Nano–nano composite powders of lanthanum–gadolinium zirconate and gadolinia-stabilized zirconia prepared by spray pyrolysis

Ceramics with structure on nanometer-length scales have a thermal conductivity much lower than their coarser-grained ceramics. But the relatively low activation energy for grain growth of nanoparticles limits the stability of nano-material at high temperatures. The objective of the present study was to investigate the preparation of the composite powders of nano (La,Gd)2Zr2O7 and nano (Zr,Gd)O2 − δ by a sol-spray pyrolysis method. The XRD results indicated that the reaction products of 0.2LaO1.5–xGdO1.5–(0.8 − x)ZrO2 (0.15 ≤ × ≤ 0.25) ternary system were composed of pyrochlore (La,Gd)2Zr2O7 and cubic (Zr,Gd)O2 phases. The composition with 0.2LaO1.5–0.2GdO1.5–0.6ZrO2 had a grain size much smaller than the lower GdO1.5 content counterpart for both the (La,Gd)2Zr2O7 and (Zr,Gd)O2 − δ phases. The relationship between grain size and GdO1.5 content was explained in terms of lattice matching.