Synthesis and properties of new cuprates (Cd0.5M0.5)Sr2YCu2O7 with the “1212” structure (M = Fe, Co)

New cuprates of composition (Cd 0.5 M 0.5 )Sr 2 YCu 2 O 7 (M=Fe, Co) with the 1212 structure are synthesized. X-ray diffraction patterns show that both cuprates exhibit a tetragonal 1212-phase structure. The lattice parameters of (Cd 0.5 Fe 0.5 )Sr 2 YCu 2 O 7 are a = 3.809 A and c = 11.423 A ; those of (Cd 0.5 Co 0.5 )Sr 2 YCu 2 O 7 are a = 3.816 A and c = 11.435 A. The results of electron diffraction for the samples show that there is a 90° twinning of the c-axis. The Raman spectra depict an apical-O(2) vibration mode appearing at 544 cm -1 for (Cd 0.5 Fe 0.5 )Sr 2 YCu 2 O 7 and 535 cm -1 for (Cd 0.5 Co 0.5 )Sr 2 YCu 2 O 7 . The samples act as semiconductors in the temperature range 12 to 300 K.