Project Title:

Physical Vapor Transport and Crystal Growth of Tellurium: A Novel Acousto-Optic Material

15.01-5800
Physical Vapor Transport and Crystal Growth of Tellurium: A Novel Acousto-Optic Material
Brimrose Corporation of America
5020 Campbell Blvd., Bldg. 1
Baltimore
MD
21236
S. B.
Trivedi
(301-529-5800)
LeRC

Abstract:

Improved understanding of vapor transport and crystal growth in microgravity requires
systematic design and optimization of ground-based experiments. Past experimental
work on compounds (i.e. HgI2, GeSe-GeI4, GeSe-Xe) has involved chemical complexities
in vapor and solid phases that caused difficulties in understanding the results.
A simple, scientifically strong experimental system using tellurium as a model material
will be defined to overcome these difficulties. Tellurium, a group VI element, is
chemically simple and is free of complex vapor-phase reactions. It has a relatively
low melting point (450 C) and a vapor pressure high enough for transport and growth
by sublimation. Applications exist for tellurium crystals in 10.6-m laser beam modulation
and steering. 
The study will address the effects on crystal growth of ampoule size and geometry,
orientation with respect to gravity and temperature gradient, and vapor transport
rates. Experimental rates will be compared with theoretical models. Vapor-grown crystals
will be characterized with respect to structural and electrical properties.

Potential Commercial Application:

Potential Commercial Applications:  This work could help grow crystals of good quality
and reasonable size under ground based conditions. Moreover, good quality tellurium
single crystals have a potential as novel acousto-optic material.