Conversion of doped polycrystalline material to single crystal
US5487353A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 14, 1994 |
| Grant date | Jan 30, 1996 |
| Priority date | — |
| Expiry date | Feb 14, 2014 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC30B29/20
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A solid state method of converting a polycrystalline ceramic body to a single crystal body includes the steps of doping the polycrystalline ceramic material with a conversion-enhancing dopant and then heating the polycrystalline body at a selected temperature for a selected time sufficient to convert the polycrystalline body to a single crystal. The selected temperature is less than the melting temperature of the polycrystalline material and greater than about one-half the melting temperature of the material. In the conversion of polycrystalline alumina to single crystal alumina (sapphire), examples of conversion-enhancing dopants include cations having a +3 valence, such as chromium, gallium, and titanium. The polycrystalline body further can be inhomogeneously doped to form a first portion of the polycrystalline body that is doped to the selected level of the conversion-enhancing dopant and a second portion that is not doped such that heating the doped polycrystalline body causes conversion of first portion to a single crystal structure and the second portion retains a polycrystalline structure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.