Passivation of the La2NiMnO6 double perovskite to hydroxylation by excess nickel, and the fate of the hydroxylated surface upon heating

•Lanthanum nickel manganese oxide formed a double perovskite, LaNi0.5Mn0.5O3.•LaNi0.75Mn0.25O3 phase separated into LaNi0.5Mn0.5O3, NiO and LaNiO3.•Stoichiometric LaNi0.5Mn0.5O3 formed an extensively hydroxylated overlayer.•Heating formed an La2O3 overlayer and did not regenerate the perovskite.•Exc...

Full description

Saved in:

Bibliographic Details
Published in:	Applied surface science Vol. 305; pp. 544 - 553
Main Authors:	Fulmer, Adam T., Dondlinger, Jasmine, Langell, Marjorie A.
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier B.V 30-06-2014 Elsevier
Subjects:	Condensed matter: electronic structure, electrical, magnetic, and optical properties Condensed matter: structure, mechanical and thermal properties Cross-disciplinary physics: materials science; rheology Double perovskite Exact sciences and technology Hydroxylation La2O3 NiO Physics XPS Double perovskite XPS La2O3 Hydroxylation NiO Inorganic compounds Transition element compounds Perovskites O La Transition elements Nickel Nickel oxide Passivation X-ray photoelectron spectra
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	•Lanthanum nickel manganese oxide formed a double perovskite, LaNi0.5Mn0.5O3.•LaNi0.75Mn0.25O3 phase separated into LaNi0.5Mn0.5O3, NiO and LaNiO3.•Stoichiometric LaNi0.5Mn0.5O3 formed an extensively hydroxylated overlayer.•Heating formed an La2O3 overlayer and did not regenerate the perovskite.•Excess nickel prevented extensive hydroxylation. The double perovskites with a total elemental content of LaNi0.5Mn0.5O3 and LaNi0.75Mn0.25O3 were synthesized by solid state methods, although the LaNi0.75Mn0.25O3 material underwent phase separation into NiO, LaNiO3 and LaNi0.5Mn0.5O3. Auger Electron Spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) indicated substantial lanthanum surface segregation for the LaNi0.5Mn0.5O3 material, which formed an altered La(OH)3 layer 50–100 monolayers in thickness. The La(OH)3 could be removed by Ar+ sputtering to achieve a surface of approximately stoichiometric concentration. Heating the La(OH)3-covered LaNi0.5Mn0.5O3 did not regenerate the double perovskite but rather produced an overlayer of La2O3. While the LaNi0.75Mn0.25O3 material displayed extensive phase separation, the excess nickel appeared to prevent substantial lanthanum surface segregation.
ISSN:	0169-4332 1873-5584
DOI:	10.1016/j.apsusc.2014.03.134