The traditional yttria-stabilized zirconia (YSZ) used in thermal barrier coatings has a limited operating temperature owing to densification and volume changes at high temperatures. A (La_1-xY_x)₂Zr₂O₇ sintered compound was prepared by the co-precipitation and oxalate methods, by adding lanthanum zirconate to yttria. The thermal properties and crystallinity obtained by the two different methods were compared. Both methods yielded pyrochlore structures, and the oxalate method confirmed phases at low temperatures. The thermal conductivity of the sintered bulk prepared by co-precipitation was 0.93 W/mK, while that prepared by the oxalate method was 0.85 W/mK. These values are superior to that of 4YSZ at 1,000℃, which is widely used in industries.