Effects of non-stoichiometry on the mechanical properties of Nd2-xZr2+xO7+x/2 (X=0, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics

Nd2Zr2O7 and its non-stoichiometry counterparts with excess ZrO2 (Nd2-xZr2+xO7+x/2, x=0.1, 0.2, 0.3, 0.4, 0.5) were synthesized by chemical-coprecipitation and the calcination method. The bulk materials were produced by sintering at 1600 C for 10 h. The effects of non-stoichiometry on the mechanical properties of Nd2-xZr2+O7+x/2 were investigated. XRD results revealed that Nd2-xZr2+xO7+x/2 (x = 0, 0.1, 0.2, 0.3, 0.4) ceramics exhibited pyrochlore phase, while Nd1.5Zr2.5O7.25 ceramic had a fluorite structure. The lattice parameters of the ceramics decreased as ZrO2 contents increased. With the increase of ZrO2 contents, the hardness of the ceramics increased, while the Young's modulus decreased. Excess ZrO2 in Nd2Zr2O7 matrix benefited the fracture toughness of the ceramic, which could be attributed to the compressive stress introduced in the ceramic due to lattice contraction. (C) 2014 Elsevier B.V. All rights reserved.