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X-ray and neutron powder diffraction studies of Ba(NdxY2−x)CuO5 |
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| Authors: | G Liu JA Kaduk C Lucas |
| Institution: | a Ceramics Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, USA b NIST Center for Neutron Research, Naperville, IL 60563, USA c INEOS Technologies, Naperville, IL 60563, USA d Yunnan Normal University, Kunming 650092, PR China e Chemistry & Biochemistry Department, University of Maryland, College Park, MD 20742, USA |
| Abstract: | Ba(R,R′)2CuO5 (R,R′=lanthanides and Y) plays an important role as a flux-pinning agent in enhancing the superconducting properties of the Ba2(R,R′)Cu3O6+x (R,R′=lanthanides and Y) coated conductors. Using X-ray diffraction and neutron diffraction, we found that the Ba(NdxY2−x)CuO5 solid solution adopts two structure types. In the Nd-rich region (1.8?x?2.0), the materials are of brown color (commonly referred to as the ‘brown phase’), and the structure is tetragonal with space group I4/mbm (no. 127). In the Y-rich region (0.0?x?1.4), the materials are green (commonly referred to as the ‘green phase’) and the structure is orthorhombic with space group Pnma (no. 62). A two-phase region (1.4<x<1.8) exists between the orthorhombic and tetragonal phases. The crystal chemistry and crystallography of the orthorhombic ‘green phase’ series, Ba(NdxY2−x)CuO5 (isostructural to BaY2CuO5), are discussed in this paper. |
| Keywords: | Ba(NdxY2&minus x)CuO5 X-ray diffraction patterns Crystal structure Orthorhombic &lsquo green phase&rsquo Tetragonal &lsquo brown phase&rsquo Coated conductors |
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