTAL STRUCTURE Slide 5: UNIT CELL The unit cell is defined as the smallest geometric figure, the translational repetition of which in all over the three dimensions gives the actual crystal structure. Slide 6: UNIT CELL Slide 7: The intercepts a, b, c and interfacial angles α , β and γ constitute the lattice parameters of the unit cell. Slide 8: The seven basic crystal systems are Triclinic Monoclinic 3. Othorhombic 4. Tetragonal 5. Hexagonal 6. Trigonal 7. Cubic Slide 9: SIMPLE CUBIC CRYSTAL a = b = c , α = β = γ = 90 Slide 10: SIMPLE CUBIC CRYSTAL Slide 11: BODY CENTERED CUBIC CRYSTAL Slide 12: Calculation of packing fraction for BCC Slide 13: A FACE CENTERED CUBIC CRYSTAL Slide 15: THE 14 BRAVIS LATTICES Slide 18: TRICLINIC CRYSTAL a ≠ b ≠ c Slide 19: MONOCLINIC CRYSTAL a ≠ b ≠ c Simple cubic Base centered cubic Slide 20: ORTHORHOMBIC CRYSTAL α = β = γ = 90 Simple cubic Base centered Body centered Face centered Slide 21: TETRAGONAL CRYSTAL α = β = γ = 90 a = b ≠ c Simple cubic Body centered Slide 22: TRIGONAL CRYSTAL α = β = γ ≠ 90 a = b = c Simple cubic Slide 23: HEXAGONAL CRYSTAL α = β = 90 , γ = 120 a = b ≠ c Simple cubic Slide 24: CUBIC CRYSTAL α = β = 90 , γ = 120 a = b ≠ c Simple cubic Body centered Face centered Slide 25: DIRECTIONS IN CRYSTALS Slide 26: MILLER INDICES Miller indices are symbolic vector representation of an atomic plane in a crystal lattice and are defined as the reciprocals of the fractional intercepts which the plane makes with the crystallographic axes Slide 27: PROCEDURE FOR FINDING MILLER INDICES Find the intercepts of the desired plane on the three coordinate axes. Let these be (pa, qb , rc ). Express the intercepts as multiples of the unit cell dimensions or lattice parameters i.e.,(p, q, r). Take the ratio of reciprocals of these numbers i.e., 1/p, 1/q, 1/r. Convert these reciprocals into whole numbers by multiplying each with their L. C. M to get the smallest whole number. This gives the Miller indices (h k l) of the plane Slide 33: When a plane is parallel to any axis, the intercept of the plane on that axis is infinity. Hence its miller index for that axis is zero. Slide 34: When the intercept of a plane on any axis is negative, a bar is put on the corresponding Miller index. Slide 35: All equally spaced parallel planes have the same miller index number (h, k, l) Slide 36: The distance between the centres of two nearest neighbouring atoms is called nearest neighbour distance. Slide 37: Coordination number is defined as the number of equidistant nearest neighbours that an atom has in a given structure. Slide 38: Atomic packing factor is the ratio of volume occupied by the atoms in an unit cell (v) to the total volume of the unit cell (V). Packing factor = v/V Slide 39: HEXAGONAL CLOSED PACKED STRUCTURE Slide 40: STRUCTURE OF DIAMOND Slide 41: STRUCTURE OF ZINC SULPHIDE Slide 42: STRUCTURE OF SODIUM CHLORIDE Slide 43: STRUCTURE OF SODIUM CHLORIDE Slide 44: STRUCTURE OF CESIUM CHLORIDE Slide 45: STRUCTURE OF CESIUM CHLORIDE Slide 46: STRUCTURE OF CESIUM CHLORIDE

Add a comment

Related presentations

Related pages

Crystallography - Wikipedia, the free encyclopedia

Crystallography is the experimental science of determining the arrangement of atoms in the crystalline solids (see crystal structure). The word ...
Read more

(IUCr) Crystallography Journals Online

Provides access to sample, current and back issues of several online crystallography journals.
Read more

Crystallography Open Database

All data on this site have been placed in the public domain by the contributors. COD Advisory Board thanks The Research Council of Lithuania ...
Read more

X-ray crystallography - Wikipedia, the free encyclopedia

X-ray crystallography is a tool used for identifying the atomic and molecular structure of a crystal, in which the crystalline atoms cause a beam of ...
Read more

International Union of Crystallography (IUCr)

Executive Secretary. The International Union of Crystallography (IUCr) is seeking an Executive Secretary to lead the organization, and to manage its day-to ...
Read more

Crystallography - CCP4 wiki - Uni Konstanz

Crystallographic Theory . Basics of Crystallography; Phase problem, and Phasing; Twinning; R-factors; Bulk solvent correction; Fiber diffraction; Disorder
Read more

IUCr - International Union of Crystallography

Welcome to the International Union of Crystallography This server supplies information on crystallography from the IUCr, and pointers to other information ...
Read more

(IUCr) Crystallography Online

Crystallography Online is available to provide extensive coverage of current and internet-based information concerning crystallography and of interest to ...
Read more

Crystallography - American Chemical Society

Crystallography is the science that examines crystals, which can be found everywhere in nature—from salt to snowflakes to gemstones. Crystallographers ...
Read more

(IUCr) IUCrJ

IUCrJ is a fully open-access peer-reviewed journal from the International Union of Crystallography (IUCr). The journal publishes high-profile articles on ...
Read more