SONG Chaowen ^1,2, HUANG Duanping ², ZHANG Feng ²

(1. 7 12th Research Institute, CSIC, Wuhan, Hubei 430064; 2. School of Materials Science and Engineering, Wuhan

University of Technology, Wuhan, Hubei 430070)

Abstract:  La₂NiO_{4 +δ} powder was prepared by a polyaminocarboxylate complex method. XRD, TG -DTA, IR and FESEM were employed to investigate the thermal decomposition of the precursor. The results indicate that the precursor has an amorphous nature, with the coordination of DTPA and metal cations forming a bi-dentate complex. With the temperature increasing, the complex precursor first decomposed into a mixture of NiO and intermediate (LaO)₂CO₃, and then transformed into La₂O₃ at the temperatures above 600℃. Further increasing the temperature to 700℃ yielded La₂NiO_4+δ phase with small amounts of intermediate phases (LaNiO₃ and La₂O₃). Homogeneous and fine powder (~100nm) with pure K₂NiF₄ phase could be produced by calcining the complex precursor at 900℃.

Key words:  La₂NiO_{4 +δ} ; mixed conductor; polyaminocarboxylate complex method; conductivity