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Vaibhav Singh posted an Question
October 25, 2021 • 20:13 pm 30 points
  • IIT JAM
  • Geology (GG)

Please explain this.i understand that nucleation requires some degree of undercooling,but i could not get what is homogeneous &heterogenous nucleation.

ncieml Imt Ildi surface-related instability. This typically requires some de- gree of undercooling (cooling of a melt below the true crys- tallization temperature of a mineral) or supersaturation before a sufficient number of ions to be stable can sponta- neously cluster together ("homogeneous nucleation"). Alter- natively, a preexisting crystal surface may be present: either a "seed crystal" of the same mineral or a different mineral with a similar structure on which the new mineral can easily nucleate and grow ("heterogeneous nucleation"). For re- ./10o0

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    Mayank vedwal Vedwal

    i hope this will clarify your doubt.. if still there is doubt then u can ask it freely

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    Mayank vedwal Vedwal

    so you need to form nucleus before clustering of ions and all the ions which are clustering before reaching undercooling temperature will not stable enough to form crystals.

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    Mayank vedwal Vedwal

    because we need some amount of undercooling to start nucleation process . Undercooling is the process in which we go below the crystallization temparature and start nucleation. But if start clustering the ions before the nucleation process then it will not be stable and after clustering it will break again.

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    Mayank vedwal Vedwal Best Answer

    There are two type of nucleation processes exist in nature. 1) One in which a crystal makes it nucleus and starts growing on its own nucleus .In this type of nucleation, nucleation process starts before clustering of different ions ,atoms . This is known as homogenous nucleation. 2)Another in which the site for crystal nucleation already present in the system ,this crystal site can be the preexisting mineral surface, any rock surface near the magma chamber etc. If a nucleation process starts on the preexisting nucleation site then it will be heterogeneous only.

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    Ok ,bhaiya,i understood that in homogenous nucleation crystal makes it nucleus and grows on its own nucleus .But why you wrote nucleation process starts before clustering of different iona,atoms??

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