Crystal Definition and 430 Threads

  1. N

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

    Is it true that, if power were applied to a one meter cube of quartz crystal and the crystal were driven to the breaking point, the gravity waves produced would definetly, 100%, be orders of magnitude too weak to be detected? Apparently Albert Einstein calculated that
  2. 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...
  3. 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?
  4. 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...
  5. P

    Crystal Planes, Miller Indices: Cubic Lattice

    Just when I thought I understood the concept of planes and miller indices, I got stuck on a 'test your understanding' Q in my book. I can't understand that there can be two or more (110) planes in a crystal lattice? I thought there can be only one such plane. The question asks me to find the...
  6. L

    Question on how to calculate bond energy in crystal.

    Dear all: Since bond energies in crystal are very important in say single crystal growth theory, and it seems very difficult to do such calculations. However, can someone give me some hints on this task, or if there is a perfect solution, please let me know. Sincerely Hongbin Zhang
  7. A

    Radius Ratio of Crystal: Interstitial vs Large Atom

    in the radius ratio of a crystal, what is the difference between the radius of the interstitial atom and large atom?
  8. J

    Decomposition temperature of ZnSe:Cl crystal

    Any one knows what the decomposition temperature of ZnSe semiconductor doped with Cl is? I am doing some annealing with a simple equipment but worring about the volatilization of Cl, which would be dangerous. Thanks a lot!
  9. Astronuc

    Fluctuating crystal structure at constant temperature

    from the Alchemist Newsletter from Chemweb.com Full story at Living metals by the European Synchrotron Radiation Facility (ESRF).
  10. T

    What Free Libraries Can I Use to Draw Crystal Lattice Structures in 3D Using C?

    Hello, my name is Kenichi, from japan. Inorder to draw Crystal Lattice 3D Structures, what libraries for free out there to be used with C programming language ? I am still a C novice. I wonder, in chemical simulation research do you also program using C language plus some libraries to...
  11. M

    Safe Home Science Experiments with Household Products

    Well I know of the boil sugar, add then let it stick. You can form sugar crystals on the stick then eat them. Well I am about 15 years to old to be doing that. What got my interest was this picture of "home grown Monoammonium Phosphate" So I was wondering. Are there any experiments I could...
  12. F

    Creating a Large NaCl Crystal: Exploring Evaporation Techniques

    How would someone go about creating a large NaCl crystal? Is there a special evaporation technique involved with a saturated solution? As a side question why is sugar in crystal form? I mean isn't sugar a covalently bonded molecule?
  13. M

    Crystal Structure: Properties of Materials Depend on Structure

    Which properties of materials depend on the crystal structure (f.c.c., b.c.c. cph etc...) of materials?
  14. R

    Bi-refraction by calcite crystal

    When light passes through calcite crystal it splits into two rays, extra ordinary and an ordinary ray. Ordinary ray travels straight and extra ordinary ray is refracted. This would mean ordinary ray travels faster and e-ordinary ray travels slower because index of refraction is inversely...
  15. B

    Perfect Crystal Brittleness: Fact or Myth?

    My physics teacher taught me that, however, when I asked my chemistry teacher, he said NO. And now ... I'm confused. Plz anyone can help me to make me clear about this with explanation.?
  16. U

    Calculate Poisson's ratio of NaCl crystal

    hello to all here is a problem i designed myself. i don't know whether it can be solved. Question: Consider NaCl lattice of edge length 'x' m. Let Na+ carry +1 C and each Cl- carry -1 charge. Calculate Poisson's ratio of NaCl crystal. Assume no heat loss when deformation takes place...
  17. C

    Symmetry in crystal structures-

    Symmetry in crystal structures- please help! Hi there, I was hoping someone here could help explain a few things about crystal symmetry to me cos it hs me so confused (we've been doing crystals for 2 weeks and things up til now have been ok, I'm just getting myself muddled as usual!). The...
  18. C

    Symmetry in crystal structures-

    Symmetry in crystal structures- please help! Hi there, I was hoping someone here could help explain a few things about crystal symmetry to me cos it hs me so confused (we've been doing crystals for 2 weeks and things up til now have been ok, I'm just getting myself muddled as usual!). The...
  19. W

    Liquid Crystal Contact Lens: The Future of Vision Correction?

    Would it be possible that Opticians will be selling to visually impaired people, Contact Lens, made from a material that has a negative index refraction, that theoretically could be altered with a Liquid Crystal "Eye-Drop" solution? Basically how far are we from a Liquid Crystal Contact Lens...
  20. J

    Can a Crystal Radio Use Lead Sulfide or Lead Selenide for Infrared Detection?

    Could a crystal radio use a lead sulfide or lead selenide antenna an pick up in the infrared?
  21. J

    Can Infrared Crystal Radios Self-Power Like Solar Cells?

    Can a crystal types radio be made to work in infrared? With an antenna of lead sulfide or lead selenide perhaps?
  22. R

    Build a Crystal Radio - Needed Parts & Where to Find Them

    has anyone here ever built a crystal radio? what parts would i need and where can i get them? in the physics forum they said one could be constructed to run off the radio waves themselves, which is the kind i would like to build. thanks
  23. S

    The Halo and the Non Linear Crystal

    Photon splitting. It's effective use in Quantum Computation? Optical Parametric Generation In the photon picture shown above, a high frequency photon (blue) enters a crystal and is split into two lower frequency photons (green and red). Conservation of energy means that the sum of...
  24. B

    Tough stuff the universe is like a crystal

    The universe acts like a crystal [1] because the observed universe is made of huge cosmic scale atoms some seen as galaxies and galactic nuclei [2]. 1. http://www.cc.rochester.edu/College/RTC/Borge/aniso.html Indication of anisotropy in electromagnetic propagation over cosmological...
  25. A

    Guiding Wave Through Diffraction in Photonic Crystal Fiber

    Hi, Can someone tell me how a wave is guided (in a fiber for instance) thinking in term of diffraction (or scattering) and not in term of successive reflections. And my second question is : would it be possible to "extrude" a plan diffractive element in a fiber to guide wave and have the...
  26. C

    Internuclear separation between ions in a crystal-

    Okay, I'm hoping someone here can explain this homework qustion I've got bcause we don't seem to have anything in our notes that covers it, so any help would be great- thanks! Potassium fluoride (K+F-) is an ionic crytal having density 2.48x10^3 kg/m^3 Assuming that the diameters of the K+...
  27. 3

    Re: carbon steel - Is a crystal the same as a grain?

    I'm still a little confused about crystals and grains. Does a crystal become a grain as the metal solidifies? I'm also not clear on molecules. For instance with a body centered lattice you have nine atoms. One on each corner and one in the center of the body. So within that lattice -- what...
  28. Evo

    How Does a Crystal Turn Space Inside Out?

    A NEW kind of crystal is so riddled with holes that a mere gram of the material has an internal surface area equivalent to 17 tennis courts, a record, the British science journal Nature reports today. http://www.heraldsun.news.com.au/common/story_page/0,5478,8588873%255E1702,00.html
  29. M

    Crystal Core Discovered in Dying Star

    http://www.newscientist.com/news/news.jsp?id=ns99994692 "A crystal the size of our Moon has been revealed hidden at the centre of a dying star, after an analysis of pulsations in the star's brightness. The measurement confirms indirect evidence that the cores of all such dying stars -...
  30. L

    What is the Crystal Structure of Aluminum and its Bonding Patterns?

    For my project, I am creating a pure aluminum model with styro foam balls and toothpicks. I know this structure is a "face-centered cubic". However, I don't know the bonding angles and what kind of bonding shape (tetrahedral, octahedral ...), I need the information for the write-up. Can someone...
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