Crystal structure of high-Tc related NdBaCuO2BO3: TEM and neutron powder diffraction study

Abstract The layered high- T c related oxyborate NdBaCuO 2 BO 3 has been investigated by ED, HREM and neutron powder diffraction. The crystal structure was refined using neutron data (space group P4bm, Z =2, a =5.52807(5) A, c =7.44636(8) A; S =0.98, R p =0.042, R wp =0.056, R I =0.030, R F =0.018). The main features of this structure are deformed (CuO 5 ) square pyramids and triangular (BO 3 ) groups which alternate along the 4-fold axis. Ba and Nd atoms are completely ordered and coordinated by 12 and 8 oxygen atoms, respectively.