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. J

    Crystal Field Splitting of Actinides

    Hello everyone, Does anyone know much about the crystal field splitting of the f orbitals in actinides, specifically uranium? I am doing research on the chemistry of uranium and have come across an interesting problem. U(IV) compounds undergo a transition to a non-magnetic singlet ground state...
  2. G

    Latent Heat of Phase Transition: Origin & Explanation

    Hello, We often hear about latent heat of vaporisation for a liquid, which basically corresponds to the energy required to break the hydrogen inter-molecular bonds in the liquid phase to form the gas. I was wondering, what is the equivalent physical explanation for the latent heat of a...
  3. chikou24i

    Drawing crystal structure software

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

    Crystal phase transition, Diffraction peak splitting problem

    Homework Statement [/B] Hi there! This is a question from a practice problem sheet I got from the lecturer of my Condensed Matter 1 course. Below are the normal vectors to the {111} and {112} lattice planes: Homework Equations [/B] Bragg Condition: \begin{equation} n \lambda = d \sin...
  5. Lensmonkey

    2 layers of birefringent crystal, how many rays?

    I am trying to solve a problem my camera exhibits. It has a sensor with 6000x3376 pixels. HD video is 1920x1080. In order to reduce the amount of information to the processor the camera throws away 2 out of 3 pixel lines. this creates a problem with thin lines tike telephone lines and makes...
  6. A

    Calculating particle velocity along crystal direction

    I am currently looking at setting up a particle, with energy 5keV, traveling along the [11bar2 0] direction in Zr but I am struggling to get my head around how to resolve the velocity into the 3 directions to make sure it travels along this specific crystal direction. Could anyone help point...
  7. U

    About Crystals in microcontroller......

    I have a question that if we use external quartz crystal in Microcontroller and connect it to battery... Crystal gives regular and very accurate electrical frequency... But it should get mechanical vibration from somewhere to give electrical pulses... From where it receives mechanical vibrations?
  8. H

    Question: how to calculate the energy of crystal

    Dear all, I am recently dealing with crystals. There is one question which puzzles me a lot. How to calculate the energy of crystals? For example, tungsten oxide has severl polymorphs such as alpha, beta , and gamma. What is the energy difference among them. Hope you can help with this...
  9. Z

    QM explanation of electron conduction in crystal

    Suppose that a static electric field E is applied on a conductive crystal. Then, how quantum mechanics describes the electron movements in the crystal? I have been trying to find an explanation, but have not found any. As I understand it, we could treat the E field as a time-dependent...
  10. SquidgyGuff

    Potential Energy of a 2D Crystal Lattice

    Homework Statement Use a computer to calculate numerically the potential energy, per ion, for an ifinite 2D square, ionic crystal with separation a; that is, a plane of equally spaced charges of magnitude e and alternating sign. Homework EquationsThe Attempt at a Solution The closest I can...
  11. kelvin490

    X-Ray Diffraction in Crystals: Exploring Scattering & Interference

    In explaining x-ray diffraction of crystals, usually the approach is to consider the atoms absorb radiation and scatter it, at some angles constructive interference occur and bright spots can be observed. It seems that it is different from the diffraction of slits or gratings because in these...
  12. Meera.sheeda

    To calculate potential energy of paraelectric crystal

    I understand that to calculate the potential energy of a paramagnet you use U=2μBBS but is there an equation to calculate the energy of a para-electric crystal. Also, if this equation required S, would that always be N/2 (is a para-electric crystal always completely polarised?)
  13. SmritiB

    Piezoelectric crystal compression (in cm)

    How much does a Piezoelectric crystal (say PZT) compress when applied the maximum amount of force it can withstand ? also it would be very helpful if someone could tell me how much is this force typically ?
  14. S

    How is the frequency unchanged in elastic wave scattering with a crystal?

    it makes sense that with an inelastic scattering process, a wave approaches a crystal, and then some energy is imparted to the phonons, so that the outgoing wave has a different frequency from the incoming wave. However, with an elastic scattering process, the frequency is unchanged-- how does...
  15. S

    Temperature increase by light absorption

    Hi, I have a question. If a crystal absorbs light and the absorption process leads to some excess energy being released as heat . Can one calculate the temperature rise or an experiment would most certainly need to be done? Apart from the heat capacity of the crystal before light absorption...
  16. G

    Distance between points in crystal

    I am wondering how can I solve following problem. I would like to see how can it be solved.
  17. A

    How to calculate the PKA velocity in a crystal?

    Hi, I need to calculate the velocity of a particle acting along a specific crystal direction. For example a PKA acting along the [135] direction in a crystal with a certain velocity, how do I find the velocity along the x, y and z direction? Also if I am looking at a hcp crystal, would this...
  18. U

    1D Chain crystal structure

    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...
  19. S

    Atoms as spheres in packing fraction of crystal lattice

    Why are atoms taken to be spheres, and not of some other shape, in the calculation of the packing fraction of different crystal lattices? In other words, what experimental evidence and theoretical reasoning motivates this form of the atomic shape?
  20. J

    Magnetic moment of paramagnetic crystal

    Hello, I've been having some trouble with a paramagnetism problem from my Statistical Mechanics class textbook (F. Mandl, Statistical Physics, 2nd edition, p. 25). The problem is as follows 1. Homework Statement 2. Homework Equations 1. The temperature parameter \displaystyle{ \beta =...
  21. S

    Cleaning crystal meth residue from car

    I had a roommate that is a regular user of meth. I recently found out that smoking meth leaves a residue behind that can be absorbed through the skin, which worries me because I let him borrow my car and he smoked meth in it before. I'm kind of a hypochondriac when it comes to health issues like...
  22. S

    Understanding Crystal Symmetries & Dielectrics

    Hi, I am currently reading the Feynman Lectures on Physics, and I have just finished the chapter about the geometry and the symmetries of crystals, and there is something I do not quite understand. There are 230 different possible symmetries which are grouped into seven classes (triclinic -->...
  23. rolotomassi

    Statistical physics: Landau theory liquid crystal (2D)

    Homework Statement A simple model for liquid crystals confined to 2 dimensions is o assume each molecule can only align in one of 2 perpendicular directions. To construct a landau model its convenient to define order parameter, s : s = 2 ( Np - 0.5Nt ) / Nt Np - number molecules...
  24. Laplas

    Density of states of photonic crystal

    Hello! Does anybody know how to calculate the DOS as a function of Neff and λ/Λ? Thanks.
  25. S

    Solid State: one-dimensional crystal

    Homework Statement Investigate electronic bands in one-dimensional crystal in weak potential $$V(x)=\sum _n V_0(H(x-na)-H(x-na-a/3))$$ if ##H(x)## is Heaviside Theta function. a) Determine primitive cell, reciprocal mesh and first Brillouin zone. b) Calculate the difference between energy...
  26. Laplas

    Density of states, photonic crystal

    Hello! I know how to calculate band structure and density of states of photonic crystal (example is pic.1) Does anybody know how to plot such DOS maps? The second picture is from the article about photonic crystal fibers by Rodrigo Amezcua.
  27. 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...
  28. R

    Basis Atom of Superconductor

    Hi everyone, I'm trying to simulated the XRD pattern of Bi2Sr2Ca2Cu3O10, but I'm having a problem of finding the basis of atom(and their respective position). Also its JCPDS is quite hard to find, so if anyone working with this, may you provide a link or articles about my problem. Thanks...
  29. M

    Questions of calculus of crystal structures

    We know the rule of cross product or Why here |absinΘ| = , and = c cos Φ in the above picture? Thanks for explanation.
  30. R

    Determine the intensities of GaAs crystal planes

    GaAs crystal structures have basis atoms: Ga: (0 0 0), (0.5 0.5 0),(0.5 0 0.5),(0 0.5 0.5) As: (0.25 0.25 0.25),(0.75 0.75 0.25),(0.75 0.25 0.75),(0.25 0.75 0.75) i'm trying to find intensities at all of its plane, using this equation: I = (F^2)*m*Lf (m= multiplicity, Lf=lorentz factor)...
  31. U

    Understanding of crystal wave vector

    Hi All, From the Schrodinger wave equation, I kind of understand what a wave function and hence a wave vector is, so I understand what a wave vector of an electron wave is. However while talking about crystals, there is also a 'crystal wave vector'. Is this a vector sum of wave vectors of...
  32. 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...
  33. R

    Rules in determining family of planes in Hexagonal

    Hi guys, I'm assume that you already know the 7 crystal system, each crystals have unique way of determining the family of planes, for example in cubic, we all know (111) plane is same (-1-1-1), and so on ((-1-11),(-11-1)...) a total of 8, in fact there is pattern to determine how many possible...
  34. F

    What's the best way to make high quality Cu(II)SO4 crystal?

    My high school chemistry teacher tossed us the task and told us to figure it out ourselves. As far as I can understand, the trick is to supersaturate the solution, put a seed on a string and hope for the best. I'm just posting here to ask if anyone happens to know any good sites I might not have...
  35. Laplas

    DOS calculation in a photonic crystal

    I have calculated the band structure of an infinite photonic crystal structure by COMSOL. So, I have an array of meanings of K-vector and different values of frequency V. I need to calculate density of states (DOS). How can I calculate it? Thanks.
  36. Q

    Wave Generator with Crystal Quartz Oscillator?

    Hi All! A little background info. I'm working with cardiac pacemaking devices with the overall scope of implementing piezoelectric energy harvesters into the devices. I'm in the initial stages of research and development. Okay, so this is my conundrum: I have an output pulse circuit as shown...
  37. D

    Crystal structures of violet phosphorus and red phosphorus

    For violet phophorus,it seems that the crystal structures given by two websites are not the same.In Openstax CNX,the link is http://cnx.org/contents/f46e8679-ee00-4073-9f5e-a87ca9955a9e@25.9:67/Chemistry_of_the_Main_Group_El and the Figure 12 displays it as follows: But in Chemwiki,the link is...
  38. A

    Crystal Oscillator Package (4 pins)

    Homework Statement I'm trying to hook up crystal oscillator package on breadboard and test for expected operation: I'm not sure how and cannot find any data sheets for the pin connection diagrams, I attached an image I found of the kind of package I'm using. There are four pins. Homework...
  39. 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...
  40. F

    Lower Q of Crystal or Ceramic Resonator

    I'm working on a school project that requires me to build a RF oscillator that is able to be started and stopped at about 100kHz. Ceramic or crystal oscillators would be good because of their tiny size, however, the high Q factor creates a problem. So my question was, can placing a resistor in...
  41. A

    Lanthanide Crystal Field Splitting Energies

    Hey all, This is a problem I can't really wrap my head around. 1.) The lanthanoid series is formed through the progressive filling of the 4f subshell, whereas the first row transition metal series is formed through the progressive filling of the 3d subshell. a) What is the relative...
  42. E

    Crystal momentum in a lattice.

    Background information: The wave function for an electron in a crystal lattice is modeled by a Bloch wave. A Bloch wave is a function with the periodicity of the lattice multiplied times a complex exponential function. This exponential function has a wave vector k, called the crystal momentum...
  43. 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...
  44. T

    Crystal oscillator and amplifier purchase

    in my previous thread i was trying to build a sine oscillator and an amplifier. decided to give up on the idea and purchase. any chips out there that can give me 30-40volts peak to peak. the frequency is not an issue as long as it is above 1 MHz. i guess i can use any crystal oscillator as long...
  45. C

    Why is the change in momentum of a crystal include reciprocal lattice vectors?

    So i don't really understand why the change in momentum of a crystal involves a reciprocal lattice vector. Surely it is just the change in momentum due to the change in the number and frequency of the phonons before and after whatever event/scattering/collision takes place. Can somebody please...
  46. J

    Crystal Reconstruction: Methods and Possibilities

    Suppose I have a substance that has been crystallized. Now suppose I break down those crystals into powder, grains, etc. How can I reconstruct that powder into a crystal again? Do I just dissolve it into a solvent and then evaporate the solvent? Another quick question - is it possible to...
  47. ZetaOfThree

    Young's modulus for cubic Van der Waals crystal

    Homework Statement Calculate the Young’s moduli for Van der Waals solids with sc, bcc, and fcc structures.Homework Equations Definition of Young's Modulus $$Y=\frac{stress}{strain}$$ Total energy due to Van der Waals interaction: $$U_{tot}=\frac{1}{2}N(4 \epsilon) \left( \sum_j{ \left( \frac{...
  48. R

    Piezoelectric Crystal Shoes?

    I was inspired by this article http://science.howstuffworks.com/environmental/green-science/house-music-energy-crisis1.htm to wonder if one could put piezoelectric crystals in the sole of a shoe and perhaps harness the energy to charge their iPod?Can someone let me know if this is feasible and...
  49. Spinnor

    1 dimensional crystal at rest, a nucleus emits gamma ray of energy E,

    Say we have a one dimensional chain of N mass points separated by springs of spring constant k. This system can be quantized? Let the quantized system above be at rest and let one of the end mass points emit a photon of energy E along the crystal axis. Will we get physics similar to he...
  50. N

    Crystal Radio Basics & Components Explained

    Can someone please tell me the basics to how a cystal radio works? And also what are all the components that makes up a crystal radio? Thank you!
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