Characterization of Defects in Nd:YAG using High Resolution Transmission Electron Microscopy
EMSL Project ID
2653
Abstract
Czochralski-growth YAG single crystals have been observed to crack during growth as the Nd dopant concentration is increased. Previous work has shown that the lattice strain associated with the substitution of Nd for Y is not sufficient enough to be the likely cause of fracture. Transmission electron microscopy of material taken from the core regions of the boules has revealed particles on the order of 0.5 – 1 micron in diameter. Electron diffraction patterns from the particles show no misorientation or structure change between the particles and matrix material. Convergent beam electron diffraction of the particles has showed that they are thicker than the surrounding matrix. This suggests that the particles and matrix mill at different rates. Because the crystal gives off light when irradiated with the electron beam, EDS of the particles is inconsistent. Limited high-resolution TEM has been conducted on matrix material, but is impossible on the particle due to the limitations of our instrument. It has been suggested that the particles are localized regions of high-Nd concentration. High-resolution TEM of the particles and matrix may help determine any differences in the lattice spacing of particles and matrix. The objective of this investigation is to determine using high-resolution TEM any differences between particles and matrix in core regions of Nd-doped YAG. By resolving the lattice of the crystal, comparisons between the lattice parameter of particle and matrix may be made. Additionally, the boundary between the particles and matrix is of interest.
Project Details
Project type
Exploratory Research
Start Date
2002-09-30
End Date
2004-10-04
Status
Closed
Released Data Link
Team
Principal Investigator