Editing Solubility (section)

==Solid solution==
This term is often used in the field of [[metallurgy]] to refer to the extent that an [[alloy]]ing element will dissolve into the [[base metal]] without forming a separate [[Phase (matter)|phase]]. The [[solvus]] or solubility line (or curve) is the line (or lines) on a [[phase diagram]] that give the limits of solute addition. That is, the lines show the maximum amount of a component that can be added to another component and still be in [[solid solution]]. In the solid's crystalline structure, the 'solute' element can either take the place of the matrix within the lattice (a substitutional position; for example, chromium in iron) or take a place in a space between the lattice points (an interstitial position; for example, carbon in iron).

In microelectronic fabrication, solid solubility refers to the maximum concentration of impurities one can place into the substrate.

In solid compounds (as opposed to elements), the solubility of a solute element can also depend on the phases separating out in equilibrium. For example, amount of Sn soluble in the ZnSb phase can depend significantly on whether the phases separating out in equilibrium are (Zn<sub>4</sub>Sb<sub>3</sub>+Sn(L)) or (ZnSnSb<sub>2</sub>+Sn(L)).<ref>{{cite journal|doi=10.1002/aenm.202100181|title=Phase Boundary Mapping of Tin-Doped ZnSb Reveals Thermodynamic Route to High Thermoelectric Efficiency|journal=Advanced Energy Materials|volume=11|issue=20|year=2020|last1=Wood|first1=Maxwell|last2=Toriyama|first2=Michael|last3=Dugar|first3=Shristi|last4=Male|first4=James|last5=Anand|first5=Shashwat|last6=Stevanović|first6=Vladan|last7=Snyder|first7=Jeff|s2cid=234807088}}</ref> Besides these, the ZnSb compound with Sn as a solute can separate out into other combinations of phases after the solubility limit is reached depending on the initial [[chemical composition]] during synthesis. Each combination produces a different solubility of Sn in ZnSb. Hence solubility studies in compounds, concluded upon the first instance of observing secondary phases separating out might underestimate solubility.<ref>{{cite journal|doi=10.1038/ncomms8584|title=Solubility design leading to high figure of merit in low-cost Ce-CoSb3 skutterudites.|journal=Nature Communications|volume=6|issue=7584|year=2015|last1=Tang|first1=Yinglu|last2=Hanus|first2=Riley|last3=Chen|first3=Sin-wen|last4=Snyder|first4=Jeff|page=7584 |pmid=26189943 |pmc=4518255 |bibcode=2015NatCo...6.7584T}}</ref> While the maximum number of phases separating out at once in equilibrium can be determined by the Gibb's [[phase rule]], for chemical compounds there is no limit on the number of such phase separating combinations itself. Hence, establishing the "maximum solubility" in solid compounds experimentally can be difficult, requiring equilibration of many samples. If the dominant [[crystallographic defect]] (mostly interstitial or substitutional point defects) involved in the solid-solution can be chemically intuited beforehand, then using some simple thermodynamic guidelines can considerably reduce the number of samples required to establish maximum solubility.<ref>{{cite journal|doi=10.1021/acs.chemmater.1c03715|title=Thermodynamic Guidelines for Maximum Solubility|journal=Chemistry of Materials|volume=34|issue=4|pages=1638–1648|year=2022|last1=Anand|first1=Shashwat|last2=Wolverton|first2=Chris|last3=Snyder|first3=Jeff|s2cid=246516386}}</ref>