Accession Number:

ADA282905

Title:

Evaluation of the Quality of Sapphire Using X-Ray Rocking Curves and Double-Crystal X-Ray Topography

Descriptive Note:

Technical rept.

Corporate Author:

AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS

Personal Author(s):

Report Date:

1994-05-01

Pagination or Media Count:

24.0

Abstract:

Single-crystal sapphire is a material with a wide range of applications as a result of its unique physical, optical, mechanical, and chemical properties. The quality of a sapphire crystal can influence its effectiveness in many applications. High-quality, near-perfect, single-crystal sapphire can be grown, but it is difficult to shape and polish because of its extreme hardness, and surface flaws and damage are commonly produced during fabrication. Since this damage may exist in a buried subsurface layer, it can be difficult to detect. X-ray rocking curves and X-ray topography are extremely sensitive to the level of defects and strains in single crystals. A number of sapphire substrates, from several suppliers were examined using these techniques in order to determine how applicable they are for detecting defects in sapphire. A wide range in quality was found in sapphire received from different suppliers. Residual grindingpolishing damage was observed in many samples. Other defects observed included dislocations and mosaic structure and twinning in lower quality material. Rocking curves and double-crystal X-ray topography appear to be simple techniques for evaluating and determining the quality of sapphire. In particular, they are sensitive to subsurface damage and microscopic defects can be imaged at low to moderate magnification.

Subject Categories:

  • Inorganic Chemistry
  • Manufacturing and Industrial Engineering and Control of Production Systems
  • Crystallography
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE