Preparation of a Large Al₇₀Pd₂₀Mn₁₀ Single-Quasicrystal by the Czochralski Method and Its Electrical Resistivity

Abstract

A partial isothermal phase diagram in the Al–Pd–Mn system was examined with the aim of determining a liquidus composition which equilibrates with a stoichiometric icosahedral(I) phase. The I phase precipitates as a primary phase in the range of 3 to 9 at% Mn and 18 to 25 at% Pd. The accurate composition of the liquid which equilibrates to the stoichiometric I–Al₇₀Pd₂₀Mn₁₀ phase at 1143 K was determined to be Al_73.5Pd_19.7Mn_6.8. By choosing the liquidus composition, the growth of a seed single-quasicrystal of Al₇₀Pd₂₀Mn₁₀ was tried by using the Czochralski method. The maximum size of the single domain ingot reached as large as 10 mm in diameter and 50 mm in length. The electrical resistivity of the single-quasicrystal has a negative temperature dependence in the range of 40 to 270 K and shows a maximum value of 65 to 107 μΩm at about 40 K. The magnitude of the resistivity is dependent on orientation and tends to increase with increase of deviation from the growth direction of five fold direction presumably due to an anisotropy of internal defects.