ABSTRACT
Phase diagrams and phase stability discussed in the last chapter are a useful guide to materials synthesis in solid state ionics to be discussed in this chapter.
The existence of a well-dened melting point is necessary for the growth of single crystals that are needed only in special circumstances such as single-crystal neutron diffraction studies. For most purposes, the focus is on polycrystalline ceramics that are obtainable from a variety of techniques discussed here. The existence of a eutectic point (one or more cusps seen in the temperature composition diagrams) in the phase diagram of, say, Li2O-P2O5 or Li2S-P2S5 helps in the synthesis of glasses and glass ceramics. The latter-type materials important for applications are made through careful heat treatments of relevant multinary glass compositions over a restricted temperature range between the so-called glass transition temperature and the crystallization temperatures. Pressure-temperature behavior of aqueous solutions of precursor materials helps in the synthesis of solid state ionic materials by hydrothermal synthesis. The solubility of organometallic precursors in (non)aqueous solvents enables powder and thin-lm synthesis by solvothermal synthesis often assisted by relatively low-temperature (~200°C-300°C) combustion. Water insolubility with very poor dissolution kinetics of silver and copper halides (and chalcogenides) helps temperature-controlled precipitation synthesis enabling not only nanoscale synthesis of individual materials but isomorphous substitution and solid solution synthesis as in AgI-CuI system. This could be extended to making ternary/quaternary compounds. Peritectic points (dened by a convex region in the phase diagram) as seen in RbI-AgI and Li2O-TiO2 binaries with narrow regions of solidliquid phase coexistence help in the synthesis of poly/nano/monocrystalline phases for basic physical property measurements and applications.
