Perturbed angular correlation studies of the MAX phases Ti2AlN and Cr2GeC using ion implanted 111In as probe nuclei

PAC measurements were done for the first time on the 211-MAX phases Ti2AlN and Cr2GeC which do not have indium as a constituent material. Radioactive In-111(+) ions were implanted at 400 keV into the MAX bulk-samples. The radiation damage was annealed under vacuum up to temperatures of 1373 K. During each heating cycle the samples were sealed in new quartz tubes, as a loss of the In-111 probes out of the samples was observed at high temperatures. Both MAX phases showed EFGs similar to the ones observed in indium containing MAX phases. In all cases they are attributed to probes residing on the A-site of the 211-structure. After high and long annealing temperatures an additional fraction of probes is observed in Cr2GeC with a different EFG. The corresponding site may be the M-site of the 211-structure, or a site in Cr2C. The comparison of the X-ray diffraction spectra, taken before the implantation and after the end of the PAC measurements, showed that Cr2GeC partly disintegrates to Cr2C. (C) 2010 Elsevier B.V. All rights reserved.