Preparation and characterization of the non-stoichiometric La-Mn perovskites

Zhiming Gao; Huishu Wang; Hongwei Ma; Zhanping Li

doi:10.1016/j.jallcom.2015.06.044

Preparation and characterization of the non-stoichiometric La-Mn perovskites

Zhiming Gao^*, Huishu Wang, Hongwei Ma, Zhanping Li

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

35 Citations (Scopus)

Abstract

Abstract Six La-Mn oxide samples with La/Mn atomic ratio x = 1.03-0.56 (denoted as sample LaxMn) were prepared by the citrate method with calcination at 700 °C for 5 h, and characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). It is confirmed that the four samples with La/Mn atomic ratio at 1.03-0.72 are all single phase perovskites by XRD patterns. Lattice parameters of the perovskites are varying with the La/Mn atomic ratio. As the La/Mn atomic ratio further lowers to 0.63 and 0.56, Mn₃O₄ phase is formed besides the main phase of perovskite. Lattice vacancy at the A-sites of the perovskites is present for all the six samples, and there are an appreciable number of Mn⁴⁺ ions in the perovskite crystal according to the refinement results of the Rietveld method. XPS analyses indicate that Mn ions are enriched on the surfaces of all the samples. In addition, catalytic activity for methane oxidation is in an order of sample La_0.89Mn > La_1.03Mn > La_0.81Mn > La_0.72Mn > La_0.63Mn > La_0.56Mn.

Original language	English
Article number	34383
Pages (from-to)	73-79
Number of pages	7
Journal	Journal of Alloys and Compounds
Volume	646
DOIs	https://doi.org/10.1016/j.jallcom.2015.06.044
Publication status	Published - 24 Jun 2015

Keywords

Lattice vacancy
Methane
Non-stoichiometric perovskite
XPS
XRD

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10.1016/j.jallcom.2015.06.044

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title = "Preparation and characterization of the non-stoichiometric La-Mn perovskites",

abstract = "Abstract Six La-Mn oxide samples with La/Mn atomic ratio x = 1.03-0.56 (denoted as sample LaxMn) were prepared by the citrate method with calcination at 700 °C for 5 h, and characterized by X-ray diffraction (XRD), N2 adsorption-desorption, temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). It is confirmed that the four samples with La/Mn atomic ratio at 1.03-0.72 are all single phase perovskites by XRD patterns. Lattice parameters of the perovskites are varying with the La/Mn atomic ratio. As the La/Mn atomic ratio further lowers to 0.63 and 0.56, Mn3O4 phase is formed besides the main phase of perovskite. Lattice vacancy at the A-sites of the perovskites is present for all the six samples, and there are an appreciable number of Mn4+ ions in the perovskite crystal according to the refinement results of the Rietveld method. XPS analyses indicate that Mn ions are enriched on the surfaces of all the samples. In addition, catalytic activity for methane oxidation is in an order of sample La0.89Mn > La1.03Mn > La0.81Mn > La0.72Mn > La0.63Mn > La0.56Mn.",

keywords = "Lattice vacancy, Methane, Non-stoichiometric perovskite, XPS, XRD",

author = "Zhiming Gao and Huishu Wang and Hongwei Ma and Zhanping Li",

note = "Publisher Copyright: {\textcopyright} 2015 Elsevier B.V.",

year = "2015",

month = jun,

day = "24",

doi = "10.1016/j.jallcom.2015.06.044",

language = "English",

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TY - JOUR

T1 - Preparation and characterization of the non-stoichiometric La-Mn perovskites

AU - Gao, Zhiming

AU - Wang, Huishu

AU - Ma, Hongwei

AU - Li, Zhanping

PY - 2015/6/24

Y1 - 2015/6/24

N2 - Abstract Six La-Mn oxide samples with La/Mn atomic ratio x = 1.03-0.56 (denoted as sample LaxMn) were prepared by the citrate method with calcination at 700 °C for 5 h, and characterized by X-ray diffraction (XRD), N2 adsorption-desorption, temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). It is confirmed that the four samples with La/Mn atomic ratio at 1.03-0.72 are all single phase perovskites by XRD patterns. Lattice parameters of the perovskites are varying with the La/Mn atomic ratio. As the La/Mn atomic ratio further lowers to 0.63 and 0.56, Mn3O4 phase is formed besides the main phase of perovskite. Lattice vacancy at the A-sites of the perovskites is present for all the six samples, and there are an appreciable number of Mn4+ ions in the perovskite crystal according to the refinement results of the Rietveld method. XPS analyses indicate that Mn ions are enriched on the surfaces of all the samples. In addition, catalytic activity for methane oxidation is in an order of sample La0.89Mn > La1.03Mn > La0.81Mn > La0.72Mn > La0.63Mn > La0.56Mn.

AB - Abstract Six La-Mn oxide samples with La/Mn atomic ratio x = 1.03-0.56 (denoted as sample LaxMn) were prepared by the citrate method with calcination at 700 °C for 5 h, and characterized by X-ray diffraction (XRD), N2 adsorption-desorption, temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). It is confirmed that the four samples with La/Mn atomic ratio at 1.03-0.72 are all single phase perovskites by XRD patterns. Lattice parameters of the perovskites are varying with the La/Mn atomic ratio. As the La/Mn atomic ratio further lowers to 0.63 and 0.56, Mn3O4 phase is formed besides the main phase of perovskite. Lattice vacancy at the A-sites of the perovskites is present for all the six samples, and there are an appreciable number of Mn4+ ions in the perovskite crystal according to the refinement results of the Rietveld method. XPS analyses indicate that Mn ions are enriched on the surfaces of all the samples. In addition, catalytic activity for methane oxidation is in an order of sample La0.89Mn > La1.03Mn > La0.81Mn > La0.72Mn > La0.63Mn > La0.56Mn.

KW - Lattice vacancy

KW - Methane

KW - Non-stoichiometric perovskite

KW - XPS

KW - XRD

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DO - 10.1016/j.jallcom.2015.06.044

M3 - Article

AN - SCOPUS:84934917075

SN - 0925-8388

VL - 646

SP - 73

EP - 79

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

M1 - 34383

ER -

Preparation and characterization of the non-stoichiometric La-Mn perovskites

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