Homogeneous nucleation is the process by which nuclei form in a homogeneous environment without the presence of any surface on which they can grow. In contrast, heterogeneous nucleation occurs on the surface of a material. The mechanism by which homogeneous nucleation occurs is not well understood.
I assume you're familiar with spinodals? If you need any special properties, send me an email. Here are the spinodal points for steam based on the 2020 formulation
Thank you for your message. I am not familiar with the spinodal technique and would appreciate more information on how I can use it to study the nucleation of HAP.
Dear Dudley J Benton
The chemical potential of each thermodynamic phase of calcium phosphate can be calculated by using the concentrations of ionic species in the supersaturated solutions and the mass balance expressions. By using these values, it is possible to find the chemical potential of each phase by successive approximations of ionic strength (I=0.15mol/L).
Spinodal refers to certain metastable points on the phase diagram of a substance. These are the inflection points where the fluid is least stable. As you heat a liquid at constant pressure when there are no flaws or sites or dirt to facilitate nucleation, the temperature rises above the saturation until a bubble explodes (on a very small scale) into existence. The same thing happens (in the opposite direction) when you cool a vapor and there are no sites to facilitate condensation. If you extend this down below the triple point into the sublimation zone, we see for example, ice crystals just sort of pop out of seemingly thin air. I can't give you a copy of this document because EPRI is extremely stingy about those things... Karimi, A., and J. H. Lienhard, "A Fundamental Equation Representing Water in the Stable, Metastable, and Unstable States," EPRI NP-3328, December, 1983. A Web search for papers by Lienhard will turn up several things you may be interested in.
Dudley J Benton thank you for your thorough explanation! I appreciate your help. I will look up the papers by Lienhard.
Last but not least two more questions, which I hope you will answer.
What is the free energy of the calcium phosphate system at the spinodal points?
How does the spinodal affect the size and shape of HAP crystals that are formed during nucleation?
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