High-temperature stability of nanozirconate-toughed IMF material lanthanum synthesized by an in situ reaction

Abstract

Herein, powders composed of La₂Zr₂O₇ (LZ) and ZrO₂ phases were synthesized by an in situ reaction using a sol-spray pyrolysis method; moreover, 24 mol% LaO_1.5–ZrO₂ (volume ratio = 1 : 1) powders were characterized by XRD, Raman spectroscopy, SEM, and TEM. XRD and Raman results showed that the samples maintained a tetragonal ZrO₂ and a pyrochlore LZ phase from 900 to 1100 °C. The addition of LZ could be helpful in the stabilization of t-ZrO₂ and decreasing the grain size of ZrO₂. The SEM results revealed that the LZ and ZrO₂ phases were homogeneously distributed in the sintered bulk. The HRTEM results suggested that the crystal orientations of the nano-LZ and nano-ZrO₂ phases were accordant; this was in agreement with the characteristics of the coherent boundaries. The fracture toughness of LZ–ZrO₂ was markedly improved by the transformation toughening of the ZrO₂ phase, and a value that was 2.2-fold that of the LZ prepared by a similar technique was achieved.