Depth Resolved Structural Studies in Multilayers Using X-ray Standing Waves

Gupta, Ajay

doi:10.1007/s10751-005-9144-x

Cited by 8 publications

(4 citation statements)

References 31 publications

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“…An avalanche photodiode detector was used for GINRS measurement, having a time resolution of ∼1 ns. The nuclear (NRR) and electronic (XRR) parts of the signal were separated by making use of the fact that nuclear transitions are delayed in time due to the finite lifetime of the Mössbauer excited state (140 ns in the case of 57 Fe isotope) [47,48]. Thus, photons detected within a few nanoseconds of the incident x-ray pulse constitute the XRR signal due to electronic scattering, while those detected in an interval of 10-160 ns after the incident x-ray pulse are used to get NRR and GINRS patterns.…”

Section: Methodsmentioning

confidence: 99%

Interface-resolved study of magnetism in MgO/FeCoB/MgO trilayers using x-ray standing wave techniques

et al. 2023

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Interfaces in MgO/FeCoB/MgO trilayer have been studied with grazing incident nuclear resonance scattering using the x-ray standing wave technique. High depth selectivity of the present method allows one to measure magnetism and structure at the two interfaces of FeCoB, namely, FeCoB on MgO and MgO on FeCoB, independently, yielding an intriguing result that both interfaces are not symmetric. A high-density layer with an increased magnetic hyperfine field at the FeCoB-on-MgO interface suggests different growth mechanisms at the two interfaces. The azimuthal angle-dependent magneto-optic Kerr effect measurements reveal the presence of unusual uniaxial magnetic anisotropy (UMA) in the trilayer. An in situ temperature-dependent study discovered that this UMA systematically reduces with temperature. After annealing at 250 • C, the trilayer starts following the standard Stoner-Wohlfarth model for in-plane UMA. The trilayer becomes isotropic at 450 • C with an order-of-magnitude increase in coercivity. The asymmetry at the interfaces is in turn explained by boron diffusion from the FeCoB interface layer into the nearby MgO layer. Stress-induced UMA is observed in the boron-deficient FeCoB layer, superimposed with the bulk FeCoB layer, and found to be responsible for unusual UMA. The temperature-dependent variation in the UMA and coercivity can be understood in terms of variations in the internal stresses and coupling between FeCoB bulk and the interface layer.

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Section: Methodsmentioning

confidence: 99%

Interface-resolved study of magnetism in MgO/FeCoB/MgO trilayers using x-ray standing wave techniques

et al. 2023

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“…This is attributed to the limited penetration depth of X-rays and the gradual increase in coating thickness with the extension of the holding time. X-rays are unable to penetrate the single-phase TiSi 2 region in the outermost layer of the coating [31,32]. Hence, after a holding time of more than 1 h, only the TiSi 2 can be detected on the coating surface by XRD.…”

Section: Effect Of Holding Time On Ti-si Coatingsmentioning

confidence: 99%

Formation Mechanism of Ti–Si Multi-Layer Coatings on the Surface of Ti–6Al–4V Alloy

Zhao,

Liang,

Zhang

et al. 2024

Coatings

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Titanium alloys are widely used in aerospace applications due to their high specific strength and exceptional corrosion resistance. In this study, a silicide coating with a multi-layer structure was designed and prepared via a pack cementation process to improve the high-temperature oxidation resistance of titanium alloy. A new theory based on the Le Chatelier’s principle is proposed to explain the generation mechanism of active Si atoms. Taking the chemical potential as a bridge, a functional model of the relationship between the diffusion driving force and the change in the Gibbs free energy of reaction diffusion is established. Experimental results indicate that the depth of the silicide coating increases with the siliconization temperature (1000–1100 °C) and time (0–5 h). The multi-layer coating prepared at 1075 °C for 3 h exhibits a thick and dense structure with a thickness of 23.52 μm. This coating consists of an outer layer of TiSi2 (9.40 μm), a middle layer of TiSi (3.36 μm), and an inner layer of Ti5Si3 (10.76 μm). Under this preparation parameter, increasing the temperature or prolonging the holding time will cause the outward diffusion flux of atoms in the substrate to be much larger than the diffusion flux of silicon atoms to the substrate, thus forming pores in the coating. The calculated value of the diffusion driving force FTiSi = 2.012S is significantly smaller than that of FTiSi2 = 13.120S and FTi5Si3 = 14.552S, which perfectly reveals the relationship between the thickness of each layer in the Ti–Si multi-layer coating.

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“…The example studied was the effects of swift heavy ion irradiation on a Si/M/Si trilayer (M = Fe, W) forming the cavity of the waveguide structure in which Fe was found to be much more sensitive that W, even in thin film form. In a second contribution, Gupta 63 further considered the issue of depth resolve structures in multilayers emphasising the benefit of generating X-ray standing waves inside the multilayer structure when using techniques such as XRF, X-ray absorption spectroscopy and nuclear resonance fluorescence.…”

Section: X-ray Optics and Microfluorescencementioning

confidence: 99%