What is Amorphous: Definition and 26 Discussions

In condensed matter physics and materials science, an amorphous (from the Greek a, without, morphé, shape, form) or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal. In some older books, the term has been used synonymously with glass. Nowadays, "glassy solid" or "amorphous solid" is considered to be the overarching concept, and glass the more special case: Glass is an amorphous solid stabilized below its glass transition temperature. Polymers are often amorphous. Other types of amorphous solids include gels, thin films, and nanostructured materials such as glass.

Amorphous materials have an internal structure made of interconnected structural blocks. These blocks can be similar to the basic structural units found in the corresponding crystalline phase of the same compound. Whether a material is liquid or solid depends primarily on the connectivity between its elementary building blocks so that solids are characterized by a high degree of connectivity whereas structural blocks in fluids have lower connectivity.In the pharmaceutical industry, the amorphous drugs were shown to have higher bio-availability than their crystalline counterparts due to the high solubility of amorphous phase. Moreover, certain compounds can undergo precipitation in their amorphous form in vivo, and they can decrease each other's bio-availability if administered together.

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  1. S

    XRD Result Analysis on Polymer

    So i just have my XRD result (Polymer Specimen) which i use to determine crystallinity of my material, and it turns out that my material has no obvious peak, and have a broad peak which usually associated with amorphous material. I added some filler to my material and it became more and more...
  2. N

    A Classifying atomic chains in Amorphous Structures

    Here are two examples of chains. The end pairs of atoms are 8.0 angstroms and 9.2 angstroms apart respectively.
  3. S

    I Why are crystals more conductive then amorphous structures?

    Hey guys basically why are copper crystals more conductive then the corresponding amorphous structure? I know generally that electrical conductivity is reliant on: σ = (e2 * (vf)2 n τ)/3 My attempt of understanding is that the crystal structures are made up of unit cells which implies every...
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    I Any stable amorphous substances?

    I´ve seen it asserted at the general physics forum that melting point of amorphous substance is "always" lower than the "melting point" of corresponding crystal. Also, amorphous solids are often described as metastable against crystallization. Does it necessarily apply to all amorphous solids...
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    Creating Amorphous Metal: The Possibility of Electroplating and Rapid Cooling

    Hello, I've been thinking about if amorphous metal (aka metallic glass) could created by using regular electroplating or if it has to be created by rapid cooling of the metal after molten. There is a method which a thin layer of metal powder is applied to a flat surface where a laser beam melts...
  6. C

    Identifying Broad Reflections in XRD Patterns

    Hello, everyone! Let's say I have an XRD pattern which has broad reflections. I don't know what material it is (don't know what temperature and conditions it is made). How to know whether those broad reflections are from nanomaterial or amorphous material?
  7. K

    A Activation Energy of Amorphous Transition Metal Oxides

    Hi, Is measuring the temperature dependent conductivity a reliable way of determining the activation energy/ the dopant level of a wide band-gap transition metal oxide. Also does the activation energy in this case change with the dopants density. Thanks.
  8. B

    Glass transition temperature; slowly cooling it

    One aspect of glasses that has confused me was the fact that the transition temperature Tg drops as you slow the rate of cooling. This has confused me because if the glass is slowly becoming more crystalline, then I would of thought that the Tg would start climbing up towards the crystal melt...
  9. 1

    Estimating Resistivity of Amorphous Metal - Condensed Matter

    Homework Statement Estimate the resistivity of an amorphous metal whose mean free path is of the order of an atomic spacing. Compare your answer to crystalline copper.Homework Equations VF = h(bar) KF / m VF = l / τ ρ = m / n e2 τ The Attempt at a Solution I think my real issue with this...
  10. R

    How to tell crystalline from amorphous on touch?

    Apologies if this is a stupid question, my basics are really weak. We have Inorganic Qualitative Analysis in our chemistry syllabus and I have somehow never been able to figure out if a substance is crystalline or amorphous. They both feel so ... powdery.
  11. N

    Does amorphous solids support phonons or nomal modes of vibration.?

    Does amorphous solids support phonons or nomal modes of vibration.?? Can we apply the concept of phonons and Debye Model in case of amorphous and poly-crystalline solids?? http://en.wikipedia.org/wiki/Phonon http://en.wikipedia.org/wiki/Debye_model The links I have attached above...
  12. B

    Is my material Nanocrystalline or Amorphous? (XRD and Raman)

    Hi! How can I tell, based on my Raman and X-Ray Diffraction studies, if a thin film is nanocrystalline or amorphous? The maximum thickness of my films is about 200nm, the XRay diffractograms showed nothing but the substrate (is it because of the thickness?), and my Raman spectra showed some...
  13. A

    Photons in amorphous glass slow because?

    In solids it is the interaciton b/w the phonons and photons that give a lower effective speed. not absorption & re-emmision. (see ZapperZ's post: https://www.physicsforums.com/showthread.php?t=511177 ) but in amorphous glass there are [B]no[B] phonons. So why does light 'slow down'...
  14. K

    Dispersion relation of amorphous materials

    Hi, I am trying to find dispersion relation of amorphous material (using data obtained by molecular dynamics simulation). As it is not periodic system one can not find it by standard method of diagonalizing the force constant matrix. I think one can do it by taking Fourier transform of...
  15. A

    Amorphous and organic semiconductors

    please explain abt amorphous and organic semiconductors...their properties ...nature of classification ...examples..etc..
  16. C

    Technique to identify amorphous phases

    Hi everyone! I want to ask if anyone knows a technique that could analyze a sample, with crystalline and amorphous phases, and in some way that I could identify and/or quantify the amorphous phase (atomic elements and/or stoichiometry). I read that could be a way using EELS technique, but...
  17. A

    Amorphous Ferromagnetic Metallic Alloys

    "Amorphous Ferromagnetic Metallic Alloys" Hello all, In a project in which I'm looking to endeavor, I have a need for a material with high magnetic permeability and high electrical resistivity. In beginning my research, I came across this in Wikipedia: "One can also make amorphous...
  18. R

    The amorphous borders between grains in a metal

    I am taking Engineering 101, and trying to get the hang of metal structure on a 'grains' level. Ok, so my understanding is this; Metals are polycrystalline materials, that can be divided up into 'grains'. These grains are basically crystals/lattices with a repeating pattern, separated by...
  19. D

    Amorphous and crystalline oxides

    Can anyone explain the difference between amorphous and crystalline oxides. I've tried google but can't find anything useful. I'm guessing that crystalline oxides should have a crystalline structure and as such crystalline properties. Would that be right?
  20. P

    Chemical attack of amorphous carbon

    Hi everyone, i wonder if anyone has an idea how to attack chemically an amorphous carbon film. Is it possible to completely dissociate an amorphous carbon in a chemical solvent? thanks for your help
  21. R

    Can Amorphous SiO2 React with Metals or Carbon to Produce Nano Sized Particles?

    I get amorphous SiO2 (quartz) using planetary ball mill after 20h of milling, although my aim was to get nano sized particles. My question is if I can react it with some metals or carbon, for example if the reaction: SiO2 + 2C = SiC + CO will occur. If anyone can help me to find some...
  22. S

    Why does't amorphous silicon oxide present piezoelectricity?

    We know quartz,viz. crystal silicon oxide is a kind of piezoelectric solid.Does the amorphous silicon oxide present piezoelectricity also. If not,Why? -------------------------------------------------------------------------- I'm not good at English, so if there is any language errors in my...
  23. H

    I want to know the microscopic mechanism of electric polarition of amorphous

    Who can tell me the microscopic mechanism of electric polarition of amorphous,such as Si3N4 or SiO2.Which dominates the permittivity of amouphors,is it Eletronic polarization,orientational polarization,Atomic ploraization or something others?thank you.
  24. Mk

    Amorphous ice is less dense than crystalline, why?

    http://www.lsbu.ac.uk/water/amorph.html puts the densities of various forms of amorphous ice at densities that are very low. g/cm-3 in fact. Is this a typographical error? If not why is it so dense? Crystalline ice's densities are attributed to all the empty space in-between crystals, amorphous...
  25. S

    Why amorphous phase materials have wider bandgap?

    I'm wondering why the amorphous phase materials have wider bandgap compared to its crystalline phase. To my best knowledge, the bonding mechanism does not changed as the material transform from crystalline phase to amorphous phase. So what causes it has larger bandgap? ST
  26. K

    Glass is a solid material with an amorphous internal structure.

    "glass" is a solid material with an amorphous internal structure. http://science.nasa.gov/headlines/y2003/14apr_zeroglass.htm So does it imply that if I have 1kg egg shell, and I heat it to 2000 F and cool it immediately before the atoms arrange themselves regularly again, then I can...