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

Herein, powders composed of La(2)Zr(2)O(7) (LZ) and ZrO(2) phases were synthesized by an in situ reaction using a sol-spray pyrolysis method; moreover, 24 mol% LaO(1.5)–ZrO(2) (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 ZrO(2) and a pyrochlore LZ phase from 900 to 1100 °C. The addition of LZ could be helpful in the stabilization of t-ZrO(2) and decreasing the grain size of ZrO(2). The SEM results revealed that the LZ and ZrO(2) phases were homogeneously distributed in the sintered bulk. The HRTEM results suggested that the crystal orientations of the nano-LZ and nano-ZrO(2) phases were accordant; this was in agreement with the characteristics of the coherent boundaries. The fracture toughness of LZ–ZrO(2) was markedly improved by the transformation toughening of the ZrO(2) phase, and a value that was 2.2-fold that of the LZ prepared by a similar technique was achieved.