Crystals and crystal growth

Crystal growth - practice Many techniques are available– choice of method depends upon the material Grow from molten solid Grow from solution– this can include solvents as diverse as water andmolten PbO! Grow from vapor phaseGrowth from the melt Very important, but not possible for mostmaterials Material must be stable above melting point Phase diagram must allow directcrystallizationLi 2 O - Nb 2 O 5 phase diagramGrowth from the vapor phase Not very common Used for some sublimable compounds Used where a material can be transported bythe addition of an appropriate reagent–ZnS (s) + I 2(g) --- ZnI 2(g) + 1/8S 8(g) (exothermic)Growth from solutionVapor and solute diffusion The most common method Based on precipitation from a saturatedsolution Saturation can be achieved in many ways– cool solution– evaporate solvent off– add things to solvent to reduce solubility