Formation Of Nanograins Research Articles

Effects of loads on corrosion-wear synergism of NiCoCrAlYTa coating in artificial seawater

Abstract NiCoCrAlYTa coating was prepared through high velocity oxy-fuel (HVOF) spraying and its corrosion-wear synergism has been systematically investigated under various loads in artificial seawater. Results indicate that the synergism varied with the change of the loads, which is attributed to the formation of nanograins at high loads in the process of tribocorrosion. The nanograins have improved the wear resistance while accelerated the corrosion process, thereby influencing the synergism between corrosion and wear. Consequently, the material loss is mainly from mechanical wear at lower loads and wear-induced corrosion made a significant contribution to the material loss at higher loads, implying that the coating has excellent load bearing capacity at high load and could be a promising anti-tribocorrosion material under seawater environment.

Observation of the early stages of GaN thermal decomposition at 1200 °C under N2

We investigated the partial decomposition of GaN layers grown in an atmospheric pressure metal organic vapor phase epitaxy (AP-MOVPE) vertical reactor at 1200 °C under N2 ambient. In these conditions, the early stages of GaN thermal decomposition were studied. The GaN decomposition was monitored by in-situ laser reflectometry (LR). The properties of the as grown and decomposed GaN samples were analyzed by scanning electron microscope (SEM). We show that GaN decomposition starts by the formation of GaN nano-grains at the early stages. Then, due to the anisotropy of the decomposition, the GaN nano-grains are more easily etched than the GaN (00.2) surface. The lateral etching may results in local smooth GaN surface formation. After that the depth etching starts again on the etched pits. Room temperature cathodoluminescence (CL) study revealed better optical properties of the GaN grains when compared to the whole GaN surface.

Nanograin formation and reaction-induced fracturing due to decarbonation: Implications for the microstructures of fault mirrors

Principal slip zones often contain highly reflective surfaces referred to as fault mirrors, shown to consist of a nanogranular coating. There is currently no consensus on how the nanograins form, or why they survive weathering on a geological time-scale. To simplify the complex system of a natural fault zone, where slip and heat generation are inherently coupled, we investigated the effect of elevated temperatures on carbonate rock surfaces, as well as their resistance to water exposure. This allows us to isolate the role of the decarbonation process in the formation of nanograins. We used cleaved crystals of Iceland spar calcite, manually polished dolomite protolith, as well as natural dolomite fault mirror surfaces. The samples were heated to 200–800 °C in a ∼5 h heating cycle, followed by slow cooling (∼12 h) to room temperature. Subsequently, we imaged the samples using scanning electron microscopy and atomic force microscopy. Nanograin formation on all sample surfaces was pervasive at and above 600 °C. The Foiana fault mirror samples were initially coated with aligned naturally-formed nanograins, but display a non-directional nanogranular coating after heating. The nanograins that were formed by heating rapidly recrystallized to bladed hydroxides upon exposure to deionized water, whereas the nanograins on unheated fault mirror samples remained unchanged in water. This shows that the nanograins formed by heating alone are different from those formed in fault zones, and calls for a better characterization of nanograins and their formation mechanisms. Furthermore, we find a characteristic star-shaped crack pattern associated with reacted regions of the carbonate surfaces. The existence of this pattern implies that the mechanical stresses set up by the decarbonation reaction can be sufficiently large to drive fracturing in these systems. We propose that this mechanism may contribute to grain size reduction in fault zones.

Swift Heavy Ion irradiation induced nanocrystallisation in Te/Cd/Te trilayer thin films

In this paper, we report Swift Heavy Ion (SHI) irradiation induced nanocrystallisation in Te/Cd/Te trilayer thin films. In the present investigation, thermally evaporated Te/Cd/Te trilayer thin films were irradiated by 100MeV 107Ag ion beam at varying fluence. The structural characterization of Te/Cd/Te trilayer thin films was carried out using X-ray diffraction (XRD) technique. XRD studies revealed that SHI irradiation results in Te/Cd/Te layer mixing leading to formation of CdTe nanocrystalline phase. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were employed for surface studies. SEM studies indicate ion beam induced surface modifications. Further, AFM pictures indicate nanograin formation in the irradiated films. The elemental analysis of trilayer films before and after irradiation was carried out using Energy Dispersive X-ray Spectroscopy (EDX). EDX analysis indicates that percentage ratio of Cd and Te remains unaffected after SHI irradiation. Optical characterization was done using UV–Vis spectroscopy. Band gap values determined on the basis of UV–Vis spectroscopy of all the irradiated films were found to be more than the reported bulk value of 1.5eV. The increase in bandgap value is attributed to the combined effect of ion induced strain and quantum confinement effect. SHI irradiation induced formation of nanocrystallisation in Te/Cd/Te trilayer films is explained mainly in the framework of Ion Beam Mixing (IBM).

Formation of nanograins in Ni-Co based superalloys compressed quasistatically at high temperature

In this study, the performance of hot compressive deformation was investigated in two newly developed Ni-Co based superalloys having different stacking fault energy (SFE). It is interesting to discover that nanograins (NGs) can be produced in superalloy deformed at high temperature and relatively low strain rate. With the decrease of SFE and strain rate, the formation of NGs will be promoted obviously, leading to the negative strain rate sensitivity of compressive stress in superalloys. The NGs, generated through the fragmentation of subgrains by microtwins, may become a candidate choice for dynamically strengthening superalloys at high temperature.

Interface characteristics and performance of magnetic pulse welded copper-Steel tubes

An attempt has been made to join two tubes of pure copper and low carbon steel by magnetic pulse welding in lap joint configuration. Satisfactory welds were obtained with an optimal set of parameters consisting of discharge energy, standoff distance and initial collision angle. The welded interface revealed a wavy morphology with pockets of intermixed metal vortices. High resolution electron microscopy and microanalysis showed the formation of nano-grains along the interface and evidence of short distance interatomic diffusion across the weld joint respectively. The strain hardening effect due to high energy impact led to significantly higher microhardness on the steel side of the interface. Torsion tests confirmed acceptable joint strength as failure took place in the copper base material.

Controlling the microstructure and associated magnetic properties of Ni0.2Mn3.2Ga0.6 melt-spun ribbons by annealing

Here we report on the structural and magnetic properties of Ni0.2Mn3.2Ga0.6 melt-spun ribbons. The as-spun ribbons were found to exhibit mixed cubic phases that transform to non-cubic structure upon annealing. Additionally, an amorphous phase was found to co-exist in all ribbons. The SEM images show that minor grain formation occurs on the as-spun ribbons. However, the formation of extensive nano-grains was observed on the surfaces of the annealed ribbons. While the as-spun ribbons exhibit predominantly paramagnetic behavior, the ribbons annealed under various thermal conditions were found to be ferromagnetic with a Curie temperature of about 380 K. The ribbons annealed at 450 °C for 30 minutes exhibit a large coercive field of about 2500 Oe. The experimental results show that the microstructure and associated magnetic properties of the ribbons can be controlled by annealing techniques. The coercive fields and the shape of the magnetic hysteresis loops vary significantly with annealing conditions. Exchange bias effects have also been observed in the annealed ribbons.

Microstructural Modification of Laser-Deposited High-Entropy CrFeCoNiMoWC Alloy by Friction Stir Processing: Nanograin Formation and Deformation Mechanism

Nanostructured CrFeCoNiMoWC high-entropy alloy layer was developed through laser-melting deposition and severe plastic deformation (SPD). The laser-deposited CrFeCoNiMoWC alloy consists of dendritic and subeutectic with a continuous network structure. After SPD, the laser-deposited microstructure with grain size 3 to 4 μm was transformed into nanostructure with grain size 5 to 100 nm and the continuous networks were crushed into dispersed nanoparticles. The new phases of WC and Co3W were presented in the plastic zone after SPD due to the worn debris of the SPD tool. More interestingly, amorphous phase was found in the plastic zone, owing to the high temperature, high hydrostatic pressure, and large shear stress. The refined microstructure resulted in the enhancement of microhardness and electrochemical corrosion property. Many nanotwins were detected in the plastic zone; thus, strengthening mechanisms were reasonably inferred as twinning strengthening, work hardening, dispersion strengthening, refinement strengthening, and dislocation strengthening. The Lomer–Cottrell lock, full dislocation interacting with a partial dislocation at the twinning boundary, and high density of dislocation at the twinning boundary, stacking fault, and grain boundary were observed, which account for the property enhancement of the nanocrystalline.

Swift heavy ion irradiation induced nanograin formation in CdTe thin films

Swift Heavy Ion (SHI) irradiation is a unique technique for nanograin formation through grain fragmentation. Contrary to the generally reported SHI irradiation induced grain growth on CdTe thin films, we report fragmentation leading to nanograin formation. Thermally evaporated polycrystalline CdTe thin films were irradiated with 100MeV 197Au, 107Ag and 58Ni ions beams up to a fluence of 5×1012ions/cm2. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were carried out for surface analysis before and after irradiation. SEM micrographs indicate that the larger grains in the as-deposited films were fragmented into smaller grains due to irradiation. The extent of fragmentation was found to increase with increasing electronic energy loss (Se). AFM pictures also supported the irradiation induced fragmentation. Structural characterization was done using X-ray Diffraction (XRD) technique. The ion induced strain and dislocation density were calculated from the XRD data. Both the strain and dislocation density were found to increase with increasing Se. The observed grain fragmentation is explained on the basis of a combined effect of strain induced disintegration of grains after the Coulomb explosion, and an ‘incomplete’ re-crystallization of the molten thermal spikes. Moreover, the optical band gap Eg (1.5eV for as-deposited film), determined from UV–vis spectroscopy, increased with Se, and possibly because of ion induced strain and defect annealing.

Dislocation Motion and the Microphysics of Flash Heating and Weakening of Faults during Earthquakes

Earthquakes are the result of slip along faults and are due to the decrease of rock frictional strength (dynamic weakening) with increasing slip and slip rate. Friction experiments simulating the abrupt accelerations (>>10 m/s2), slip rates (~1 m/s), and normal stresses (>>10 MPa) expected at the passage of the earthquake rupture along the front of fault patches, measured large fault dynamic weakening for slip rates larger than a critical velocity of 0.01–0.1 m/s. The dynamic weakening corresponds to a decrease of the friction coefficient (defined as the ratio of shear stress vs. normal stress) up to 40%–50% after few millimetres of slip (flash weakening), almost independently of rock type. The microstructural evolution of the sliding interfaces with slip may yield hints on the microphysical processes responsible for flash weakening. At the microscopic scale, the frictional strength results from the interaction of micro- to nano-scale surface irregularities (asperities) which deform during fault sliding. During flash weakening, the visco-plastic and brittle work on the asperities results in abrupt frictional heating (flash heating) and grain size reduction associated with mechano-chemical reactions (e.g., decarbonation in CO2-bearing minerals such as calcite and dolomite; dehydration in water-bearing minerals such as clays, serpentine, etc.) and phase transitions (e.g., flash melting in silicate-bearing rocks). However, flash weakening is also associated with grain size reduction down to the nanoscale. Using focused ion beam scanning and transmission electron microscopy, we studied the micro-physical mechanisms associated with flash heating and nanograin formation in carbonate-bearing fault rocks. Experiments were conducted on pre-cut Carrara marble (99.9% calcite) cylinders using a rotary shear apparatus at conditions relevant to seismic rupture propagation. Flash heating and weakening in calcite-bearing rocks is associated with a shock-like stress release due to the migration of fast-moving dislocations and the conversion of their kinetic energy into heat. From a review of the current natural and experimental observations we speculate that this mechanism tested for calcite-bearing rocks, is a general mechanism operating during flash weakening (e.g., also precursory to flash melting in the case of silicate-bearing rocks) for all fault rock types undergoing fast slip acceleration due to the passage of the seismic rupture front.

Nanograin nucleation at the growth front in melt crystallization of syndiotactic polystyrene

Melt-crystallization of syndiotactic polystyrene (sPS) is studied using simultaneous small/wide angle X-ray scattering (SAXS/WAXS). Emergence, intensification, and saturation of WAXS reflections within 120 s at isothermal crystallization temperature Tc = 250 °C after quenching from 300 °C illustrate crystallinity development through successive nucleation of instantaneously stabilized crystallites of lateral (hk0) coherence length Λ ≈ 75 nm. The corresponding SAXS profiles exhibit increased density heterogeneity due to formation of nanograins; fitting of time-resolved SAXS data with a model of arrayed disks reveals slightly thickened (lc = 7.4–8.4 nm) disks of radius R ≈ 9 nm and long period L ≈ 19 nm with polydisperse stacking number slowly enhanced from an average of 1.2 to 2.4. The moderate ratio of Λ/2R ≈ 4 indicates imperfect coalescence of nanograins in the lamellar assembly process. More importantly, with successively increased Tc from 250 to 260 °C the development of density heterogeneity of SAXS invariant Qinv is found to precede that of the WAXS-determined crystallinity Xc increasingly more, suggesting a precursor mesophase with non-crystalline nanograins. Avrami analysis for the developments of Xc and Qinv further reveals the same Avrami exponent n ≈ 3, consistent with heterogeneous nucleation of crystallites; the corresponding Avrami rate constant κ1/n(Tc) extracted from Xc is correlated to the crystal growth rates G(Tc) described by the Hoffman-Lauritzen theory with a common surface-nucleation rate constant Kg. A lateral surface energy σ ≈ 17 mJ m−2 can be deduced on the basis of Kg using previously determined fold surface energy σe ≈ 27 mJ m−2. Correspondingly, κ1/n(Tc) extracted from Qinv is described by a mesophase model proposed by Strobl with a zero-growth temperature of the nanograin mesophase ca. 30 K below the β-crystal melting point of sPS. Together, these results suggest that sPS melt-crystallization proceeds with nucleation of non-crystalline nanograins (SAXS-before-WAXS regime) at the crystal growth front, followed by crystallization of the nanograins with similar kinetics to sustain the growth front. Branching/twisting can occur at the lamellar growth front due to frustrated nanograin alignment, favoring the microscopically observed sheaf-like crystal morphology.

Synthesis and characterization of a new class of single-phase AlVO4 precursors

Reactions of [Al(OPri)3] with [VO(OPri)3] in presence of halo-acetic acid, CX3COOH in anhydrous benzene yielded complexes of the type, [AlVO(OOCCX3)2(OPri)4], where X = F (1) or Cl (2). The compounds were characterised by elemental analyses, FT-IR and NMR (1H, 27Al & 51V) spectral studies. The desired single-phase aluminium vanadate, AlVO4, (a & b) have been obtained easily from the precursors, (1) and (2), respectively, by the sol-gel process. Formation of triclinic phase in both of the AlVO4 (a & b) samples was confirmed by powder XRD patterns. SEM image of (b) exhibits formation of nano-grains with agglomers like surface morphologies. Composition of AlVO4 sample (b) was investigated by EDX analysis, which shows presence of aluminium and vanadium in 1:1 atomic ratio. Absorption spectra of (a) and (b) samples indicate an energy band gap of 3.60 and 3.75 eV, respectively.

How the Conditions of Preparation Process Affect the Electrochemical Properties of C/Sn Anode Materials?

How the conditions of preparation process affect the electrochemical properties of C/Sn anode materials? The application of tin in commercially available Li-ion batteries is limited by the poor cyclic performance due to the pulverization caused by cyclic volume changes of elementary cell, during the insertion and extraction processes of lithium ions [1]. Consequently, it results in loss of electrical contact between active material and current collector. One of the ways to overcome this issue is development of tin-carbon nanocomposite, in which nanometric tin grains are encapsulated in a flexible and conductive carbon layers. Such nanocomposites are able to provide appropriate electrochemical properties, only if the formed carbon layer is flexible, has appropriate porosity which featuring local free space to compensate volume changes. The goal of the presented studies is to examine the effects of carbonization temperature as well as origin and content of carbon on the electrochemical performance of carbon-tin nanocomposites. Electrode materials consisted of tin-based nanograins encapsulated in carbon buffer matrix of different origins (starch or water soluble polymer) were obtained in a simple and inexpensive process. The tin precursor (SnO2) was prepared using a modified reverse nanoemulsion method (w/o) and then was coated by a various source of carbon (potato starch or modified poly(N-vinylformamide)) [2,3]. The carbon-tin precursors were pyrolyzed, providing formation of tin-based nanograins encapsulated in buffer matrix. The optimal condition for preparation process was studied using thermal analysis method (EGA-TGA/DTG/SDTA). The structure and the morphology of the samples were characterized by X-Ray diffraction analysis (XRD), low-temperature nitrogen adsorption method (N2-BET) and transmission electron microscopy (TEM) as well. The quality of carbon matrix in resulting composites was determined by Raman spectroscopy (RS) measurements. The working electrodes were prepared from a carbon-tin active material and polyvinylidene fluoride (PVDF) binder in N-methylpyrrolidone (NMP) solvent on copper foil. R-2032 coin type cells were assembled using obtained electrodes combined with Li metal discs as a counter electrode. The electrolyte consisted of a solution of 1M LiPF6in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with EC/DEC molar ratio of 1:1. The lithium cells were characterized by cyclic voltammetry (CV), charge-discharge tests (CELL TEST) as well as electrochemical impedance spectroscopy (EIS). The thermal analysis results enabled determination of the optimal carbonization temperature for obtaining carbon-tin anode materials. N2-BET data as well as TEM images indicated that samples, in which the potato starch was used as a carbon source, have high specific surface area and pore volume as well as reveal presence of the opened pores through the composites. The electrochemical tests showed that better encapsutation of tin nanograins in carbon buffer matrix resulted in higher gravimetric capacity and better cell performance. The C/Sn material in which carbon matrix was fabricated from modified polymer exhibited higher gravimetric capacity and better cell performance (589 mAh g-1 after 70 cycles). The authors acknowledge a financial support from the National Science Centre of Poland under research grant No. 2012/07/N/ST8/03725. [1] S. Ding, X.W. Lou, Nanoscale, 3 (2011) 3586[2] M. Molenda, A. Chojnacka, M. Bakierska, R. Dziembaj, Mater. Technol., 29 (2014) A88[3] A. Chojnacka, M. Molenda, M. Bakierska, R. Dziembaj, Procedia Eng., 98 (2014) 2

Structural elucidation of AgAsS2 glass by the analysis of clusters formed during laser desorption ionisation applying quadrupole ion trap time-of-flight mass spectrometry.

The structure of AgA(s)S2 glass, which has a broad range of applications, is still not well understood and a systematic mass spectrometric analysis of AgA(s)S2 glass is currently not available. Elucidation of the structure should help in the development of this material. The AgA(s)S2 glass was prepared by the melt-quenched technique. Laser desorption ionisation (LDI) using quadrupole ion trap time-of-flight mass spectrometry (QIT-TOFMS) was used to follow the generation of Ag(m)As(n)S(x) clusters. The stoichiometry of the clusters generated was determined via collision-induced dissociation (CID) and modelling of isotopic patterns. The AgA(s)S2 glass was characterised by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The LDI of AgA(s)S2 glass leads to the formation of unary (Ag+/− and As(3+)) species, 38 binary (As(n)S(x), Ag(m)S(x)), and 98 ternary (Ag(m)As(n)S(x)) singly charged clusters. The formation of silver-rich nano-grains during AgA(s)S2 glass synthesis has been identified using TEM analysis and also verified by QIT-TOFMS. TOFMS was shown to be a useful technique to study the generation of Ag(m)As(n)S(x )clusters. SEM, TEM and EDX analysis proved that the structure of AgA(s)S2 glass is ‘grain-like’ where grains are either: (1) Silver-rich ‘islands’ (Ag(m,) m up to 39) connected by arsenic and/or sulfur or arsenic sulfide chains or (2) silver sulfide (Ag2S)m (m = 9-20) clusters also similarly inter-connected. This obtained structural information may be useful for the development of ultra-high-density phase-change storage and memory devices using this kind of glass as a base.

Microstructure evolution and strengthening mechanisms of pure titanium with nano-structured surface obtained by high energy shot peening

In this study, the microstructure evolution and strengthening mechanisms of pure titanium processed by high energy shot peening (HESP) have been studied. The results show that the deformation layer is formed on the surface and the microstructure exhibits with the equiaxed 20–40 μm grains in the matrix after HESP. A nanocrystal surface layer is produced by means of HESP on pure titanium. The formation of nano-grains on the surface can be separated into four steps: (1) the formation of the dislocations tangles; (2) the occurrence of the intersection of twins; (3) the appearance of slip band and subgrains; (4) the formation of uniformly distributed nanometer-scale grains. With increasing the holding time, the strength increases and the elongation decreases due to the work hardening effect and the formation of the nanocrystals on the surface.

Microstructural Evolution of Cu-10at%C Nanocomposite Powder During High Energy Mechanical Milling

The microstructural evolution of Cu-10at%C nanocomposite powder during high energy mechanical milling (HEMM) of Cu/graphite powder mixture was studied. It was found that the efficiency of milling in refining the microstructure of the copper matrix was very high with the presence of graphite in the Cu/graphite powder mixture. The average grain size of the Cu matrix reaches its minimum value of about 30 nm just after milling for 6 h, and the graphite particles were refined down to about 10~20 nm after milling for 24 h. It envisaged that the refining of graphite particles down to 10 nm would be accompanied by formation of nanograins of copper matrix, and it appears that high energy mechanical milling can greatly enhance the solubility of carbon in copper though it is very hard to determine the exact solubility.

Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes.

Rupture fronts can cause fault displacement, reaching speeds up to several ms−1 within a few milliseconds, at any distance away from the earthquake nucleation area. In the case of silicate-bearing rocks the abrupt slip acceleration results in melting at asperity contacts causing a large reduction in fault frictional strength (i.e., flash weakening). Flash weakening is also observed in experiments performed in carbonate-bearing rocks but evidence for melting is lacking. To unravel the micro-physical mechanisms associated with flash weakening in carbonates, experiments were conducted on pre-cut Carrara marble cylinders using a rotary shear apparatus at conditions relevant to earthquakes propagation. In the first 5 mm of slip the shear stress was reduced up to 30% and CO2 was released. Focused ion beam, scanning and transmission electron microscopy investigations of the slipping zones reveal the presence of calcite nanograins and amorphous carbon. We interpret the CO2 release, the formation of nanograins and amorphous carbon to be the result of a shock-like stress release associated with the migration of fast-moving dislocations. Amorphous carbon, given its low friction coefficient, is responsible for flash weakening and promotes the propagation of the seismic rupture in carbonate-bearing fault patches.

Evolution of microstructure and property of NiTi alloy induced by cold rolling

We investigated the combination effect of plastic deformation and phase transformation on the evolution of microstructure and property of NiTi alloy. Samples of Ni50.9Ti49.1 alloy were deformed by cold rolling to different strains/thickness reductions (4%–56%). X-ray diffraction, transmission electronic microscopy (TEM) and microhardness measurements were applied for characterization of the microstructure and property of the cold-rolled samples. Experimental results indicated the non-monotonic variations of microstructure parameters and mechanical property with strain, indicating the different processes in microstructure and property evolution of NiTi subjected to cold rolling. TEM observations further showed the dominating mechanisms of microstructure evolution at different strain levels, leading to the gradual reduction of grain size of NiTi to the nanoscale by cold rolling. The results were discussed and related to deformation of martensite, forward and reverse martensitic transformations and dynamic recrystallization. The present study provided experimental evidences for the enhanced formation of nanograins in NiTi by plastic deformation coupled with phase transformation.

Grain refinement via formation and subdivision of microbands and thin laths structures in cold-rolled hafnium

The microstructural evolution and mechanical properties of pure hafnium subjected to cold rolling were investigated in this paper. Structural characterization indicates that slip dominated the plastic deformation and the microstructural evolution follows the sequence: original coarse grains – formation of microbands – formation of thin laths in microbands and formation of elongated grains in locally formed shear bands – the longitudinal splitting and transverse breakdown of laths to elongated segments – formation of nano-grains through further transverse breakdown of elongated segments. Hardness results indicate that strain hardening occurred during the whole rolling process, which can be attributed to dislocation activities and grain refinement effect.

Electrochemical Properties of Tin Nanoparticles Encapsulated in Different Origin Carbon Buffer Matrix

Tin seems to be a promising anode material due to its lithium uptake at low potential and high theoretical capacity (994 mAh/g for Li4.4Sn alloy phase). However, the major problem during formation of LixSny alloys are cyclic changes of elementary cell volume, reaching up to 300%, which lead to loss of electrical contact between active material and current collector as well as physical damage of the cell caused by high strains. Over the last decade most of the studies related to anode materials based on tin were focused on designing composites containing Sn and a stress-accommodating phase [1-4]. Nevertheless, the multi-step processes used to synthesis of such composites are complex and expensive [5]. The goal of the present work was development two types of carbon-tin nanocomposite anode materials and comparison of their electrochemical properties. In both cases the nanocomposites were obtained in a simple and inexpensive process, consisted of tin-based nanograins encapsulated in a flexible carbon buffer matrix derived from plant polysaccharides in the first series and from water soluble polymer in the latter. The precursor of active material was obtained using a modified reverse microemulsion technique (w/o) and then coated by a source of carbon (potato starch or poly(N-vinylformamide) mixed with pyromellitic acid) [6,7]. The carbon-tin precursors were pyrolyzed, affording formation of tin-based nanograins encapsulated in conductive carbon buffer matrix. Optimal conditions of the thermal treatment were determined by thermal analysis methods (EGA-TGA). The resulting materials with different carbon loading (20-60 wt.%) were investigated by X-ray diffraction (XRD) and by transmission electron microscopy (TEM) as well. Comprehensive electrochemical characterization of obtained nanocomposites including the electrical conductivity (EC), cyclic voltammetry (CV) and impedance spectroscopy (IS) was carried out. Discharge - charge tests were performed in R2032-type coin cells within 0.01–1.5 V potential range. TEM images indicate that the type of carbon precursor has strong impact on morphology of obtained carbon buffer matrix. The study also showed that columbic efficiency and capacity retention in discharge-charge tests strongly depend on carbon loading and sort of a carbon precursor. The authors acknowledge a financial support from the National Science Center of Poland under research grant No. 2012/07/N/ST8/03725 and from the European Institute of Innovation and Technology under the KIC InnoEnergy NewMat project. [1] J. W. Zheng, S. M. L. Nai, M. F. Ng, P. Wu, J. Wei, M. Gupta, J. Phys. Chem. 113 (2009) 14015-14019.[2] L. Zhao, S. Hu, W. Li, L. Li, X. Hou, Rare Metals 27 (2008) 507-512.[3] D. Deng, J.Y. Lee, Angew. Chem. Int. Edit. 48 (2009) 1660-1663.[4] H. Kim, M. G. Kim, T.J. Shin, H. J. Shin, J. Cho, Electrochem. Commun. 10 (2008) 1669-1672.[5] A. Kamali, D.J. Fray, Rev. Adv. Mater. Sci. 27 (2011) 14–24.[6] M. Molenda, A. Chojnacka, M. Bakierska, R. Dziembaj, Mater. Technol. 29 (2014) A88-A92.[7] A. Chojnacka, M. Molenda, M. Bakierska, R. Dziembaj, Procedia Eng. 98 (2014) 2-7.