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Changes in Fe site occupancy and Tc in YBa sub 2 (Cu sub 1-x Fe sub x ) sub 3 O sub y through processing

Conference ·
OSTI ID:6895167
 [1];  [2];  [3]
  1. California Univ., San Diego, CA (USA)
  2. Los Alamos National Lab., NM (USA) California Univ., San Diego, CA (USA)
  3. Los Alamos National Lab., NM (USA)
Fe substitution for Cu in YBa{sub 2}Cu{sub 3}O{sub y} can give information about the local environment on the two crystallographic Cu sites through Mossbauer effect measurements. In this paper, we explore the possibility of forcing larger amounts of Fe onto the Cu (2) site which represents the CuO planes. At values near y = 6, the chain Cu (1) site is characteristic for Cu{sup +} in its linear 0 coordination and should preclude Fe occupation. We therefore prepared materials at elevated temperatures under N{sub 2} where y {approximately}6. Oxygenation to y {approximately}7 was achieved at temperatures where metal diffusion is minimized. We used Mossbauer spectroscopy to determine the Fe site occupancy. Site preference can be expressed in terms of a distribution ratio r = MCul/ MCu2. Creating materials with low r allows studying the effects of spatially constrained Fe on T{sub c}, separating influences from the spatially more complex Cu (1) site.
Research Organization:
Los Alamos National Lab., NM (USA)
Sponsoring Organization:
DOE/MA
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
6895167
Report Number(s):
LA-UR-90-1402; CONF-900527--2; ON: DE90010614
Country of Publication:
United States
Language:
English