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6609 |
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Effects of Yb3+ doping on phase structure, thermal conductivity and fracture toughness of (Nd1-xYbx)2Zr2O7 |
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Yang Wu* / Beihang University, P.R. China Lei Zheng / School of Materials Science and Engineering, Beihang University, China Wenting He/ School of Materials Science and Engineering, Beihang University, China Jian He/ School of Materials Science and Engineering, Beihang University, China Hongbo Guo/ School of Materials Science and Engineering, Beihang University, China |
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To investigate the effects of Yb3+ doping on phase structure, thermal conductivity and fracture toughness of bulk Nd2Zr2O7, a series of (Nd1-xYbx)2Zr2O7 (x=0, 0.2, 0.4, 0.6, 0.8, 1.0) ceramics were synthesized using a solid-state reaction sintering method at 1600 C for 10 h. The phase structures were sensitive to the Yb3+ content. With increasing doping concentration, a pyrochlore-fluorite transformation of (Nd1-xYbx)2Zr2O7 ceramics occurred. Meanwhile, the ordering degree of crystal structure decreased. The substitution mechanism of Yb3+ doping was confirmed by analyzing the lattice parameter variation and chemical bond of bulk ceramics. The thermal conductivities of (Nd1-xYbx)2Zr2O7 ceramics decreased first and then increased with the increase of Yb3+ content. The lowest thermal conductivity of approximately 1.2 W·m-1·K-1 at 800 C was attained at x=0.4, around 20% lower than that of pure Nd2Zr2O7. Besides, the fracture toughness reached a maximum value of ~ 1.59 MPa·m1/2 at x=0.8 but decreased with further increasing Yb3+ doping concentration. The mechanism for the change of fracture toughness was discussed to result from the lattice distortion and structure disorder caused by Yb3+ doping. |