The study of the binary quasicrystal Cd 17 Ca 3 and its 1/1 approximant Cd 6 Ca by positron annihilation spectroscopy.

Takagiwa, Y.; Akiyama, T.; Kanazawa, I.; Sato, K.; Murakami, H.; Kobayashi, Y.; Tamura, R.; Takeuchi, S.

The positron annihilation lifetime measurements for the Cd 17 Ca 3 quasicrystal and its 1/1 Cd 6 Ca approximant were carried out at 300?K. The observed lifetime of the Cd 17 Ca 3 quasicrystal is close to that of the 1/1 Cd 6 Ca approximant, implying the existence of the same type of structural vacancies. The temperature variations in the positron lifetime were investigated in the temperature region from 10 to 300?K for the Cd 17 Ca 3 quasicrystal annealed at 773?K and the Cd 17 Ca 3 quasicrystal cooled in the furnace. We found clear differences between both the absolute value and the temperature gradient of the positron lifetimes of the two quasicrystals. The results will be discussed in terms of the fluctuation in the four-Cd tetrahedron inside the 20-Cd dodecahedron between two quasicrystals.

POSITRON annihilation; QUASICRYSTALS; CADMIUM crystals; ANNEALING of crystals; POSITRONS

Philosophical Magazine, 2006, Vol 86, Issue 3-5, p513

1478-6435

Academic Journal

10.1080/14786430500269121