The hidden story in BaNiO₃to BaNiO₂transformation: adaptive structural series and NiO exsolution

Abstract

Crystal-to-crystal transformation from BaNiO3 to BaNiO2 is reported.

Characterization of Ruddlesden-Popper La2−xBaxNiO4±δ Nickelates as Potential Electrocatalysts for Solid Oxide Cells

“…Overall, these observations confirm the precipitation of barium and barium-nickel oxides during the preparation of ceramics at elevated temperatures, with reversible formation/decomposition of barium carbonate and transformations between different Ba-Ni-O phases (for instance, Ref. [ 40 ]) on thermal cycling. The presence of BaNiO 3 (and apparently other secondary phases) was noted earlier in variable-temperature XRD patterns of LaBaNiO 4±δ [ 23 ].…”

Barium promoted Ni/Sm2O3 catalysts for enhanced CO2 methanation

“…However, at 10% of Ba loading, BaNiO 3 peak was observed at 2 θ = 18.8°, 36.8° and 42.3° (JCPDS 072-0403). 17 Increasing the Ba loading to 15%, BaNiO 2.36 peaks appeared at 2 θ = 21.9°, 38.3°, 48.9° and 50.4° corresponded to (110), (020), (220), (131), (310) and (240) planes respectively (JCPDS 072-0403). BaNiO 3 was reported as less stable than BaNiO 2.36, which will be decomposed gradually at higher temperatures.…”

“…47 The average oxidation states of Ni in BaNiO 2 is 2+, and it is interchangeable to 4+ under oxygen at high temperature to form BaNiO 3 . 17 Since it was crucial for Ni to be in its reduction state in order to catalyze hydrogen dissociation in CO 2 methanation reaction, 48 the formation of BaNiO 3 -BaNiO 2.36 reduced the activity of 5Ni-15Ba/Sm 2 O 3 . Furthermore, BaNiO 3 -BaNiO 2.36 inhibited the contribution of Ba as the additional basic sites evidenced by the CO 2 -TPD analysis thus resulting in a low catalytic activity at temperature below 350 C. However, as the temperature was increased to 450 C, there is a possibility that NiO segregating from BaNiO 3 -BaNiO 2.36 under the presence of H 2 .…”

Oxide nanoparticle exsolution in Lu-doped (Ba,La)CoO3

“…28 For example, in the case of the La 0.43 Ca 0.37 Ti 0.94 Ni 0.06 O 3 perovskite, Ni nanoparticles were released from the host lattice as a result of thermal treatment in hydrogen, resulting in evenly distributed nanosized metal particles. 3 The exsolution of oxide nanoparticles has also been reported, [29][30][31] but to a lesser extent, and still, many aspects of this process are uncovered. It is noted that oxide nanoparticles can be formed under an oxidizing atmosphere, which significantly spreads the possibilities of their application.…”

“…The exsolution of oxide nanoparticles has also been reported, 29–31 but to a lesser extent, and still, many aspects of this process are uncovered. It is noted that oxide nanoparticles can be formed under an oxidizing atmosphere, which significantly spreads the possibilities of their application.…”