A mechanically switchable metal–insulator transition in Mg2NiH4 discovers a strain sensitive, nanoscale modulated resistivity connected to a stacking fault

Lelis, Martynas; Milčius, D.; Wirth, E.; Hålenius, Ulf; Eriksson, Lars; Jansson, Kjell; Kadir, K.; Ruan, Juanfang; Sato, Toyoto; Yokosawa, Tadahiro; Noréus, Dag

doi:10.1016/j.jallcom.2010.02.135

Cited by 18 publications

(28 citation statements)

References 27 publications

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“…MgH 2 and Mg 2 NiH 4 stores respectively 7.6 wt% and 3.6 wt% hydrogen [1]. Also several other applications have been proposed, involving thin films of Mg-Ni-H for use in smart windows [2], hydrogen sensors [3], semiconductor electronics [4], solar cells [5] and data storage [6]. These applications rely on the respectively insulating and semiconducting nature of the hydrides of Mg and Mg 2 Ni.…”

Section: Introductionmentioning

confidence: 99%

“…For Mg y Ni 1-y H x thin films, metallic Mg-Ni films are normally deposited by magnetron sputtering or evaporation and hydrogenated ex-situ after the deposition. A few nanometers of Pd capping is commonly used in order to protect the films from oxidation and as a catalyst to accelerate the hydrogen uptake [9], but also films without Pd cap layers can be hydrogenated under exposure to hydrogen for several hours [6,10]. Direct formation of metal hydride films in-situ can be performed by activated reactive evaporation [11,12] or reactive sputtering deposition as applied in the current work.…”

Section: Introductionmentioning

confidence: 99%

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MgyNi1−y(Hx) thin films deposited by magnetron co-sputtering

Mongstad

You

Thøgersen

et al. 2012

Journal of Alloys and Compounds

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Abstract:In this work we have synthesised thin films of Mg y Ni 1-y (H x ) metal and metal hydride with y between 0 and 1. The films are deposited by magnetron co-sputtering of metallic targets of Mg and Ni. Metallic Mg y Ni 1-y films were deposited with pure Ar plasma while Mg y Ni 1-y H x hydride films were deposited reactively with 30% H 2 in the Ar plasma. The depositions were done with a fixed substrate carrier, producing films with a spatial gradient in the Mg and Ni composition. The combinatorial method of co-sputtering gives an insight into the phase diagram of Mg y Ni 1-y and Mg y Ni 1-y H x , and allows us to investigate structural, optical and electrical properties of the resulting alloys. Our results show that reactive sputtering gives direct deposition of metal hydride films, with high purity in the case of Mg~2NiH~4. We have observed limited oxidation after several months of exposure to ambient conditions. Mg y Ni 1-y and Mg y Ni 1-y H x films might be applied for optical control in smart windows, optical sensors and as a semiconducting material for photovoltaic solar cells.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

MgyNi1−y(Hx) thin films deposited by magnetron co-sputtering

Mongstad

You

Thøgersen

et al. 2012

Journal of Alloys and Compounds

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“…The LT2 phase is a modification of the LT1 phase with micro-twinning or stacking faults [38]. It is a minor change in the structure, but there is a large difference in optical and electrical properties of the two phases [39]. If the hydride is heated up to temperatures above 237 ºC, it undergoes a transition to the HT structure.…”

Section: Magnesium Nickel Hydridementioning

confidence: 99%

Reactive Sputtering of Magnesium Hydride Thin Films for Photovoltaic Applications

et al. 2009

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Deposition of MgHx (MgH2 + Mg) thin films is performed using RF reactive sputtering in argon-hydrogen plasma. Films are characterized using x-ray diffraction (XRD), scanning electron microscopy, optical and resistivity measurements. Formation of crystalline MgH2 is confirmed by XRD, but the formation of some metallic Mg in the films could not be avoided. Increased H/Mg ratio by deposition at high hydrogen flow or high total pressure gives films that oxidize within days or weeks. Deposition at elevated substrate temperature results in improved crystallinity and stability. Initial studies of MgHx for silicon surface passivation are presented.

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“…In a way this is unfortunate for all the efforts trying to destabilize magnesium hydride (MgH 2 ) for hydrogen storage by alloying it with nickel, which the well investigated Small disturbances in the counter ion lattice have strong impact on the band gaps and the hydrides can switch from conducting to non-conducting by the use of mechanical strain. 8,9 We thus believe that it is interesting to further study how substitution in the counter ion frame works influence the stability of could not make the corresponding barium analogue.…”

Section: Introductionmentioning

confidence: 99%