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A hybrid dirhodium tetracarboxylate-based metal–organic polyhedron (MOP):PCBM electron transport layer is demonstrated to give rise to a 9% enhancement in power conversion efficiency for the derived inverted perovskite solar cell.

Regardless of the impressive photovoltaic performances demonstrated for lead halide perovskite solar cells, their practical implementation is severely impeded by the low device stability. Complex lead halides are sensitive to both light and heat, which are unavoidable under realistic solar cell operational conditions. Suppressing these intrinsic degradation pathways requires a thorough understanding of their mechanistic aspects. Herein, we explored the temperature effects in the light-induced decomposition of MAPbI3 and PbI2 thin films under anoxic conditions. The analysis of the aging kinetics revealed that MAPbI3 photolysis and PbI2 photolysis have quite high effective activation energies of ∼85 and ∼106 kJ mol-1, respectively, so decreasing the temperature from 55 to 30 °C can extend the perovskite lifetime by factors of >10-100. These findings suggest that controlling the temperature of the perovskite solar panels might allow the long operational lifetimes (>20 years) required for the practical implementation of this promising technology.

As the known allotropes of carbon have expanded, increasing interest has been shown in one-dimensional carbyne. One approach to studying carbyne has been to synthesize linear carbon chains (LCCs) w...

X-ray reflectometry (XRR) and X-ray photoelectron spectroscopy (XPS) measurements (core levels and valence bands) were made of Cu thin films that were prepared and coated by capping Ta layers with different thicknesses (5, 10, 15, 20, and 30 Å), and are presented. The XRR and XPS Ta 4f-spectra revealed a complete oxidation of the protective layer up to a thickness of 10 Å. From the thickness of the capping layer of 15 Å, a pure Ta-metal line appeared in the XPS Ta 4f-spectrum, the contribution of which increased up to 30 Å. The XPS Cu 2p-spectra of the underlying copper layer revealed the oxidation with the formation of CuO up to a thickness of the Ta-layer of 10 Å. Starting from a thickness of 15 Å, the complete protection of the Cu layer against oxidation was ensured during exposure to the ambient atmosphere.

We investigated the photochemical stability of PbX2 (X = I and Br) halides by optical and X-ray photoelectron spectroscopy (XPS). The optical absorbance displayed a strong reduction for PbI2 with light soaking and permanent behavior for PbBr2. The XPS survey spectra showed a sharp drop in the I:Pb ratio for PbI2 from 1.63 to 1.14 with exposure time from 0 to 1000 h while for PbBr2, it remains practically unchanged (1.59–1.55). The measurements of the XPS Pb 4f and Pb 5d spectra have shown the partial photolysis of PbI2 with the release of metallic lead whereas PbBr2 demonstrated remarkable photochemical stability. According to the density functional theory (DFT), calculations of the metal and iodide vacancy formation energies for PbBr2 are higher than for PbI2 which confirms the better stability to light soaking. The high photochemical stability of PbBr2 means that it can be used as excess under MAPbBr3 perovskite synthesis to improve not only the power conversion efficiency but also stability to light soaking.

Over the last decade, perovskite solar cells (PSCs) have demonstrated tremendous growth in power conversion efficiencies. Different strategies toward developing new perovskite film deposition techn...

Hybrid perovskite solar cells attract a great deal of attention due to the feasibility of their low-cost production and their demonstration of impressive power conversion efficiencies (PCEs) exceeding 25%. However, the insufficient intrinsic stability of lead halides under light soaking and thermal stress impedes practical implementation of this technology. Herein, we show that the photothermal aging of a widely used perovskite light absorber such as MAPbI3 can be suppressed significantly by using polyvinylcarbazole (PVC) as a stabilizing agent. By applying a few complementary methods, we reveal that the PVC additive leads to passivation of defects in the absorber material. Introducing an optimal content of PVC into MAPbI3 delivers a PCE of 18.7% in combination with a significantly improved solar cell operational lifetime: devices retained ∼70% of the initial efficiency after light soaking for 1500 h, whereas the control samples without PVC degraded almost completely under the same conditions.

The influence of light soaking and heat stress on the degradation of indium tin oxide (ITO)/CH3NH3SnI3 and SiO2/CH3NH3SnI3 hybrid perovskite is studied. The measurements of X-ray photoelectron surv...

We investigated the impact of a series of hole transport layer (HTL) materials such as Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), NiOx, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), and polytriarylamine (PTA) on photostability of thin films and solar cells based on MAPbI3, Cs0.15FA0.85PbI3, Cs0.1MA0.15FA0.75PbI3, Cs0.1MA0.15FA0.75Pb(Br0.15I0.85)3, and Cs0.15FA0.85Pb(Br0.15I0.85)3 complex lead halides. Mixed halide perovskites showed reduced photostability in comparison with similar iodide-only compositions. In particular, we observed light-induced recrystallization of all perovskite films except MAPbI3 with the strongest effects revealed for Br-containing systems. Moreover, halide and β FAPbI3 phase segregations were also observed mostly in mixed-halide systems. Interestingly, coating perovskite films with the PCBM layer spectacularly suppressed light-induced growth of crystalline domains as well as segregation of Br-rich and I-rich phases or β FAPbI3. We strongly believe that all three effects are promoted by the light-induced formation of surface defects, which are healed by adjacent PCBM coating. While comparing different hole-transport materials, we found that NiOx and PEDOT:PSS are the least suitable HTLs because of their interfacial (photo)chemical interactions with perovskite absorbers. On the contrary, polyarylamine-type HTLs PTA and PTAA form rather stable interfaces, which makes them the best candidates for durable p-i-n perovskite solar cells. Indeed, multilayered ITO/PTA(A)/MAPbI3/PCBM stacks revealed no aging effects within 1000 h of continuous light soaking and delivered stable and high power conversion efficiencies in solar cells. The obtained results suggest that using polyarylamine-type HTLs and simple single-phase perovskite compositions pave a way for designing stable and efficient perovskite solar cells.

In this work, we report a comparative study of the gamma ray stability of perovskite solar cells based on a series of perovskite absorbers including MAPbI3 (MA = methylammonium), MAPbBr3, Cs0.15FA0...

We report the application of a Ni-based coordination polymer derived from 1,2,4,5-tetraaminobenzene (P1) as a fast and stable potassium battery anode. In a voltage range of 0.5-2.0 V vs. K+/K, a reversible capacity of 220 mA h g-1 was obtained at 0.1 A g-1. Even with a relatively high electrode loading of 5.0 mg cm-2 and only 10 wt% carbon additive, 118 mA h g-1 was still retained at 1 A g-1. For thinner electrodes with 30 wt% carbon, a capacity of up to 104 mA h g-1 was observed at 10 A g-1 (charging in ∼40 seconds). An areal capacity of up to 2.73 mA h cm-2 was demonstrated. The capacity fade at 1 A g-1 was only 4.4% after 200 cycles. Structure transformations of P1 during charge/discharge were studied using X-ray photoelectron spectroscopy and in situ X-ray diffraction.

We report the synthesis and electrochemical characterization of octahydroxytetraazapentacenedione (OHTAPQ). The potassium batteries using OHTAPQ as electrode material delivered the specific capacity of 190 mAh g−1 at the current density of 0.6 A g−1. The use of the concentrated (2.2 M KPF6) diglyme-based electrolyte suppressed significantly the capacity fading of the potassium half-cells with OHTAPQ electrodes thus enabling their stable operation for 1200 charge-discharge cycles. Furthermore, OHTAPQ delivered the specific discharge capacity of 82–103 mAh g−1 at high current densities of 9–21 A g−1, which leads to high power densities approaching 41000 W kg−1. Thus, we demonstrate that the rationally designed organic electrode material enables high-capacity and high-power potassium batteries, which can be considered as a more environment-friendly and scalable alternative to the mainstream lithium-ion battery technology.

Here, phenyl-C61-butyric acid (PCBA) is presented as a generic passivation coating for metal oxide electron transport layers used in planar n–i–p configuration of perovskite solar cells. PCBA shows...

Thermal effects in organo-metal halide perovskites are studied by ab initio molecular dynamics (MD) simulations performed at effective temperatures of 293 and 383 K and by X-ray photoelectron spectroscopy (XPS). We find that the cause of thermal instability in this class of perovskites is the rotation of the methylammonium (MA) groups that destroy the rigid lattice of pure compounds (MAPbI3 and MAPbBr3). When the Pb-I lattice is initially distorted by partial replacement of the I with Cl or Br, this not only prevents formation of PbI2 seeds but also improves lattice flexibility and stability against the temperature-induced motion and rotation of MA groups.

Here, we present a systematic study of the thermal and photochemical degradation pathways for a series of complex tin-based halides ASnX3 (X = I, Br) with organic (CH3NH3+, H2NCHNH2+) and inorganic...

Dilute magnetic semiconductors (DMSs) are a highly attractive field of research due to their potential to open new technological functionality. Here, we perform a systematic study of In2O3 thin films with dopant ions of Mn, Co, Ni, and Fe to investigate the unique interaction of each of these ions and their incorporation into the semiconductor lattice. We report substitutional positioning of Fe atoms into the In3+ site and a mixture of interstitial, metallic clustering, and substitutional positioning for Co, Mn, and Ni, discriminating between oxidation states for all dopant atoms.

Highly conductive electrochemically active materials are required for developing a new generation of ultrafast lithium-ion batteries (LIBs). Recently, a novel family of transition metal coordinatio...

Vanadium- and aluminium-free biomedical Ti alloys are getting more and more attention because of the harmful character of these alloying elements. For this reason, it was proposed to substitute them with more biocompatible elements such as Ta, Nb and Zr. So-called gum metal alloys (Ti-Nb-Zr-Ta systems) belong to β-type Ti alloys which are characterized by excellent biocompatibility and possess the modulus of elasticity more closely related to that of a human bone. The present study aims at elucidating the process stages during DC plasma electrolytic oxidation (PEO) of gum metal (Ti-36Nb-3Zr-2Ta alloy) in calcium hypophosphite-based electrolyte system. The effect of the stages on the surface characteristics of the obtained oxide coatings was also determined. The coatings were characterized using SEM/EDS, XPS and contact angle measurements. It was found that the process comprised at least five different stages. The initiation of relatively strong B-type sparks in the third stage of the treatment was necessary to induce significant incorporation of electrolyte components into the oxide coatings. As the treatment continued beyond that point, the composition of the oxide films was getting more similar to that of hydroxyapatite as it was determined from the valence band XPS spectra. The surface morphology of the films was also closely related to the process stage at which the further growth of the oxide was halted. The composition of the electrolyte (regarding the salts used and their concentration) had a tremendous influence on the duration of the process stages and the surface characteristics of the obtained films. The process was also tested for its usefulness in coating gum metal dental implants in order to form bioactive interfaces. Keeping the voltage below a certain limit (before the onset of more powerful surface sparks) was crucial to obtaining good-quality coatings.

Organic redox-active compounds represent a promising family of materials for metal-ion batteries. They can be produced from renewable resources and contain no toxic or expensive heavy metals. Moreover, they are much less specific to the nature of the mobile ion, such as Li+, Na+ or K+, which facilitates the development of cheaper alternatives to the currently dominating lithium-ion battery technology. Here we report stable and ultrafast lithium-, sodium- and potassium-ion batteries (LIBs, SIBs and PIBs) comprising a polymer cathode based on hexaazatriphenylene, which is synthesized from 3,3′-diaminobenzidine and triquinoyl. Using LIBs as a model system, it is shown that the application of dimethoxyethane (DME) as the electrolyte solvent is crucial for achieving a superior performance. Using a DME-based electrolyte, a specific capacity of 169 mA h g−1 is reached for PIBs at an impressive current density of 10 A g−1 (charging/discharging in ca. one minute) after 4600 cycles. At a lower current density of 50 mA g−1, the capacity of PIBs approaches 245 mA h g−1. The performance of the designed polymer cathode is among the best ever reported for K-ion battery materials in terms of specific capacity, energy and power density. The polymer-based devices demonstrated record cycling stability, outperforming all non-aqueous potassium-ion batteries reported to date.

In this work, we systematically explored the photochemical stability of MAPbI3 interfaces with five different charge transport layers (CTLs): substituted naphthalene (NDI) and perylene (PDI) diimides, fullerene derivatives PC61BM and PC71BM, and widely used hole transport material spiro-OMeTAD. While studying these model systems, we revealed several important interfacial degradation pathways. First, we demonstrated that diimides (both NDI and PDI) strongly accelerate the photodegradation of MAPbI3 since they specifically interact with PbI2 formed as one of the perovskite degradation products. Fullerene derivatives, in turn, absorb another decomposition product, methylammonium iodide (MAI), which also results in accelerated ageing of the perovskite films deposited atop fullerene-based CTLs. However, both fullerene derivatives and spiro-OMeTAD have excellent encapsulation properties and strongly suppress photodecomposition of MAPbI3, when the perovskite films are placed underneath. Unfortunately, the observed impressive perovskite bulk phase stabilization using PC61BM, PC71BM and spiro-OMeTAD coatings does not improve the operation lifetime of photovoltaic cells due to interfacial degradation processes. TOF-SIMS analysis has revealed accumulation of the perovskite decomposition products (presumably CH3I) in the spiro-OMeTAD layer as well as a noticeable degradation at the interface with the electron transport tin dioxide layer. The obtained results emphasize the major challenge in the development of perovskite solar cells with long operation lifetime related to poor stability of the functional perovskite/CTL interfaces.

The experimental results of X-ray diffraction (XRD), optical absorbance, scanning electron microscopy (SEM), and X-ray photoelectron spectra (XPS) of the core levels and valence bands of MAPbBr3 (MA-CH3NH3+) perovskite before and after exposure to visible light for 700 h at temperatures of 10 and 60 °C are presented. It reveals that the light soaking at 60 °C induces the decomposition of MAPbBr3 perovskite accompanied with the decay of organic cation and the release of a PbBr2 phase as a degradation product whereas the photochemical degradation completely disappears while the aging temperature is decreased to 10 °C. © 2022 by the authors. Russian Foundation for Basic Research, РФФИ: 21-52-52002; Ministry of Education and Science of the Russian Federation, Minobrnauka: AAAA-A18–118020190098-5, FEUZ 2020-0060; Ministry of Science and Technology, Taiwan, MOST: 110-2923-E-002-007-MY3; Russian Science Foundation, RSF: 19-73-30020 I.S.Z. and A.I.K. thank the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) for support. This work was supported by the Russian Science Foundation (Project 19-73-30020) at IPCP RAS. The XPS measurements were supported by the Ministry of Science and Higher Education of the Russian Federation under the theme “Electron” No. AAAA-A18–118020190098-5 and Project FEUZ 2020-0060 as well as the Russian Foundation for Basic Research (Project No. 21-52-52002). The research fundings from the Ministry of Science and Technology in Taiwan (MOST 110-2923-E-002-007-MY3) are gratefully acknowledged.

Regardless of the impressive photovoltaic performances demonstrated for lead halide perovskite solar cells, their practical implementation is severely impeded by the low device stability. Complex lead halides are sensitive to both light and heat, which are unavoidable under realistic solar cell operational conditions. Suppressing these intrinsic degradation pathways requires a thorough understanding of their mechanistic aspects. Herein, we explored the temperature effects in the light-induced decomposition of MAPbI

A two step laser-assisted synthesis method in water was employed to produce Pt@C hybrid structures. The structure and chemical composition of the produced Pt@C species were studied by Raman and X-ray photoelectron (XPS) spectroscopies. Raman analysis clearly evidences the formation of two different regions, one dominated by Pt nanoparticles (Pt NPs) surrounded by linear carbon chains and another where Pt-catalysed graphene-like foils take over. The high-energy resolved XPS Pt 4f and C 1s spectra show that the interaction of Pt NPs with polyynes give rise to the formation of strong Pt@C bonds, preventing the oxidation of the nanoparticles during their growth. The produced Pt@C systems could be proposed as catalysts towards several chemical reactions and preliminary tests using Methylene blue as probe molecules to evaluate the photocatalytic activities of Pt NPs and Pt@LCC nanostructures are reported.

Perovskite solar cells represent a highly promising third-generation photovoltaic technology. However, their practical implementation is hindered by low device operational stability, mostly related to facile degradation of the absorber materials under exposure to light and elevated temperatures. Improving the intrinsic stability of complex lead halides is a big scientific challenge, which might be addressed using various &ldquo, molecular modifiers&rdquo, These modifiers are usually represented by some additives undergoing strong interactions with the perovskite absorber material, resulting in enhanced solar cell efficiency and/or operational stability. Herein, we present a derivative of 1,4,6,10-tetraazaadamantane, NAdCl, as a promising molecular modifier for lead halide perovskites. NAdCl spectacularly improved both the thermal and photochemical stability of methylammonium lead iodide (MAPbI3) films and, most importantly, prevented the formation of metallic lead Pb0 as a photolysis product. NAdCl improves the electronic quality of perovskite films by healing the traps for charge carriers. Furthermore, it strongly interacts with the perovskite framework and most likely stabilizes undercoordinated Pb2+ ions, which are responsible for Pb0 formation under light exposure. The obtained results feature 1,4,6,10-tetraazaadamantane derivatives as highly promising molecular modifiers that might help to improve the operational lifetime of perovskite solar cells and facilitate the practical implementation of this photovoltaic technology.

We report results of comprehensive experimental exploration (X-ray photoemission, Raman and optical spectroscopy) of carbon nanofibers (CNFs) in combination with first-principles modeling. Core-level spectra demonstrate prevalence of sp2 hybridization of carbon atoms in CNF with a trace amount of carbon–oxygen bonds. The density functional theory (DFT)-based calculations demonstrated no visible difference between mono- and bilayers because σ-orbitals are related to in-plane covalent bonds. The influence of the distortions on π-peak is found to be significant only for bilayers as a result of π–π interlayer bonds formation. These results are supported by both experimental Raman and XPS valence band spectra. The combination of optical measurements with a theoretical modeling indicates the formation of optically active graphene quantum dots (GQDs) in the CNF matrix, with a radiative relaxation of the excited π* state. The calculated electronic structure of these GQDs is in quantitative agreement with the measured optical transitions and provides an explanation of the absence of visible contribution from these GQDs to the measured valence bands spectra., XPS measurements calculations are supported by Ministry of Science and Education of Russian Federation: Theme “Electron” № AAAA-A18-118020190098-5 and Project FEUZ-2020-0059. Optical measurements were additionally supported by RFBR project № 20-42-660012 and RSF project № 21-12-00392. DWB acknowledges the support from Jiangsu innovative and Entrepreneurial Talents Project.

Hybrid perovskite solar cells attract a great deal of attention due to the feasibility of their low-cost production and their demonstration of impressive power conversion efficiencies (PCEs) exceeding 25%. However, the insufficient intrinsic stability of lead halides under light soaking and thermal stress impedes practical implementation of this technology. Herein, we show that the photothermal aging of a widely used perovskite light absorber such as MAPbI

The effect of Co and Mn co-doping and annealing on electronic structure and magnetic properties of nanoscale SnO2 were investigated using complementary experimental techniques. The high resolution transmission electron microscope (HRTEM) image showed spherical-like morphology and signalled the nanoscale regime of investigated samples. The results of X-ray photoelectron spectroscopy (XPS) analysis indicated the oxidation state of Co and Mn mostly as 2+. Moreover, XPS and Raman analysis corroborated the formation of oxygen vacancies as result of substitution tetravalent Sn with divalent Co and Mn. The XPS valence band spectra unveiled the formation of occupied states above the top of the valence band in as-synthesized Co and Mn co-doped SnO2 samples. Magnetic measurements disclosed the paramagnetic nature for the as-synthesized Co and Mn co-doped SnO2 samples and also demonstrated the dominating antiferromagnetic exchange interactions between the magnetic moments of Co and Mn. Interestingly, the annealed samples (Sn0.96Co0.02Mn0.02O2, Sn0.94Co0.02Mn0.04O2 and Sn0.94Co0.04Mn0.02O2) exhibited weak room temperature ferromagnetism (RTFM). The observed RTFM was explained based on the bound magnetic polaron (BMP) model. The comprehensive experimental investigations provide an interesting insight into the magnetic behaviour within the co-doped system.

In this work, we report a comparative study of the gamma ray stability of perovskite solar cells based on a series of perovskite absorbers including MAPbI

By using X-ray photoelectron spectroscopy and density functional theory based calculations, it has been found that graphene in BaTiO3/graphene oxide composites prepared by inexpensive traditional ceramic processing behaves as an active filler. It also induces an interfacial bonding with the formation of Ti–O–C chemical bonds that lead to a reduction of the band gap from 3.4 to 2.4 eV, which is attractive for various photocatalytic applications. The pathway and energetics of hydrogen evolution reaction in acidic and alkaline media over BaTiO3/graphene oxide substrates were checked., XPS measurements are supported by Ministry of Science and Education of Russian Federation: Themes “Electron” № АААА-А18-118020190098-5 and the Government of the Russian Federation (Act 211, agreement No. 02.A03.21.0006).

In this study, we investigate the photo-/thermal degradation mechanism of hybrid perovskites by using x-ray photoelectron (XPS) valence band (VB) spectra coupling with density functional theory (DFT) calculations. Herein, CH3NH3PbI3 is respectively subjected to irradiation with visible light and annealing at an exposure of 0-1000 h. It is found from XPS survey spectra that, in both cases (irradiation and annealing), a decrease in the I:Pb ratio is observed with aging time, which unambiguously indicates the formation of PbI2 as the product of photo/thermal degradation. The comparison of the XPS VB spectra of irradiated and annealed perovskites with the DFT calculations of CH3NH3PbI3 and PbI2 compounds have showed a systematic decrease in the contribution of I-5p states, which allows us to determine the respective threshold for degradation, which is 500 h for light irradiation and 200 h for annealing. This discrepancy might be due to the fact that the relaxation of thermal excitations of the system is carried out only by the phonons (which are non-radiative physical processes) while the radiative processes occurred during the photoexcitation will elastically or inelastically divert part of the external energy from the system to reduce its impact on perovskite degradation. © 2019 IOP Publishing Ltd.

The X-ray photoelectron spectra (XPS) of Au colloidal nanoparticles (Au NPs) and Au–NPs/linear carbon chain (LCC) structures (Au@LCC) prepared by nanosecond pulsed laser ablation in liquid water were measured. The Au 4f XPS peaks of Au NPs coincided with those of metallic gold to confirm that a metallic state was retained in colloidal Au nanoparticles. On the other hand, the Au 4f XPS spectra of Au@LCC showed a low-energy broadening due to the formation of Au–C bonds between Au NPs and LCC.

X-ray photoelectron spectroscopy and electronic structure calculations in the framework of the coherent potential approach show that impurity Fe3+ ions substituting In in iron-doped In2O3 indium oxide(III) are in a paramagnetic state in the absence of oxygen vacancies.

A density functional study of substitutional carbon impurities in ZnO-host matrix with 6.25 at. % was performed applying both the supercell method and the coherent potential approximation. The first of these methods assumes the spatially ordered arrangement of carbon impurities in oxygen sites, whereas the second one simulates the spatially disordered impurity substitution of oxygen sublattice. In conjunction with a theoretical part, the X-ray photoelectron spectra of pure and C-doped zinc oxide were measured. The mapping of the valence band of the carbon-loaded ZnO allows establishing the appearance of impurity C 2p electronic states on the valence band top. The experimental energy position of these impurity C 2p states is theoretically reproducing essentially better by the assumption about random distribution of carbon impurities in oxygen sublattice.

The magnetic structures and magnetic phase transitions in intermetallic layered La 1 - x Tb x Mn 2 Si 2 compounds (the ThCr2Si2-type structure) are investigated using the first-principles method and XPS measurements. The experimentally observed transition from ferromagnetic (FM) to antiferromagnetic (AFM) ordering of Mn sublattice with increase of terbium concentration is successfully reproduced in calculations for collinear magnetic moments model. The FM → AFM change of interplane magnetic ordering at small x is irrelevant to the number of f-electrons of the rare-earth ion. In contrast it was shown to be related to the Mn-Mn in-plane distance. Calculated Tb critical concentration for this transition x ≈ 0.14 corresponds to the Mn-Mn in-plane distance 0.289 nm, very close to the experimentally observed transition distance 0.287 nm. The crystal cell compression due to substitution increases an overlap between Mn d xz , yz and the rare-earth ion d orbitals. Resulting hybridized states manifest themselves as an additional peak in the density of states. We suggest that a corresponding interlayer Mn-R-Mn superexchange interaction stabilizes AFM magnetic ordering in these compounds with Tb doping level x > 0.2 . The results of DFT calculations are in agreement with X-ray photoemission spectra for La 1 - x Tb x Mn 2 Si 2 .

The electronic structures of native oxides formed on Fe-15Cr, Fe-5Al and Fe-15Cr-5Al (all in wt.%) alloys, and the corresponding effects on diamond nucleation and growth in plasma enhanced CH4-H2 atmosphere were investigated. The ambient environment exposure produces a mixed surface oxide layer containing the oxides of both Fe and Cr or Al on Fe-15Cr or Fe-5Al alloys, respectively. A selective oxidation of Al occurs on Fe-15Cr-5Al and it protects the other two substrate elements from oxidation. The diamond deposition behavior indicates that prior to diamond growth, a graphite intermediate layer preferentially forms on Fe-15Cr and Fe-5Al alloys, along with an internal carburization of the substrates. For Fe-15Cr-5Al, only a single diamond coating with enhanced interfacial adhesion is produced, which is attributed to the effective barrier property of the aluminum oxide passive layer.