Synthesis and properties of new cuprates (Cd_0.5M_0.5)Sr₂YCu₂O₇ with the “1212” structure (M = Fe, Co)

New cuprates of composition (Cd_0.5M_0.5)Sr₂YCu₂O₇ (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_0.5Fe_0.5)Sr₂YCu₂O₇ are a = 3.809 Å and c = 11.423 Å; those of (Cd_0.5Co_0.5)Sr₂YCu₂O₇ are a = 3.816 Å and c = 11.435 Å. 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_0.5Fe_0.5)Sr₂YCu₂O₇ and 535 cm⁻¹ for (Cd_0.5Co_0.5)Sr₂YCu₂O₇. The samples act as semiconductors in the temperature range 12 to 300 K.