solvothermale

Solvothermal synthesis, occasionally spelled solvothermale, refers to chemical reactions or crystallization carried out in a solvent at elevated temperature and pressure within a sealed vessel, usually an autoclave. It extends hydrothermal synthesis to nonaqueous or mixed solvents, enabling phases and morphologies not accessible at ambient conditions.

In solvothermal processing, precursors dissolve in a solvent or solvent mixture, and the sealed reactor is heated above the solvent’s boiling point. The resulting pressure drives nucleation and crystal growth. Times range from hours to days; temperatures commonly span 100–400 C, depending on materials and solvent.

Common solvents include polar aprotic or high-boiling liquids such as DMF, DMSO, ethylene glycol, alcohols, or acetic acid. Water may be used in mixed systems. Solvent choice influences solubility, kinetics, crystal phase, and particle size.

Equipment consists of pressure-rated reactors, typically stainless steel autoclaves, capable of withstanding elevated temperatures and pressures.

Applications include synthesis of inorganic crystals, semiconductors, and nanomaterials; production of metal-organic frameworks and coordination polymers; control of particle size and morphology; and access to exotic phases not available at ambient pressure.

Advantages include enabling poorly soluble precursors to react, improved crystallinity and uniform morphology, and tunable phases via solvent and temperature. Limitations include safety risks from high pressure, solvent toxicity and cost, and challenges in scaling up.

Solvothermal methods differ from hydrothermal ones, which use water as solvent; solvothermal broadens solvent choice and materials accessed.