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Improvement of Electrical Conductivity of Trivalent Rare‐earth Cation‐doped Neodymium Zirconate by Co‐doping Gadolinium and Ytterbium
Author(s) -
Liu Z.G.,
Ouyang J.H.,
Sun K.N.
Publication year - 2010
Publication title -
fuel cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 69
eISSN - 1615-6854
pISSN - 1615-6846
DOI - 10.1002/fuce.201000107
Subject(s) - pyrochlore , zirconate , materials science , analytical chemistry (journal) , doping , neodymium , conductivity , ionic conductivity , lanthanide , electrical resistivity and conductivity , oxide , ytterbium , ionic radius , ceramic , inorganic chemistry , mineralogy , phase (matter) , ion , chemistry , electrolyte , metallurgy , laser , engineering , optics , chromatography , titanate , physics , optoelectronics , organic chemistry , electrode , electrical engineering
Pyrochlore oxides of A 2 Zr 2 O 7 , where A represents trivalent rare‐earth elements, have a high electrical conductivity, which makes them suitable for applications as high‐temperature solid electrolytes. The influence of Gd and Yb cations co‐doping at the Nd site on structure and electrical conductivity of a pyrochlore oxide Nd 2 Zr 2 O 7 is investigated using X‐ray diffraction and impedance spectra measurements. Different zirconate ceramics of Nd 2 Zr 2 O 7 , Nd 1.8 Gd 0.2 Zr 2 O 7 , Nd 1.8 Gd 0.1 Yb 0.1 Zr 2 O 7 , Nd 1.4 Gd 0.6 Zr 2 O 7 and Nd 1.4 Gd 0.3 Yb 0.3 Zr 2 O 7 are prepared by pressureless‐sintering method at 1,973 K for 10 h in air. Nd 2 Zr 2 O 7 doped with Gd and Yb cations at the Nd site exhibit a single phase of pyrochlore‐type structure. The measured values of the total conductivity obey the Arrhenius relation. Nd 2 Zr 2 O 7 and its doped zirconate ceramics are oxide‐ion conductors in the oxygen partial pressure range of 1.0 × 10 –4 to 1.0 atm at all test temperature levels. The total conductivity increases with reducing average ionic radii of A‐site rare‐earth cations. The dual Yb+Gd intermix doping causes a distinctly enhanced total conductivity as compared to unmodified Nd 2 Zr 2 O 7 and singly Gd‐doped zirconate ceramics. The highest total conductivity value obtained in this work is 1.02 × 10 –2 S cm × 1 at 1,173 K for Nd 1.4 Gd 0.3 Yb 0.3 Zr 2 O 7 ceramic.