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

2. 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.

3. 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.

4. 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

5. 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.

6. 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.