Accession Number:

ADA254905

Title:

Surface Analysis of Ln(2-x)Ce(x)CuO4 (Ln = Pr and Nd) Single Crystals Grown by the Top Seeded Solution Method

Descriptive Note:

Final rept.,

Corporate Author:

ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB

Report Date:

1992-05-01

Pagination or Media Count:

18.0

Abstract:

Large single crystals of Ln2-xCexCU04 Ln Pr and Nd, the average size is approximately 5 mm x 5 mm x 1 mm, were grown by the Top Seeded Solution Growth TSSG technique. The optical constants of the crystals were determined by Variable Angle Spectroscopic Ellipsometry VASE and the results seem to indicate that a 1.5 eV absorption peak appears in the undoped material and is weakened and shifted downward in energy upon annealing. The compositions and crystal structure were examined using Rutherford Backscattering Spectroscopy RBS with ion beam channeling. Also, the effect of annealing on the crystalline structure was probed by ion beam channeling. The orientation and lattice parameters of the crystals were determined by X-ray diffraction and the superconductivity of the specimens was monitored using a SQUID magnetometer. The results indicate that the crystals grown by the TSSG method are very uniform in composition and well-oriented however, analysis of the RBS data indicated up to 1 Pt inclusion in the crystals from contact with the Pt crucibles. The inclusion of Pt acted to quench the superconducting transition temperatures and Pt was found to substitute for Cu.

Subject Categories:

  • Electrical and Electronic Equipment
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE