X-ray Study of Phason Strains in an AlCuFeMn Decagonal Phase
Wang Yang, Tomoyo Ando, Kazuki Yamamoto
The peak profiles, shifts, and splittings of Bragg reflections, which are inherent in the phason strain of a quasicrystal, are carefully examined using a precise powder X-ray diffraction method for a wide range of different AlCuFeMn alloys and annealing temperatures. Based on the peak-shift dependences of the Bragg reflections on the phason momentum Q⊥, two kinds of new approximant phases are identified. These phases have linear phason strains θ1 = τ−6 and θ2 = τ−5, and θ1 = τ−10 and θ2 = τ−5, corresponding to lattice spacings a = 3.814 nm and b = 2.005 nm, and a = 9.985 nm and b = 2.005 nm in the quasiperiodic plane of the orthorhombic system, respectively.