Interstitial Diffusion Research Articles

Renal functional diagnostics using magnetic resonance imaging

Due to progress in the development of sequences and techniques magnetic resonance imaging (MRI) methods, such as functional MR urography (fMRU), arterial spin labeling (ASL), diffusion-weighted imaging (DWI), diffusion tension imaging (DTI) and blood oxygen level dependent MRI (BOLD-MRI) have become available for renal functional evaluation. In recent years research of these imaging techniques has demonstrated that they provide valid functional data with respect to renal perfusion, oxygenation and interstitial diffusion as well as glomerular filtration and the extent of an obstructive uropathy. Many pathophysiological renal processes, e. g. in transplanted kidneys, in the setting of chronic kidney disease and in the diagnostics of renal tumors, can therefore be fully evaluated. The fMRU, which enables a reliable assessment of renal function combined with high-resolution morphological evaluation of the kidneys and the entire urinary tract, has already become an inherent component in the clinical setting, at least in specialized pediatric radiology centers. To establish the new imaging methods in the clinical routine, further technical improvements and large-scale prospective clinical studies are necessary to validate the determined functional parameters, to generate standard protocols and to unify and facilitate data post-processing.

Diffusion of interstitial species (H and O atoms) in fcc systems (Al, Cu, Co, Ni and Pd): Contribution of first and second order transition states

We present a discussion on the influence of high-order transition states on interstitial diffusion in fcc systems using first-principles calculations. In earlier works, only first-order transition states (1TS) were used to compute the diffusivity at the atomic-scale: the direct diffusion between tetrahedral (t) and octahedral (o) sites has been proposed to describe atomic-scale diffusion mechanisms. However, we show here that if this direct diffusion makes it possible to reproduce displacements remarkably well, neglecting higher-order transition states induces an underestimation of the diffusion coefficient at high temperature. We hereinafter revisit the diffusion coefficient of interstitial species in different fcc-systems. The effect of these configurations on atom diffusion in Al, Co, Cu, Ni and Pd, whose only stable sites are the tetrahedral and octahedral positions (H and O atoms) is thus discussed here. We show that if the correction is low, taking into account higher-transition states can modify the diffusivity values at high temperature.

Mechanisms of volume diffusion in metals near the Debye temperature

The paper offers a phenomenological model of volume self-diffusion and interstitial diffusion at high (T > TD) and low (T < TD) temperatures (where TD stands for the Debye temperature). Diffusion mechanisms at high and low temperatures were shown to differ greatly. Diffusion at high temperatures occurs as a result of fluctuations that can be described in the localized melting terms – 'liquid diffusion corridor' formation. At low temperatures when melting is difficult for a number of reasons, diffusion occurs through a 'hollow diffusion corridor' formed by fluctuation. Activation energy calculations for self-diffusion agree well with the T > TD experiment and show a dramatic increase in the activation energy at T < TD. Interstitial diffusion activation energy calculated for BCC metals agrees well with the experiment of the whole temperature range and helps to explain why diffusion activation energy goes down at low temperatures.

Microstructure and interface characteristics of NiCrBSi thick coating remelted by TIG process

A NiCrBSi coating of 800 μm thick is prepared on AISI 1045 steel via plasma spraying, subsequently, the coating is remelted by tungsten inert gas arc (TIG) process. The microstructure and interface characteristics of remelted coating were intensively studied. The results show that, upon remelting, the microstructure of the thick coating comprises planar crystal and dendritic crystal. And the main phases in the as-sprayed coating are changed from γ-Ni, Cr7C3 and Cr2B to γ-(Ni,Fe), (Fe,Cr)23C6, CrB, Ni3B and Fe3C. The combining state between the coating and the substrate is changed from mechanical bonding to metallurgical bonding. A ″bright area" was formed between the remelted coating and substrate. The diffusion mechanism of Fe, Ni and Cr atoms at the interface is vacancy diffusion, and that of C and B atoms is interstitial diffusion. In addition, the differences of elastic modulus and hardness between the both sides of the interface of the coating is greatly reduced by remelting, which is beneficial to improve the bonding strength of the interface. Therefore, TIG remelting treatment is a feasible method to improve the microstructure and the interfacial characteristics of the thick as-sprayed coating.

First principles study of point defect effects on iodine diffusion in zirconium

The formation energies, diffusion barriers, and vibration frequencies of complex iodine defects in zirconium are calculated with first principles calculations and nudged elastic band method. The effective diffusion rates of these complex defects are evaluated in the temperature range from 300 K to 2000 K. The iodine interstitial diffusion and the iodine diffusion via IZr−VZr are the dominant diffusion mechanisms. The vacancies may be traps for iodine diffusion and they can slow down the diffusion of iodine atoms. For the zirconium cladding materials in light water reactors, various point defects may be generated. Our calculated effective diffusion coefficients agree with the experimental data well and it indicates that bulk diffusion may be a main diffusion mechanism for the iodine diffusion in zirconium alloy.

First-principles prediction of oxygen diffusivity near the [formula omitted] twin boundary in titanium

We study the diffusivity of oxygen interstitials around a (101¯2) twin boundary in Titanium. First, we identify all possible stable interstitial sites around the twin boundary and compute the corresponding site energies and transition energy barriers for jumps between these sites, using density functional theory. We show that the site energies and the barriers are consistently lower than in bulk, suggesting the higher tendency of oxygen to segregate to the twin boundary region. Using the site and transition energies and an exact solution to the master equation, we then compute the diffusivity of oxygen in the presence of the twin boundary and find enhanced diffusivity around the boundary in all directions. Enhanced diffusivity towards the boundary determines the feasibility of oxygen segregation to favorable sites at the boundary, while increased diffusivity in the boundary plane provides a path for fast diffusion of oxygen. This result reveals the underlying mechanism governing the slow growth of (101¯2) twin by pinning at the segregated oxygen interstitials.

Relationship between Dislocation Density and Oxygen Concentration in Silicon Crystals during Directional Solidification

This paper reports the relationship between oxygen concentration and dislocation multiplication in silicon crystals during directional solidification using numerical analysis. Based on the Alexander–Haasen–Sumino model, this analysis involved oxygen diffusion from the bulk to dislocation cores during crystal growth and annealing processes in a furnace. The results showed that the dislocation density mainly increased during cooling process, rather than crystal growth, when the effect of oxygen diffusion to dislocation cores was ignored. On the contrary, the dislocation density increased during both crystal growth and cooling processes when the effect of interstitial oxygen diffusion was considered. At a dislocation density larger than 1.0 × 105 cm−2, the interstitial oxygen concentration in bulk decreased due to the diffusion process, if interstitial oxygen atoms were between dislocations, whereas the concentration at dislocation cores increases.

Inferring diameters of spheres and cylinders using interstitial water.

Most early methods to infer axon diameter distributions using magnetic resonance imaging (MRI) used single diffusion encoding sequences such as pulsed gradient spin echo (SE) and are thus sensitive to axons of diameters > 5 μm. We previously simulated oscillating gradient (OG) SE sequences for diffusion spectroscopy to study smaller axons including the majority constituting cortical connections. That study suggested the model of constant extra-axonal diffusion breaks down at OG accessible frequencies. In this study we present data from phantoms to test a time-varying interstitial apparent diffusion coefficient. Diffusion spectra were measured in four samples from water packed around beads of diameters 3, 6 and 10 μm; and 151 μm diameter tubes. Surface-to-volume ratios, and diameters were inferred. The bead pore radii estimates were 0.60±0.08 μm, 0.54±0.06 μm and 1.0±0.1 μm corresponding to bead diameters ranging from 2.9±0.4 μm to 5.3±0.7 μm, 2.6±0.3 μm to 4.8±0.6 μm, and 4.9±0.7 μm to 9±1 μm. The tube surface-to-volume ratio estimate was 0.06±0.02 μm-1 corresponding to a tube diameter of 180±70 μm. Interstitial models with OG inferred 3-10 μm bead diameters from 0.54±0.06 μm to 1.0±0.1 μm pore radii and 151 μm tube diameters from 0.06±0.02 μm-1 surface-to-volume ratios.

BIOPHISICAL MODEL OF ISOLATED LUNG CHEMOPERFUSION AND PHARMACOKINETICS OF CISPLATIN

The individualization of cytostatic agent dose is an actual problem in isolated lung chemoperfusion (ILP). Hitherto it has been carried out according to anthropometric data, in particular, the surface area of the body. A biophysical model of ILP based on diffusion cisplatin transfer in the lung is proposed. The model indicates to get the individual drug dose according to physical lung volume, which can be measured by CT-volumetry. Cisplatin pharmacokinetics and model compliance with actual data are considered on the material of 28 ILP. Estimates of lung interstitial and vascular space volumes and diffusion characteristic of capillary membrane are obtained.

Anisotropy of interstitial diffusion in bcc-crystals due to stress-induced unequal occupancies of different types of sites

Deposition of an interstitial atom in octahedral or tetrahedral sites in a bcc-crystal provokes one of three types of local tensorial eigenstrains. Interaction of the interstitial atoms with an external and/or defect-generated stress state and their diffusion cause different occupancies of individual types of sites. The diffusion paths are analyzed for atoms occupying octahedral or tetrahedral sites. The current original model quantifies the anisotropy of diffusion by factors being functions of occupancies of individual types of sites. Coupling of this new model with a very recent model of interstitial diffusion, already accounting for various types of interstitial sites, provides a rather sophisticated theoretical model for simulation of interstitial diffusion in stressed crystals.

First-Principles Investigation of Native Interstitial Diffusion in Cr2O3

First-principles density functional theory investigation of native interstitials and the associated self-diffusion mechanisms in α-Cr2O3 reveals that interstitials are more mobile than vacancies of corresponding species. Cr interstitials occupy the unoccupied Cr sublattice sites that are octahedrally coordinated by 6 O atoms, and O interstitials form a dumbbell configuration orientated along the [221] direction (diagonal) of the corundum lattice. Calculations predict that neutral O interstitials are predominant in O-rich conditions and Cr interstitials in +2 and +1 charge states are the dominant interstitial defects in Cr-rich conditions. Similar to that of the vacancies, the charge transition levels of both O and Cr interstitials are located deep within the band gap. Transport calculations reveal a rich variety of interstitial diffusion mechanisms that are species-, charge-, and orientation-dependent. Cr interstitials diffuse preferably along the diagonal of corundum lattice in a two-step process via an ...

Mg diffusion in Si on a thermodynamic basis

In the present work, magnesium diffusion in silicon studied recently in the temperature range 600–1200 °C (Astrov et al. in Phys Status Solidi A 214:1700192, 2017; Shuman et al. in Semiconductors 51:5, 2017) is investigated on the basis of the cBΩ thermodynamic model, which connects point defect parameters with the macroscopic elastic and expansion properties. The calculated activation Gibbs free energy, activation enthalpy, activation entropy, activation volume and activation specific heat of Mg diffusion exhibit non-linear temperature dependence, due to the anharmonic behavior of the isothermal bulk modulus of Si. The calculated activation enthalpy of diffusion (1.67–2.12 eV) is in agreement with the reported experimental value (1.83 ± 0.02 eV) of Mg diffusion in Si, whereas the calculated activation volume (60% of the mean atomic volume) is compatible with the reported interstitial diffusion of Mg impurities.

First-principles investigation on diffusion mechanism of alloying elements in dilute Zr alloys

Impurity diffusion in Zr is potentially important for many applications of Zr alloys, and in particular for their use of nuclear reactor cladding. However, significant uncertainty presently exists about which elements are vacancy vs. interstitial diffusers, which can inhibit understanding and prediction of their behavior under different temperature, irradiation, and alloying conditions. Therefore, first-principles calculations based on density functional theory (DFT) have been employed to predict the temperature-dependent dilute impurity diffusion coefficients for 14 substitutional alloying elements in hexagonal closed packed (HCP) Zr. Vacancy-mediated diffusion was modeled with the eight-frequency model. Interstitial contributions to diffusion are estimated from interstitial formation and select migration energies. Formation energies for each impurity in nine high-symmetry interstitial sites were determined, including significant effects of thermal expansion. The dominant diffusion mechanism of each solute in HCP Zr was identified in terms of the calculated vacancy-mediated activation energy, lower and upper bounds of interstitial activation energy, and the formation entropy, suggesting a rough relation with the metallic radii of solutes. It is predicted that Cr, Cu, V, Zn, Mo, W, Au, Ag, Al, Nb, Ta and Ti all diffuse predominantly by an interstitial mechanism, while Hf, Zr, and Sn are likely to be predominantly vacancy-mediated diffusers at low temperature and interstitial diffusers at high temperature, although the identification of mechanisms for these elements at high-temperature is quite uncertain.

Trapping/detrapping kinetic rates of hydrogen around a vacancy in nickel and some consequences on the hydrogen-vacancy clusters thermodynamic equilibrium

The jump rates of H in the interstitial sites of a perfect crystal and in the vicinity of a vacancy in nickel have been determined accurately from ab initio calculations up to 1200 K. The migration free energy of H implemented in the Wert and Zener theory for interstitial diffusion is expressed as a sum of static energy, thermal expansion, vibration and electronic contributions. We show that the thermal expansion and the vibrations of the lattice are the major corrections to the migration energy at finite temperature. The computation of the jump rates indicates that the ratio between the trapping and the detrapping frequencies decrease from ∼104 at 300 K to ∼100 at 1200 K. The effects of the elastic displacement field induced by the vacancy on the jump kinetic rates are minor and the solute diffuses similarly to the perfect crystal out of the vacancy core. Finally, we implement a macroscopic rate equation model to evaluate the concentration of mobile and trapped hydrogen atoms as function of time in a one-dimension sample of 1 μm. The comparison of the H-vacancy cluster concentrations formed during H diffusion with the concentrations given by the quasi-equilibrium condition indicates that the system can develop internal stresses at low temperature due to an oversaturation of H-poor defects. These internal stress fields may be associated with the formation of superabundant vacancies and voids implied on the H embrittlement processes.

Theoretical prediction and atomic kinetic Monte Carlo simulations of void superlattice self-organization under irradiation

Nano-structured superlattices may have novel physical properties and irradiation is a powerful mean to drive their self-organization. However, the formation mechanism of superlattice under irradiation is still open for debate. Here we use atomic kinetic Monte Carlo simulations in conjunction with a theoretical analysis to understand and predict the self-organization of nano-void superlattices under irradiation, which have been observed in various types of materials for more than 40 years but yet to be well understood. The superlattice is found to be a result of spontaneous precipitation of voids from the matrix, a process similar to phase separation in regular solid solution, with the symmetry dictated by anisotropic materials properties such as one-dimensional interstitial atom diffusion. This discovery challenges the widely accepted empirical rule of the coherency between the superlattice and host matrix crystal lattice. The atomic scale perspective has enabled a new theoretical analysis to successfully predict the superlattice parameters, which are in good agreement with independent experiments. The theory developed in this work can provide guidelines for designing target experiments to tailor desired microstructure under irradiation. It may also be generalized for situations beyond irradiation, such as spontaneous phase separation with reaction.

Permeation, Solubility, Diffusion and Segregation of Lithium in Amorphous Silicon Layers

The permeation, solubility, diffusion and segregation of lithium in amorphous silicon layers (∼100 nm) were experimentally determined at temperatures up to 500 °C (773 K). For the experiments, silicon was embedded between 6Li and 7Li enriched solid state Li reservoir layers and the exchange of the isotopes was monitored by secondary ion mass spectrometry. The silicon layers effectively block Li permeation for more than four years at room temperature. At higher temperatures, a fast and a slow Li permeation process can be discriminated. The activation enthalpy for the two processes amounts to (0.9 ± 0.2) and (1.9 ± 0.2) eV, respectively. The first process is based on fast interstitial diffusion leading to Li segregation at the surface and at the substrate interface. The second slower process is due to trap-limited Li diffusion in silicon. An activation enthalpy of Li solubility of (0.5 ± 0.1) eV is found to be identical to that in crystalline silicon, even if absolute values are higher. The activation entha...

Emission and structure variations at aging ZnO:Ag nanocrystals prepared by spray pyrolysis

The emission and structure of ZnO:Ag nanocrystal (NC) films obtained by ultrasonic spray pyrolysis have been studied in the as-grown state and after aging. The scanning electronic microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) methods have been applied. The films are characterized by the wurtzite crystal structure with the NC sizes about of 8.0–10.0 nm in the as-grown state and 6.0–8.0 nm after aging in ambient air. The Ag content was varied within the range of 1–4 at.% in the ZnO films. PL spectra of as-grown ZnO:Ag films are complex and can be presented as a set of PL bands at 10 K: the near band edge emission with the peak at 3.18 eV, two Ag doping—related PL bands centered at 2.95 and 2.68 eV, and native defect-related green (2.40 eV) and orange (1.90 eV) PL bands. The high PL intensities of Ag doping-related PL bands were detected for the Ag concentrations of 2–3 at.%. PL intensities of high energy PL bands (3.18, 2.95 and 2.68 eV) fall down at aging together with intensity stimulating the orange and green PL bands. The joint analysis of XRD and PL results permit to confirm that the 2.95 eV PL band is connected with the optical transition via the substitutional AgZn defects. It was shown as well that aging in ambient air is owing to the diffusion of oxygen interstitials in the ZnO:Ag NCs that leads to intensity increasing the orange PL band and modification of the AgZn radiative defects.

High-Temperature Neutron Diffraction and Oxide Ion Conduction Path for Pb1-XLa2x/3WO4

Introduction Partially substituting lanthanum ions for lead site of the Scheelite-type structured PbWO4, oxide ion interstitials are formed as Pb1-xLaxWO4+x/2 and high oxide ion conduction appears at high temperature [1]. While most of the oxide ion conductors including zirconias, cerias, or LSGM cause high oxide ion conduction by oxide ion vacancies, the present system utilizes oxide ion interstitials. For the vacancy diffusion, conduction paths can be predicted by connecting regular oxide ions by straight or curved lines. On the other hand, for interstitial diffusion as the present system, conduction path would be complicated. We have conducted high-temperature neutron diffraction on the oxide ion conductor Pb1-xLaxWO4+x/2 (x = 0.2) with oxide ion interstitials to estimate the conduction path by means of the Rietveld analysis and Maximum Entropy Method (MEM) [2]. As a result, two types of oxide ion interstitial sites Oi(1) and Oi(2) were detected. The former can be detected even at room temperature, while the latter appears only at high-temperatures. We have concluded that the oxide ion conduction is performed through the regular oxide ion sites and these two interstitial sites. However, it is still uncertain whether the interstitial site is simply a localized position or surely contributes to the oxide ion conduction. In this study, high-temperature neutron diffraction has been carried out on Pb1-xLa2x/3WO4 (x = 0.1), which has the isostructure with the Pb1-xLaxWO4+x/2 but without apparent interstitials. Comparing the occupancy of the interstitials in these systems, we evaluate the contribution of interstitials to the oxide ion conduction. Experimental Pb1-xLa2x/3WO4 (x = 0.1) sample has been prepared by conventional solid-state reaction method starting from PbO, H2WO4 and La2O3. Before the weighing, La2O3 has been calcined at 900 °C for 6 hours. Stoichiometric mixtures of the starting materials were fired at first at 800 °C in air for 10 hours, finely ground, pressed into pellets under a hydrostatic pressure of 100 MPa for 3 minutes, and finally sintered at 900 °C in air for 10 hours. Crystalline phase of sintered samples was identified by X-ray diffraction measurement. About 10 g of the sample pellets were set in vanadium holder through a thin quartz tube and the neutron powder diffraction experiments were performed in the temperature range between 200 °C and 800 °C by using SHRPD diffractometer in J-PARC. The Rietveld refinements were carried out by using Z-Rietveld code, and the oxide ion conduction path at high temperatures was estimated with Maximum Entropy Method using Z-MEM. Results and Discussions Fig. 1 shows the temperature dependence of the lattice constant obtained by the Rietveld analysis. Both a and c-lengths increase linearly with increasing temperature. The a-length of Pb1-xLa2x/3WO4 is close to that of PbWO4, while Pb1-xLaxWO4+x/2 shows a smaller a-length. On the other hand, c-lengths were not largely varied within all the systems. Fig. 2 shows the temperature dependence of the W-O bond length. In Pb1-xLaxWO4+x/2, it decreases with temperature, whereas it increased in Pb1-xLa2x/3WO4 as PbWO4. In the Pb1-xLaxWO4+x/2 system, it is supposed that WO4 tetrahedra shrink with temperature for the activation of the movement of the oxide ions localized at the interstitial sites. For Pb1-xLa2x/3WO4 system, due to the absence of excess oxide ions, WO4 tetrahedra do not shrink with temperature. Considering the possibility of the oxide ion conduction through the oxide ion interstitials, the Rietveld refinements were carried out on Pb1-xLa2x/3WO4 assuming Oi(1) and Oi(2) of the two types of interstitials as represented in Fig. 3. The refined occupation factor of Oi(1) and Oi(2) for Pb1-xLa2x/3WO4 system are 0.0343 and 0.0129, respectively, while those for Pb1-xLaxWO4+x/2 are 0.0316 and 0.0092, respectively. Since the similar occupation factors are obtained between these two systems even for no apparent interstitial, the deduced oxide ion interstitial position would be attributed to the oxide ion conduction.

The Effect of Pulsed Current and Organic Additives on the Hydrogen Incorporation in Electroformed Copper Used in High Vacuum Applications

The trend in electron accelerators design consists in approaching the poles of the steering magnets close to the electron beam. This implies reducing the bore hosting the vacuum chamber and using very small diameter vacuum pipes [1]. The application of functional thin films by physical vapour deposition in such small diameter chambers becomes then very difficult. A new approach relies on copper electroforming to build the vacuum chamber onto a pre-deposited thin film coating [2]. In this method, unlike the usual process, the pipe is built from the inside out. An aluminium mandrel is coated with a functional thin film first, then by a copper film and finally followed by a thick electroplated copper (1-3mm) structural layer. The replacement of high-purity copper parts by electroformed ones may nevertheless lead to the incorporation of various impurities among which hydrogen, which is generated by solvent reduction and thus trapped into the coating. The aim of the present study is the evaluation of the effect of two main triggers, namely polarization wave modulation and copper electrolyte composition by the addition of organic additives. For this purpose, transient curves in response to pulsed currents have been studied for various cathodic current densities. Two main patterns have been observed as shown in figure 1a in the absence of additive. At low current densities, i.e. below 50 A/dm2, the potential increases rapidly and reaches an average constant value. For higher current densities, two characteristic plateaux can be observed: the first one corresponds to the faradic reduction of copper below the diffusion limit, and the second one, at higher potential, is attributed to the diffusion-limited range that is well known for promoting the hydrogen generation. When adding 33 mg/L of d-xylose, it is possible to reach higher current densities before the occurrence of the transition between the faradic reduction of copper, near the electrode, and the diffusion-limited mechanism. The d-xylose acts clearly by inhibiting the hydrogen discharge. Thank to this, four singular situations have been identified on the curves (marked by the stars on figure 1). They correspond to four pulse sequences (40A/dm2, Ton=20 ms), (40A/dm2, Ton=80 ms), (70A/dm2, Ton=20 ms), (70A/dm2, Ton=80 ms), which were used to prepare samples for characterization in terms of hydrogen outgassing by Thermal Desorption Spectroscopy (TDS) and X-Ray Diffraction (XRD) measurements. TDS experiments show two peaks (figure 2), corresponding to the release of hydrogen trapped into the copper under different forms. The temperature of desorption of the first peak (around 420°C for a ramp of 10K/min) corresponds well to hydrogen interstitial diffusion in the copper deposit [3]. The nature of the second peak (around 600°C) is not yet understood. [1] C. Steier, A. Anders, D. Arbelaez, J.M. Byrd, K. Chow, S. De Santis, R.M. Duarte, J.-Y. Jung, T.H. Luo, A. Madur, H. Nishimura, J.R. Osborn, G.C. Pappas, L.R. Reginato, D. Robin, F. Sannibale, D. Schlueter, C. Sun, C.A. Swenson, W.L. Waldron, E.J. Wallen and W. Wan, "Progress of the R&D towards a diffraction limited upgrade of the Advanced Light Source", in Proceedings of IPAC, Richmond, USA (2015), p. 1840. [2] L. Lain Amador, P. Chiggiato, L. M.A Ferreira, V. Nistor, A. T. Perez Fontenla, M. Taborelli, W. Vollenberg, M-L Doche, J-Y Hihn “Development of copper electroformed vacuum chambers with integrated non-evaporable getter thin film coatings” Journal of Vacuum Science and Technology A, accepted. [3] Y. Fukai “Formation of superabundant vacancies in M–H alloys and some of its consequences: a review” Journal of Alloys and Compounds 356–357 (2003) 270–273. Figure 1

&lt;i&gt;In Situ&lt;/i&gt; XRD Experiments on the Growth of Expanded Austenite Using Different Process Gases

In this work we show our result of in-situ nitrocarburizing and nitriding treatments AISI316L specimens. Part of the samples have been depassivated ex-situ and coated with a Ni layer, while other specimens received in-situ depassivation. Processing was carried out in a custom built reaction chamber attached to a Bruker D8 Advance diffractometer. We monitored the 111 peak of both the base material and expanded austenite. From the shrinkage of the base material peak the total thickness of the expanded austenite can be determined. Applying both N and C resulted in a more than 10 times faster growth of the expanded austenite than with N only. The growth is thermally activated. The activation energy for nitrocarburizing is 164 kJ/mol. This is in agreement with the activation energy of the diffusion of interstitials. Detailed analysis of the expanded austenite peak allowed the derivation of a “master curve” for the composition depth profile. This suggest that two interacting process controls the evolution. The width of the reaction zone is limited by the diffusion at low concentration side. The total concentration is determined by the reaction at the interface.