What is Crystal: Definition and 427 Discussions

A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations. The scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification.
The word crystal derives from the Ancient Greek word κρύσταλλος (krustallos), meaning both "ice" and "rock crystal", from κρύος (kruos), "icy cold, frost".Examples of large crystals include snowflakes, diamonds, and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Examples of polycrystals include most metals, rocks, ceramics, and ice. A third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever. Examples of amorphous solids include glass, wax, and many plastics.
Despite the name, lead crystal, crystal glass, and related products are not crystals, but rather types of glass, i.e. amorphous solids.
Crystals are often used in pseudoscientific practices such as crystal therapy, and, along with gemstones, are sometimes associated with spellwork in Wiccan beliefs and related religious movements.

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  1. T

    % lost to liquid crystal filters

    Hi, I've got a random question. To my knowledge a liquid crystal filter bends incoming light coming in from various angles towards one particular angle as light leaves the filter. Does anybody know the % loss of light caused by this action?
  2. K

    Limit of Crystal Growth Furnace

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  3. Somefantastik

    Resistance in a lasing crystal

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  4. L

    Quantum - 1D crystal model using evenly spaced delta functions

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  5. D

    Atomic Radius and Lattice Parameter Relationship in HCP Crystals?

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  6. T

    Unveiling the Mystery of Crystal Babies

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  7. P

    Crystal Goblet-Opera Singer Frequency Problem

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  8. I

    Question on crystal oscillators

  9. H

    Elastic Anisotropy vs Crystal packing

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  10. 2

    Calculating the Density of a BCC Crystal with Ta Substitution

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  11. S

    How many atoms are in the unit cell of graphite?

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  12. C

    Cesium Chloride Crystal Structure

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  13. I

    Electric potential energy in an infinite 2d crystal

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  14. L

    Are the ions at the edge of an ionic crystal complete spheres?

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  15. A

    Crystal Lattice/crystaline structure

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  16. T

    Angles Between crystal Planes

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  17. P

    Crystal Vibrations: Impurity in a monoatomic chain

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  18. C

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  19. H

    Preparing for a Test: Struggling with Crystal Structures

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  20. L

    X ray diffraction For crystal structure Analysis

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  21. J

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  22. rcgldr

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  23. C

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  24. H

    Crystal Planes: Definition & Meaning

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  25. S

    Predicting Crystal Structures in Metals: Is There a Simple Explanation?

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  26. A

    Drive a piezo crystal to produce ultrasound?

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  27. M

    Exploring CoIr Alloys: Crystal Structures & Lattice Parameters

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  28. A

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  29. B

    Perfect crystal - is there such thing?

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  30. S

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  31. WolfOfTheSteps

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  32. Loren Booda

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  33. L

    Exploring Liquid Crystal Displays: Answers to Common Questions

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  34. S

    What Is the Difference Between a Crystal and a Crystallite?

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  35. B

    Crystal field theory, what is spin?

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  36. N

    Crystal Book Suggestions

    Do yall know of any good books on: crystal thermodynamics, crystalography, and phonons? I am looking for introductory books that assume knowledge of the basics like thermodynamics, calculus, etc... Any help would be appreciated. Thanks.
  37. B

    Crystal Questions: Calculating Distances & Atom Positions

    Homework Statement I'm calculating the distances between to nearest atoms from various planes an a cubic crystal. For example I know that the distance from the [111] plane to the nearest atom is for a fcc lattice d=\frac{\sqrt{3}a}{3} What I'm unsure about is where the 1/3 factor...
  38. V

    Stoichiometric and non stoichiometric defects in the crystal lattice

    friends i studied abt the crystalline structures of compounds but i am just failing to understand the defects of the crystal lattice so i hope some one will help me in sorting out this problem of mineo:)
  39. H

    NaCl Crystal Reflection: Determining Wavelength & Sinus

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  40. B

    Reciprocal crystal lattice

    I know this might be a really stupid question, but to convert a crystal lattice 2D representation to a 2D reciprocal lattice do you justdo you just invert the scaling. I know this is a pretty poor explanation so I will try and illustrate what I mean. Let's say that you have a reciprocal lattice...
  41. W

    Electrical Analogue Simulating a crystal Lattice

    hey guys...im stuck with this experiment of an Electrical Analogue Simulating a crystal Lattice...could anyone explain me the whole concept of relating a set of LC filters to a crystal lattice?
  42. S

    Crystal Formation at Low Temperatures: Understanding the Physics Behind It

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  43. 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...
  44. A

    What distinguishes a crystal lattice from a unit cell?

    what's the difference between those two?
  45. S

    Why Does Crystal Violet Show Different Reaction Orders at Different Wavelengths?

    In the reaction of CV with NaOH, the order of CV is 1 (first order). However, in an experiment that I did with a colorimeter, I did not entirely come up with this value. Graphical analysis was done to determine the best wavelength from the absorption spectrum and lambda_max = 590 nm. After...
  46. L

    Question on Virtual Crystal Approx.(VCA)

    Dear all, I am now intended to do some first-principle calculations on disordered system, where VCA is an effective method. However, as to practical implementation using different methods, say Plane-Wave Pseudopotential, FPLMTO, FPLAPW, it's a litter hard to get a clear picture about how to set...
  47. V

    The relationship between crystal and hardness

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  48. N

    If power were applied to a one meter cube of quartz crystal

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  49. P

    How can hydrogen and lead crystals be differentiated through x-ray diffraction?

    I was given the following question: A crystal of hydrogen atoms and a crystal of lead atoms have exactly the same crystal structure, including lattice constant. How can they be distinguished by x-ray diffraction? The solutions say that the beams diffracted off the lead crystal would be much...
  50. Reshma

    What Determines the Void Space in Cubic Crystalline Structures?

    The problem here is to find the maximum radius of the interstitial sphere that could just fit into the void space of cubic crystalline structures of: the simple cube body centered cubic face centered cubic My question is how is position of the void space determined in these structures?
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