Investigation of the thermal stability of Ni/C multilayers by X-ray methods

Krawietz, Rhena; Wehner, B.; Meyer, Dirk C.; Richter, K; Mai, H.; Dietsch, R.; Hopfe, S.; Scholz, Roland; Pompe, W.

doi:10.1007/bf00322045

Cited by 8 publications

(14 citation statements)

References 11 publications

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“…One diffraction ring was observed corresponding to the Ni(111) planes diffraction with Ni fcc structure. The observed phase is consistent with the reported XRD results2526. No obvious intensity modulations are observed in this blurred diffraction ring, which indicates that these Ni crystalline grains have no preferred orientation inside the Ni layers.…”

Section: Resultssupporting

confidence: 91%

Microstructure evolution with varied layer thickness in magnetron-sputtered Ni/C multilayer films

Peng

Huang

et al. 2016

Sci Rep

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The microstructure evolution of magnetron-sputtered Ni/C multilayers was investigated by varying the Ni and C layer thickness in the region of a few nanometers. For the samples having 2.6-nm-thick C layers, the interface width increases from 0.37 to 0.81 nm as the Ni layer thickness decreases from 4.3 to 1.3 nm. Especially for the samples with Ni layers less than 2.0 nm, the interface width changes significantly due to the discontinuously distributed Ni crystallites. For the samples having 2.8-nm-thick Ni layers, the interface width increases from 0.37 to 0.59 nm when the C layer thickness decreases from 4.3 to 0.7 nm. The evolution of interface microstructures with varied Ni and C layers is explained based on a proposed simple growth model of Ni and C layers.

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Section: Resultssupporting

confidence: 91%

Microstructure evolution with varied layer thickness in magnetron-sputtered Ni/C multilayer films

Peng

Huang

et al. 2016

Sci Rep

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“…In contrast to Ref. [5], we do not observe any indication for crystalline Ni(111) nor Ni(200) formation in our curves, although the layers of the multilayer described here are thicker and the effect is therefore expected to be more pronounced.…”

Section: Resultscontrasting

confidence: 99%

“…To test the thermal stability of the grown multi-layer, we followed a different approach compared to the straightforward heating of the multi-layer as described in Ref. [5]. There it is found that the reflectivity of the multi-layer is destroyed upon heating beyond 300 • C, explained by the formation of carbides which decompose upon heating at higher temperatures.…”

Section: Resultsmentioning

confidence: 99%

Studying Pulsed Laser Deposition conditions for Ni/C-based multi-layers

Bollmann

2018

Applied Surface Science

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Nickel carbon based multi-layers are a viable route towards future hard X-ray and soft γ-ray focusing telescopes. Here, we study the Pulsed Laser Deposition growth conditions of such bilayers by Reflective High Energy Electron Diffraction, X-ray Reflectivity and Diffraction, Atomic Force Microscopy, X-ray Photoelectron Spectroscopy and cross-sectional Transmission Electron Microscopy analysis, with emphasis on optimization of process pressure and substrate temperature during growth. The thin multi-layers are grown on a treated SiO substrate resulting in Ni and C layers with surface roughnesses (RMS) of ≤0.2 nm. Small droplets resulting during melting of the targets surface increase the roughness, however, and can not be avoided. The sequential process at temperatures beyond 300• C results into intermixing between the two layers, being destructive for the reflectivity of the multi-layer.

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“…According to our previous experience [8,15,16] we believe that the two types of nanostructures reflect different stages of local heat-processing of the metastable multilayers. We have found that irreversible structural modifications in nm-period Ni/C multilayers have already started at an annealing temperature of 200 • C. Formation and further reduction of metastable nickel carbide, agglomeration and coarsening of nickel clusters was observed within a temperature range of 200-400 • C. Complete decomposition of Ni/C film structures with the formation of separated Ni particles can take place upon annealing at a temperature of about 500 • C.…”

Section: Discussionmentioning

confidence: 98%

“…The Ni/C multilayer system possesses a simple eutectic-type stable phase diagram with practically zero solubility of the components into each other at room temperature. An excess of free Gibbs energy of the multilayer gives rise to irreversible decomposition processes in Ni/C multilayers by annealing at temperatures ≥ 200 • C [14][15][16]. At room temperature these multilayers are stable within years.…”

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confidence: 99%

Nanoprocessing of metastable nm-period multilayers

Gorbunov

Richter

Pompe

1998

Applied Physics A: Materials Science & Processing

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Nanometer-period nickel-carbon multilayers were used as a medium for the fabrication of nanostructures by gap voltage manipulations in a scanning tunneling microscope. The written metallic structures were stable over at least several weeks. No traces of tip material were found in the processed areas. Two well-distinguished hillock-like nanostructure types were observed depending on the tip-sample separation, polarity and interaction time. Relatively slow local annealing under positive sample potential without a direct tip-sample contact resulted in the formation of nanostructures about 20 nm wide and a few nm high. Rapid melting followed by metal melt extrusion was observed if the tip contacted the sample during the nanostructure formation. These metal-like structures were tens of nm high and had a good electronic contrast to the initial carbon-coated surface. The formation of nanostructures was strongly dependent on the tip condition. Possible mechanisms of nanostructure formation are discussed.The temporal stability of metallic nanostructures is one of the most serious limitations of possible applications, for example for ultrahigh-density data storage or nanoelectronic applications. One had to perform the exciting experiments on formation of patterned atomic arrays or "quantum coralls" [1, 2] under liquid-helium temperatures in order to prevent atoms from surface migration for a reasonably long time. The works [3-7] on formation of golden nanostructures in ultrahigh vacuum (UHV) showed diffusional dissolution of written features on a time scale of minutes or hours.A possible solution for the stability problem was proposed in [8,9]. It was shown that metastable nm-period metal-carbon multilayers are a promising medium for stable nanoprocessing. In contrast to the bulk crystalline materials, multilayer thin films have the advantage that their physical properties can be continuously adjusted, for example by varying the material composition, the thickness of the layers, or the number of layer periods. It was recognized that because of internal stresses and forced intermixing of finite miscible materials at the interfaces the multilayers frequently occur in some frozen-in non-equilibrium metastable state [10]. This metastable state is kinetically stable under normal conditions, but upon application of sufficient activation energy the multilayers exhibit well-defined morphological or phase transitions with corresponding alteration of physical properties. The initial metastability opens unique possibilities to fabricate stable nanostructures through local annealing, since the written nanostructures are in a more favorable energetic state than the initial multilayer.In the last decade a considerable interest has grown in the nanostructure fabrication by various scanning probe techniques. To date the scanning tunneling microscope (STM) is the only instrument that can provide a nanometer-sized beam of low energy electrons (0-20 eV). These energies are comparable to the bonding energies of atoms in solids, but are still ...

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Investigation of the thermal stability of Ni/C multilayers by X-ray methods

Cited by 8 publications

References 11 publications

Microstructure evolution with varied layer thickness in magnetron-sputtered Ni/C multilayer films

Microstructure evolution with varied layer thickness in magnetron-sputtered Ni/C multilayer films

Studying Pulsed Laser Deposition conditions for Ni/C-based multi-layers

Nanoprocessing of metastable nm-period multilayers

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