Nanocrystalline Phase Research Articles

Effect of the Implantation of Al+ Ions on the Composition, Electronic and Crystalline Structure of the GaP(111) Surface

Nanocrystalline phases and GaAlP films are obtained by implanting Al+ ions with E0 = 1 keV at different doses on the surface of a GaP(111) single crystal, and their electronic and crystalline structures are studied. It is shown that the type and the lattice parameters of the three-component nanostructure are in good agreement with those for the substrate. The relationship between the band gap Eg and the sizes of the nanocrystalline phases is studied. It is established that quantum-size effects arise in the Ga0.6Al0.4P nanocrystalline phases in the case of surface sizes d of phases of less than 35–40 nm (3.5–4 nm thick).

Preparation, Microstructure, and Magnetic Properties of Electrodeposited Nanocrystalline L10 FePt Films

In this work, we prepared the nanocrystalline near-equiatomic FePt thin films by electrodeposition and explored the effects of annealing temperature and annealing time on morphology, structure, and magnetic properties of FePt film. The fcc-FePt phase starts to form when annealing at 400 °C under the 15% H2 gas mixture. With increasing annealing temperature from 400 to 800 °C, the FePt film experiences a gradual phase transformation from the soft magnetic fcc phase to the permanent magnetic fct L10 phase. The transition degree of the L10 phase is achieved to be 0.94 and coercivity reaches a maximum of 1.5 T for the sample annealed at 800 °C for 4 h. A shoulder behavior in the M(H) curves is found in the electrodeposited FePt films. Through fitting the M(H) curves by the model based on the transition degree of the L10 FePt phase, the shoulder behavior is quantitatively confirmed to originate from the coexistence of the soft magnetic fcc phase and the permanent magnetic L10 phase. The magnetic exchange coupling between the soft magnetic and permanent magnetic nanocrystalline phases is negligible in the electrodeposited FePt films due to that the substrate Ag diffusion into the FePt film separates the FePt nanocrystalline phases.

One-step synthesis of diopside (CaMgSi2O6) ceramic powder by solution combustion method

We report the synthesis of diopside (CaMgSi2O6) ceramic powder, a multifunctional material, through an energy efficient, quick and one-step solution combustion (SC) method. Synthesis of diopside by SC method requires oxidizers, especially metal-nitrates, and a suitable fuel. However, unavailability of the silicon-nitrate makes the process of diopside formation by SC method challenging, which forces researchers to synthesize diopside by alternate high temperature solid state reaction route. Here, we demonstrate a simple way to overcome this difficulty by using an extra amount of ammonium nitrate (AN, as the suitable oxidizer), but still using the fumed-silica (an economical ceramic powder) and the solution of Ca-nitrate, Mg-nitrate and the fuel. A systematic investigation was carried out using different extra amounts (0, 5 or 10 mol) of AN, in combination with stoichiometric amounts of one of the three chosen fuels, viz., urea, glycine and alanine. For a specific combination of the fuel and extra oxidizer, namely ‘alanine and 10 mol of AN’, we observed the formation of nano-crystalline diopside phase, which generates enough heat for the incorporation of Si atoms from the SiO2 precursor into diopside phase directly during the combustion process in one-step. This one-step process does not require any extra high temperature calcination step, thereby saving time, cost and complex equipments, whereas all other powders synthesized using other fuels require an extra calcination step, although the calcination temperature is low (≤ 900 °C), for crystalline diopside phase formation. Hence, our work demonstrates the one-step synthesis of diopside nanopowders by SC method through the direct use of the earth abundant SiO2 ceramics.

Influence of nano crystalline behavior of Nb2O5 – Sb2O3 – TeO2 glass ceramics on structural and thermal studies

xNb2O5–(25-x)Sb2O3–75TeO2 (Where x = 5,10,15,20 mol% of Nb2O5) glass system have been successfully prepared by using conventional melt-quenching route. Nano clusters and crystalline phases are obtained with the employment of heat treatment (HT) procedure executed at various temperatures depending upon composition. These samples are characterized using XRD, SEM, DTA, IR and RAMAN studies. X-ray diffraction (XRD) have been done for both glass and glass ceramics to confirm the crystalline and amorphous nature of the samples respectively. XRD patterns of glass ceramic samples exhibit various structural changes such as Sb2Te2O9, Nb2Te4O13, Nb2Te3O11, Senarmontite (α-Sb2O3), Valentinite (β-Sb2O3), γ, α -TeO2, Sb6O13 and Nb0.5O4Sb1.5 associated with the glass ceramics. From XRD, it is clear that the antimony and tellurium ions co-exist in mixed valence states (Sb5+, Sb3+ and Te4+, Te6+)in host matrix of glass ceramics. Nano crystalline clusters are identified by using scanning electron microscopy (SEM) and are found to be in the range of size approximately 149.1–193.6 nm. The percentage of various elements associated with the glass ceramics is discussed by the EDX analysis. The thermal parameters such as glass transition temperature (Tg) and onset crystalline temperature (To) are determined from DTA spectra for all the samples. As Nb2O5 content is increased, the values of glass transition temperature are found to be increased from 329 °C to 418 °C (Tg) and 467 °C to 531 °C (To) for glasses and glass ceramics for 262 °C to 385 °C (Tg), 431 °C to 493 °C (To) respectively. IR and Raman studies reveals that the presence of various structural units such as [TeO4]tbp, [TeO3]tp, [TeO3+1] and TeO6 are interconnected with SbO6, NbO6 and NbO4 units associated with glass and glass ceramic host matrix. The optical absorption spectra have been studied for the samples and data is correlated with the DSC spectra.

Towards a Correlation between Structural, Magnetic, and Luminescence Properties of CeF3:Tb3+ Nanocrystals.

In this study, we report on the structural, magnetic, and optical properties of Tb3+-doped CeF3 nanocrystals prepared via a polyol-assisted route, followed by calcination. X-ray diffraction analysis and electron microscopy investigations have shown the formation of a dominant Ce0.75F3 nanocrystalline phase (of about 99%), with a relatively uniform distribution of nanocrystals about 15 nm in size. Magnetization curves showed typical paramagnetic properties related to the presence of Ce3+ and Tb3+ ions. The magnetic susceptibility showed a weak inflexion at about 150 K, assigned to the cerium ions’ crystal field splitting. Under UV light excitation of the Ce3+ ions, we observed Tb3+ green luminescence with a quantum yield of about 20%.

Solid-state synthesis, magnetic and structural properties of interfacial B2-FeRh(001) layers in Rh/Fe(001) films

Here we first report results of the start of the solid-state reaction at the Rh/Fe(001) interface and the structural and magnetic phase transformations in 52Rh/48Fe(001), 45Rh/55Fe(001), 68Rh/32Fe(001) bilayers from room temperature to 800 °C. For all bilayers the non-magnetic nanocrystalline phase with a B2 structure (nfm-B2) is the first phase that is formed on the Rh/Fe(001) interface near 100 °C. Above 300 °C, without changing the nanocrystalline B2 structure, the phase grows into the low-magnetization modification αlʹ (MSl ~ 825 emu/cm3) of the ferromagnetic αʹ phase which has a reversible αlʹ ↔ αʺ transition. After annealing 52Rh/48Fe(001) bilayers above 600 °C the αlʹ phase increases in grain size and either develops into αhʹ with high magnetization (MSh ~ 1,220 emu/cm3) or remains in the αlʹ phase. In contrast to αlʹ, the αhʹ ↔ αʺ transition in the αhʹ films is completely suppressed. When the annealing temperature of the 45Rh/55Fe(001) samples is increased from 450 to 800 °C the low-magnetization nanocrystalline αlʹ films develop into high crystalline perfection epitaxial αhʹ(001) layers, which have a high magnetization of ~ 1,275 emu/cm3. αhʹ(001) films do not undergo a transition to an antiferromagnetic αʺ phase. In 68Rh/32Fe(001) samples above 500 °C non-magnetic epitaxial γ(001) layers grow on the Fe(001) interface as a result of the solid-state reaction between the epitaxial αlʹ(001) and polycrystalline Rh films. Our results demonstrate not only the complex nature of chemical interactions at the low-temperature synthesis of the nfm-B2 and αlʹ phases in Rh/Fe(001) bilayers, but also establish their continuous link with chemical mechanisms underlying reversible αlʹ ↔ αʺ transitions.

The effect of Fe3O4 concentration to photocatalytic activity of Fe3O4@TiO2-PVP core-shell nanocomposite

A study on the preparation of Congo red textile dyes using nanocatalysts, Fe3O4@TiO2 material, and Polyvinyl Pyrrolidone (PVP) has been successfully carried out. The preparation of these dyes is intended as a controller of the shape and size of particles and as a superior adhesive in solution. Fe3O4@TiO2 core-shell (FTP) nanocomposite was carried out by coprecipitation method. The Fe3O4 nanoparticles were designed as cores that were synthesized from Cilacap iron sand, while TiO2 nanoparticles were selected as a shell through the synthesis of Titanium (III) chloride. Fe3O4@TiO2 core-shell nanocomposite is characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), and UV-Visible Spectroscopic (UV-Vis). Through XRD data analysis, the crystalline nano-phase composite of Fe3O4@TiO2 core-shell did not experience significant changes with the addition of Fe3O4 concentration. The contribution of the addition of Fe3O4 concentration can be observed in changes in sample grain size. The higher the concentration of Fe3O4 is, the smaller the grain size of the samples produced, ranging between 6-9 nm and can increase the percentage of degradation of Congo red dyes. In addition, optimum degradation in UV-Vis characterization occurred in FTP 0.5 samples that reached 78.20% at minute 100. The photodegradation effect that occurs in Congo red dyes is caused by photocatalytic mechanisms.

Microstructure and magnetic properties of Co58Ni10Fe5B16Si11 and Co58Ni10Fe5B16Si11–Al2O3 bulk amorphous coatings prepared by plasma spraying

The bulk soft magnetic glassy Co58Ni10Fe5B16Si11 alloy specimens have been prepared by plasma spray deposition. In order to increase resistivity of the material, the bulk Co58Ni10Fe5B16Si11–Al2O3 composite materials were fabricated. The investigations of structure and magnetic properties of the bulk samples were carried out by X-ray diffraction, electron microscopy and magnetic measurements. The relation of the structural features and magnetic characteristics of the bulk coating to the main parameters of the deposition regimes was determined. Optimized plasma spray deposition parameters allowed obtaining bulk glassy samples with magnetic parameters that are not inferior to the characteristics of a thermally treated rapidly quenched ribbon with the same composition. It was found that the bulk amorphous coatings can be characterized as a heterophase system. The relaxation annealing of the Co58Ni10Fe5B16Si11 bulk coating leads to a phase transition in this alloy in the precrystallization temperature range. The magnetic properties of the both kinds of coatings are correlated with changes in the microstructure. The appearance of nanocrystalline phase with TC˜640 K during relaxation heat treatment leads to a decrease of the coercivity and to an increase of the permeability. A comparison between the magnetic properties of the CoNiFe-BSi coating and (CoNiFe-BSi)–Al2O3, composite coating is carried out.

Interfacial characteristics and bending properties of a Ti6Al4V-Mg3AlZn laminate metal composite

In this paper, a Ti6Al4V-Mg3AlZn laminate metal composite (TC4-AZ31 LMC) was successfully prepared by hot pressing sintering. The interfacial microstructure of this composite was investigated using scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and high resolution transmission electron microscopy (HR-TEM). The three-point bending (TPB) tests of TC4-AZ31 LMC were performed to determine the foil-foil interface bonding properties. Results show that the AZ31 matrix of the TC4-AZ31 LMC possesses a strong {10-10} <0001> sheet texture and the adjacent AZ31 foils are bonded well through the migration of grain boundaries across the original boundaries of the foils. A continuous interfacial reaction layer consisting of an intermetallics layer, a nanocrystalline-amorphous mixture layer and a bulk-precipitated particles region was formed around the TC4/AZ31 interface. The intermetallics layer bordering on TC4 reinforcement was identified as Al192.40Fe46.22 phase. The nanocrystalline-amorphous mixture layer was composed of MgO nanocrystalline and Mg-O amorphous phase. The bulk-precipitated particles locating at the boundary of AZ31 matrix were determined as complex precipitates containing Al6Mn and Al13Fe4 phases. Compared with the AZ31 alloy, the TC4-AZ31 LMC possessed a superior bending strength, which is attributed to the effective load transfer capability from the AZ31 matrix to high strength TC4 reinforcement through the well-bonded TC4/AZ31 interface.

Investigation of nano- and micro-scale structural evolution and resulting corrosion resistance in plasma sprayed Fe-based (Fe-Cr-B-C-P) amorphous coatings

Fe-based (Fe63Cr9B16C7P5, at. %) amorphous/nanocrystalline coatings were synthesized by plasma spraying at various heat inputs (plasma power of 20–40 kW). Influence of heat input on the resulting microstructural evolution and subsequent effect on corrosion resistance of the coatings were investigated. Structural evolution at nano-scale studied by transmission electron microscopy revealed that degree of crystallization in the coatings increased gradually with increasing plasma power. Micro-scale distribution of amorphous and nanocrystalline phases was envisaged via contour plots of nanohardness and reduced modulus. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies demonstrated that corrosion resistance of the coatings was significantly influenced by heat input, attributed to the development of local microstructural and compositional variations. Coatings deposited at the power of 20 and 40 kW displayed higher extent of structural heterogeneities and poor corrosion resistance. However, coating synthesized at moderate power of 30 kW exhibited the best anti-corrosion behavior, i.e. the lowest corrosion current density (4.3 μA/cm2), noblest corrosion potential (−647 mVSCE) and highest charge transfer resistance (1060 Ω.cm2). The superior corrosion resistance of coating deposited at 30 kW was ascribed to the combined effect of lower porosity, higher amorphous content and formation of protective α-CrOOH and complex ferro-chromate in the coating.

Quasi‐2D Crystalline γ‐Alumina Grown by Graphene‐Assisted Atomic Layer Deposition

AbstractThis study presents a facile high‐yield bottom‐up fabrication and morphology‐structure investigations of a free‐standing network of multi‐layer quasi‐2D flakes consisting of intrinsically nonlayered γ‐Al2O3. The synthesis comprises a multi‐cycle atomic layer deposition (ALD) of amorphous alumina that uses an interconnected graphene network as a growth scaffold followed by ≈800 °C air anneal. The structures are studied by X‐ray diffraction, selected area electron diffraction, and high‐resolution transmission electron microscopy, while electric properties are assessed with the help of two‐terminal dc‐transport measurements. The individual flakes comprise nanocrystalline phase cubic spinel γ‐Al2O3 with a close‐packed cubic texture in the 〈111〉cubic ALD‐induced growth direction. The charge transport is confirmed to be Ohmic with the room temperature electrical conductivity approaching ≈10−8 S m−1. This work opens a door to a low‐cost highly scalable synthesis of a variety of quasi‐2D metal oxides for widespread uses ranging from support material, sensing to environmental remediation.

Ceramic processing and multiferroic properties of the perovskite YMnO3‐BiFeO3 binary system

AbstractThe perovskite (1−x)YMnO3−xBiFeO3 binary system is very promising because of its multiferroic end members. Nanocrystalline phases have been recently obtained by mechanosynthesis across the system, and the perovskite structural evolution has been described. Two continuous solid solutions with orthorhombic Pnma and rhombohedral R3c symmetries were found, which coexist within a broad compositional interval of 0.5 ≤ x ≤ 0.9. This might be a polar‐nonpolar morphotropic phase boundary region, at which strong phase‐change magnetoelectric responses can be expected. A major issue is phase decomposition at moderate temperatures that highly complicates ceramic processing. This is required for carrying out a sound electrical characterization and also for their use in devices. We present here the application of Spark Plasma Sintering to the ceramic processing of YMnO3‐BiFeO3 phases. This advanced technique, when combined with nanocrystalline powders, allowed densifying phases at reduced processing temperatures and times, so that perovskite decomposition was avoided. Electrical measurements were accomplished, and the response was shown to be mostly dominated by conduction. Nonetheless, the intrinsic dielectric permittivity was obtained, and a distinctive enhancement in the phase coexistence region was revealed. Besides, Rayleigh‐type behavior characteristic of ferroelectrics was also demonstrated for all rhombohedral phases. Magnetic characterization was performed in this region, and antiferromagnetism was shown.

Study of (Ti,Zr)C:H/a-C:H nanocomposite thin film formation by low temperature reactive high power impulse magnetron sputtering

Single-phase nanocrystalline hydrogen-containing titanium zirconium carbide thin films and hydrogen-containing nanocomposite thin films consisting of a nanocrystalline hydrogen-containing titanium zirconium carbide phase in combination with an amorphous hydrogen-containing carbon network, (Ti1-xZrx)C1-δ:H/a-C:H, were deposited by low temperature reactive high power impulse magnetron sputtering (HiPIMS) in a methane-argon atmosphere. High power impulse magnetron sputtering offers a high degree of ionization of sputtered particles and therefore a precise control of the thin film growth. The thin film deposition in the Ti-Zr-C-H system was carried out by a combinatorial approach via the variation of both the titanium-to-zirconium ratio as well as the carbon and hydrogen content in the coatings. A single, metallic, segmented target consisting of two triangles of pure titanium and zirconium enabled the deposition of thin films with different titanium-to‑zirconium-ratio dependent of the substrate position in front of the target within one deposition process. By variation of the CH4 reactive gas flow at a constant Argon gas flow the carbon and hydrogen content of individual thin films was precisely adjusted. During the HiPIMS process a short pulse time of 50 μs was combined with a comparably low duty cycle of 3.3% in order to ensure a high ionization. In order to investigate the chemical composition of the thin films including hydrogen content electron probe microanalysis was combined in a self-consistent way with elastic recoil detection analysis. Structural analysis was done by a combination of different techniques: Raman spectroscopy suggests metal‑carbon bonds attributable to a nanocrystalline metal carbide phase as well as the formation of an amorphous hydrogen-containing carbon network. X-ray diffraction shows fcc (Ti1-xZrx)C1-δ:H grains with different sizes in all coatings. Transmission electron microscopy confirms the structure model of single phase nanocrystalline (Ti1-xZrx)C1-δ:H grains embedded in a hydrogen-containing amorphous carbon matrix. Scope of this work is the low temperature deposition of the (Ti,Zr)C1-δ:H thin films and the (Ti,Zr)C1-δ:H/a-C:H nanocomposites by HiPIMS with precise control of the resulting chemical composition and microstructure.

Microstructural evolution and hydrogen storage proprieties of melt-spun eutectic Mg76.87Ni12.78Y10.35 alloy with low hydrides formation/decomposition enthalpy

Ternary eutectic Mg76.87Ni12.78Y10.35 (at. %) ribbons with mixed amorphous and nanocrystalline phases were prepared by melt spinning. The microstructures of the melt-spun, hydrogenated and dehydrogenated samples were examined and compared by X-ray diffraction and transmission electron microscopy. The amorphous structure transforms into a thermally stable nanocrystalline structure with a grain size of about 5 nm during hydrogen ab/desorption cycles. The Mg, Mg2Ni and phases with Y in the melt-spun state transform into MgH2, Mg2NiH4, Mg2NiH0.3, YH2 and YH3 after hydrogenation, and transform back to Mg, Mg2Ni and YH2 upon subsequent dehydrogenation. The reaction enthalpy (ΔH) and entropy (ΔS) of the higher plateau pressure corresponding to Mg2Ni hydride formation are −53.25 kJ mol−1 and −107.74 J K−1 mol−1, respectively. The amorphous/nanocrystalline structure effectively reduces the enthalpy and entropy of Mg2Ni hydride formation, but has little effect on Mg. The activation energy for dehydrogenation of the hydrogenated ribbons is 69 kJ mol−1. This suggests that Mg–Ni–Y with ternary eutectic composition can form an amorphous/nanocrystalline structure by melt spinning, and this nanostructure efficiently improves the thermodynamics and kinetics for hydrogen storage.

Free-Standing Porous Silicon Film Produced by a Pulsed Anodic Etching of n+-Silicon Substrate in an HF: HCl: C2H5 OH: H2O2:H2O Electrolyte: Characterization and Adsorption of Colchicine

Porous silicon (PSi) has been established as a promising candidate for a variety of applications in many fields of science and technology. Currently, free-standing PSi is receiving an increasing attention for biomedical applications, such as drug delivery carriers and bio-sensing. In this study, fabrication of free-standing PSi film with attractive structural and optical properties for a prospective biomedical uses, is reported. The film is produced in the dark by a pulsed anodic etching of n+- type silicon substrate in an unconventional (HF: HCl: C2H5 OH: H2O2:H2O) electrolyte. The macro-porous nature of the produced film is revealed by scanning electron microscopy (SEM) imaging. X-ray diffraction (XRD) and Raman scattering investigations show both amorphous and nano-crystalline phases coexist in the produced film. On ageing it for two months, Fourier transformation infrared (FTIR) spectroscopy results reveal that the produced film exhibits the characteristic of efficiently oxidized PSi with a good stability. In addition to the strong S-band, the room temperature photoluminescence (PL) spectrum of the film exhibits a weaker F-band, which is attributed to the recombination in SiO2 allocated at surface defects. Moreover, the film adsorption of colchicine drug via immersion process has been investigated by FTIR and UV-spectrophotometric measurements. The results demonstrate that the colchicine is specifically and efficiently adsorbed, with adsorption capacity of around 33%. The results in this study suggest that our fabricated free-standing PSi film can be effectively utilized to prepare PSi nanoparticles for forthcoming drug delivery applications.

Role of Sn as a Process Control Agent on Mechanical Alloying Behavior of Nanocrystalline Titanium Based Powders.

In this study, the effects of Sn as a process control agent (PCA) on the final powder sizes, morphology, homogenization and alloying process of a new titanium alloy were investigated. Two kinds of powders, Ti10Ta8Mo and Ti10Ta8Mo3Sn (wt %), were prepared using a mechanical alloying process. For the Ti10Ta8Mo3Sn (wt %) alloy, the Sn element was used as PCA to enhance the milling process in the planetary ball mill. The milling process of both compositions was carried out with 200 rpm for 10, 15, 20, 40, 60, 80 and 100 h. The results confirmed that using Sn as a process control agent can result in a relatively good size distribution and better yield performance compared to samples without Sn addition. The phase analysis using X-ray diffraction proved the formation of the α nanocrystalline phase and the partial phase transformation from α to nanocrystalline β phases of both alloy compositions. The Scaning Electron Micoscope- Backscattered Electrons SEM-BSE results confirmed that the use of Sn as the PCA can provide a better homogenization of samples prepared by at least 60 h of ball milling. Furthermore, the presence of Sn yielded the most uniform, spheroidal and finest particles after the longest milling time.

Mechanically-induced martensite transformation of NiTiFe shape memory alloy subjected to plane strain compression

Abstract Based on the channel die compression, NiTiFe shape memory alloy (SMA) was subjected to plane strain compression. Mechanically-induced martensite transformation, nanocrystalline and amorphous phase can be observed in the case of large plastic strain. Mechanically-induced martensite transformation is obviously different from the conventional stress-induced martensite transformation. The former generally occurs after dislocation slip, whereas the latter arises prior to dislocation slip. The occurrence of B19’ martensite phase contributes to accommodating subsequent plastic deformation of NiTiFe SMA. Mechanically-induced B19’ martensite is partially stabilized due to the existence of local high stress field and consequently it is unable to be reverted to B2 austenite phase during unloading.

The Prospects of Applying the Mechanical Activation Method to the Manufacturing of Powder Steel Blades

Pure carbon phases formed in samples of soot-alloyed powder steel produced by mechanical activation were investigated using transmission electron microscopy and Auger-electron energy loss fine spectroscopy. A theoretical approach was proposed that considers the escape depth of the signal under analysis when modelling the functions of the radial distribution of atoms in the crystal lattice. The approach proposed allowed for the identification of the nano-crystalline pure carbon phase as a structure similar to natural diamond. The presence of nanosized diamond particles will allow for noticeable enhancement of the consumer qualities of powder steel used to manufacture blades.

Formation of Nanocrystalline Silicon in Tin-Doped Amorphous Silicon Films

The process of crystalline silicon phase formation in tin-doped amorphous silicon (a-SiSn) films has been studied. The inclusions of metallic tin are shown to play a key role in the crystallization of researched a-SiSn specimens with Sn contents of 1–10 at% at temperatures of 300–500 ∘C. The crystallization process can conditionally be divided into two stages. At the first stage, the formation of metallic tin inclusions occurs in the bulk of as-precipitated films owing to the diffusion of tin atoms in the amorphous silicon matrix. At the second stage, the formation of the nanocrystalline phase of silicon occurs as a result of the motion of silicon atoms from the amorphous phase to the crystalline one through the formed metallic tin inclusions. The presence of the latter ensures the formation of silicon crystallites at a much lower temperature than the solid-phase recrystallization temperature (about 750 ∘C). A possibility for a relation to exist between the sizes of growing silicon nanocrystallites and metallic tin inclusions favoring the formation of nanocrystallites has been analyzed.

Synthesis of nanocomposite coating of electrodeposed amorphic layers of the Ni–P–W system

The processes of the formation of the nanocomposite coating of Ni–11.5% P–5%W were studied during the heat treatment of amorphous electrodeposited layers. Using the method of differential scanning calorimetry, the temperature of the onset of crystallization of the nanocrystalline phase Ni3P was determined. X-ray diffraction analysis showed that heat treatment produces Ni3P phosphides and, presumably, Ni5P2, the size of which, according to electron microscopy, is 5–50 nm. The influence of the duration of heat treatment on the phase composition and microhardness of coatings is investigated.