Nonstoichiometric melt

Top-seeded solution growth of oxide crystals from nonstoichiometric melts . Mater. Res. Bull. 6, 899-906. 

Nonstoichiometric Nature of Some Binary Congruently Melting... 

Clathrate Formation. Ethylene oxide forms a stable clathrate with water (20). It is nonstoichiometric, with 6.38 to 6.80 molecules of ethylene oxide to 46 molecules of water in the unit cell (37). The maximum observed melting point is 11.1°C. An x-ray structure of the clathrate revealed that it is a type I gas hydrate, with six equivalent tetrakaidecahedral (14-sided) cavities fully occupied by ethylene oxide, and two dodecahedral cavities 20—34% occupied (38). 

The material has a high vapor pressure at its melting point, or one component has a high vapor pressure, so that it tends to be nonstoichiometric when grown from the melt. 

Paraceleus said that antimony is a fascinating element and that one could spend a lifetime studying its compounds and chemistry. Antimony sulfide is an unusual material. It is a naturally occurring semiconductor. It is usually given the formula Sb2S3. The compound is usually nonstoichiometric, that is, it is nearly Sb2S3 but not quite. If a crucible full is melted and allowed to resolidify, there is usually a multitude of natural diodes in the mass. The author found a crude transistor formed in such an experiment. The material is of the n-type if sulfur is above the stoichiometric and of the p-type if antimony is in excess. The n-type is much more sensitive with chlorates. 

Europium monoxide is the only ionic rare earth monoxide. It is a dark red compound with the NaCl structure, slightly nonstoichiometric, and has semiconducting properties that vary as a function of composition [45]. It has been prepared as slightly nonstoichiometric material EuOi,o2 by reaction of Eu metal with stoichiometric EU2O3 in a sealed tube as a polycrystalline solid [32,46] or (stoichiometry not reported) from a melt as single crystals [45]. When heated it decomposes ... 

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