Controlled synthesis of photoluminescent Bi<Subscript>4</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> nanoparticles from metal-organic polymeric precursor

Bi₄Ti₃O₁₂ (BIT) nanoparticles with a narrow average particle size distribution in the range of 11–46 nm was synthesized via a metal-organic polymeric precursor process. The crystallite size and lattice parameter of BIT were determined by XRD analysis. At annealing temperatures >550 °C, the orthorhombic BIT compound with lattice parameters a = 5.4489 Å, b = 5.4147 Å, and c = 32.8362 Å was formed while at lower annealing temperatures orthorhombicity was absent. Reaction proceeded via the formation of an intermediate phase at 500 °C with a stoichiometry close to Bi₂Ti₂O₇. The particle size and the agglomerates of the primary particles have been confirmed by FESEM and TEM. The decomposition of the polymeric gel was ascertained in order to evaluate the crystallization process from TG-DSC analysis. Raman spectroscopy was used to investigate the lattice dynamics in BIT nanoparticles. In addition, investigation of the dependence of the visible emission band around the blue–green color emission on annealing temperatures and grain sizes showed that the effect of grain size plays important roles, and that oxygen vacancies may act as the radiative centers responsible for the observed visible emission band.     

Structural transformations in the Al<Subscript>85</Subscript>Ni<Subscript>6.1</Subscript>Co<Subscript>2</Subscript>Gd<Subscript>6</Subscript>Si<Subscript>0.9</Subscript> amorphous alloy during multiple rolling

The effect of multiple rolling at room temperature on the structure and crystallization of the Al₈₅Ni_6.1Co₂Gd₆Si_0.9 amorphous alloy has been studied using transmission electron microscopy, differential scanning calorimetry, and X-ray diffraction. The total plastic strain is 33%. It has been shown that the deformation results in the formation of aluminum nanocrystals with the average size that does not exceed 10–15 nm. The nanocrystals are formed in regions of localization of plastic deformation. The deformation decreases the thermal effect of nanocrystallization (∼15%) as compared to the heat release at the first stage of crystallization of the unstrained sample. The morphology, structure, and distribution of precipitates have been investigated. Possible mechanisms of the formation of nanocrystals during the deformation have been discussed.     

Glass-forming ability and thermal stability of Fe<Subscript>62</Subscript>Nb<Subscript>8−x</Subscript>Zr<Subscript>x</Subscript>B<Subscript>30</Subscript> and Fe<Subscript>72</Subscript>Zr<Subscript>8</Subscript>B<Subscript>20</Subscript> amorphous alloys?

Glass-forming ability (GFA) and thermal stability of Fe₆₂Nb₈B₃₀, Fe₆₂Nb₆Zr₂B₃₀ and Fe₇₂Zr₈B₂₀ at % amorphous alloys were investigated by calorimetric (DSC and DTA) measurements. The crystallization kinetics was studied by DSC in the mode of continuous versus linear heating and it was found that both the glass transition temperature, T _g , and the crystallization peak temperature, T _p , display strong dependence on the heating rate. The partial replacement of Nb by Zr leads to lower T _g and T _x temperatures and causes a decrease of the supercooled liquid region. JMA analysis of isothermal transformation data measured between T _g and T _x suggests that the crystallization of the Fe₆₂Nb₈B₃₀ and Fe₆₂Nb₆Zr₂B₃₀ amorphous alloys take place by three-dimensional growth with constant nucleation rate. Nb enhances the precipitation of the metastable Fe₂₃B₆ phase and stabilizes it up to the third crystallization stage. Zr addition increases the lattice constant of Fe₂₃B₆ and, at the same time, decreases the grain size.     

Electromagnetic wave absorption properties of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> octahedral nanocrystallines in gigahertz range

Large-scale octahedral Fe₃O₄ nanocrystallines with crystalline size of 100−500 nm were synthesized by a facile solvent-thermal method for electromagnetic wave application. The Fe₃O₄ nanocrystallines showed a higher saturation magnetization (M _s ) value of 86.8 emu/g and larger coercivity (H _cj ) value of 255 Oe than that of magnetite polycrystallines because of their good crystallization and dispersion. The epoxy resin composites with 40 vol% Fe₃O₄ powders provided good electromagnetic wave absorption performance (RL < −20 dB) in the range of 2.0–4.3 GHz over the absorber thicknesses of 3.5–6.8 mm. A minimum RL value of −47 dB was observed at 3.1 GHz with a thickness of 4.8 mm.     

I. Electron-impact ionization and dissociation of C<Subscript>2</Subscript>H<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and C<Subscript>2</Subscript>D<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack>

Absolute cross-sections for electron-impact ionization and dissociation of C₂H₂⁺ and C₂D₂⁺ have been measured for electron energies ranging from the corresponding thresholds up to 2.5 keV. The animated crossed beams experiment has been used. Light as well as heavy fragment ions that are produced from the ionization and the dissociation of the target have been detected for the first time. The maximum of the cross-section for single ionization is found to be (5.56 ± 0.03)× 10^-17 cm² around 140 eV. Cross-sections for dissociation of C₂ H₂⁺ (C₂D₂⁺) to ionic products are seen to decrease for two orders of magnitude, from C₂D⁺ (12.6 ± 0.3) × 10^-17 cm² over CH⁺(9.55 ± 0.06) × 10^-17 cm², C⁺ (6.66 ± 0.05) × 10^-17 cm², C₂⁺ (5.36 ± 0.27) × 10^-17 cm², H⁺ (4.73 ± 0.29) × 10^-17 cm² and CH₂⁺ (4.56 ± 0.27) × 10^-18 cm² to H₂⁺ (5.68 ± 0.49) × 10^-19 cm². Absolute cross-sections and threshold energies have been compared with the scarce data available in the literature.     

Magnetic and dielectric properties of Mn<Subscript>0.2</Subscript>Ni<Subscript>0.8</Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles synthesized by PEG-assisted hydrothermal method

We present a systematic investigation on the structural and magnetic properties of Mn_0.2Ni_0.8Fe₂O₄ nanoparticles synthesized by a polyethylene glycol (PEG)-assisted hydrothermal route. XRD, FT-IR, TEM and VSM were used for the structural, morphological, dielectric properties and magnetic investigation of the products, respectively. Average crystallite size of product was estimated using Line profile fitting as 6 ± 1 nm and particle size as 6.5 ± 1.0 nm from TEM micrographs. Magnetization measurements have shown that the particles have a blocking temperature of 134 K. Magnetization and the coercive field of the sample increase by decreasing the temperature. The conductivity measurements reveal the semiconducting behaviour for the sample. Temperature-dependent dielectric properties: dielectric permittivity (ε) and ac conductivity (σ_ac) for the sample were studied as a function of applied frequency in the range from 1 Hz to 3 MHz. These studies indicated that the dielectric dispersion curve for the sample showed usual dielectric dispersion which can be explained on the basis of Koop’s theory, which is based on the Maxwell–Wagner model for the interfacial polarization of homogeneous double structure.     

Structural evolutions of the mechanically alloyed Al<Subscript>70</Subscript>Cu<Subscript>20</Subscript>Fe<Subscript>10</Subscript> powders

Elemental mixtures of Al, Cu, Fe powders with the nominal composition of Al₇₀Cu₂₀Fe₁₀ were mechanically alloyed in a planetary ball mill for 80 h. Subsequent annealing of the as-milled powders were performed at 600–800°C temperature range for 4 h. Structural characteristics of the mechanically alloyed Al₇₀Cu₂₀Fe₁₀ powders with the milling time and the heat treatment were investigated by X-ray diffraction (XRD), differential scanning calorimeter (DSC) and differential thermal analysis (DTA). Mechanical alloying of the Al₇₀Cu₂₀Fe₁₀ did not result in the formation of icosahedral quasicrystalline phase (i-phase) and a long time milling resulted in the formation of β-Al(Cu,Fe) solid solution phase (β-phase). The i-phase was observed only for short-time milled powders after heat treatment above 600°C. The β-phase was one of the major phases in the Al₇₀Cu₂₀Fe₁₀ alloy. The w-Al₇Cu₂Fe₁ phase (w-phase) was obtained only after heat treatment of the short-time milled and unmilled samples. The present investigation indicated that a suitable technique to obtain a large amount of quasicrystalline powders is to use a combination of short-time milling and subsequent annealing.     

Electro-optic properties of epitaxial Sr<Subscript>0.6</Subscript>Ba<Subscript>0.4</Subscript>Nb<Subscript>2</Subscript>O<Subscript>6</Subscript> films grown on MgO substrates using Li<Subscript>x</Subscript>Ni<Subscript>2-x</Subscript>O buffer layer

Textured Li_xNi_2-xO (LNO) thin films have been fabricated on (001)MgO substrates by pulsed laser deposition technique. The as-deposited LNO films shows a conductivity of 2.5×10^-3 Ω m and possess a transmittance of about 35% in the visible region. Subsequent deposition of Sr_0.6Ba_0.4Nb₂O₆ (SBN60) thin film on these LNO-coated MgO substrates resulted in a textured SBN layer with a 〈001〉 orientation perpendicular to the substrate plane. Phi scans on the (221) plane of the SBN layer indicated that the films have two in-plane orientations with respect to the substrate. The SBN unit cells were rotated in the plane of the film by ± 8.2° as well as ± 45° with respect to the LNO/MgO substrate. Besides the highly (00l)-orientation, the SBN films also exhibited a dense microstructure as shown by scanning electron microscopy. The electro-optic coefficient (r₃₃) of the SBN film was measured to be 186 pm/V. On the basis of our results, we have demonstrated that the LNO film can be used as a buffer layer as well as a transparent bottom electrode for waveguide applications. The SBN/LNO heterostructure is also a suitable candidate for integrated electro-optics devices. PACS  42.79.Gn; 42.82.Et; 78.20.Ci     

II. Electron-impact dissociative excitation of C<Subscript>2</Subscript>H<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and C<Subscript>2</Subscript>D<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack>

Absolute cross-sections for electron-impact dissociative ionization of C₂ H₂⁺ and C₂ D₂⁺ to CH⁺, C⁺, C₂⁺ , H⁺, CH₂⁺ and C₂D⁺ fragments are determined for electron energies ranging from the corresponding threshold to 2.5 keV. Results obtained in a crossed beams experiment are analyzed to estimate the contribution of dissociative ionization to each fragment formation. The dissociative ionization cross sections are seen to decrease for more than an order of magnitude, from CH⁺ (5.37±0.10) × 10^-17 cm² over C⁺ (4.19± 0.16) × 10^-17 cm², C₂D⁺ (3.94±0.38) × 10^-17 cm², C₂⁺ (3.82±0.15) × 10^-17 cm² and H⁺ (3.37±0.21) × 10^-17 cm² to CH₂⁺ (2.66±0.14) × 10^-18 cm². Kinetic energy release distributions of fragment ions are also determined from the analysis of the product velocity distribution. Cross section values, threshold energies and kinetic energies are compared with the data available from the literature. Conforming to the scheme used in the study of the dissociative excitation of C₂H₂⁺ ( C₂ D₂⁺ )\left( {\rm C}_2 {\rm D}_2^+ \right), the cross-sections are presented in a format suitable for their implementation in plasma simulation codes.     

Spectroscopic Properties and Energy Transfer Analysis of Tm<Superscript>3+</Superscript>-Doped BaF<Subscript>2</Subscript>-Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>-GeO<Subscript>2</Subscript>-La<Subscript>2</Subscript>O<Subscript>3</Subscript> Glass

This paper reports on the spectroscopic properties and energy transfer analysis of Tm³⁺-doped BaF₂-Ga₂O₃-GeO₂-La₂O₃ glasses with different Tm₂O₃ doping concentrations (0.2, 0.5, 2.0, 2.5, 3.0, 3.5, 3.5, 4.0 wt%). Mid-IR fluorescence intensities in the range of 1,300 nm−2,200 nm have been measured when excited under an 808 nm LD for all the samples with the same pump power. Energy level structure and Judd-Ofelt parameters have been calculated based on the absorption spectra of Tm³⁺, cross-relaxation rates and multi-phonon relaxation rates have been estimated with different Tm₂O₃ doping concentrations. The maximum fluorescence intensity at around 1.8 μm has been obtained in Tm₂O₃-3 wt% sample and the maximum value of calculated stimulated emission cross-section of Tm³⁺ in this sample is about 0.48 × 10⁻²⁰ cm² at 1,793 nm, and there is not any crystallization peak in the DSC curve of this sample, which indicate the potential utility of Tm³⁺-doped BaF₂-Ga₂O₃-GeO₂- La₂O₃ glass for 2.0-μm optical fiber laser.     

Electron-impact ionization and dissociation of C<Subscript>2</Subscript>D<Superscript>+</Superscript>

Absolute cross sections for electron-impact single ionization, dissociative excitation and dissociative ionization of the ethynyl radical ion (C₂D⁺)^+) have been measured for electron energies ranging from the corresponding reaction thresholds to 2.5 keV. The animated crossed electron-ion beam experiment is used and results have been obtained for the production of C₂D²⁺, C²⁺, C₂⁺_2^+ , CD⁺, C⁺ and D⁺. The maximum of the cross section for single ionization is found to be (2.01 ± 0.02) × 10^-17 cm², at the incident electron energy of 105 eV. Absolute total cross sections for the various singly charged fragments production are observed to decrease by a factor of almost three, from the largest cross-section measured for C⁺, over C₂⁺_2^+ and CD⁺ down to that of D⁺. The maxima of the cross sections are obtained to be (14.5 ± 0.5) × 10^-17 cm² for C₂⁺_2^+, (12.1 ± 0.1) × 10^-17 cm² for CD⁺, (27.7 ± 0.2) × 10^-17 cm² for C⁺ and (11.1 ± 0.8) × 10^-17 cm² for D⁺. The smallest cross section is measured to be (1.50 ± 0.04) × 10^-18 cm² for the production of the doubly charged ion C²⁺. Individual contributions for dissociative excitation and dissociative ionization are determined for each singly-charged product. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. Kinetic energy release distributions of dissociation fragments are seen to extend from 0 to 6 eV for the heaviest fragment C₂⁺_2^+, up to 11.0 eV for CD⁺, 14.2 eV for C⁺ and 11.2 eV for D⁺ products.     

Magnetic properties of nanoparticle La<Subscript>0.7</Subscript>Ca<Subscript>0.3</Subscript>MnO<Subscript>3</Subscript> under applied hydrostatic pressure

Pressure effects on magnetic properties of two La_0.7Ca_0.3MnO₃ nanoparticle samples with different mean particle sizes were investigated. Both the samples were prepared by the glycine-nitrate method: sample S—as-prepared (10 nm), and sample S₉₀₀—subsequently annealed at 900 °C for 2 h (50 nm). Magnetization measurements revealed remarkable differences in magnetic properties with the applied pressure up to 0.75 GPa: (i) for S sample, both transition temperatures, para-to-ferromagnetic T _C = 120 K and spin-glass-like transition T _f = 102 K, decrease with the pressure with the respective pressure coefficients dT _C/dP = −2.9 K/GPa and dT _f/dP = −4.4 K/GPa; (ii) for S₉₀₀ sample, para-to-ferromagnetic transition temperature T _C = 261 K increases with pressure with the pressure coefficient dT _C/dP = 14.8 K/GPa. At the same time, saturation magnetization M _S recorded at 10 K decreases/increases with pressure for S/S₉₀₀ sample, respectively. Explanation of these unusual pressure effects on the magnetism of sample S is proposed within the scenario of the combined contributions of two types of disorders present in the system: surface disorder introduced by the particle shell, and structural disorder of the particle core caused by the prominent Jahn–Teller distortion. Both disorders tend to vanish with the annealing of the system (i.e., with the nanoparticle growth), and so the behavior of the sample S₉₀₀ is similar to that previously observed for the bulk counterpart.     

Synthesis and magnetic characterization of CoMoN<Subscript>2</Subscript> nanoparticles

A new ternary nitride, CoMoN₂, was prepared in the nanosize regime of 9.0 ± 2.0 nm, by nitridation of the precursor intermetallic nitride Co₃Mo₃N. XRD–Rietveld analysis revealed the presence of 0.60 (±0.02) mass % of Co impurity phase. The calculated space groups of CoMoN₂ and Co are P6 ₃ /mmc and Fm-3m, respectively. The N atoms lie at the interstitial sites and the 12 calculated nitrogen sites indicate the presence of a layered structure. The XPS studies indicated the presence of the nitride and surface oxynitride/oxide phases. CoMoN₂ is an interstitial nitride with Co and Mo in the zero oxidation state. The room temperature susceptibility is estimated after subtracting the ferromagnetic contribution from cobalt and found to be 2.7 × 10⁻⁴ emu g⁻¹ Oe⁻¹, indicating the Pauli-paramagnetic nature. The ferromagnetic exchange interactions between the Co atoms in CoMoN₂ are reduced due to the presence of Mo and N in the crystal lattice. The hysteresis loop shift 19 Oe is attributed to the demagnetizing dipolar fields created in the soft CoMoN₂ phase by the hard Co phase.     

Study of mechanochemically prepared nanocrystalline La<Subscript>0.8</Subscript>Sr<Subscript>0.2</Subscript>MnO<Subscript>3</Subscript>

The nanocrystalline La_0.8Sr_0.2MnO₃ (LSM) is prepared by varying the revolutions per minute and milling time of planetary monomill during the mechanochemical method. The LSM forms in a relatively shorter milling time with an increase in the milling speed from 250 to 600 rpm. The structural phase transition from orthorhombic to rhombohedral phase in the LSM prepared by ball milling at the speed 250 rpm for 36 h is seen due to sintering it at 700 °C for 4 h. The crystallite size reduces with the increase in both the milling speed and the milling time individually or combined. The microhardness (HV) and sintered density increase with the reduction in the crystallite size. The temperature-activated transition temperature is suppressed by reducing the grain size in the nanometer range. The electrical dc conductivity increases with the reduction in the grain/crystallite size.     

Fluorescent Carbon Dots Capped with PEG<Subscript>200</Subscript> and Mercaptosuccinic Acid

The synthesis and functionalization of carbon nanoparticles with PEG₂₀₀ and mercaptosuccinic acid, rendering fluorescent carbon dots, is described. Fluorescent carbon dots (maximum excitation and emission at 320 and 430 nm, respectively) with average dimension 267 nm were obtained. The lifetime decay of the functionalized carbon dots is complex and a three component decay time model originated a good fit with the following lifetimes: τ ₁ = 2.71 ns; τ ₂ = 7.36 ns; τ ₃ = 0.38 ns. The fluorescence intensity of the carbon dots is affected by the solvent, pH (apparent pK _a of 7.4 ± 0.2) and iodide (Stern-Volmer constant of 78 ± 2 M⁻¹).     

Flip Angle for the Optimal <Emphasis Type="Italic">T</Emphasis><Subscript>1</Subscript>-weighted Image in the 3-D Volumetric Interpolated Breath-hold Examination Abdominal Magnetic Resonance Imaging Technique

The purpose of this study was to determine an optimal flip angle for T ₁-weighted images on abdominal examination by comparing the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) depending on the change in flip angle based on the volumetric interpolated breath-hold examination (VIBE) technique. The subjects in this study included 50 patients (20 men and 10 women; average age, 60 years) who visited the hospital between October 2009 and March 2010 to receive an abdominal magnetic resonance imaging (MRI) examination. Among the 50 patients, there were 27 patients with hypervascular hepatocellular carcinomas (HCCs) and 23 patients with hemorrhagic HCCs. A 3 T MR scanner (Magnetom Tim Trio; Siemens, Germany) with a 12-channel body coil was used. For the pulse sequence, the VIBE (time of repetition TR, 3.18 ms; time of echo TE, 1.16 ms; matrix, 384 × 307; slice thickness, 3 mm; field of view FOV, 380 mm; bandwidth BW, 720 Hz) and breath-hold examination with an examination time of 19 s were used. Images of the axial and coronal planes at three flip angles (10°, 25°, and 35°) were obtained. Based on the images obtained, the signal intensities of the liver, lesions, and background noise were measured and the SNR and CNR were calculated. For evaluation of the optimal flip angle, SPSS for Windows (version 17.0) was used to conduct the non-parametric Kruskal–Wallis test. The SNRs for hypervascular and hemorrhagic HCCs, depending on changes in flip angle of the VIBE, were 11.12 ± 0.98, 10.83 ± 1.44, and 9.61 ± 1.66, and 76.00 ± 6.43, 43.32 ± 5.89, and 30.45 ± 4.27 at angles of 10°, 25°, and 35°, respectively. The CNRs were 14.83 ± 0.12, 7.38 ± 0.41, and 5.70 ± 0.66, and 3.95 ± 0.21, 2.42 ± 0.58, and 1.69 ± 0.93, respectively (p < 0.05). At a flip angle of 10°, the SNR and CNR were the highest. When the flip angles were 25° and 35°, the contrast of the image, as well as the SNR, were shown to have a downward trend (p < 0.05). A flip angle of 10° is considered to be useful for the optimal T ₁-weighted image to detect HCC in the three-dimensional VIBE abdominal MRI technique.     

Structural and electrical properties of pure and H<Subscript>2</Subscript>SO<Subscript>4</Subscript> doped (PVA)<Subscript>0.7</Subscript>(NaI)<Subscript>0.3</Subscript> solid polymer electrolyte

Solid polymer electrolytes (SPE) based on poly-(vinyl alcohol) (PVA)_0.7 and sodium iodide (NaI)_0.3 complexed with sulfuric acid (SA) at different concentrations were prepared using solution casting technique. The structural properties of these electrolyte films were examined by X-ray diffraction (XRD) studies. The XRD data revealed that sulfuric acid disrupt the semi-crystalline nature of (PVA)_0.7(NaI)_0.3 and convert it into an amorphous phase. The proton conductivity and impedance of the electrolyte were studied with changing sulfuric acid concentration from 0 to 5.1 mol/liter (M). The highest conductivity of (PVA)_0.7(NaI)_0.3 matrix at room temperature was 10⁻⁵ S cm⁻¹ and this increased to 10⁻³ S cm⁻¹ with doping by 5.1 M sulfuric acid. The electrical conductivity (σ) and dielectric permittivity (ε′) of the solid polymer electrolyte in frequency range (500 Hz–1 MHz) and temperature range (300–400) K were carried out. The electrolyte with the highest electrical conductivity was used in the fabrication of a sodium battery with the configuration Na/SPE/MnO₂. The fabricated cells give open circuit voltage of 3.34 V and have an internal resistance of 4.5 kΩ.     

H<Subscript>2</Subscript>O/CuIn<Subscript>3</Subscript>Se<Subscript>5</Subscript> photoelectrochemical cells: Fabrication and properties

Single-phase coarse-grained CuIn₃Se₅ ingots are grown by horizontal oriented crystallization from the near-stoichiometric melt. Photosensitive structures based on the interface between these crystals and an electrolyte (H₂O) are created. It is shown that the CuIn₃Se₅ ternary compound is a direct-gap semiconductor with an energy gap Eg ≃ 1.1 eV (T = 300 K). H₂O/CuIn₃Se₅ photoelectrochemical cells seem to be promising for efficient wide-band photodetectors of natural light.     

Biotemplate fabrication of SnO<Subscript>2</Subscript> nanotubular materials by a sonochemical method for gas sensors

A sonochemical method is developed to fabricate SnO₂ nanotubular materials from biological substances (here, it is cotton). The cotton fibers in SnCl₂ solution were first treated with ultrasonic waves in air, followed by calcinations to give nanotubular materials that faithfully retain the initial cotton morphology. The microstructure and morphology of the obtained SnO₂ nanotubules were characterized by the combination of field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and N₂ adsorption/desorption measurements. The thermal behavior and crystalline properties were examined in the temperature range of 450–700 °C. The nanocrystals composing of SnO₂ nanotubules were estimated about 8.5, 13.2, and 14.2 nm corresponding to calcination temperatures of 450, 550, and 700 °C, respectively. The sensor performance of biomorphic SnO₂ nanotubules calcined at 700 °C was investigated in the atmosphere of ethanol, formaldehyde, carbinol, carbon monoxide, hydrogen, ammonia, and acetone, respectively, which exhibited a good selectivity for acetone at a working temperature of 350 °C. The sensitivity to 20 ppm acetone, S, was 6.4 at 350 °C with rapid response and recovery (around 10–9 s). These behaviors were well explained in relation to the morphology of the nanotubules thus produced.     

Nanocrystallization of an amorphous Fe<Subscript>80</Subscript>B<Subscript>20</Subscript> alloy during severe plastic deformation

The structural evolution of an amorphous Fe₈₀B₂₀ alloy subjected to severe plastic deformation at room temperature or at 200°C was studied. Deformation leads to the formation of α-Fe nanocrystals in an amorphous phase. After room-temperature deformation, nanocrystals are localized in shear bands. After deformation at 200°C, the nanocrystal distribution over the alloy is more uniform. Possible causes of the crystallization of the amorphous phase during severe plastic deformation are discussed.