Mössbauer studies of site preference, relaxation and magnetic order in YBa2(Cu1-xFex)3O7-δ

Diffuse x-ray scattering study of an oxygen-disordered tetragonal YBa_{2}(Cu_{0.955}Al_{0.045})_{3}O_{7} crystal

“…The crystal plate was then trimmed to 0.6x0.18x0.056 mm 3 so that it could be bathed in the uniform area of an x-ray beam. Using a conventional rotating-anode supply and four-circle diffractometer the tetragonal structure was confirmed, with a =6 =3.8668(11) A and c = l 1.7060(35) A, and a full x-ray crystallographic analysis was conducted [16] from which we determined that there is no significant Al content at the Cu(2) sites in agreement with other investigations [6][7][8][9][10][11][12][13]. The x-ray diffuse scattering experiments were carried out on the X14 beam line at the Brookhaven National Synchrotron Light Source.…”

“…Above x c , however, high-TV values persist in these compounds, disappearing only for substantial x (>0.10). It has been determined by a variety of experiments [6][7][8][9][10][11][12][13] that Al, Co, and Fe substitute initially in the Cu(l) positions, thereby disordering the chains to produce the phase transition. Below x c there are characteristic twin-spot splittings in the electron-diffraction patterns which merge into diffuse reflections as x c is approached.…”