Premium
Preparation of pure and fully dense lanthanum nickelates La n +1 Ni n O 3 n +1 ( n = 2, 3, ∞) by post‐sintering oxidation process
Author(s) -
Adachi Yoshinobu,
Hatada Naoyuki,
Hirota Ken,
Kato Masaki,
Uda Tetsuya
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16611
Subject(s) - non blocking i/o , lanio , materials science , sintering , lanthanum , analytical chemistry (journal) , partial pressure , perovskite (structure) , oxygen , mineralogy , metallurgy , crystallography , inorganic chemistry , chemistry , biochemistry , organic chemistry , chromatography , catalysis , optoelectronics , dielectric , ferroelectricity
Lanthanum nickelates with Ruddlesden‐Popper structure (La 2 NiO 4 , La 3 Ni 2 O 7 , and La 4 Ni 3 O 10 ) and perovskite structure (LaNiO 3 ) have attracted considerable attention due to their potential applications such as solid oxide fuel cells. Currently, the ionic and electronic conduction properties of La 3 Ni 2 O 7 , La 4 Ni 3 O 10 , and LaNiO 3 are not fully understood because it is quite difficult to prepare their dense bodies required for the characterization. The difficulty arises from their narrow thermodynamic stable temperature and oxygen partial pressure ranges. In this study, we successfully obtained dense bodies of single‐phase La 3 Ni 2 O 7 , La 4 Ni 3 O 10 , and LaNiO 3 via a post‐sintering oxidation process. First, dense pellets composed of fine‐grain precursors La 2 NiO 4 and NiO (~0.5 μm) were prepared by nitrate freeze‐drying technique and low‐temperature sintering at 1150°C‐1225°C. Then they were converted into almost single‐phase La 3 Ni 2 O 7 , La 4 Ni 3 O 10 , and LaNiO 3 by high‐temperature oxidation. La 3 Ni 2 O 7 and La 4 Ni 3 O 10 were obtained under an oxygen partial pressure p O 2of 1 bar at 1275°C and 1200°C‐1250°C, respectively, while LaNiO 3 was obtained under p O 2of 392 bar at 1250°C using hot isostatic pressing. The relative densities of the pellets exceeded 90%. With regard to their phase stability, decomposition was not detected at 600°C‐1100°C in air for at least 100 hour despite their thermodynamic instability.