In this work, we present a detailed study on the magnetocaloric effect near the first-to-second order magnetic phase transformation of La_0.7Ca_0.25Ba_0.05MnO₃ nanoparticles with averaged crystallite sizes D = 39–79 nm. The ferromagnetic-paramagnetic phase-transition region of the bulk sample (exhibiting the first-order nature) becomes more broadened in nanoparticles (exhibiting the second-order nature). Based on isothermal magnetization data, M(H), we calculated magnetic entropy change versus temperature, ΔS_m(T), of the samples under magnetic-field changes ΔH = 0–30 kOe. As a result, |ΔS_m| reaches the maximum value (|ΔS_max|) around T_C = 258–262 K. With ΔH = 30 kOe, |ΔS_max| values obtained from the samples are located in the range 4.38–5.63 J·kg⁻¹·K⁻¹, corresponding to refrigerant-capacity values RC = 138–141 J·kg⁻¹. Field dependences of |ΔS_max| and RC can be expressed by a power law, with |ΔS_max| = a·Hⁿ and RC = b·H^N. Interestingly, all the ΔS_m(T) curves of the samples undergoing the second-order phase transition at different applied fields are collapsed onto a universal curve, which is obtained by normalizing the ΔS_m(T, H) curves to their respective ΔS_max value, and rescaling the temperature axis above and below T_C with θ = (T − T_C)/(T_r − T_C), where T_r is the reference temperature.

The Ising spin model with random competing ferromagnetic, antiferromagnetic exchange interactions in the external field is used to investigate the First Order Magnetization Process at low temperature in doped polycrystalline magnetic perovskite Pr_0.5Ca_0.5Mn_1−xM_xO₃ (M = Co, Ga). Using Callen identity in the correlated effective field approximation, our calculation describes well the experimental behavior, which is explained by the reorientation of antiferromagnetic clusters and by the expansion of ferromagnetic clusters in the external field at low temperature. The origin of the number of critical fields at which the steps of magnetization occurred, the magnitude of these steps and the related jumps in the magnetic field dependent resistivity are also discussed.

The influence of the tantalum buffer layer on the magnetic anisotropy of perpendicular Co-Fe-B/MgO based magnetic tunnel junctions is studied using magneto-optical Kerr-spectroscopy. Samples without a tantalum buffer are found to exhibit no perpendicular magnetization. The transport of boron into the tantalum buffer is considered to play an important role on the switching currents of those devices. With the optimized layer stack of a perpendicular tunnel junction, a minimal critical switching current density of only 9.3 kA/cm² is observed and the thermally activated switching probability distribution is discussed.

The Co-Ni-P nanorods were fabricated by electrodeposition method by using the porous polycarbonate template. The investigation by mean of X-ray diffraction and high-resolution transmission electron microscopy indicated that samples were nanocrystalline clusters embedded in the amorphous base. The samples exhibited a room temperature ferromagnetism with the high magnetic anisotropy along the rod. The applied magnetic fields during the fabrication of the Co-Ni-P nanorods was strongly influenced by the magnetic properties. The M_R/M_S ratio and coercivity rapidly increased when the magnetic applied field changed from 0 to 0.21 T.

We used the modified Arrott plot method to analyze magnetic-field dependences of magnetization, M(H), around the ferromagnetic-paramagnetic (FM-PM) phase-transition temperature (T_C) of three nanocrystalline La_0.7Ca_0.3MnO₃ samples with average crystallite sizes d = 40, 23, and 16 nm. The analyses obtained the values of critical parameters to be T_C ≈ 261 K, β = 0.485 ± 0.005, γ = 1.051 ± 0.094 and δ = 3.1 ± 0.1 for the sample with d = 40 nm, T_C ≈ 252 K, β = 0.525 ± 0.010, γ = 0.893 ± 0.139 and δ = 2.7 ± 0.1 for d = 23 nm, and T_C ≈ 236 K, β = 0.621 ± 0.008, γ = 0.825 ± 0.007 and δ = 2.2 ± 0.2 for d = 16 nm. With these critical values, the M(H) data points around T_C of the samples fall into two universal branches of a scaling function M(H, ε) = |ε|^βf_±(H/|ε|^β+γ), with ε = (T − T_C)/T_C, f₊ for T > T_C and f₋ for T < T_C. The results reveal that the crystallite-size reduction of nanoparticles decreases the T_C value. This is ascribed to the decrease of FM double-exchange interactions between Mn³⁺ and Mn⁴⁺ ions, which is related to the β change from 0.485 for d = 40 nm to 0.621 for d = 16 nm, corresponding to the change in FM order from the long-range type to the short-range one.

Crystal structure and magnetic properties of Cerium-doped La_1−yCe_yFe_11.44Si_1.56 (y = 0.0 − 0.3) compounds are reported. The compounds possess the NaZn₁₃-type cubic structure with ferromagnetic arrangement. The substitution of Ce into the host lattice slightly decreased the lattice constant from 1.1477 to 1.1471 Å, and as the doping content increased, the saturation magnetization and Curie temperature of the samples were also reduced. A large value of the magnetic entropy change ΔS_m was observed at low doping concentration.

We report the effect of nickel doping on the structural, optical, and magnetic properties of Bi_0.5K_0.5TiO₃ nanocrystal. The X-ray diffraction results indicated that Ni was substituted into the Ti sites in Bi_0.5K_0.5TiO₃ and the NiTiO₃ phase was formed when Ni concentration was higher than 3 mol%. The band gap value decreased from 3.31 eV to 2.96 eV when the Ni concentration changed from 0 to 3 mol% and then increased with higher Ni concentration. Both weak-ferromagnetism and diamagnetism coexisted in un-doped Bi_0.5K_0.5TiO₃ samples. The ferromagnetic signal strongly influenced the paramagnetic signal for Ni-doped Bi_0.5K_0.5TiO₃ samples at room temperature. The room-temperature ferromagnetism in Ni-doped Bi_0.5K_0.5TiO₃ samples could be contributed by intrinsic reason due to presence of Ni ion in Bi_0.5K_0.5TiO₃ crystal and by extrinsic reason due to segregation of NiTiO₃ clusters when Ni concentration was over 3 mol% threshold. This method may provide a useful way to get both single-phase multiferroics and composite multiferroics materials.

The site-selective occupation of point defects, Y³⁺ ions (Y′_Zr) and O²⁻ vacancies (V_\ddot{O}), and their associations at a symmetric tilt grain boundary (GB) are studied to understand their competitive contribution to energetically favorable atomic arrangements by using atomistic simulations. It is found that at the GB there are the favorable sites for segregation of an isolated Y′_Zr and V_\ddot{O}. This indicates that the driving force for the site-selective segregation is present. Moreover, our results of Y′_Zr-V_\ddot{O} association at the GB show that the lattice energies are very dispersed despite that a second-nearest neighbor (SNN) vacancy to Y′_Zr is favored for bulk Y₂O₃-doped ZrO₂. The result suggests that the site-selective segregation has significant effects on the favorable point defect arrangement at the GB core, competing with the point defect associations. For more realistic cases, Monte Carlo simulations are performed to reveal favorable atomic arrangements for a high dopant concentration, where point defects are crowded at the GB. The results show that the region of GB segregation can be classified with respect to O²⁻ coordination to cation species; at the GB core the favorable configuration is not necessarily a SNN O²⁻ vacancy relative to Y³⁺. On the other hand, eight-fold O²⁻ coordination is sustained for Y³⁺ ions more than ∼3 Å distant from the GB plane. The difference in O²⁻ coordination may play an important role in O²⁻ ionic conductivity at GBs via the energetics for O²⁻ migration.

Stability of 12CaO·7Al₂O₃ (C12A7) crystal under high-pressure conditions is investigated by sample recovery experiments and first-principles calculations. After high-pressure and high-temperature treatments, C12A7 crystal is mainly decomposed to 2CaO·Al₂O₃ (C2A) and 4CaO·3Al₂O₃ (C4A3). According to first-principles calculations, the volume of C12A7 crystal is larger than that of [4(C2A)+C4A3]. From energetic point of view, C12A7 is stable at 0 GPa but it becomes unstable as pressure increases. This is caused by large volume of C12A7 at 0 GPa while the contribution of volume shrink of each substance is rather small. This indicated that the volume at 0 GPa is a dominant factor in these systems under high-pressure.

A facile method for fabricating thin films of granular tungsten oxide (WO₃) particles decorated with nickel oxide (Ni₂O₃) nanoparticles was developed for high response NH₃ gas sensor. The WO₃ granular film was fabricated by sputter deposition of tungsten, followed by oxidation. Ni₂O₃ nanoparticles were deposited onto the WO₃ film by arc-discharge deposition of single-wall carbon nanotubes (SWCNTs) with Ni catalyst nanowires, followed by burning the carbon nanotubes. The Ni nanoparticle catalysts deposited on the SWCNTs were then oxidized to Ni₂O₃. The Ni₂O₃ nanoparticles on the surface exhibited a catalytic role in ammonia gas reactions. A maximum response of 13.5 at operating temperature of 250°C to 200 ppm NH₃ gas concentration was found. In addition, the gas sensing mechanism of Ni₂O₃ decorated WO₃ film was also discussed in this study.

A series of sol-gel lead nickel titanate powder with composition of PbTi_1−xNi_xO₃, where x = 0.00, 0.03, 0.06, 0.08, 0.10 and 0.12, were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and magnetization (M-H) curves. XRD patterns show that PbTi_1−xNi_xO₃ materials well crystallize in tetragonal phase. The tetragonal distorted ratio c/a of PbTi_1−xNi_xO₃ was found to decrease with the increase of Ni content and to increase with increasing calcining temperature. The mean size of PbTi_1−xNi_xO₃ crystal particles gradually decreased with increasing Ni content. Some Raman modes shifted to lower wavenumbers when Ni content increases, that is assigned to the variation of crystal structure due to the incorporation of Ni into PbTiO₃ crystal. In addition, the results of room temperature magnetization measurements present an obvious improvement of ferromagnetism when Ni content increases in the range from 3 to 12 mol%.

We have grown un-doped and transition metal (V, Cr, Mn, Fe, Co, Ni, Cu)-doped Ge bulk single crystals using the vertical gradient solidification method. The electrical resistivities of V, Ni, Co, and Fe-doped Ge crystals significantly increased, 10⁴∼10⁵ times, between 5 and 100 K, which were 100 times larger than that of the commercial Ge resistance temperature device (RTD). The large variation of electrical resistance at low temperature arises from decreased carrier density and mobility at low temperature. The mobility reduction at low temperature might be caused by ionized impurity scattering.

This paper presents a systematic investigation of typical characterizations of Sr(_1-1.5x-0.5y)Dy_xTi_1-yNb_yO₃ composition based on single Nb- and Dy-doped as well as Nb/Dy co-doped SrTiO3. Nb concentration of 10, 13, 17, 20 and 24 at% and Dy concentration of 4, 8, 10, and 13 at% were used for different doping compounds. XRD data was used to calculate the lattice constants. The limit of solubility of doped element in host lattice was determined based on the graph showing the dependence of lattice parameters on doping concentration. The thermoelectric properties were investigated from 20 to 1000°C or 293 to 1273 K. The electrical conductivity increases below 600 K but decreases above 600 K with increasing doping content for all cases. This characterization reached about 900 S/cm at 570 K with 4% dysprosium and 20% niobium doped in STO. Both the electrical and thermal conductivity of single Nb-doped samples increase with increasing Nb content. In contrast, the thermal conductivity of single Dy doping decreases with increasing Dy content and consequently best absolute values of Seebeck coefficient. Generally, increasing doping concentration provides larger magnitude of Seebeck coefficient for all cases of doping. The best magnitude of the figure of merit reaches approximately 0.17 at 1273 K. The optimized composition should comprise quaternary compounds of which is Sr_0.84Dy_0.04Ti_0.80Nb_0.2O₃, especially for fast cooling regime.

Lead-free BCT-xBZT solid solutions were prepared by the conventional solid-state reaction route. A full set of elastic, piezoelectric, and dielectric parameters were measured using a resonance method and calculated following the formulae in the IEEE standard for piezoelectric ceramics. In addition, ferroelectric properties were also investigated to demonstrate the “softening” and the diffuse transitions in the material.

Ba_1−xCa_xTiO₃ samples (x = 0.0–0.30) were prepared by a solid state reaction method. X-ray diffraction patterns of the prepared samples show that the samples containing Ca²⁺ concentration lower than 14 at% were identified to tetragonal phase of BaTiO₃. In the samples with Ca²⁺ concentration higher than 14 at% CaTiO₃ appears and coexists with BaTiO₃. The dielectric constant at room temperature of all the samples was measured in a frequency range from zero to 2.5 MHz. A modified Cole-Cole formula was used to fit the experimental data. The fitting results show that the samples exhibit a single relaxation process that suggests BaTiO₃ and CaTiO₃ coexist in a nested hybrid form in the samples with Ca concentration in a range of (0.14–0.30). An abnormal dependence on the Ca²⁺ concentration of the dielectric relaxation time was observed and supposed to be related with a pinning effect due to the local point-deformation caused by Ca²⁺ substitution and/or with a nesting of BaTiO₃ and CaTiO₃ in a hybrid form.

Lead-free ceramics of composition (0.97 − x)Bi_0.5Na_0.4K_0.1TiO₃-0.03BiAlO₃-xBi_0.5Li_0.5TiO₃ (BNKTBA-xBLTO) were synthesized using solid state technique. The strong enhancements in ferroelectric and electric-field-induced strain were obtained. The electric-field-induced strain values were increased from 410 pm/V to 688 pm/V for 6 mol% BLTO-added which results from the phase transition from rhombohedral to tetragonal structure. The maximum spontaneous polarization increased from 26.5 µC/cm² to 30.8 µC/cm² for 4 mol% BLTO solid solution in BNKTBA and then decreased as BLTO was further added. We expect that this work could be helpful for further understanding the original enhancement in electrical field-induced strain in lead-free BNKT-based ceramics due to comparison between A- and B-site co-modifications.

The exemplars of gold carbide AuC in cubic F-43m structure and cluster form Au₆C₃ are reported. The characteristics of structures were obtained on basis of Time-Dependent Density Functional Theory (TD-DFT) embedded within the framework of Generalized Gradient Approximation (GGA) and utilized Pardew-Burke-Ernzerhof functional (PBE) and spin-polarized wave functions. We found that the modeled forms of gold carbide exhibited no ferromagnetism while maintaining metallic ground state. The calculation showed the dominance of optical transitions which preserved spin.

We studied the optical, electrical, and structural properties of indium-free Zr-doped ZnO (ZZO)/Ag/ZZO multilayers prepared on poly(ether sulfone) (PES) substrates by RF magnetron sputtering at room temperature. The optical and electrical characteristics of the crystalline ZZO/Ag/ZZO multilayer electrodes can be improved by the insertion of a nano-sized Ag interlayer with an optimized thickness between top and bottom ZZO films, owing to the very low resistivity. The ZZO/Ag (12 nm)/ZZO/PES exhibited high transmittance of ∼85.6% in the wavelength range from 450 to 600 nm and a low resistivity of ∼6 × 10⁻⁵ Ω·cm. Additionally, X-ray photoelectron spectroscopy (XPS) investigations for the ZZO/Ag/ZZO multilayers confirmed no interfacial reaction between the ZZO and Ag films. The performances indicate that the indium-free ZZO/Ag/ZZO multilayers are promising as transparent conducting films for low-cost flexible optoelectronics applications.

We simulated the interaction of the small nucleotide chain (NC) with gold nanoparticles (NPs) inside carbon nanotube (CNT) of an open ended boundary. Such system represents a great interest in many aspects of today biochemical and nanotechnological research (diagnostic applications, drug delivery in cell, nanorobotic design and related manipulations). The entire system (the NC chain, gold NPs and CNT) were allowed to interact with each other by the Van der Waals (VdW) forces only. The CNT was described through a quantum-chemistry potential, though the trajectory calculation for the whole NC-NP-CNT model was performed via the classical molecular dynamics (MD) approach. The Lennard-Jones short-ranged interaction is assumed between the NC, NP and CNT. We have carried out a series of MD simulations on different NC-NP-CNT configurations to investigate the pequliarities of NC-NP bonding and structural formation along with dynamical behavior inside a CNT matrix under rather a weak VdW interaction.

The MnBi low temperature phase with high value and positive temperature coefficient of its coercivity has a potential for production of both the nanocomposite and hybrid permanent magnets. In this report, we present our results of investigation of fabrication of Mn₅₅Bi₄₅ nanoparticles by using high energy ball milling method. The Mn₅₅Bi₄₅ alloy was first arc-melted and then ball-milled for various time of 0.25–8 h in different environments of Argon, Alcohol, Petrol and Xylene. The resulted powder was subsequently annealed at temperatures of 200 and 250°C for time periods of 0.5–4 h in Ar gas. The fraction of the MnBi low temperature phase and the size of the particles strongly depend on the fabrication conditions. The desired MnBi nanoparticles with size of 25–100 nm and coercivity μ₀H_c > 1 T can be achieved by choosing appropriate fabrication conditions.

Multi-walled carbon nanotubes (CNTs) were directly grown on alumina substrates patterned with Pt interdigitated electrodes by chemical vapor deposition method to fabricate gas sensor. Pt and Ag thin layers with nominal thicknesses of 2 and 4 nm were coated on the CNT layer by evaporation method to modify the CNT properties. The gas sensing results showed that the CNT/Pt- and CNT/Ag-based sensors exhibited enhanced sensitivity to NH₃ gas at room temperature. The responses of the CNT/Pt (3.0%) and CNT/Ag (6.9%) sensors with a 4 nm thick metallic layer to 70 ppm NH₃ were higher than that of pristine CNT sensor (1.5%).

Three Pt-CuO nanocatalysts PtCu/Al, PtCu/CeAl and PtCu/Ce have been successfully prepared. The characterization of the catalysts was examined by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray energy dispersive analysis (EDS), temperature-programmed reduction (TPR), nitrogen physisorption measurements, and IR-CO adsorption. The kinetics of CO oxidation using these catalysts was studied in a gradientless flow-circulating system at 398–498 K. The obtained kinetic equation confirmed that the reaction proceeds in medium surface coverage with the participation of CO molecules and oxygen atoms.

The quantum acoustoelectric (QAE) current is studied by a quantum kinetic equation method and we obtain analytic expression for QAE in a cylindrical quantum wire with an infinite potential (CQWIP) GaAs/GaAsAl. The computational results show that the dependence of the QAE current on the radius of CQWIP GaAs/GaAsAl, the Fermi energy ε_F and temperature T is non-monotonic, and the appearance of peak when the condition ω _q = ω _k + ћ²(B²_n’,N’ - B²_n,N) / 2mR² (n ≠ n’ and N ≠ N’) is satisfied. Our result indicates that the dominant mechanism for such a behavior is the electron confinement in the CQWIP GaAs/GaAsAl and transitions between mini-bands. All these results are compared with those for normal bulk semiconductors and superlattice to show the differences. The dependence of a QAE current on some qualities in a CQWIP GaAs/GaAsAl is newly developed.

We have used a top-down approach of the mechanical milling to fabricate Y₂O₃:Eu³⁺ nanoparticles (NPs), and then studied their crystal structure and photoluminescence (PL) properties based on X-ray diffraction (XRD), electron paramagnetic resonance (EPR) and PL spectroscopy. XRD results revealed that the change of the milling time (t_m) from 0 to 540 minutes (min) decreased the average crystallite size (d) of NPs from ∼83 nm (for t_m = 0 min) to below 3.5 nm (for t_m = 540 min). This varied lattice strain and defects, and caused the structural changes, which influenced directly the PL properties of NPs. Among the fabricated NP samples, those with t_m = 5–10 min (corresponding to d ≈ 25–40 nm) offer strongest PL intensity at ∼611 nm (due to the electronic transition ⁵D₀ → ⁷F₂). The increase of the longer milling time (i.e., lowering d) reduces quickly the intensity of this emission, but slightly increased the intensity of auxiliary emissions. The nature of the observed phenomena was discussed.

Preparation and spectroscopic studies of the TiO₂ nanopowders doped with Eu³⁺ ions are described. Efficient emission in the red part of the visible spectrum can be obtained due to the ⁵D₀ → ⁷F₂ emission of europium ions. Quantum efficiency of such emission was estimated to be about 0.83, which indicates a rather weak role of the non-radiative losses. However, the increase of Eu³⁺ concentration up to 10 at% significantly lowers the quantum efficiency because of the energy transfer and re-absorption processes. Higher doping concentrations (larger than 3 at% of Eu³⁺) also decrease the covalency of the Eu³⁺–O²⁻ chemical bonds.

In this work, the Ce/Tb/Sm doped glasses with the composition of TeO₂-B₂O₃-ZnO-Na₂O were synthesized by melt quenching process. The photoluminescence properties of glasses doped with Ce³⁺, Tb³⁺ and Sm³⁺ single, doubly and triply doped TeO₂-B₂O₃-ZnO-Na₂O (TBZN) were studied by mean of emission and excitation spectra. There was an overlap between Ce³⁺ emission and Tb³⁺, Sm³⁺ absorption in the wavelength range of 350–500 nm. Therefore, it was expected that an efficient energy transfer occurred from Ce³⁺ to Tb³⁺ and Ce³⁺ to Sm³⁺ ions. When excited by ultraviolet wavelengths the co-doped glasses emit a combination of blue, green and red orange forming white light.

LaPO₄ nanowires doped with 0, 1, 2, 3, 4 and 5 mol% Sm³⁺ were prepared by co-precipitation technique. These nanowires were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), photoluminescence excitation (PLE) spectra and energy-dispersive X-ray spectra (EDS). The PL spectra exhibited 4 groups of emission peaks, which are assigned to the transitions from the excited state ⁴G_5/2 to the ground states ⁶H_J with J = 5/2; 7/2; 9/2 and 11/2 of Sm³⁺ ions. The intensity of PL related to Sm³⁺ ion reached to a maximum when the Sm doping content was 2 mol%. The PLE spectra show 8 peaks, which are attributed to the absorption transitions from the ⁶H_5/2 ground state to the ⁴K_15/2, ⁴D_3/2, ⁶P_7/2, ⁴F_7/2, ⁶P_5/2, ⁴G_9/2, ⁴I_13/2 and ⁴I_11/2 excited states.

The molecular and electronic structure of the 1:1 charge-transfer complex between ferrocene (Fc) and zinc porphyrin (ZnP) are investigated with the aid of dispersion-corrected density functional theory (DFT) calculations. Four stable configurations were obtained, two with the Fc molecule laying on the ZnP plane and the other two where Fc interacts with the porphyrin’s perimeter. The dipole moment vectors of these Fc:ZnP complexes indicate that they are stabilized by the transfer of electronic charge density from Fc to ZnP or vice versa.

A solid-contact ion-selective electrode for mercury (II) ions was fabricated to determine Mercury (II) in aqueous environment. A conductive polymer membrane (polypyrrole-PPy) was synthesized electrochemically on paste carbon electrode, which is covered by the ion-selective membrane (ISM) — an important part of a complete solid contact ion selective electrode (SCISE). The electrode showed excellent potentiometric response over a wide concentration range from 10⁻⁹ M to 10⁻² M and detection limit down to 6 × 10⁻¹⁰ M. A good selectivity towards Hg²⁺ ions in comparison with other common ions in water has also been observed. The electrode was employed for determination of Hg²⁺ in ballast water samples with high sensitivity and accuracy.

In this work we present a study on sorting and trapping some living human cells, including red blood cells (RBCs) and breast cancer cells (denoted T47D), by using patterned micro-magnets with dimensions of each micro-magnet 50 × 50 µm². The diamagnetic properties of these cells and the force exerted on them along the z-axis have been investigated. The diamagnetic levitation height of each cell has been both theoretically calculated and experimentally studied. The results open a novel possibility for positioning living cells with further applications to medical diagnostics.

Mesoporous poly(vinylsulfonic-co-divinylbenzene) (VS-DVB) and magnetic polymer (VS-DVB/CoFe₂O₄) are prepared and used as solid acidic catalysts to directly transform cellulose into 5-hydroxymethylfurfural (5-HMF). The characteristic and morphology of the polymers were examined by Fourier transformed infrared spectroscopy, X-ray diffraction, vibrating sample magnetometer, field-emission scanning microscope, and transmission electron microscopy. The yield of 5-HMF can reach as high as 98% from the dehydration of glucose using CrCl₃·6H₂O catalyst in tetrabutylammonium chloride at 120°C for 90 min. Cellulose conversion using the prepared VS-DVB in 1-butyl-3-methyl imidazolium chloride at 120°C for 180 min showed high yields of 50% glucose and 10% 5-HMF. An enhancement in 5-HMF yield was observed as reaction time increased. A combination of VS-DVB/CoFe₂O₄ and CrCl₃·6H₂O in ionic liquids was employed at optimal conditions for cellulose conversion. Magnetic catalysts were readily separated from resulting products in the magnetic field, as well as recycled and reused with negligible loss in activity. Glucose and 5-HMF yields were determined through high-performance liquid chromatography analysis.

A new method of extracting interatomic separation of CO₂ is proposed based on using the dipole moment extracted from high-order harmonic generation (HHG) spectra. For this method, we show that the Bragg’s equations related to the electron interference effect can be obtained from the zero-points of the dipole moment. Using not only HHG with parallel polarization but also HHG with perpendicular one we discover an error-compensation effect which means that the errors of interatomic separation extracted from the two components of dipole moment are always opposite in the sign. Therefore, the final result of the interatomic separation obtained by the proposed method has a very high accuracy with the systematic error less than 1%.

In situ measurements of work function of indium tin oxide after UV/ozone treatment were carried out using a photoemission yield spectrometer with an open counter. Although the work function increased just after UV/ozone treatment, it decreased as time passed and finally returned to the initial value. The continuous change in work function with exposure to air was observed under dry atmosphere and at various temperatures. The returning process at higher temperature proceeded faster than at lower temperature. By contrast, humidity has no influence on the work function recovery. The exponential decay of work function was consistent with the first-order reaction rate equation. The rate constant obeyed Arrhenius’ equation, and the activation energy was estimated to be 22 kJ/mol.

Soft X-ray absorption near-edge structures (XANES) at the L_2,3-edges of transition metal has been widely used for investigating the chemical reactions during charge-discharge cycles in the cathode materials of lithium ion batteries. In order to extract the information about the electronic structures from the experimental results, however, a theoretical tool that can deal with the strong electronic correlations between 2p and 3d electrons is necessary. In this study, the ab-initio multiplet method based on the relativistic configuration interaction (CI) method has been applied to the calculations of Fe-L_2,3 XANES of LiFePO₄ and FePO₄. Experimental XANES spectra were quantitatively reproduced by this method. The effects of local symmetries around Fe ions to the spectral shapes were also discussed.

We have performed theoretical analysis of thermal expansion of carbon and boron nitrides under finite temperature based on first principles phonon state calculations. Volume dependence of phonon density of states and thermodynamic functions such as heat capacity and vibrational free energy were theoretically examined. Through the volume dependence of vibrational free energy, thermal expansion at finite temperature is reproduced within quasi-harmonic approximation (QHA). Our calculation results have demonstrated that thermal expansion coefficients of typical ceramics materials (diamond, graphite, c-BN and h-BN) are reasonably well reproduced with the first principles approach employing QHA calculations.

Na-incorporated β-tricalcium phosphate (β-TCP) was synthesized via the solid-state reaction method and a substitution mechanism for Na ions in the synthesized materials has been investigated by X-ray absorption near-edge structure (XANES) analysis. In addition, total electronic energy calculations within density functional theory were also carried out to obtain the most energetically favorable substitution site for Na ions in β-TCP. Both the spectroscopic and computational analysis indicate that substituted Na ions are likely to occupy Ca(4) site in β-TCP.

Systematic atomistic simulations of homo- and hetero-phase boundaries have been carried out to quantify interphase boundary energies in iron including δ-phase and γ-phase grain boundaries and δ/γ, δ/liquid and γ/liquid interfaces. Due to structural mismatch between body centered cubic (BCC) and face centered cubic (FCC) structures of the δ and γ phases, the minimum interface energy of the δ/γ interface is as high as 0.41 J/m², much higher than the minimum interface energies of the δ/δ and γ/γ homo-phase interfaces, which are zero, suggesting that the high interface energy is one of the key factors that lead to the massive-like phase transformation from the δ phase to the γ phase observed by in situ radiography. Although the minimum δ/γ interface energy is not significantly higher than the δ/liquid interface energy that determines the δ nucleation upon solidification, it is yet high enough for the small entropy change upon the phase transformation to inhibit γ nucleation at a given critical radius until more than one orders of magnitude higher undercooling is achieved according to the classical theory of homogeneous nucleation.

Effective interface energies of various homo- and hetero-interfaces of iron were calculated with an aid of phase-field modeling, taking into account geometric constraints by competition among grains or interfaces. Calculated effective interface energies for δ/γ, δ/δ, and γ/γ interfaces are 0.56, 0.44 and 0.37 J/m², respectively. Using two simple geometric models for nucleation on or off an interface in the matrix, the optimal shape of a nucleus at a given radius and undercooling, a critical radius and an energy barrier for nucleation for each possible circumstance were numerically calculated. It is found that, although the energy barrier for γ-phase nucleation in homogeneous δ-phase matrix is more than three orders of magnitude greater than that for homogeneous solidification of δ-phase, the γ nucleation on a δ/δ grain boundary in the solidifying matrix suppresses the energy barrier, increasing a nucleation rate. Furthermore, it is found that the γ-phase nucleation on an existing γ nucleus halves undercooling needed with smaller critical radius. This suggests that, once γ nucleation is initiated, then following γ nucleation is promoted by doubled driving force, enabling multiple γ nucleation as in chain reaction. These findings are sufficient to explain experimentally observed phenomena during the δ-γ massive-like phase transformation even if other factors such as solute re-distribution or transformation is neglected.

First principles calculations have been carried out in conjunction with lattice dynamics to evaluate free energies of ternary intermetallic phases, Al₂Si₂X (X = Ca, Sr, Ba, Eu, Y, Yb). The most stable crystal structure is identified for each X as a function of temperature. It is found that some of the intermetallic phases are stable over wide temperature range, thereby giving ability to modify and refine Al-Si eutectic phases with better mechanical properties. Substitution energy of the intermetallic phase is evaluated to aiming at examining the magnitude tolerance of the intermetallic phases with respect to deviation of chemical composition. Finally, the role of Al₂Si₂X as a modifier is examined from a solely geometric viewpoint, which provides yet another possible factors among many behind the X species dependence on modification of eutectic Si without using existing theories.

It is shown that 21 monolayers of Manganese films grown on Cu₃Au(100) at room temperature have an uncompensated layered antiferromagnetic structure that show a deviation from this configuration due to structural imperfections. In some areas of the film a p(2 × 2) magnetic super-structure was observed on the surface.

Investigated the nano-scale Fe₃O₄ which is ferrimagnetic material that has attracted attention as an application of the spintronics. In order to investigate the magnetization process of Fe₃O₄ of ferrimagnetism, we report the results that derive the magnetic hysteresis loop with various parameter by the computer simulation using the retarded trace method.

The Curie temperature, phase transformation, microstructure and magnetic properties of Fe-10Cr-xCo alloys with low Cobalt content were analyzed after casted and solid solution quenched, respectively. The results show that the experimental Curie temperature increases from 1043 K to 1065 K with differential Co content addition, and which is about 50 K higher (as can be called “the degree of superheat”) compared with the calculated data. Besides, addition of Co promotes the formation of α-ferrite phase, and thus leads to the decrease of Vickers hardness. According to X-ray diffraction results, B2 type ordered structure forms, and Cr_1.07Fe_18.93 was observed in all the samples, whereas, CoFe_15.7 only can be found in the sample with the addition of Co is more than 2 mass%.

In a recent work, a hydrogenation process of palladium has been studied by the acoustic emission (AE) method with a new gas pressure cell. The high H₂ gas pressure condition can, however, be easily provided by an electrochemical hydrogen charging technique. In this paper, characteristic AE power spectra caused by cavitation and/or bubble burst have been appraised by using an electrochemical separated AE cell. A typical AE signal induced by Pd hydride formation has been observed. The fundamental AE mode was 250 kHz in the Pd hydride formation stage, which was equal to the frequency measured by using the gas pressure cell as a standard hydrogenation technique.

Fe-Ni system has been attracting broad attentions as an Invar alloy. Although the origin of the Invar effects has been explained based on the temperature variation of alignments and magnitudes of magnetic moments, two of the present authors (YC and TM) reported that the non-monotonous temperature dependence of Coefficient of Thermal Expansion (CTE) were realized even without considering spin configurations explicitly. In the present study, we clarified that the main cause of the non-monotonous temperature dependence in CTE was atomic configuration effects which were originated from a peculiar concentration dependence of lattice constant in Fe-Ni system.

We have studied the variation in tensile strength (σ_b), fracture strain (ε_f) and Young modulus (dσ/dε) of low voltage electron beam irradiation (HLEBI) on powdered ultra-high molecular weight-polyethylene from 0.043 to 0.43 MGy prior to sintering. The low dose of 0.043 MGy-HLEBI enhanced the σ_b, ε_f and dσ/dε, as well as increased the crystallinity ratio from 37 to 46% evaluated by differential scanning calorimetry (DSC). An additional dose apparently decreased the σ_b and ε_f, as well as the melting point from approximately 412 to 406 K and the crystallinity ratio from 46 to 43% for 0.043 to 0.43 MGy, respectively. Irradiation induces two competitive mechanisms, namely (i) the scission of chains and (ii) the crosslinking of chains. The discussion is focused on these mechanisms.

Calcium carbonates, the main component of seashell waste, can be converted to hydroxyapatite (HA) via phosphate solution treatment. HA can remove F⁻ from water, as recommended by the World Health Organization (WHO), and HA particles of small sizes and/or large amounts are expected to remove F⁻ more effectively. To control the size and amount of synthesized HA, oyster shells were treated in the (NH₄)₂HPO₄ solution whose pH value was adjusted to 10 at 4–120°C for 24 h. The HA particle size and amount increased with increasing reaction temperature. The samples’ abilities to remove F⁻ were evaluated by immersing them in F⁻-containing solutions. The sample treated at 30°C removed F⁻ the most effectively, achieving a F⁻ concentration below 1.5 mg·dm⁻³, which is the level recommended by the WHO. The HA surface area is important in F⁻ removal.

The diffusivity and solubility limit of Cu in A533B steel, which is used in reactor pressure vessels, were studied by atom probe tomography (APT). Cu-A533B steel diffusion couples were annealed at temperatures of 550, 600, and 700°C, and the resulting Cu concentration profiles were measured. At the temperature of 700°C, the diffusivity of Cu in A533B steel was about 3 times higher than that in pure Fe, whereas at the temperature of 550°C, the diffusivity of Cu in A533B steel is almost closer to that in pure Fe. The solubility limit of Cu in A533B steel was similar to pure Fe. APT was also used to study the effect of the grain boundary (GB) diffusion. The results indicated that no Cu segregation occurred at GB near the Cu/A533B steel interface, which may imply that GB diffusion of Cu was not effective in A533B steel.

The effects of homogeneous low energy (170 keV) electron beam irradiation (HLEBI) on the adhesion force indicated by peeling resistance (^oF_p) at each accumulative probability of peeling resistance (P_p) of laminated sheets of carbon fiber reinforced epoxy polymer (CFRP) and polytetrafluoroethylene (PTFE) were investigated. The slight detectable adhesive force of ^oF_p before treatment were 0.3 and 7.6 Nm⁻¹ at low and mid P_p of 0.06 and 0.50, respectively, since the intermolecular attractive force exists at PTFE and epoxy polymers at cross-linking zone. Although additional dose of HLEBI apparently reduced the ^oF_p of laminated sheets irradiated at more than 0.30 MGy as usual radiation damages, small dose of 0.04 to 0.22 MGy-HLEBI increased the adhesive force of peeling (^oF_p) substantially over the untreated. 0.13 MGy-HLEBI enhanced the ^oF_p up to the largest values of 9.8 and 44.0 Nm⁻¹, respectively, which were more than 30.5 and 5.8 times larger than those before treatment. Based on the 3-parameter Weibull equation, the statistically lowest ^oF_p value at P_p = 0 (F_s) was increased from zero to 9.2 Nm⁻¹ by applying the 0.13 MGy HLEBI. XPS (X-ray photoelectron spectrometry) measurements detected the fluorine (1s) signal on peeled surface of CFRP side indicating the residual PTFE adhered well to the epoxy of CFRP by the HLEBI. Thus, the fracture probably propagated through the PTFE inside near cross-linking zone of interface. This is probably a result of adhesion force of PTFE/CFRP being made stronger than the cohesive force of epoxy polymer. When HLEBI cut the chemical bonds and generated active terminated atoms with dangling bonds of Epoxy and PTFE polymers in cross-linking zone with chemical bonding around adhesive interface, strengthening the adhesive force indicated by ^oF_p was mainly induced by the chemical bonding, as well as intermolecular attractive force in cross-linking polymers.

NiAl bronze (NAB) was produced using the friction stir processing (FSP) technique at various tool rotation rates (ω) and traverse speeds (υ). Optical microstructure (OM) observation results indicated that inhomogeneous microstructures were produced from top to bottom in the stir zone (SZ), cavity defects were found in the retreating side (RS) area due to inadequate fill of NAB material flow during FSP. Results indicate that FSP processing parameters have a significant influence on the microstructure of NAB alloy. An optimized FSP processing map was obtained from the analysis of the pseudo heat index ω²/υ. Five optimum processing parameters were selected from the processing map, which were used to investigate the effect of FSP parameters on the corrosion properties of NAB by the salt fogging corrosion test. It was determined that the corrosion properties were improved by decreasing the rotation rate at a constant traverse speed, and the grain size and the volume fraction of retained β phases were reduced by using the optimum FSP parameters. These results could optimize the microstructure and deepen the understanding of the corrosion behavior of FSP NAB.

The effects of reheating temperature and time on the microstructure and mechanical properties of thixoforged ZW21 alloy were investigated. The results indicate that the ZW21 alloy is suitable for thixoforming in view of its thixoformability and the resulting mechanical properties. The reheating temperature and duration mainly affect the microstructure, including the size and fraction of primary particles, the microstructure compactness, the solubilities of the solute elements and W phase content, and thus the mechanical properties of the thixoforged alloy. The effects of the reheating temperature are larger than that of the reheating time. These two parameters have an optimum critical value, and values less than or higher than this value decrease the mechanical properties. The appropriate reheating technique is heating for 70 min at 913 K, and the resulting ultimate tensile strength, elongation, and hardness can be up to 238 MPa, 19.4%, and 58 HV, respectively. As the reheating temperature or reheating time increases, the fracture regime has a tendency to change from intergranular mode to transgranular mode and finally to intergranular mode again.

The microstructures of Ti(C_0.7N_0.3)-19Mo₂C-xNbC-24Ni cermets (x = 0, 5, 10, 15, and 20) were studied. The cermets consisted of Ti(C,N) and solid-soluted Ti(C,N) as the hard phase with metallic Ni as a binder phase. The solid-soluted Ti(C,N) was found to surround Ti(C,N) phases, forming core-rim structures in the cermets with low NbC content. Phase separation between the Ti(C,N) and solid-soluted Ti(C,N) occurred in the cermets with higher NbC content. TEM analysis showed solid-soluted Ti(C,N) to nucleate surrouunding Ti(C,N) for 5NbC, but in 20NbC it nucleated within the Ni binder phase. The Nb content in the solid-soluted Ti(C,N) of the composite with 20NbC was higher than that of 5NbC. A hard phase separation occurred when the lattice constant of solid-soluted Ti(C,N) exceeded 4.328 Å.

A large-scale ingot of Zr-1Mo alloy was produced for industrial manufacturing to investigate whether it is possible to produce an ingot with homogeneity. The homogeneous ingot with a chemical composition of Zr-1 mass%Mo was prepared successfully. The microstructure, mechanical properties, and magnetic susceptibility were evaluated. The microstructure showed a coarse colony structure of a plate-like α phase and a thin β phase. An ω phase precipitation was observed in the β phase. Elongation of 23% and magnetic susceptibility of 12.4 × 10⁻⁹ m³ kg⁻¹ (0.98 × 10⁻⁶ cm³ g⁻¹) were achieved. We found that it is possible to produce a homogeneous large-scale ingot of Zr-1Mo with high elongation and low magnetic susceptibility.

The 304/316 series of austenite stainless steels are used in light water reactors as structural materials. As a result of the high temperatures and neutron irradiation in reactor, dislocation defects will form in stainless steel, causing an increase in the hardness and a decrease in the ductility of the material. In this work, high purity 316L stainless steel model alloys with three different Si contents were ion irradiated at 290°C or 400°C to investigate the black dot and Frank loop formation mechanism influenced by Si addition. Black dot defect formation mainly occurs at 290°C. It is Frank loop in nature with its formation not affected by Si addition. Frank loop is the main defect at 400°C, and both loop density and the average size are substantially suppressed by Si addition. This may be caused by silicon’s role in enhancing effective vacancy diffusivity and thus promoting recombination. The trend of irradiation hardening measured verses temperature matches the microstructure observed.

The influence of Nb addition on phase constitution, microstructure and mechanical properties of biomedical equi-atomic Ti-Zr based alloys was investigated. Phase constitution of Ti-Zr based alloys containing Nb rapidly cooled from β single phase changed with Nb addition as follows: α′ → α′′ + α′ + β → β + α′′ → β. Young’s moduli of Ti-Zr based alloys subjected to water quenching initially decreased with increasing Nb content. The minimal value was obtained in the Ti-48Zr-4Nb (mol%) composition alloy. The Young’s moduli increased in relation to the phase constitution change. In the alloys containing over 4% Nb, their principal phase was changed by subsequent cold rolling, this is mainly because β → α′ and β → α′′ stress-induced martensitic transformation occurred. This phase transformation resulted in a decrease of Young’s modulus. Furthermore, cold rolling impartd anisotropy to the Young’s modulus which caused the value to drop. The Ti-47Zr-6Nb alloy had the lowest value of Young’s modulus after cold rolling in this study, 59.5 GPa.