8) Gpoins) Comparsion of homogencous nucleation and heterogencous mackeation, th
ID: 3349022 • Letter: 8
Question
8) Gpoins) Comparsion of homogencous nucleation and heterogencous mackeation, the hetcrogencous nucleation has · acrtcalnucleus with smiler ndis than a crtical nicks orhomogeneous nrkation a critical nucleus with barger radius than a crtical nuckeus of homogencous muckeation · acrtcal nucleus with same radus as a critical ruckus of homogeneous mceation h) (3points) Heterogeneous macleation is more viable than homogencous nucleation because the heterogeneo us nucleation Has a crtical nucleus with smaller activation energy barrier than activation energy barrer of homogeneous nucleatn Has a critical nuckus with higher activation energy barrier than activation energy barrier of homogeneous nucleation Has a critical nuckeus with same activation energy barrier as activation energy barrier of homogeneo us nucleation 0 (3 points) About eflect of temperature on microstructure of materas, Tm is meting temperature of a material TExplanation / Answer
(g)In homogenous nucleation, you form an entirely new surface directly, while heterogeneous nucleation takes place on already existing surface (growth). Heterogeneous nucleation creates less new surface per mass which means it is energetically favourable to homogeneous nucleation, thus it happens at less favourable conditions (higher temperature etc).
Critical Nucleus is the minimum size that must be formed by atoms or molecules clustering together (in a gas, liquid or solid matrix) before a new-phase inclusion (a bubble, a droplet, or a solid particle) is stable and begins to grow. Formation of such stable "nuclei" is called nucleation.
The heterogeneous nucleation has a critical Nucleus larger radius than a homogeneous nucleus.
(h) Heterogeneous nucleation is more viable because has a critical nucleus with smaller activation barrier energy than the homogeneous nucleation.
(i)low temperature with low nucleation and low growth rates resulting in coarse microstructure with large grains.
(j)impurity catalyst will help make lateral growth rate is significantly smaller than the longitudinal one.
(k)The growth rate will increase as the increasing in vapour pressure takes place in the VLS
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