Solution State Synthesis Hydrothermal Method Sol-gel method Flux Method Metathesis Additional Topic: Zeolite

Hydrothermal Autoclave Reactor 1. Hydrothermal Method Hydrothermal Autoclave Reactor Quartz Crystals ■ Principle & Process Crystal grows in aqueous solution at high temperature and pressure. (Closed system) Water function both as pressure transmitting medium and as solvent. ■ Characteristics Lower temperature than melt growth kg size of single crystals. Drawback: difficult to predict morphology of product. ■ Usages & Applications Mostly used in quartz industry. Metal oxides.

2. Sol-gel Method ■ Principle & Process Simple setup ■ Principle & Process Method for producing solid materials from small molecules. The process involves conversion of monomers into a colloidal solution (sol) that acts as the precursor for an integrated network (gel). ■ Characteristics Simple way to produce many different kinds of materials due to wide range of precursor choices. Drawback: slow growth rate ■ Usages & Applications Fabrication of metal oxides, especially the oxides of silicon and titanium. Fabrication of thin film, fibers, and powders.

3. Flux Method BaFe2As2 crystal Ba, FeAs, CoAs ■ Principle & Process Furnace Ruby crystal grown by Al2O3, Cr2O3 solutes and MoO3 flux. BaFe2As2 crystal Ba, FeAs, CoAs ■ Principle & Process Mixing starting materials with metal or alloy solvent (flux), and then seal it in glass tube. Put the glass into furnace and heat it. Centrifugation to separate Flux solvent could be low melting point metals {e.g. Sn(232°C), Pb(327°C)..} ■ Characteristics Crystal is easily separated from the products. It needs small amount of starting materials. Drawback: difficult to predict morphology of product. ■ Usages & Applications Metal phosphides, silicides, oxides, and ceramics

4. Metathesis ■ Principle & Process Solution Gas Solid ■ Principle & Process - Double replacement reaction (A-B + C-D → A-D + C-B) ■ Characteristics Thermal metathesis requires high temperature to break down metal-organic bonds. Light induced metathesis can be happen. Solution-based metathesis can be occur under acidic, basic, and catalytic conditions. Various kinds of products can be synthesized by choosing various precursors. ■ Usages & Applications Chemical synthesis of various kinds of crystals.

Zeolite ■ Structures & compositions Definition: Microporous mineral consist of aluminum and silicon oxide framework. Chemical formula: Na+ or Ca2+ salt includes hydrated aluminum oxide and silicon oxide. e.g.) Na2Al2Si3O10·2H2O, Ca2[Al2Si4O12]2·12H2O Structures: Hollow hole (50% of total volume) accommodate cations (Na+, K+, Ca2+, Mg2+,etc.) Synthetic zeolite Sol-gel zeolite Hydrothermal zeolite ■ Synthesis Sol-gel process: Si(CH2CH2OH)4 + Al(CH2CHCH2OH)3 in NaOH and NaCl solution. Hydrothermal synthesis: Heating up amorphous SiO2·Al2O3 ■ Applications Catalysis: Pore facilitates catalytic reaction. (e.g. petrocemistry: cracking, isomerization) Ion exchange: detergent, soap, cleanser for contaminants like radioactive ions. Gas separation: as a seive molecule, it captures gas molecules. Heating and refrigeration: hydration and dehydration coupled with heat adsorption and emission.