how do you do crystalisation

Question: how do you do crystalisation
- Keywords:
  Crystallisation
Asked by anon-267503 on 5 Nov 2020.
- Alex Dickinson-Lomas answered on 5 Nov 2020:
  
  Crystallisation is basically when atoms or molecules in a liquid arrange themselves in an repeating pattern to form a solid. In my work crystallisation happens when you cool a heated metal and the atoms arrange themselves into repeating structures where atoms are closer together rather than being arranged so they are far apart.
  You can do it at home if you dissolve sugar in a cup of water until no more will dissolve. Then you can tie a string to a knife or fork and dangle the end into the cup. Then wait for a few days/weeks and crystals will grow up the string! If you put food colouring in the cup they’ll go that colour. 🙂
- Bradley Young answered on 5 Nov 2020:
  
  Alex’s answer is a fantastic explanation.
  
  A lot of my work involves crystallising metals in to different formations, by cooling a metal down at different speeds we can crystallise it in different ways and give it really different properties. This is the same in chocolate and cooling it fast or slow when you make it crystallise differently and taste very different.
- Adrien Chauvet answered on 5 Nov 2020:
  
  I usually let my samples evaporate or precipitate.
  
  There are few different ways for both, using heat, vacuum, or other chemicals; it all depends on what you are trying to crystalize.
- Juan Pereiro Viterbo answered on 5 Nov 2020:
  
  There are different methods… it depends on what kind of crystal you want to grow. You can grow large crystals or thin films, crystals made of smaller crystals, crystals where the atoms are very well ordered and others where the atoms are not very well ordered… and the crystal you want depends on what you want it to use it for.
  I grow very thin crystals. The atoms are very well ordered and they are used to fabricate LEDs, to make electronic components, the lasers in a playstation or blue ray reader, some of the chips in mobile phones…
  The way we grow them is sending individual atoms of the elements we want in the crystal towards a surface that is held at very high temperature and then we wait for the atoms to find their positions to form the crystal we want.
- Daisy Shearer answered on 7 Nov 2020:
  
  There are lots of different ways to do crystallisation. It’s essentially when you get atoms to order themselves into an organised structure called a lattice. When I was little, I remember growing crystals at home using a dolomite rock and vinegar which makes calcium carbonate crystals. You can also grow salt crystals at home!
  
  In my research, I work with semiconductors which have a crystalline structure (usually a ‘zinc blende’ crystal). My semiconductors are grown using a technique called ‘Molecular Beam Epitaxy’ which is where an awesome looking machine makes a really thin layer of crystals (which we call a ‘thin film’) and then keeps adding layers until it’s thick enough for what we want to use it for. The machine usually does this by heating the elements you want to make into a crystal so that it becomes a gas and then condensing them on a ‘wafer’ substrate. So if we want to make a crystal of, say, indium antimonide (which I work with most of the time) then we would heat indium and antimony so that they combine to form crystalline indium antimonide when it reaches the wafer. It’s a pretty awesome technique!

Question: how do you do crystalisation

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