Effect of the element substitutions in Cu position on positron annihilation spectra

The effect of the element substitutions in Cu position on positron annihilation spectra was studied systematically by the measurement of one-dimensional angular correlation spectra of positron annihilation radiation for YBa2 Cu3-xMxOy (M = Sn, Al) samples. The results show that 1D ACPAR of YBaCuO superconductor is constituted by two Gaussian parts, corresponding to annihilation position sampled in the Cu-O plane and Cu-O chain respectively. The parabola like the positron annihilation with Fermi electron gas in metals and alloys is not found out. Positron annihilation spectra are sensitive to the element substitution in Cu positions, especially in Cu-chains, and could be used to probe the substituting positions in Y-Ba-Cu-O superconductors