Effects of dopant content on optical and electrical properties of In<Subscript>2</Subscript>O<Subscript>3</Subscript>: W transparent conductive films

The In2O3:W (IWO) films with different W content were deposited on glass substrate using direct current sputtering method. The structure, surface morphology, and optical and electrical properties were investigated. Results showed that both the carrier concentration and carrier mobility were increased with the doping of W. The IWO film with the lowest resistivity of 1. 0× 10-3 Ω· cm, highest carrier mobility of 43. 7 cm2. W-1. s-1 and carrier concentration of 1. 4× 1020 cm-3 was obtained at the content of 2. 8 wt. ％. The average optical transmittance from 300 nm to 900 nm reached 87. 6％.     

Preparation of TiAl<Subscript>3</Subscript>-Al Composite Coating by Cold Spray and Its High Temperature Oxidation Behavior

A novel TiAl₃-Al coating was prepared by cold spray for high temperature protection of titanium aluminum-based alloy. The substrate alloy was orthorhombic-Ti-22Al-26Nb (at.%). The composite coating was mainly composed of TiAl₃ embedded in the matrix of residual aluminum. An interlayer about 10 μm was formed between the coating and the substrate. The oxidation test indicated that this composite coating was very effective in improving the high-temperature oxidation resistance of the substrate alloy at 950 °C in the tested 150 cycles without any sign of degradation. The microstructure analysis of the oxidized composite coating showed that an Al₂O₃ scale with a complex structure can be formed outside the interlayer during oxidation and no oxides beneath the interlayer were detected, which indicated that the complex continuous Al₂O₃ and the interlayer provide the protection of the substrate at high-temperature oxidation condition.     

Effects of Sc doping on electrical conductivity of BaZrO<Subscript>3</Subscript> protonic conductors

BaZr1-xScxO3-0.5x (x=0.07,0.10,0.13,0.16) powders were prepared by solid-state reaction method,and ZnO was used as sintering aid.Samples with different amount of ZnO additive were sintered at 1450 ℃ for 6 h in air.Single cubic perovskite phase proton conductors were obtained.Conductivity was measured by electrochemical workstation.It was shown that Sc doping could increase conductivity through enhancing the carrier concentration in the material,but excessive Sc content might decrease the carrier concentration because of its charge compensation.ZnO had an influence on carrier concentration and mobility and affected the electrical conductivity.2 mol％ ZnO and 13 mol％ ScO1.5 doped sample showed the highest DC conductivity of 3.6 × 10-3 S·cm-1 tested at 800 ℃ in wet hydrogen atmosphere.     

Electrochemical properties of carbon-coated LiFePO<Subscript>4</Subscript> and LiFe<Subscript>0.98</Subscript>Mn<Subscript>0.02</Subscript>PO<Subscript>4</Subscript> cathode materials synthesized by solid-state reaction

Olivine structured LiFePO4/C (lithium iron phosphate) and Mn2+-doped LiFe0. 98Mn0. 024/C powders were synthesized by the solid-state reaction. The effects of manganese partial substitution and different carbon content coating on the surface of LiFePO4 were considered. The structures and electrochemical properties of the samples were measured by X-ray diffraction (XRD), cyclic voltammetry (CV), charge/discharge tests at different current densities, and electrochemical impedance spectroscopy (EIS). The electrochemical properties of LiFePO4 cathodes with x wt. ％ carbon coating (x=3, 7, 11, 15) at γ=0. 2C, 2C (1C=170 mAh·g-1) between 2. 5 and 4. 3 V were investigated. The measured results mean that the LiFePO4 with 7 wt. ％ carbon coating shows the best rate performance. The discharge capacity of LiFe0. 98Mn0. 02PO4/C composite is found to be 165 mAh·g 1 at a discharge rate, γ=0. 2C, and 105 mAh·g-1 at γ=2C, respectively. After 10cycles, the discharge capacity has rarely fallen, while that of the pristine LiFePO4/C cathode is 150 mAh·g-1 and 98 mAh·g-1 at γ=0. 2 and 2C, respectively. Compared to the discharge capacities of both electrodes above, the evident improvement of the electrochemical performance is observed, which is ascribed to the enhancement of the electronic conductivity and diffusion kinetics by carbon coating and Mn2+-substitution.     

Kinetics of forward extraction of Ti（IV） from H_2SO_4 medium by P_（507） in kerosene using the single drop technique

The kinetics of forward extraction of Ti(IV) from H2SO4 medium by P507 in kerosene has been investigated using the single drop technique.In the low concentration region of Ti(IV),the rate of forward extraction at 298 K can be represented by F(kmol·m-2·s-1)=10-5.07 [TiO 2 + ][H+]-1 [NaHA 2 ](o)·Analysis of the rate expression reveals that the rate determining step is(TiO)(i)2+ +(HA 2)(i)-[TiO(HA2)](i)+.The values of Ea,H±,S±,and G±298 are calculated to be 22 kJ·mol-1,25 kJ·mol-1,-218 J·mol-1·K-1,and 25 kJ·mol-1,respectively.The experimental negative S± values indicate that the reaction step occurs via SN2 mechanism.     

Obtaining ZrO<Subscript>2</Subscript> + CeO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> + TiO<Subscript>2</Subscript>/Ti compositions by plasma-electrolytic oxidation of titanium and investigating their properties

Regularities of the effect produced by Ce₂(SO₄)₃ salt introduced in an aqueous electrolyte containing Zr(SO₄)₂ on the plasma-electrolytic formation of oxide coatings on titanium, their composition, and structure are studied. ZrO₂ + CeO _x + TiO₂ three-phase oxide coatings with a thickness about 10 μm are obtained. The coatings involve ZrO₂ cubic phase. The ZrO₂-to-TiO₂ phase ratio in the coatings can be controlled. The zirconium content in the coatings reaches 20 at %, while that of cerium is 3–5 at %. The surface layer (∼3-nm thick) contains Ce³⁺ (∼30%) and Ce⁴⁺ (∼70%). Pores in the surface part of coatings have diameters around or smaller than 1 μm and are regularly arranged. The obtained systems have a certain catalytic activity with respect to the oxidation of CO to CO₂ at temperatures above 400–450°C. The coatings are corrosion-resistant in chloride-containing environments. The thickness h of coatings depending on the charge Q supplied to the cell is described by the equation h = h ₀(Q/Q ₀) ⁿ , where n = 0.35 and h ₀ is the thickness of the coating formed at Q ₀ = 1 C/cm².     

Formation of high-density TiN/Ti<Subscript>5</Subscript>Si<Subscript>3</Subscript> ceramic composites using preceramic polymer

The formation, microstructure and properties of high-density TiN/Ti₅Si₃ ceramic composites created by the pyrolysis of preceramic polymer with filler were investigated. Methylpolysiloxane was mixed with TiH₂ as filler and ceramic composites prepared by pyrolysis at 1200°C to 1600°C under N₂, Ar and vacuum were studied. When a specimen with 70 vol.% TiH₂ was pyrolyzed up to 1600°C in a vacuum after a preheat treatment at 850°C in a N₂ atmosphere and subsequently heat-treated at 1600°C for 1 h under Ar at a pressure of 2 MPa, a ceramic composite with full density was obtained. The microstructure of the ceramic composite was composed of TiN and Ti₅Si₃ phases. Under specific pyrolysis conditions, a ceramic composite with a density of 99.2 TD%, a Vickers hardness of 18 GPa, a fracture toughness of 3.5 MPam^1/2, a flexural strength of 270 MPa and a electrical conductivity of 6200 ohm⁻¹·cm⁻¹ was obtained.     

Thermodynamic Calculation of HfB<Subscript>2</Subscript> Volatility Diagram

The thermodynamics of the oxidation of HfB₂ at temperatures of 1000, 1500, 2000, and 2500 K have been studied using volatility diagrams. Both the equilibrium oxygen partial pressure ( P_\textO2 P_{{{\text{O}}_{2} }} ) for the HfB₂(s) to HfO₂(s) plus B₂O₃(l) and the partial pressures of B-O vapor species formed due to B₂O₃(l) volatilization increase with increasing temperature. Vapor pressures of the predominant gaseous species also increase with P_\textO2 P_{{{\text{O}}_{2} }} . At 1000 K, the predominant vapor transition sequence is predicted be BO(g) → B₂O₂(g) → B₂O₃(g) → BO₂(g) with increasing P_\textO2 P_{{{\text{O}}_{2} }} , and the predominant gas is BO₂(g) with a pressure of 1.27 × 10⁻⁶ Pa under the condition of P_\textO2 P_{{{\text{O}}_{2} }}  = 20 kPa. At higher temperatures of 1500, 2000, and 2500 K, the system undergoes vapor transitions in the same sequence of B(g) → BO(g) → B₂O₂(g) → B₂O₃(g) → BO₂(g). Under the same condition of P_\textO2 P_{{{\text{O}}_{2} }}  = 20 kPa, the predominant vapor species is B₂O₃(g) with pressures of 2.38, 4.49 × 10³, and 3.55 × 10⁵ Pa, respectively. Volatilization of B₂O₃(l) may produce porous HfO₂ scale, which is consistent with the experimental observations of HfB₂ oxidation in air. The present volatility diagram of HfB₂ shows that HfB₂ exhibits oxidation behavior similar to ZrB₂, and factors other than volatility of gaseous species affect the oxidation rate.     

Preparation of ZrO<Subscript>2</Subscript> dielectric layers by subsequent oxidation after Zr film deposition with negative substrate bias voltage

ZrO₂ dielectric layers were prepared by a two-step process, a deposition of pure Zr film with and without a negative substrate bias voltage and a subsequent oxidation of the Zr films. We focused on the effect of the negative substrate bias voltage on the Zr film deposition and the subsequent oxidation of the Zr films. As a result, the Zr film deposited at the substrate bias voltage of −50 V (Vs = −50 V) was found to have a high intensity peak of Zr (100) and a uniform and smooth surface. From the capacitance-voltage and current-voltage measurements of the ZrO₂ films, a high dielectric constant of 21 and the equivalent oxide thickness (EOT) of 2.6 nm were obtained on the oxidation layer of the Zr film deposited at Vs = −50 V. On the other hand, a low dielectric constant of 15 and the EOT of 3.6 nm was obtained on that of the Zr film deposited at Vs = 0 V. The leakage current density of the ZrO₂ film (Vs = −50 V) was 5.69×10⁻⁴ A/cm², and this value was much lower than the 1.21×10⁻⁴ A/cm² for the ZrO₂ film (Vs = 0 V). It was found that the two-step process by subsequent oxidation after film deposition using a negative substrate bias voltage is useful for obtaining high-quality dielectric layers.     

Recovery of V<Subscript>2</Subscript>O<Subscript>5</Subscript> from Bayer liquor by ion exchange

A new technology was developed to recover V2O5 from Bayer spent liquor by ion exchange.The experimental results show that in the conditions of 105°C and 0.20-0.25 mass ratios between CaO in lime and Al2O3 in spent liquor, the precipitation rate of vanadium in Bayer liquor is more than 85%.The vanadium-bearing precipitation is leached by NaHCO3 solution.The leaching rate of vanadium can reach 85% in the conditions of 95°C, 40 g·L-1 of NaHCO3 concentration, and ventilating of CO2.The 201 × 7 type of resin has...     

Thermoelectric properties of n-type Bi<Subscript>2</Subscript>Te<Subscript>2.7</Subscript>Se<Subscript>0.3</Subscript> compounds prepared by spark plasma sintering

In this study, the thermoelectric properties of 0.1 wt.% Cdl₂-doped n-type Bi₂Te_2.7Sb_0.3 compounds, fabrieated by SPS in a temperature range of 250°C to 350°C, were characterized. The density of the compounds was increased to approximately 100% of the theoretical density by carrying out consolidation at 350°C. The Seebeck coefficient, thermal conductivity, and electrical resistivity were dependent on a hydrogen reduction process and the sintering temperature. The Seebeck coefficient and the electrical resistivity increased with the reduction process. Also, electrical resistivity decreased and thermal conductivity increased with sintering temperature. The results suggest that carrier density and mobility vary according to the reduction process and sintering temperature. The highest figure of merit, 1.93×10⁻³ K⁻¹, was obtained for the compound consolidated at 350°C for 2 min.     

Interdiffusion in <Emphasis Type="Italic">L</Emphasis>1<Subscript>2</Subscript>-Ni<Subscript>3</Subscript>Al Alloyed with Re

Ternary interdiffusion in L1₂-Ni₃Al with ternary alloying addition of Re was investigated at 1473 K using solid-to-solid diffusion couples. Interdiffusion flux of Ni, Al, and Re were directly calculated from experimental concentration profiles and integrated for the determination of average ternary interdiffusion coefficients. The magnitude of main interdiffusion coefficients and was determined to be much larger than that of the main interdiffusion coefficient A moderate tendency for Re to substitute for Al sites was reflected by its influence on interdiffusion of Al, quantified by large and positive coefficients. Similar trends were observed from ternary interdiffusion coefficients determined by Boltzmann-Matano analysis. Profiles of concentrations and interdiffusion fluxes were also examined to estimate binary interdiffusion coefficients in Ni₃Al, and tracer diffusion coefficients of Re (5.4 × 10⁻¹⁶ ± 2.3 × 10⁻¹⁶ m²/s) in Ni₃Al.     

Cr doping effect in B-site of La<Subscript>0.75</Subscript>Sr<Subscript>0.25</Subscript>MnO<Subscript>3</Subscript> on its phase stability and performance as an SOFC anode

La_0.75Sr_0.25Cr _y Mn_1−y O₃ (LSCM) (y = 0.0–0.6) composite oxides were synthesized by a complexing process of combining ethylene diamine tetraacetic acid (EDTA) and citrate. X-ray diffraction (XRD), temperature-programmed reduction, electrical conductivity, I–V polarization, and impedance spectroscopy were conducted to investigate the Cr doping effect of La_0.75Sr_0.25MnO₃ on its phase stability and electrochemical performance as a solid-oxide fuel cell (SOFC) anode. The chemical and structural stabilities of the oxides increased steadily with increasing Cr doping concentration, while the electrical conductivity decreased on the contrary. At y ≥ 0.4, the basic perovskite structure under the anode operating condition was sustained. a cell with 0.5-mm-thick scandia-stabilized zirconia electrolyte and La_0.75Sr_0.25Cr _y Mn_1−y O₃ anode delivered a power density of ∼15 mW·cm⁻² at 850°C.     

Solvothermal synthesis and thermoelectric properties of skutterudite compound Fe（0.25）Ni（0.25）Co（0.5）Sb3

Nanostructured skutterudite-related compound Fe_0.25Ni_0.25Co_0.5Sb₃ was synthesized by a solvothermal method using FeCl₃, NiCl₂, CoCl₂, and SbCl₃ as the precursors and NaBH₄ as the reductant. The solvothermally synthesized powders consisted of fine granules with an average particle size of tens of nanometers. The bulk material was prepared by hot pressing the powders. Transport property measurements indicated a heavily doped semiconductor behavior with n-type conduction. The thermal conductivity is about 1.83 W·m⁻¹·K⁻¹ at room temperature and decreases to 1.57 W·m⁻¹·K⁻¹ at 673 K. The low thermal conductivity is attributed to small grain size and high porosity. A maximum dimensionless figure of merit of 0.15 is obtained at 673 K.     

Dielectric properties of Ta<Subscript>2</Subscript>O<Subscript>5</Subscript> thin films deposited onto Ti and TiO<Subscript>2</Subscript> layer

The present study describes the dielectric properties of RF sputtered Ta₂O₅ thin films as a function of the buffer layer and annealing condition. The buffer layers were Ti or TiO₂. And the thin film was annealed in various conditions. The X-ray pattern results showed that the phase of the RF sputtered Ta₂O₅ thin films was amorphous and this state was kept stable to RTA (rapid thermal annealing) even at 700°C. Measurements of the electrical and dielectric properties of the reactive sputtered Ta₂O₅ fabricated in two simple metal insulator semiconductor (MIS) structures, (Cu/Ta₂O₅/Ti/Si/Cu and Cu/Ta₂O₅/TiO₂/Si/Cu) indicated that the amorphous Ta₂O₅ grown on Ti possesses a high dielectric constant (30–70) and high leakage current (10⁻¹–10⁻⁴ A/cm²), whereas a relatively low dielectric constant (−10) and low leakage current (−10⁻¹⁰ A/cm²) were observed in the amorphous Ta₂O₅ deposited on the TiO₂ buffer layer. In addition, the leakage current mechanisms of the two amorphous Ta₂O₅ thin films were investigated by plotting the relation of current density (J) vs. applied electric field (E). The Ta₂O₅/Ti film exhibited three dominant conduction mechanism regimes contributed by the Ohmic emission at low electrical field, by the Schottky emission at intermediate field and by the Poole-Frenkel emission at high field. In the case of Ta₂O₅/TiO₂ film, the two conduction mechanisms, the Ohmic and Schottky emissions, governed the leakage current density behavior. The conduction mechanisms at various electric fields applied were related to the diffusion of Ta, Ti and O, followed by the creation of vacancies, in the rapid thermal treated capacitors.     

Electrochemical properties of spinel compound LiNi_（0.5）Mn_（1.2）Ti_（0.3）O_4 as cathode materials for lithium ion batteries

The electrochemical properties of spinel compound LiNi0.5Mn1.2Ti0.3O4 were investigated in this study.The chemicals LiAc·2H2O,Mn(Ac)2·2H2O,Ni(Ac)2·4H2O,and Ti(OCH3)4 were used to synthesize LiNi0.5Mn1.2Ti0.3O4 by a simple sol-gel method.The discharge capacity of the sample reached 134 mAh/g at a current rate of 0.1C.The first and fifth cycle voltammogram almost overlapped,which showed that the prepared sample LiNi0.5Mn1.2Ti0.3O4 had excellent good cycle performance.There were two oxidation peaks at 4.21 V and 4.86 V,and two reduction peaks at 4.55 V and 3.88 V in the cycle voltammogram,respectively.By electrochemical impedance spectroscopy and its fitted result,the lithium ion diffusion coefficient was measured to be approximately 7.76 × 10?11 cm2/s.     

Effect of calcination temperature and atmosphere on crystal structure of BaTiO<Subscript>3</Subscript> nanofibers

Barium titanate (BaTiO₃, BT) nanofibers with a diameter range of 160 nm to 300 nm were prepared by drying electrospun BT/polyvinylpyrrolidone (BT/PVP) composite fibers for 1 h at 80 °C in vacuum with a subsequent calcination in air for 1 h at a temperature range of 650 °C to 750 °C. The morphology and crystal structure of calcined BT nanofibers were characterized with the aid of XRD, FT-IR, SEM, and TEM. The XRD and FR-IR measurements confirm that BT nanofibers with a diameter of about 160 nm and a tetragonal perovskite structure were present in the electrospun fibers after calcination for 1 h at 750 °C. The FR-IR analysis of the BT fibers reveals that the intensity level of the O-H stretching vibration bands (at 3430 cm⁻¹ and 1425 cm⁻¹) become weaker as the calcination temperature is increased and that a broad band at 570 cm⁻¹, which represents the Ti-O vibration, appears sharper and narrower after calcination at 750 °C due to the formation of metal oxide bonds. In contrast, BT fibers prepared by a refluxing process in a nitrogen atmosphere show a dramatic change in crystal structure: the tetragonal structure changes to a cubic perovskite structure, probably due to the suppression of carbonate contamination. Thus, the calcination temperature and atmosphere appear to have a significant influence on the crystal structure of BT.     

Fabrication and characterization of SmO_（0.7）F_（0.2）FeAs bulk with a transition temperature of 56.5 K

The superconductivity of iron-based superconductor SmO 0.7 F 0.2 FeAs was investigated. The SmO 0.7 F 0.2 FeAs sample was prepared by the two-step solid-state reaction method. The onset resistivity transition temperature is as high as 56.5 K. X-ray diffraction (XRD) results show that the lattice parameters a and c are 0.39261 and 0.84751 nm, respectively. Furthermore, the global J c was more than 2.3 × 10 5 A/cm 2 at T = 10 K and H = 9 T, which was calculated by the formula of J c = 20ΔM/[a(1-a/(3b))]. The upper critical fields, H c2 ≈ 256 T (T = 0 K), was determined according to the Werthamer-Helfand-Hohenberg formula, indicating that the SmO 0.7 F 0.2 FeAs was a superconductor with a very promising application.     

Electrochemical synthesis,studies and modification of TiO<Subscript>2</Subscript> nanotubes

TiO₂ nanotubes (TiO₂ NTs) were synthesized using the electrochemical method in a 1 M H₂SO₄ + 0.15% HF electrolyte. The initial nanotubes have a diameter of 100 ± 10 nm (with the length of up to 150–200 nm) and a wall thickness of 20 ± 5 nm. Nanotube treatment at 400°C results in negligible changes in their structure compared to the initial samples. At 600°C, a change occurs in the nanotube structure and morphology, i.e., the amount decreases drastically; the diameter changes; and, as a consequence, the surface area value decreases. Changes in the structure lead to changes in the electrochemical properties, which is apparently related to a transition from the amorphous structure to anatase and rutile. It is shown that a reversible two-electron reaction, including hydrogen intercalation and Ti⁴⁺/Ti³⁺ oxidation/reduction in the potential range of (−0.6−0.4 V), occurs as a result of moderate thermal treatment. The possibility of the use and promising character of TiO₂ NTs as support for a nonplatinum catalyst based on cobalt tetra(p-methoxyphenyl)porphyrin are brought to light. The electrocatalytic activity of the synthesized catalyst per nominal CoTMPP mass in the reaction of O₂ reduction at E = 0.7 V is ≈25 A/g_CoTMPP, which is comparable to nonplatinum systems on a carbon support.     

Phase Relations in the Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-V<Subscript>2</Subscript>O<Subscript>5</Subscript>-MoO<Subscript>3</Subscript> System in the Solid State. The Crystal Structure of AlVO<Subscript>4</Subscript>

Phase relations in the ternary oxide system Al₂O₃-V₂O₅-MoO₃ in the solid state in air have been investigated by using the x-ray diffraction (XRD) and differential thermal analysis/thermogravimetric (DTA/TG) methods. It was confirmed that in the subsolidus area of the Al₂O₃-V₂O₅-MoO₃ system, there exist seven phases, that is Al₂O₃, V₂O_5(s.s.), MoO₃, AlVO₄, Al₂(MoO₄)₃, AlVMoO₇, and V₉Mo₆O₄₀. Seven fields, in which particular phases coexist at equilibrium, were isolated. The crystal structure of AlVO₄ has been refined from x-ray powder diffraction data. Its space group is triclinic, , Z = 6, with a = 0.65323(1) nm, b = 0.77498(2) nm, c = 0.91233(3) nm, α = 96.175(2)°, β = 107.234(3)°, γ = 101.404(3)°, V = 0.42555 nm³. The crystal structure of the compound is isotypic with FeVO₄. Infrared (IR) spectra of AlVO₄ and FeVO₄ are compared.