CP熔盐电化学方法检测LiCl-KCl熔盐La（Ⅲ）浓度

在773 K氩气环境下,采用CP熔盐电化学方法对LiCl-KCl电解质体系中不同组分LaCl₃(0.98 %、2.0 %和3.3 %)进行La离子浓度检测.研究结果表明:La（Ⅲ）在钨电极上相对于银/氯化银参比电极的还原析出电位在-2.0~-2.2 V左右,通过阴极峰电流值、过渡时间与深度三者关系计算,773 K下La离子扩散系数在1.29×10-5~5.42×10-5 cm2/s之间.通过对比计时电位法（CP）和电感耦合等离子体原子发射光谱法（ICP）检测的La离子浓度结果,相对误差依次为1.25 %、1.11 %和1.72 %.LiCl-KCl熔盐中La电沉积的峰值电流和过渡时间平方根乘积与浓度呈良好线性关系,说明以CP熔盐电化学方法检测离子浓度可行性好.      

Electrode process of La(III) in molten LiCl-KCl

The electrode process of La(III) at Mo electrode in the molten LiCl-KCl for temperatures ranging from 683 K to 773 K was studied by cyclic voltammetry and chronopotentiometry, respectively. The results showed that in the molten LiCl-KCl, reduction of La(III) occurred in a step with a global exchange of three electrons. Cyclic voltammetry studies indicated that at a sweep rate lower than 0.2 V/s, the electroreduction of La(III) to lanthanum metal was reversible and controlled by diffusion of La(III). However, the process became under a mixed control of both diffusion and electron transfer when sweep rate exceeded 0.2 V/s. And an empirical temperature dependence of the diffusion coefficient of La(III) was proposed: lnD_La(III)=7.742–1.441×10⁴/T. And the relation between the formal potential of La(III)/La versus Ag/AgCl reference electrode and temperature was described in the following equation: E^θ'=–1.402–4.689×10²/T.     

Solubility products of metal sulfides in molten salts: II. Measurements and calculations for lead sulfide in the LiCl-KCl and the LiCl-LiF eutectic compositions

The solubilities of lithium sulfide and the solubility products of lead sulfide in the LiCl-KCI and LiCI-LiF eutectic mixtures have been measured by an electrochemical titration method in the temperature range from 673 to 823 K. At 823 K, the solubility of Li₂S in the LiCI-LiF eutectic was much larger than in the LiCI-KCI eutectic (1.95 × 10⁻¹ compared with 3.50 × 10⁻³). The measured solubility product of PbS in the LiCI-KCI eutectic (1.0 × 10⁻¹⁰ at 823 K) did not differ greatly from that in the LiCI-LiF eutectic (6.8 × 10⁻¹¹ at 823 K).A priori calculations were made of the solubility products of PbS and several transition and heavy metal Sulfides in the molten LiCI-KCI eutectic at 723 K. Fundamental theories of reciprocal and additive ternary molten salt solutions are used to explain the influence of the solvent on the solubilities of Li₂S and on the solubility products of PbS. The correlation of experiments with theory illustrates the utility of known theories of ionic systems in making predictions of solubilities and solubility products in ionic systems.     

Formation of alloy coatings by no-current diffusion saturation of nickel by ytterbium in an LiCl-KCl-YbCl3 melt

Gravimetry is used to study the effect of the temperature and time of no-current diffusion ytterbium saturation of nickel in a molten mixture of the LiCl-KCl eutectic with YbCl₃ on the specific change in the nickel sample weight w = Δm/s, where Δm is the change in the sample weight and s is the sample surface area. The dependences of w on the process time are obtained in the temperature range 773–973 K. The experimentally formed alloy Ni-Yb coatings on nickel are examined by chemical analysis, X-ray fluorescence analysis, and X-ray diffraction. The experimental results demonstrate the presence of one structural zone, which consists of a Laves phase, in the diffusion layer.     

Electrode process of La(Ⅲ) in molten LiCl-KCl

The electrode process of La(Ⅲ) at Mo electrode in the molten LiCl-KCl for temperatures ranging from 683 K to 773 K was studied by cyclic voltammetry and chronopotentiometry,respectively.The results showed that in the molten LiCl-KCl,reduction of La(Ⅲ) occurred in a step with a global exchange of three electrons.Cyclic voltammetry studies indicated that at a sweep rate lower than 0.2 V/s,the electroreduction of La(Ⅲ) to lanthanum metal was reversible and controlled by diffusion of La(Ⅲ).However,the process b...     

Electrochemical behavior of cerium ion in molten LiCI-KCI

The electrode process of cerium(Ⅲ) on the Mo electrode in eutectic LiCl-KCl melt was investigated by electrochemical transient techniques in the temperature range of 673-783 K,respectively.These results unanimously indicated that the reduction process of cerium(Ⅲ) to cerium metal was a single step exchanging three electrons which was controlled by diffusion of cerium(Ⅲ).Diffusion coefficients(D Ce(Ⅲ)) in eutectic LiCl-KCl melt were determined by cyclic voltammetry,chronopotentiometry and square wave voltammetry.An empirical diffusion coefficient function depending on temperature was proposed:lnD Ce(Ⅲ) =-2.129-5704/T.The formal potentials(Eθ’ Ce(Ⅲ)/Ce(0) versus Ag/AgCl reference electrode) at different temperatures were obtained from chronopotentiometry,which were-2.10 V(673 K) and-2.07 V(733 K),respectively.     

Corrosion and Microstructure Correlation in Molten LiCl-KCl Medium

Pyrochemical reprocessing in molten chloride salt medium has been considered as one of the best options for the reprocessing of spent metallic fuels of future fast breeder reactors. The unit operations such as salt preparation, electrorefining, and cathode processing involve the presence of molten LiCl-KCl eutectic salt from 673 to 1373 K (400 to 1100 °C). The present work discusses the corrosion behavior of electroformed nickel (EF Ni) without and with nickel-tungsten (Ni-W) coating, 316L SS, and INCONEL 625 alloy in molten LiCl-KCl eutectic salt at 673 K, 773 K, and 873 K (400 °C, 500 °C, and 600 °C) in the presence of air. The weight percent loss of the exposed samples was determined by the weight loss method and surface morphology of the salt exposed, and product layers were examined by scanning electron microscopy (SEM). X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis were also carried out on the exposed and corrosion product layers to understand the phases present and the corrosion mechanism involved. The results of the present study indicated that INCONEL 625 alloy showed superior corrosion resistance compared to electroformed nickel (EF Ni), EF Ni with nickel-tungsten (Ni-W) coating (EF Ni-W), and 316L SS. The EF Ni with Ni-W coating exhibits better corrosion resistance than EF Ni without tungsten coating. Based on the surface morphology, XRD, and EDX analysis of corrosion product layers, the mechanism of corrosion of INCONEL 625 and 316L involves formation of chromium-rich compound at the surface and subsequent spallation. For the EF Ni, the porous thick NiO corrosion product allows the penetration of salt, thus accelerating the corrosion. Improved corrosion resistance of EF Ni-W was attributed to the W-rich NiO layer, while for INCONEL 625, the adherent and protective NiO layer improved the corrosion resistance. The article highlights the results of the present investigation.     

CaCl2-NaCl熔盐中La2O3电脱氧反应的电化学研究

采用熔盐电解法研究了La2O3电脱氧反应过程。由电位阶越实验及取样电流电位分析和对电解产物进行X衍射分析表明La2O3的电脱氧反应是可以进行的，La2O3得电子还原为低价脱氧产物LaO，接着LaO作为中间产物与阳极气体Cl结合生成氯氧镧。     

Electrochemical properties of a lithium-potassium chloride molten eutectic mixture held in contact with neodymium and dysprosium

The dependence of the reaction capacity (R) of the lithium-potassium chloride molten eutectic mixture held in contact with neodymium and dysprosium on the content of the ions of the corresponding rare earth metal (REM) is investigated at 773, 873, and 973 K. The data on the values of R made it possible to evaluate the magnitude of charges of the Nd and Dy ions transferring into the melt during the corrosion of studied REMs and concretize the mechanism of their no-current transfer to more electropositive metals (by the example of nickel).     

LiCl-KCl熔盐中电解还原钛铁矿的研究

在LiCl-KCl熔盐中,采用熔盐电解法还原钛铁矿,研究了电解时间、槽电压及电解温度对还原钛铁矿的影响,探讨了在熔盐中钛铁矿电解脱氧的机理。结果表明,钛铁矿还原优先生成铁,钛氧化物由高价到低价逐步还原,而未得到金属钛及其合金,说明在LiCl-KCl熔盐中,TiO的脱氧还原是钛铁矿熔盐电解生成金属钛及其合金的反应限制性步骤。     

Dissolution rate of lead(II) oxide in an equimolar KCl-PbCl2 melt

Dissolution rates (W) of lead(II) oxide in a KCl-PbCl₂ equimolar melt are determined experimentally using the gravimetric method at T = 773, 823, and 873 K. It is shown that, as the temperature increases from 773 to 873 K, the initial magnitude of W increases from 23.9 to 45.6 mg/(cm² min) with a conventional roughness coefficient of 10. Then the values of W for all temperatures are leveled, being close to zero after 25 min, which indicates the diffusion mode of the process in natural convection conditions. The activation energy of the interaction between PbO and the KCl-PbCl₂ melt was 37.370 ± 0.118 kJ/mol. The limiting concentration of PbO in the equimolar KCl-PbCl₂ melt was determined, being 9.1, 10.6, and 13.5 wt % at T = 773, 823, and 873 K, respectively.     

Phase Equilibria of the Cu-Ti-Er System at 773?K (500?°C) and Stability of the CuTi3 Phase

The phase relationships of the Cu-Ti-Er ternary phase diagram at 773?K (500?°C) were investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and differential thermal analysis (DTA). It is confirmed in this work that the binary compounds Cu₉Er₂ and Cu₇Er₂ exist in the Cu-Er binary system at 773?K (500?°C). The stability of the CuTi₃ phase is confirmed in the Cu-Ti system. After heat treatment at 1023?K (750?°C) for 90 hours, the phase CuTi₃ is observed in the microstructure of the alloy 25Cu75Ti. The temperature of the eutectoid transformation, namely, ??-Ti ? ??-Ti?+?CuTi₃, is determined to be 1078?K (805?°C) in this work. The 773?K (500?°C) isothermal section consists of 14 single-phase regions, 25 two-phase regions, and 12 three-phase regions. None of the phases in this system reveals a remarkable homogeneity range at 773?K (500?°C).     

Stability of complex molybdenum(III) ions in molten alkali metal chlorides

High-temperature absorption spectroscopy is used to study the effect of temperature in the range 550?C750°C and the cation composition of a solvent salt on the spectroscopic characteristics and stability of MoCl ₆ ^3? complex ions in melts based on alkali metal chlorides (LiCl; CsCl; LiCl-KCl, NaCl-CsCl, KCl-CsCl, and NaCl-KCl-CsCl eutectic mixtures; and equimolar NaCl-KCl mixture).     

Interaction of strontium oxide with Sr-Cl<Subscript>2</Subscript>-<Emphasis Type="Italic">M</Emphasis>Cl melts

The kinetics of dissolution and the solubility of strontium oxide in melts of KCl, NaCl, CsCl, (3Li-2K)C_leut (eutectic), and LiCl containing 5, 7, and 12 mol % SrCl₂ at 973–1073 K are determined by the isothermal saturation method. The diffusion coefficients of strontium ions in these salt systems are estimated.     

LiCl-KCl熔盐La^3+在钨电极上的电化学还原机理

以LiCl-KCl为电解质体系,LaCl3为原料,利用循环伏安法、计时电位法和计时电流法研究773K时镧离子在钨电极上的电化学还原过程。结果表明,在773K、50%KCl-50%LiCl-2%LaCl3的熔盐体系中,镧离子在钨电极上还原是一步转移3个电子反应(La^3++3e→La),相对于Ag/AgCl电极析出电位为-2.05V;镧在钨电极析出过程中出现成核极化现象,且通过循环伏安和计时电流法可判断镧离子在钨电极上的析出还原过程为受扩散控制的准可逆反应,扩散系数D=6.36×10^-5 cm^2/s。     

Synthesis and characterization of rare earth metal doped tungsten trioxide photocatalyst for degradation of Rhodamine B dye

Nowadays,it is concern for researchers that due to high recombination rate of photogenerated charge carriers in tungsten trioxide(WO₃) nanoparticles,the future applications are limited in the field of photocatalysis.Herein we attempt to synthesize tungsten trioxide nanoparticles with different doping concentrations of lanthanum i.e.2 wt%,4 wt%,6 wt% and 8 wt%.The synthesized samples were characterized by using various characterization techniques:X-ray diffraction(XRD),Raman spectrosco...     

Characterization and bacterial toxicity of lanthanum oxide bulk and nanoparticles

This study evaluated the bacterial toxicity of lanthanum oxide micron and nano sized particles using shake flask method against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. Particle size, morphology and chemical composition were determined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Re-sults indicated that lanthanum oxide nanoparticles showed antimicrobial activity against Staphylococcus aureus, but not against Escherichia coli and Pseudomonas aeruginosa. It was speculated that lanthanum oxide produced this effect by interacting with the gram-positive bacte-rial cell wall. Furthermore, lanthanum oxide bulk particles were found to enhance the pyocyanin pigment production in Pseudomonas aeruginosa.)     

Preparation of La2O3 by ion-exchange membrane electrolysis of LaCl3 aqueous solution

The ion-exchange membrane electrolysis technology was applied inventively in the preparation of lanthanum hydroxide, after calcination, lanthanum oxide was obtained eventually. The effect of the concentration of lanthanum chloride solution on electrolytic product was mainly investigated. The phase composition, micro morphology, particle size and chlorine content of the product were characterized, respectively. Under the conditions of this work, the product that forms by electrolysis of LaCl₃ aqueous solution directly is La(OH)₃. When the initial concentration of LaCl₃ changes from 0.1 to 0.5 mol/L, the current efficiency of La(OH)₃ increases from 60% to 85%, the product roasted at 800 °C for 1.5 h is La₂O₃, whose median particle size (D₅₀) is 10–20 μm, the mass fraction of chloride ion is less than 0.02 wt%. Additionally, the prepared La₂O₃ particles are porous and non-spherical particles, which are composed of small crystals with sheet structure.     

Age Hardening of the Al0.5CoCrNiTi0.5 High-Entropy Alloy

Al_0.5CoCrNiTi_0.5 high-entropy alloy was synthesized by vacuum arc melting in a copper mold. This alloy was aged at 773 K to 1473 K (500 °C to 1200 °C) for 24 hours to investigate the microstructure and hardness. The hardness of the as-cast alloy is HV743, and it exhibits a dendritic structure, in which dendrite is composed of body-centered cubic (bcc), face-centered cubic (fcc), and σ phases, and interdendrite is an eutectic structure consisting of bcc and order bcc phases. Apparent age hardening appears at 873 K to 1173 K (600 °C to 900 °C), and no age softening occurs even after 1473 K (1200 °C) aging. The age hardening of this alloy is attributed to the transformation of the bcc phase to σ phase. Detailed variations of hardness and the microstructure of aged alloys are reported in this article.     

Microstructural Investigation and Phase Relationships of Fe-Al-Hf Alloys

The effect of Hf addition on microstructures, phase relationships, microhardness, and magnetic properties of Fe₅₀Al_50?n Hf _n alloys for n = 1, 3, 5, 7, and 9 at. pct has been investigated. At all investigated compositions, the ternary intermetallic HfFe₆Al₆ τ ₁ phase forms due to the limited solid solubility of Hf in FeAl phase and tends to develop a eutectic phase mixture with the Fe-Al-based phase. The Hf concentration of the eutectic composition is found to be 7 at. pct from the microstructural examinations and the eutectic phase transition temperature is determined as 1521 K (1248 °C) independent of Hf amount by differential scanning calorimetry measurements. Furthermore, the enthalpies and activation energies (based on Kissinger and Ozawa methods) of eutectic phase transitions are reported. The minimum activation energy is calculated for the fully eutectic composition. Moreover, variation of the microhardness of Fe-Al-based alloys as a function of the Hf content is investigated, and its dependence on the thermal history of the alloys is explained.