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) 2 Zr 2 O 7 and nano (Zr,Gd)O 2   −   δ by a sol-spray pyrolysis method. The XRD results indicated that the reaction products of 0.2LaO 1.5 –xGdO 1.5 –(0.8   −   x)ZrO 2 (0.15   ≤   ×   ≤   0.25) ternary system were composed of pyrochlore (La,Gd) 2 Zr 2 O 7 and cubic (Zr,Gd)O 2 phases. The composition with 0.2LaO 1.5 –0.2GdO 1.5 –0.6ZrO 2 had a grain size much smaller than the lower GdO 1.5 content counterpart for both the (La,Gd) 2 Zr 2 O 7 and (Zr,Gd)O 2   −   δ phases. The relationship between grain size and GdO 1.5 content was explained in terms of lattice matching.