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La₂Zr₂O₇ powders were synthesized by solid-state reaction method. After spray granulation, the La₂Zr₂O₇ coatings were fabricated by air plasma spray technique. The effect of heat treatment time on the properties of La₂Zr₂O₇ coatings was investigated, focusing on phase composition, microstructure evolution and thermal conductivity. The results show that a single pyrochlore phase of La₂Zr₂O₇ coating has been successfully fabricated. And the average porosity is 11.3%. The phase composition and porosity do not change with the prolongation of heat treatment time. The thermal conductivity of the as-sprayed coating can be as low as 0.392 W?m^–1?K^–1. A number of amorphous structures exist in the as-sprayed coating, which can effectively block the transmission of phonons. With an increase of thermal exposure time at 1300 ℃ in air, the amorphous structure is gradually transformed into crystalline structure, and the phonon transfer efficiency is obviously improved, resulting in a significant increase in the thermal conductivity of the coating. Interestingly, after heat treatment, the rebound effect of thermal conductivity at high temperature didn’t appear in this research.