A positron annihilation study of vacancy-type defects in Al-Cu-Fe quasicrystals

Chidambaram, R. ; Sanyal, M. K. ; Nambissan, P. M. G. ; Sen, P. (1990) A positron annihilation study of vacancy-type defects in Al-Cu-Fe quasicrystals Journal of Physics: Condensed Matter, 2 (49). pp. 9941-9948. ISSN 0953-8984

Full text not available from this repository.

Official URL: http://iopscience.iop.org/0953-8984/2/49/018

Related URL: http://dx.doi.org/10.1088/0953-8984/2/49/018


A positron annihilation study of the icosahedral Al-Cu-Fe alloy system has been carried out using both Doppler broadening and lifetime measurement techniques. Isochronal annealing studies show that a nearly unchanged two-component lifetime spectrum is obtained up to the highest annealing temperature of 450 degrees C used in the present work, indicating the stability of the structure and the defect state in this quasicrystalline phase up to this annealing temperature. The vacancy defect concentration is about 8 ppm which is higher than that observed in the authors' earlier study on icosahedral Al-Mn-Si, though the vacancy size is lower-approximately a monovacancy size on average in Al-Cu-Fe against a divacancy size in Al-Mn-Si. The existence of such a high concentration of vacancy defects even in quasicrystalline Al-Cu-Fe, which has little phason disorder, should be significant from the point of view of developing a structural model for quasicrystals. It appears that a two-component positron lifetime spectrum indicative of a high concentration of vacancy-type defects is characteristic of the icosahedral quasicrystalline phase. The possibility of a central hole in the icosahedral building block in this phase is ruled out from the authors' positron annihilation experiments.

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics.
ID Code:86238
Deposited On:08 Mar 2012 11:32
Last Modified:11 Jul 2012 10:12

Repository Staff Only: item control page