Monoclinic phosphorus formed from vapor in the presence of an alkali metal
US4620968A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 17, 1982 |
| Grant date | Nov 4, 1986 |
| Priority date | — |
| Expiry date | Sep 17, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10K10/462
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Monoclinic phosphorus is produced in a single source vapor transport apparatus comprising a sealed evacuated ampoule containing a mixture or compound of phosphorus and an alkali metal with the phosphorus to alkali metal ratio being 11 or greater. The charge is heated to 550.degree.-560.degree. C. and the monoclinic phosphorus crystals are formed on the cooler surface at the top of the ampoule over the temperature range of 500.degree.-560.degree. C. The preferred heating temperature is in the neighborhood of 555.degree. C. and the preferred deposition temperature is in the neighborhood of 539.degree. C. Alkali metals that may be employed include sodium, potassium, rubidium and cesium. The monoclinic phosphorus crystals form in two habits. Those formed in the presence of sodium and cesium are in the form of flat square platelets up to 4 mm on a side and 2 mm thick. These platelets may be easily cleaved into thinner platelets, like mica. The other habit formed in the presence of potassium and rubidium is in the form of a truncated pyramid up to 4 mm.times.3 mm.times.2 mm high. This habit is hard to cleave. The crystals are semiconductors with a band gap, indicated by photoluminescence…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.