X-ray Photoelectron Spectroscopy (XPS) Investigation of the Surface Film on Magnesium Powders

Abstract

Magnesium (Mg) and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. Powder metallurgy may be a suitable solution for forming near-net-shape parts. However, sintering pure magnesium presents difficulties due to surface film that forms on the magnesium powder particles. The present work investigates the composition of the surface film that forms on the surface of pure magnesium powders exposed to atmospheric conditions and on pure magnesium powders after compaction under uniaxial pressing at a pressure of 500 MPa and sintering under argon at 600 °C for 40 minutes. Initially, focused ion beam microscopy was utilized to determine the thickness of the surface layer of the magnesium powder and found it to be ∼10 nm. The X-ray photoelectron analysis of the green magnesium sample prior to sintering confirmed the presence of MgO, MgCO3·3H2O, and Mg(OH)2 in the surface layer of the powder with a core of pure magnesium. The outer portion of the surface layer was found to contain MgCO3·3H2O and Mg(OH)2, while the inner portion of the layer is primarily MgO. After sintering, the MgCO3·3H2O was found to be almost completely absent, and the amount of Mg(OH)2 was also decreased significantly. This is postulated to occur by decomposition of the compounds to MgO and gases during the high temperature of sintering. An increase in the MgO content after sintering supports this theory.

Comparative Study of Conventional Electrolytes for Rechargeable Magnesium Batteries

“…The broad signal in low binding energy of Mg 2p spectra (49 eV) is assigned to Mg‐dangling bond [31] . The O 1s spectrum confirms the observation of MgO (529.1 eV [28b] ), Mg(OH) 2 /MgCO 3 (530.9 eV), [29a,b,32] and C−O (532.6 eV [28b] ). It should be noted that the B 1s spectra in all samples show no clear signal of boron containing species, which is probably due to low concentration of TBABH 4 in electrolyte solutions (Figure S10A).…”

Using a Chloride-Free Magnesium Battery Electrolyte to Form a Robust Anode–Electrolyte Nanointerface

“…A broad signal at 48.2–48.6 eV is assigned to Mg dangling bonds on the magnesium oxide surface . The O 1s spectrum further corroborates the existence of MgO (529.6 eV) and Mg­(OH) 2 /MgCO 3 (533.6 eV). ,,− The O 1s peak at 531.4 eV is assigned to the existence of oxygen vacancy in the MgO lattice. − The O 1s spectrum also confirms the presence of organic species indicated by a strong peak at 532.8 eV, corresponding to C–O and/or CO containing species . The presence of organic species is further confirmed by the signals of C–O bonds (285.9 eV), , CO (287.4 eV), C 2 O 4 2– and/or CO 3 2– (290.1 eV), and C–C bonds (284.3 eV) in the C 1s spectrum, which originated from the decomposition of DME solvent. , The presence of MgCO 3 could also be due to contamination from the glovebox; a signal in the low binding energy of 283.1 eV in the C 1s spectrum is likely to arise from Mg–C bond .…”

“…Samples were sealed in a customized XPS holder under argon atmosphere and transferred directly to the XPS loading chamber without ambient contamination. At the top surface, the Mg 2p spectrum indicates the existence of Mg metal (49.8 eV), − MgO (51.0 eV), − and MgCO 3 and/or Mg­(OH) 2 (51.8 eV) . A broad signal at 48.2–48.6 eV is assigned to Mg dangling bonds on the magnesium oxide surface .…”

XPS Study on Calcining Mixtures of Brucite with Titania

“…Pei Yun et al, also reported O1s in MgO at 530.05 eV, they obtained MgO/TiO 2 compounds, through a suspension of magnesium carbonate hydroxide nanowires with ethanol and tetrabutyl titanate, the suspension was stirred, filtered, washed, dried, and calcined at 450 • C [24]. In another work, compacted and sintered Mg powder specimens were made at 600 • C for 40 min, the results in the binding energy of O1s for MgO of the specimens before sintering was 531.1 eV, and 532.2 after sintering [25]. Therefore, it is known that O1s peaks related to magnesium oxide have bending energies of approximately 530-531 eV, and magnesium hydrates have bending energies of approximately 530.0-533.2 eV [26][27][28][29][30].…”