Anomalous expansion of tungsten-carbon multilayers used in x-ray optics

Lepêtre, Y.; Ziegler, Eric; Schuller, Iván K.; Rivoira, R.

doi:10.1063/1.337192

Cited by 38 publications

(8 citation statements)

References 3 publications

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“…X-ray measuments of the low-angle Bragg peaks of the WC/C multilayers reveal the expansion of the multilayer periods upon annealing, as observed in the W/C system in various studies [3][4][5][6][7]11].…”

Section: Resultsmentioning

confidence: 99%

“…Many techniques have been applied to characterize this system. X-ray scattering [3,4] and EXAFS [5] give information about the interatomic structure within the layers, and transmission electron microscopy [6][7][8][9][10][11] reveals the the quality of the layering and the nature of the phases within the layers. Previous annealing studies on the tungsten-carbon system have shown that for short periods the W -rich layers .…”

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confidence: 99%

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Microstructure and Stability Comparison of Nanometer Period W/C, Wc/C, and Ru/C Multilayer Structures

1990

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Multilayer structures of W/C, WC/C, and Ru/C, of various periods were prepared and studied by high-resolution transmission electron microscopy. Comparison of the phases in the layered structures is made for as-prepared and annealed samples. Both as-prepared and annealed WC/C multilayers are predominantly amorphous, while the phases in the W/C depend on the periods. The 2 nm period W/C multilayer remains amorphous after annealing, and the longer periods recrystallize to form W2C. The layered microstructures of W/C and WC/C are stable on annealing at all periods, while the amorphous Ru-rich layers in the 2 nm period Ru/C multilayer agglomerate upon annealing to form elemental hexagonal Ru crystallites. Larger period Ru/C multilayers show stable layered structures, and indicate hexagonal Ru in the Ru-rich layers. X-ray measurements show that the multilayer periods expand on annealing for all metal-carbon multilayers studied.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Microstructure and Stability Comparison of Nanometer Period W/C, Wc/C, and Ru/C Multilayer Structures

1990

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“…[14][15][16] One important feature of annealed Mo/Si multilayers is the reduction of period due to the formation of the much denser silicide. 16 In sharp contrast to Mo/Si multilayers, the annealing process induces an expansion in the period of W/C multilayers, 17 which has been commonly observed, and is usually explained as ͑1͒ the expansion in carbon sublayers due to more graphite microstructures, 18,19 ͑2͒ the agglomeration in W sublayers, 20 and ͑3͒ the formation of W-C compound. 21,22 It was also found that the structural nature of both the as-deposited and annealed W/C multilayers relates to their period, 21,23 their thermal history, [21][22][23][24] the relative thickness of the different layers 24 and possibly on their preparation technique.…”

Section: Introductionmentioning

confidence: 98%

Thermal evolution of carbon in annealed Co/C soft x-ray multilayers

Bai

Jiang

Wang

1996

Journal of Applied Physics

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The structures of the carbon sublayers in the annealed Co/C soft x-ray multilayers fabricated using a dual-facing-target sputtering system have been characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy (RS). The results suggest that the structural variations in the carbon layers can be roughly divided into three stages, i.e. ordering, crystalline and grain growth stages. In the ordering stage with annealing temperatures below 400 °C, the upward shift of D and G lines in Raman spectra indicates that the amorphous carbon layers are changing from ones with bond-angle disorder and fourfold-bonding only to ones containing threefold-bonding. In the crystalline stage, the amorphous carbon layers in the as-deposited multilayers crystallize to graphite crystallites in the annealing temperature range of 500–600 °C. The rapid increase in the intensity ratio of D line to G line and dramatic decrease in linewidth further confirm this substantial structural change. In the grain growth stage, the specimens are annealed at temperatures higher than 700 °C. The decrease in the intensity ratio implies a growth in the graphite crystallite dimensions, which is consistent with the XRD and TEM results.

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“…C ARBON and tungsten films have a potential application as high-reflectivity coatings for X-ray optics of monochromators for synchrotron light, particularly due to their high thermal stability [1]- [3], and were investigated as multilayer coatings [4], [5]. More recently, interaction of these materials with the fusion plasma has led to the formation of mixed material layers that can change tritium retention properties.…”

Section: Introductionmentioning

confidence: 98%

Carbon–Tungsten Thin-Film Deposition by a Dual Thermionic Vacuum Arc

Lungu

Marcu

Poroşnicu

et al. 2012

IEEE Trans. Plasma Sci.

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Carbon and tungsten films were deposited simultaneously from two separate plasmas produced by the thermionic vacuum arc method. Total film thickness, surface roughness, atomic composition, and chemical bonds of atoms at the surface and inside the deposited films were analyzed for different substrate positions of the samples. X-ray photoelectron spectroscopy analyses suggest that tungsten carbide forms predominantly at preferential substrate positions. Variations in the carbon plasma deposition rate were also used to dynamically control the film composition. Larger target-substrate distances result in smoother films but slower composition variations.

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Anomalous expansion of tungsten-carbon multilayers used in x-ray optics

Cited by 38 publications

References 3 publications

Microstructure and Stability Comparison of Nanometer Period W/C, Wc/C, and Ru/C Multilayer Structures

Microstructure and Stability Comparison of Nanometer Period W/C, Wc/C, and Ru/C Multilayer Structures

Thermal evolution of carbon in annealed Co/C soft x-ray multilayers

Carbon–Tungsten Thin-Film Deposition by a Dual Thermionic Vacuum Arc

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