Why is a solid solution's vapor pressure lower than a pure solid which causes it to become more stable so that it form before the pure one while cooling in Liquid State sintering? For example when we have Si, Al, O and N the first crystalline phase to form will be SiAlON and not Si3N4...after that Si3N4 will form...thermodynamically we know that solutions are more stable than pure phases; how can I find a convincing and scientific answer? What papers and books should I search in?
Have a look in text books that deal with the thermodynamics of solutions in general. Due to the presence of a solute the entropy of the total system is lower. As a consequence the chemical potential of the solvent is lowered by the presence of the solute. And therefore the solvent can be in equilibrium with a vapor with a lower density (read chemical potential). You should look for textbooks that derive the chemical potentials for binary mixtures and introduce the notion of osmotic pressure. A book that I like is from Kedem & Katchalsky: http://www.amazon.com/Nonequilibrium-Thermodynamics-Biophysics-Aharon-Katchalsky/dp/0674625501/ref=sr_1_1?ie=UTF8&qid=1387123174&sr=8-1&keywords=katchalsky+thermodynamics
Actually the book is about non-equilibrium thermodynamics, but is contains a concise and clear description of equilibrium thermodynamics.
The thermodynamic behavior for solid solutions is the same as that for liquid solutions. You can read any thermodynamic textbook on activities of liquid solutions and phase transformations of liquid vapor. Just substitute solid solutions and solid-vapor transformations appropriately in the mathematical notations.
One addition is, solids can have surface segregation of different components. So the concentrations that are in equilibrium with the vapor are not necessarily those of the bulk.
Thank you Mr.Huinink and Mr.Weimer your answers were really helpful.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science