I have a binary system of polyalcohols. When I cool the mixture down past it's solid-solid transition point, it usually forms a metastable phase. We know this because upon reheating promptly after the cooling, the transition temperature is different than if we let the sample anneal for a few days.
Is there an alternative to annealing for several days? How can we speed up the process by which it transitions to it's stable phase? Mechanical engineer here, I apologize if this is a rookie materials science question.
It is not a rookie question at all. Personally, I do not think that there exists a "nucleation-like" method for solid-solid transitions, at least not a universal one. Something specific to polyalcohols? Well, I would not exclude it, but I would be surprised.
You may want to check the signalled RG discussions: https://www.researchgate.net/post/Freezing_point_of_Glycerol_Glycol_mixtures https://www.researchgate.net/post/What_is_the_triethylene_glycols_melting_temperature
Polyalcohol systems typically have a strong tendency to supercool ― For a generic discussion on glass transition, you may see: C.A. Queiroz, J. Šesták, "Aspects of the non-crystalline state", Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B, 51(3) June 2010, 165-172:
Article Aspects of the non-crystalline state
Have you tried a the constrained crystallisation approach? This allows the most stable form to crystallise first via the 'Ostwald's rule of stages'
You heat your sample rapidly (e.g. at a 40 degrees/minute) to its melting point, ensure it is completely melted without decomposing, then 'quench' it rapidly by cooling at a similar rate to below zero temperature (e.g. negative 40 degrees), this approach should trap your sample in an amorphous state, then slowly heat it back up to its melting point again at 1 degree per minute, the most stable form should crystallise out first according to the Ostwald's rule of stages.
Sounds like an easy method, I'll go ahead and give that a shot. I just read up on Ostwald's rule of stages (Article The Ostwald Rule of Stages
), and am confused about one thing: The rule of stages says that the metastable phases will crystallize first, followed by recrystallization to the thermodynamically stable phases. In this procedure, why would the most stable form crystallize out first? Shouldn't it be last?
The thermodynamically stable form will crystallise out last, sorry for the mix up, you might one to use DSC first.
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