What is Crystal structure: Definition and 53 Discussions

In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter.
The smallest group of particles in the material that constitutes this repeating pattern is the unit cell of the structure. The unit cell completely reflects the symmetry and structure of the entire crystal, which is built up by repetitive translation of the unit cell along its principal axes. The translation vectors define the nodes of the Bravais lattice.
The lengths of the principal axes, or edges, of the unit cell and the angles between them are the lattice constants, also called lattice parameters or cell parameters. The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space may be described by the 230 space groups.
The crystal structure and symmetry play a critical role in determining many physical properties, such as cleavage, electronic band structure, and optical transparency.

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  1. Junaidjami

    A Real vs complex spherical harmonics for hexagonal symmetry

    Are real spherical harmonics better than complex spherical harmonics for hexagonal symmetry, which are directly associated to a finite Lz?
  2. I

    What Does d Represent in Interatomic Spacing Diagrams?

    according to the figure, it's look like d is the distance between the center of two adjacent atoms, and so it should be simply L. I don't understand what d represents in the figure. that's the solution: Even if d is half the distance between two adjacent atoms that positioned diagonally (I...
  3. S

    A What is the Structure of Gallium Oxide?

    I have three questions regarding the material Gallium Oxide. I was reading in several articles and they introduced its structure as it has monoclinic structure and it consists tetrahedral and octahedral structures in it. What I can't understand I can connect this structure to the chemical...
  4. amjad-sh

    I Van Laue Formulation: X-ray Diffraction from Crystal Structure

    When we shine an X-ray beam on a crystal, according to Van Laue formulation, for a sharp intensity peak to be observed on the screen there is a specific direction ##\mathbf{\hat{n}}## , in which for all the X-rays with wavelength ##\lambda## and wavevector...
  5. X

    A Question about crystal structure of long chain fatty acids (XRD)

    Hello, we are studying potato periderm before/after digestion and dewaxing and native vs wounded. One of the techniques is XRD, hence my user name. Among other things we are trying to use XRD to determine the arrangement of fatty acids, esters, and other long-chain aliphatics that are present...
  6. I

    I Center of inversion of cubic diamond structure?

    I'm having hard time finding the center of inversion of cubic diamond structure. At first I thought (2,2,2) would be the center of inversion, but (1,1,3), (3,3,3), (1,3,1), (3,1,1) (i.e. four atoms inside the cube) are not centrosymmetric about (2,2,2).
  7. B

    The crystal structure for Ba2TiO explained with symmetries

    Hello! I would love to get help on this particular question that I find extremely difficult to answer. -"Bariumtitanate can under a certain set of conditions crystallize in the given structure. With the help of the compounds symmetries, explain how it is possible for it to achieve such a...
  8. G

    I Predicting new crystal structures

    Hello, Sorry if this is a rather basic question, but my memories of solid-state chemistry are a bit rusty. Basically I'm trying to predict new crystal structures. I understand the crystallographic aspects quite well and know that at given external temperature and pressure the most stable...
  9. qnach

    Nearest neighbour, nnn....etc. of an atom in a crystal

    There are some software can provide visualization of crystal or protein structure, i.e. VESTA. I want to know how many atoms is the nearest neightbour (and their distance), and the next nearest neighbour...etc of a particular atom. Is there any software (or perhaps some data book?) can do this?
  10. qnach

    I Crystal Structure Database (Pb0.5Sn0.5)Te

    I would like to find the crystal structure of (Pb0.5Sn0.5)Te I was told it is similar to NaCl basically an XY crystal I think it is called Space Group: 225 I would like to know the first, second, third ...layer of atoms closest to a X atom...and perhaps their distance... I found...
  11. G

    A Is there anyone who can explain Strukturbericht symbol?

    I have found about Strukturbericht and got some information. But I don`t know what these number means. I heard that Mn_5Ge_3 is a D8_8 type structure. I already found that D means A_m B_n compound. But I can`t find anywhere what the number mean.
  12. S

    I Monoclinic Cell Rotation for Surface Calculations

    Dear All, I have a monoclinic cell with a=18.7,b=3.55,c=9.069 and beta=134 degrees, angle between a and c. Now I need to make the c axis parallel to z axis for surface calculations, ie to introduce a vacuum. What is the rotation matrix that would do this?? Thank you.
  13. S

    I What factors influence the crystal structure of metals?

    What determines the crystal structure taken by metals? For example Sr has FCC and Ba BCC. The packing fraction is greater for FCC. However, due apparently to coordination number and number of "next nearest" neighbors, BCC is favored in the case of Barium despite its lower packing fraction...
  14. B

    Preferred Crystal Structure of Steel (BCC vs FCC)

    What are the reasons behind the different microstructures of steel at different temperatures? I don't understand why steel at high temperatures (austenite phase) would favor an FCC crystal structure while steel at lower temperature (ferrite) would favor a BCC crystal structure.
  15. chikou24i

    Drawing crystal structure software

    Hi, is there any software that I can use for drawing a crystal structure from atoms coordinates ?
  16. U

    How Is the Polyacetylene Chain Structured in a 1D Lattice Model?

    Homework Statement The polyacetylene chain is a 1D chain of Carbon atoms with single bonds and double bonds in succession. Spacing for single bond is ##a_s = 0.144~nm## and spacing for double bond is ##a_d = 0.136~nm##. Describe the structure using a "lattice" and a "basis". Sketch the...
  17. K

    How do I build this crystal structure in computing programs?

    It's Ti2Ni, which is in FD-3M spacegroup. I have its .cif file which can be loaded by many crystal building program. So I try to build the structure according to the loaded images. I started building a structure with FD-3M lattice. But when I tried to add atoms at the position read from the...
  18. L

    Which plane of GaN gives an image of dots placed hexagonally

    An electron microscope image of GaN seen in projection shows white dots which correspond to columns of gallium atoms observed in projection. The dots show a hexagonal pattern but there is not a dot in the centre of each hexagonal. No nitrogen atoms are seen in the image. Which plane of this...
  19. R

    Determine Crystal structure of non-cubic crystal in XRD plot

    Given only 2theta and intensity, how to know the crystal structure (except cubic) of non cubic crystals, and also determine their lattice parametera,b,and c, if there's a link or website discussing techniques to determine crystal structure of all crystals, please don't hesitate to put it here...
  20. R

    Derive Primitive Vectors in Complex Crystal Structure

    Hi Guys, please help me. how can i derive the primitive vector of copper oxide (I)? basically this is cuprous oxide having a cubic crystal structure but since it has oxygen in it the directions and magnitude of primitive vector are far different compare to basic cubic structure. also please help...
  21. R

    Crystal Structure of TiO2 and Aluminum Nitride

    Hey guys, I'm actually had a hard time in figuring out about our assignment in crystallography of semiconductors, the problem said that, Identify the atomic line lattice axes in a, b,c axis and basal plane diagonal, face plane diagonal, and body plane diagonal of TiO2 and Aluminum Nitride...
  22. T

    Stainless steel crystal structure

    Hi, I'm looking for a simple s.s crystal unit cell structure and can't find it anywhere. I understand that stainless steel is a very general word and takes many forms and has many different types, but isn't there a standard type that people use in the industry and ususlay talk about when they...
  23. C

    Crystal Structure vector question

    Homework Statement Identify the [221] vector? A B C D E Homework Equations The Attempt at a Solution I reduce [221] to [1 1 0.5].BUT after getting the wrong answer, the feed back is as follows "Feedback: [221]: has a 0.5 component along the x-axis...
  24. A

    What is the unit cell and coordinates for wurtzite crystal structure?

    As far as I understand wurtzite is the name given to the crystal structure defined by the stacking sequence ABABABAB.. However, I am having a hard time understanding what the unit cell is of wurtzite. From what I know the unit cell is the smallest repetitive unit and in it you specify the...
  25. A

    Understanding the Unit Cell of Wurtzite Crystal Structure: A Brief Overview

    My teacher wrote down something to day which I wish I had written down myself. It was about the crystal structure of wurtzite, which is an ABABABAB stacking of hexagonal lattices. What he wrote was two different specifications of the unit cell of wurtzite depending on which groups of elements in...
  26. SSGD

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    I have been trying to find information on the crystal structure or phase of solid elemental metals at temperatures close to absolute zero, but I can only find information on there ambient structures. Does anyone know of any sources that would have thermodynamic tables for solid metals at low...
  27. R

    Crystal Structure & Metallic Bond: What Comes First?

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  28. T

    Software/database for simple crystal structure design?

    Hello, Does anyone know any (free) software for generating simple crystal structures like forms of SiO2 or TiO2? It must be a really common problem. My current strategy is to search the web for hours until I get lucky. There are online databases which have really complicated structures from...
  29. S

    Understanding Crystal Structure Basics: Q&A with the Experts

    Hello experts! Q#1) Write down the family members of {110} plane in a cubic crystal. Attempted Answer) According to my study the this family has 6 members. But what are they? Are these the members (110),(101),(011),(-1-10),(-10-1),(0-1-1)? Q#2) Describe the method to construct the...
  30. E

    Derivation of lattice parameter of zinc blende crystal structure

    I need to derive the lattice parameter in terms of the Zn-S separation distance, l. I looked up the value and I've found it to be a = \frac{4}{\sqrt{3}}l The way that I started my derivation was saying that each tetrahedron has a sulfide ion in the center, so then we can make a triangle from...
  31. S

    Diffraction pattern to crystal structure

    How do crystallographers go from a diffraction pattern to actually determining the structure of the crystal? http://pwatlas.mt.umist.ac.uk/internetmicroscope/micrographs/microscopy/decr5a-a-big.jpg
  32. A

    Deriving the Relationship of Cubic Crystal Structure

    How can one derive the relationship for a cubic crystal: d= \frac{a}{\sqrt{h^2 + k^2 + l^2}} It is shown here. This is probably trivial but I am having trouble proving it as the Miller indices are reciprocals but the reciprocal is not distributive. This isn't for homework by the way - I...
  33. L

    CSCL Crystal Structure - Confused by Clarity?

    Hello, I'm really confused by something. Cscl is simple cubic. But how it this possible? With the cl in the middle it looks like a bcc structure. Also howcome when you have 2 caesium its bcc and not simple cubic? its the same structure yet it changes to bcc. Is it because they are both atoms...
  34. D

    Understanding HCP Crystal Structure: Confusion with Coordinates of Center Atom

    Considering only the 4 lower-right atoms (one unit cell), I'm somewhat confused as to why the coordinates for the center atom (b) is (1/3, 2/3, 1/2) with respect to (a1, a2, c). c is pretty self explanatory, but I don't quite get the other 2. I think one of my main confusions is where the...
  35. Z

    How is the microscopic crystal structure visible?

    I just noticed that it's often taken for granted that a macroscopic crystal has a similar geometric structure as in the atomic scale. What is the physical explanation for this (assuming it is true)?
  36. M

    Unit cell dimensions of crystal structure

    Hello all, I already have the answer to my question, but what I would like to know is why. My question is: why in the question below is the plane 111 used to find ao and not another plane? An ordered compound of NiAl has a cubic structure with one formula unit/cell. One Al atom at...
  37. H

    Transmission Electron Microscopy - Crystal Structure

    Hi I have a tutorial problem involving determining the ideal methods for identifying material properties of a layered semiconductor structure. The problem states to use either scanning or transmission electron microscopy. THe structure consists of several monolayers (around 5nm) of AlGaAs...
  38. E

    Inorganic crystal structure theory for linear birefringence

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  39. E

    Inorganic crystal structure theory for linear birefringenc

    There is a crystal structure relationship for circular birefringence which can tell you if a crystal structure will have circular birefringence and its handedness (left,right) (e.g. "On the origin of optical activity in crystal structures" J. Appl. Cryst. 1986. 19, 108-122, A. M. Glazer and K...
  40. S

    Crystal Structure Lattice Problem

    1. Homework Statement Using the powder XRD data below, show that the substance has a face centred cubic structure. (xray lamda = 0.154056 nm) Peak No.------2(theta) 1 -------------38.06 2 -------------44.24 3 -------------64.34 4 -------------68.77 5 -------------73.07 2...
  41. M

    Crystal structure and diffraction

    Homework Statement You wish to study a crystal's structure by diffracting thermal, non relativistic neutrons from the crystal, so you go to a nuclear reactor and set up your diffraction experiment on one of the neutron beam lines. The neutrons emerge from the reactor with a range of...
  42. S

    What Is the Nearest Neighbor Distance in an FCC Lattice of Aluminum?

    Hi all I am new here but i have a major question, iv been told by people that this question is easy but I am just going around in circles with it and i was wondering if you could help. here is the questionAluminium cystallises in the fcc structure with a single atom basis. the lattice constant...
  43. R

    Unit cells (crystal structure)

    I'm trying to clarify for myself the difference between a Unit Cell, a Primitive Unit Cell and a Conventional Unit Cell. As far as I know, Primitive Unit Cells contain only one lattice point and are the smallest possible unit cell Unit Cells are the crystal's smallest building block, and...
  44. S

    How many atoms are in the unit cell of graphite?

    Homework Statement How many atoms are there in the unit cell of graphite? 2. The attempt at a solution I know graphite is hexagonal crystal structure. hcp also know that hcp has basis of hexagonal lattice which as 2 basis atoms. is there some other info i need because the answer...
  45. C

    Cesium Chloride Crystal Structure

    I am working this problem... http://www.fiu.edu/~saulj/Teaching/Physics2/01-Electric_Force/CrystalStructure.html I got the answer to a as 0, but don't understand b.
  46. S

    Materials Engineering (Crystal Structure) - C/A Ratio?

    Hi there, This may be a very basic question, but I have almost no knowledge of chemistry, unfortunately! Homework Statement Beryllium (Be) is a HCP metal with an atomic weight of 9, an atomic radius of 0.112nm and a density of 1850kg/m^3. Calculate its c/a ratio given that Avogadro's Number...
  47. L

    X ray diffraction For crystal structure Analysis

    1. Find the crystal structure , the lattice parameter of the metal. Known 2\theta of the peaks 17 21 28 33 35 41 45 46 2. bragg's law \lambda=2 d_{h,k,l} /b]sin^{2}(\theta) Also, the cubic interplanes distance d_{h,k,l} = a0/(squr(h^{2}+k^{2}+l^{2}) [b]3. The Attempt at a Solution ...
  48. J

    Dispersion relations in diamond crystal structure

    I know acoustic and optical phonons can interact with one another. Also, longitudinal and transverse phonons can interact with one another. I am wondering can a longitudinal phonon in one plane act with a transverse phonon from another plane to create a third phonon? Or, do these...
  49. G

    Group theory and crystal structure

    Hi, I have the following problem : I generate GaAs (zinc blende structure) supercells, and then I want to replace some As atoms by N atoms. Let's say I have fcc conventional cell repeated twice in the x, y and z direction so that I have a total of 64 atoms, 32 of Ga and 32 of As. 8 atoms...
  50. A

    Crystal Structure: Primitive base vectors etc

    This is the question: http://www.maths.tcd.ie/~cockburd/Question.jpg It's not a homework question, merely one from a previous years tutorial sheet. Okay so it's tetragonal conventional unit cell, has a sort of face centered structure right? Em.. so that would mean it has a four point basis...