Preparation and Characterization of New 1-2-1-2 Compounds MA2RECu2O8-δ and Nb1-xRuxSr2RECu2O8-δ (M = Nb or Ta, A = Ba or Sr, and RE = Pr or Sm)

Subsolidus phase relations of the SrO–Ta2O5–CuO system at 900°C in air

“…In relation to superconductivity, it is interesting to note that the phases of the TaM 2 RECu 2 O 8−ı (M = Sr, Ba; RE = Pr, Nd, Sm, Eu, Gd) series crystallize in a structure type similar to that of the high-temperature superconductor (HTS) YBa 2 Cu 3 O 7−ı , where Ta 5+ ions are accommodated in the basal plane, whereas the double CuO 2 pyramidal planes are maintained [50][51][52][53]. TaSr 2 (NdCe) 2 Cu 2 O y is the Ta analog of the phase TlBa 2 NdCeCu 2 O 9 [54] and Pb 2 Sr 2 Cu 2 TaO 8 Cl crystallizes in a layered tetragonal structure reminiscent of that of HTS materials [55].…”

Effect of chemical composition on superconductivity and magnetism in layered ruthenocuprates

“…The existence of such phase separations appears to result from the particular crystal structure of the ruthenocuprates. In fact, the 'T1212 type', originally observed with the transition metals T = Nb, Ta [40,41], later in solid solutions (Nb, Ru) [42], with a variety of rare earth and alkaline earth elements replacing the Y and Ba of Y-123, has been described in spacegroup P4/mmm [9,20,40,42] (with a 0.384 nm, c 1.155 nm for RuSr 2 GdCu 2 O 8 [1,11]) leading to straight T-O-T bonds in the octahedron layer.…”

Synthesis of a new (Ta1-xSnx)Sr2EuCu2Ozsuperconductor

“…MSr 2 RCu 2 O 8 (M-1212, M = Nb or Ta) compounds (R = rare earths) [1][2][3][4][5][6] are derived from the RBa 2 Cu 3 O 7 (R-123 or Cu-212) phase by replacement of the CuO chain layer and Ba atoms in Cu-1212 phase by MO 2 layer and Sr atoms, respectively. Previous work on various M-1212 compounds (M = Nb, Ta, R = Nd, Sm, Eu, Gd and Tb) has shown them to be nonsuperconducting and insulators.…”