Quantitative Analysis of Hydrogen in High-Hydrogen-Content Material of Magnesium Hydride via Laser-Induced Breakdown Spectroscopy

Abstract

An analytical approach that can rapidly determine a wide range of hydrogen concentration in solid-state materials has been recently demanded to contribute to the hydrogen economy. This study presents a method for estimating hydrogen concentrations ranging from 0.2 to 7.6 mass % via laser-induced breakdown spectroscopy (LIBS) in a few seconds, with an improvement in the upper limit of determination (7.6 mass %) by approximately 1.3 times compared with a previous work (5.7 mass %). This extension of the determinable concentration range was achieved by measuring the emission intensity at 656.28 nm from the sample in a helium atmosphere at 3000 Pa under focused laser irradiation and by reducing the water residues in both the sample and gas line of the LIBS system. The as-determined hydrogen concentrations in magnesium hydride (MgH 2 ) samples agreed well with those estimated through inert gas fusion/gas chromatography. The calibration curve for LIBS analysis was acquired by measuring the emission intensity at 656.28 nm of standard Mg/MgH 2 mixtures containing various hydrogen concentrations (0, 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 7.6 mass %). Results indicated that the proposed LIBS-based method is applicable to the rapid quantitative analysis of hydrogen in hydrogencontaining material of MgH 2 .

Laser-induced breakdown spectroscopy to obtain quantitative three-dimensional hydrogen mapping in a nickel–metal-hydride battery cathode for interpreting its reaction distribution

“…3(f)) and the emission intensity was zero at 0 mass% of hydrogen. Additionally, we considered that the emission intensity of the H I 656.28 nm line increased linearly with an increase in hydrogen concentration in the model cathode because our previous study demonstrated that the emission intensities of the H I 656.28 nm line increased linearly with an increase in hydrogen concentration of up to 7.6 mass%, 37 as shown in Fig. S1 †.…”

“…We also confirmed that the effect of hydrogen originating from water molecules on the sample surfaces and in the measurement atmosphere on intensities of the H I 656.28 nm line can be minimized by storing the samples in a desiccator for over 3 days and attaching the moisture trap to the helium gas line. 37 Additionally, we used a pristine cathode, whose structure was almost the same as the model cathode after the fifth charging, as a reference sample to establish a calibration line for determining the hydrogen contents. Ni(OH) 2 is only involved in the charge reaction of the cathodes, and the molecular weight changes from 92.7 (Ni(OH) 2 ) to 91.7 (NiOOH) by the charge reaction.…”

“…We performed LIBS measurements of the cathodes using a custom LIBS system described previously. 37 In brief, the laser used in the present study was a Q-switched Nd:YAG laser (LS-2137, LOTIS TII Ltd, Minsk, Belarus) with a wavelength of 532 nm. The energy and duration of the pulsed laser used to irradiate the cathodes were 30 mJ per pulse and 16-18 ns, respectively.…”

“…By contrast, we have recently presented a method for estimating hydrogen concentrations ranging from 0.2 to 7.6 mass% in the bulk samples of MgH 2 using LIBS, where only the hydrogen emission line (H I 656.28 nm) and reference samples with known hydrogen concentration were used to establish the calibration line. 37 Thus, our LIBS method can measure hydrogen concentrations in any materials, including the cathodes of Ni–MH batteries. Then, we obtained a semi-quantitative two-dimensional hydrogen mapping of a model cathode of a Ni–MH battery using our LIBS method.…”

Analysis of Hydrogen in Inorganic Materials and Coatings: A Critical Review

“…Applications of the analysis of hydrogen by LIBS involve hydrogen and deuterium analysis in plasma-facing materials for thermonuclear fusion devices [60,61,63,64], materials for nuclear fission reactors, such as Zircalloy [65], hydrogen in weldments [66], hydrogen-storage materials (MgH 2 ) [67], isotopic analysis of hydrogen in titanium [68,69], and even hydrogen analysis in H-bearing minerals on Mars by the rover Curiosity [70]. Isotopic analysis is traditionally a domain of mass spectrometry; however, the isotopic shift in the hydrogen spectrum also allows distinguishing between hydrogen and deuterium by optical emission.…”