PREPARATION OF A LARGE AL70PD20MN10 SINGLE-QUASI-CRYSTAL BY THE CZOCHRALSKI METHOD AND ITS ELECTRICAL-RESISTIVITY

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 Al73.5Pd19.7Mn6.8. 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-mu-OMEGA-m 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.