Thermophysical properties of Cu–In–Sn liquid Pb-free alloys: viscosity and surface tension

The viscosity of a few Cu–In–Sn liquid alloys has been investigated by a number of geometric (Muggianu, Kohler, Toop) and physical thermodynamic models (Kozlov–Romanov–Petrov, Budai–Benko–Kaptay, Schick et al.) and GSM for the cross section (z/y = 1/3) in Pb-free liquid alloy Cu_x–In_y–Sn_z at 1073 K. Moreover, the surface tensions of the same liquid alloys have been investigated by a number of geometric models and the Butler model for the cross section Cu_x–In_y–Sn_z (z/(y + z) = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) at the same temperature. The best agreement of the surface tensions was obtained in the Kohler model for x_Cu = 10 at % and the Butler model for x_Cu = 20 at % and x_Cu = 30 at.%, respectively. The best agreement among chosen geometric and physical models and experiment for these selected sections Cu₈₀In₁₅Sn₅, Cu₇₅In₁₅Sn₁₀, Cu₅₅In₇Sn₃₈, Cu₃₃In₅₀Sn₁₇ and Cu₂₆In₅₅Sn₁₉ at 1073 K was obtained for the Budai–Benkö–Kaptay model.     

Geometric modelling of viscosity of copper-containing liquid alloys

In this work, viscosities of ternary Au–Ag–Cu and Al–Cu–Si liquid alloys have been calculated as a function of gold, aluminium and copper compositions for the sections Au–Ag–Cu (x_Ag/x_Cu = 0.543 at 1373 K), Al_x(Cu₅₀–Si₅₀)_(1–x) and Cu_x(Al₅₀–Si₅₀)_(1–x) at 1375 K using Chou’s general solution model, Muggianu, Kohler, Toop, Hillert, Budai et al., Kozlov et al., Schick et al. and Kaptay et al. models. The present study finds that a comparison of the predicted values of viscosities associated with the geometric and physical models indicate good mutual agreement. The Muggianu model indicates the best agreement with the results obtained for Au–Ag–Cu and Al_x–Cu₅₀–Si₅₀ alloy systems and the Kaptay et al. model, which is a physical model, indicates the best agreement with the results obtained for Al₅₀–Cu_x–Si₅₀.     

An investigation of influencing of Sb and Bi contents on surface tensions associated with Pb-free Sn-Zn-Sb-Bi quaternary and sub-quaternary solder alloys

The surface tensions of ternary and quaternary systems of Sn-based Pb-free solder alloys have been calculated using geometric models, such as Muggianu, Kohler, Chou’s general solution model (GSM), Toop, Guggenheim, ideal Butler and Butler models. It is observed from the calculation carried out in the present work that Sb and Bi contents decrease the surface tension of the solder alloys Sn-Zn-Sb-Bi. It is inferred from the statistical analysis that the best agreement between the experimental results and the corresponding calculated values of the surface tensions is generally observed in GSM and Muggianu models among the geometric models. Whereas Muggianu model is the most appropriate. Relatively good agreements have been observed between models considered in this study and experimental data.     

A study of the microstructure,thermal properties and wetting kinetics of Sn–3Ag–<Emphasis Type="Italic">x</Emphasis>Zn lead-free solders

Microstructure, thermal properties and wetting kinetics of Sn–3Ag–xZn solders (x = 0.4, 0.6, 0.8, 1, 2 and 4 wt%) were systematically investigated. The results indicate that a small amount of Zn (Zn wt% ≤ 1 wt%) has a rather moderate effect on the microstructure morphology of the Sn–3Ag–xZn solders. The microstructures are composed of a β-Sn phase and the mixture of Ag₃Sn and ζ-AgZn particles. However, the β-Sn phase reduces its volume fraction in the entire microstructure and the intermetallic compounds population increases with the increasing of Zn content. The microstructure is dramatically changed with a further increase in the Zn content. The γ-AgZn phase is formed in a Sn–3Ag–2Zn solder. The ε-AgZn phase is formed in a Sn–3Ag–4Zn solder. The melting temperature and the undercooling of the Sn–3Ag–xZn solder alloys decrease with the increase in Zn content, reach to a minimum value when the content of Zn is 1 wt%, and then increase with further increase in Zn content. The Sn–3Ag–1Zn demonstrates the minimum value of 228.13 °C in the melting temperature and 13.87 °C in undercooling. The wetting kinetics of the main spreading stage features the power law of R ⁿ  ~ t (n = 1), which is controlled by chemical reactions at the triple line.     

Synthesis of compositionally controllable Cu<Subscript>2</Subscript>(Sn<Subscript>1−x</Subscript>Ge<Subscript>x</Subscript>)S<Subscript>3</Subscript> nanocrystals with tunable band gaps

In this work, we show that compositionally controlled Cu₂(Sn_1–xGe_x)S₃ nanocrystals can be successfully synthesized by the hot-injection method through careful tuning the Ge/(Sn+Ge) precursor ratio. The band gaps of the resultant nanocrystals are demonstrated to be linearly tuned from 1.45 to 2.33 eV by adjusting the composition parameter x of the Ge/(Sn+Ge) ratio from 0.0 to 1.0. The crystalline structures of the resultant NCs have been studied by the X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), select area electron diffraction (SAED), and Raman spectroscopy. A ligand exchange procedure is further performed to replace the native ligands on the surface of the NCs with sulfur ions. The photoresponsive behavior indicates the potential use of as-prepared Cu₂(Sn_1–xGe_x)S₃ nanocrystals in solar energy conversion systems. The synthesis of compositionally controlled Cu₂(Sn_1–xGe_x)S₃ nanocrystals reported herein provides a way for probing the effect of Ge inclusion in the Cu-Sn-S system thin films.     

Laser-induced voltage (LIV) enhancement of La2/3Sr1/3MnO3 films with Ag addition

La_2/3Sr_1/3MnO₃:Ag _x (LSMO:Ag _x , x=0, 0.04, 0.08, 0.10, 0.20, 0.30) films were grown on vicinal cut LaAlO₃ (LAO) substrates by pulsed laser deposition technique (PLD). It is found that laser-induced voltage (LIV) of LSMO:Ag _x films is improved and enhanced by Ag addition. With x increasing, figure of merit (F _m ) and anisotropic Seebeck coefficient (ΔS) of LSMO:Ag _x (x=0.08) films reach the maximum values of 28.25 mV/ns and 0.38 μV/K, respectively. The results suggest that the LIV enhancement of LSMO:Ag _x films is due to the anisotropy of the Seebeck tensor, which is produced by long range cooperative Jahn–Teller distortions with Ag addition.     

Wear resistance of CuZr-based amorphous-forming alloys against bearing steel in 3.5% NaCl solution

Abstract

To investigate the amorphous-crystalline microstructure on the tribocorrosion of bulk metallic glasses (BMGs), 6 mm diameter rods of Cu_46-xZr₄₇Al₇Ag_x (x = 0, 2, 4) amorphous-forming alloys with in situ crystalline and amorphous phases were fabricated by arc-melting and Cu-mould casting. Using a pin-on-disc tribometer, the tribo-pair composed by CuZr-based amorphous-forming alloys and AISI 52100 steel were studied in 3.5% NaCl solution. With the increase of Ag content from 0 to 4 at.%, the compressive fracture strength and the average hardness decrease firstly and then increase. Moreover, 4 at.% Ag addition increases the amount of amorphous phase obviously and inhibits the formation of brittle crystalline phase, resulting in the improvement of corrosion resistance and the corrosive wear resistance. The primary wear mechanism of the BMG composites is abrasive wear accompanying with corrosive wear. The tribocorrosion mass loss of Cu₄₂Zr₄₇Al₇Ag₄ composite is 1.5 mg after 816.8 m sliding distance at 0.75 m s^?1 sliding velocity under 10 N load in NaCl solution. And the volume loss evaluated from the mass loss is about 20 times lower than that of AISI 304 SS. Thus, Cu₄₂Zr₄₇Al₇Ag₄ composite may be a good candidate in the tribology application under marine environment.     

Determination of surface tension of liquid ternary Ni–Cu–Fe and sub-binary alloys

Experimental data in the literature are almost limited to determine the thermophysical properties of multicomponent complex alloys, especially due to the inability of laboratories to achieve the desired ideal conditions, due to the difficulty of protection from oxidation at high temperatures and other contamination at high temperatures, due to time and cost in laboratory studies. Due to these reasons, the theoretical data obtained in this subject is of great importance. In this study, a series of geometric and physical models, such as Chou’s general solution model (GSM), Muggianu’s Model, Kohler’s Model, Toop’s Model, Hillert’s Model, Guggenheim’s Model, Butler’s Model, Egry’s Model and ideal solution model for quasi-binary alloy system for Section A: Ni_{0.4(1 – x)}Cu_xFe_{0.6(1 – x)}. and Section B: (Ni_xCu_0.2Fe_{0.8 – x}) are used to calculate the surface tension-composition and surface tension-temperature curves of the Cu-Fe-Ni ternary liquid system are plotted. The data for this process is evaluated by means of an extended Redlich-Kister-Muggianu polynomial fit to the experimental values of the surface tensions of the binary liquid alloy systems. The obtained results for these models are also compared with the available data in the literature and relatively good agreements are observed. In addition, the surface segregation having important key factor in determining surface tension of the liquid alloy Ni-Fe-Cu has also been investigated in this work.     

在工频外磁场下高温超导体的交流损耗

在工频外磁场条件下,研究了不同工艺的Bi-2223/Ag带和Cu位元素替代的YBa₂Cu_3-xSn_xO_y超导体的交流损耗.实验结果表明：在单芯Bi-2223/Ag带中,热处理时间、温度及超导芯厚度的增加都将增加Bi-2223相的含量,因而导致磁滞损耗增加.将单芯带细分成19芯Bi-2223/Ag带能减少磁滞损耗,但另一方面,超导芯间的耦合增加了银基体的涡流损耗,因此19芯带的损耗只比单芯带减少20%左右.在YBa关键词：     

Phase transitions in CuS–Ag2S nanoparticle system

(Ag₂)_xCu_1?xS, x = .2, .4, .6 and .8 nanoparticles were synthesized by the solvothermal method. The as-synthesized nanoparticles were characterized by X-ray diffraction to study the crystal structure and size. The surface morphologies of the above samples were studied using scanning electron microscope. As there is continuous shift in the lower wavelength absorption edge of the UV–VIS spectrum of these samples with concentration, (Ag₂)_xCu_1?xS nanoparticles can be tuned to different band gap energies by varying the composition. The D.C. electrical resistance was measured in the temperature range 310–485 K. As Ag₂S transforms from monoclinic to bcc at around 450 K, copper sulfide nanoparticles also shows a phase transition at around 470 K, the effects of these two transitions are seen in the resistance measurements and in the UV–VIS spectra of the entire system. The electrical resistance of (Ag₂)_xCu_1?xS nanoparticles rapidly reduces as more and more copper sulfide is added.     

A survey of surface tension,molar volume and density for Sn–Ag–Cu–Bi–Sb quinary alloys as lead-free solders

ABSTRACT

By applying the geometric models and the theoretical equation, the surface tension, the molar volume and the density were studied. The empirical calculations were carried out in temperature range 623?K?≤?T?≤?1123?K. Only few thermophysical properties were estimated for eight quinary alloys: Sn3.55Ag0.5Cu3Bi3Sb, Sn3.48Ag0.5Cu3Bi5Sb, Sn3.48 Ag0.5Cu5Bi3Sb, Sn3.40 Ag0.5Cu5Bi5Sb, Sn3.53Ag1Cu3Bi3Sb, Sn3.46Ag1Cu3Bi5Sb, Sn3.46Ag1Cu5Bi3Sb, Sn3.38Ag1Cu5Bi5Sb. The results show that surface tension and density have a linear appearance for all temperatures. We have also studied the influence of the composition and temperature in the studied alloys. The obtained theoretical results are compared with the experimental ones and with the conventional Pb–Sn welds.     

Surface tension and density of liquid Bi–Pb,Bi–Sn and Bi–Pb–Sn eutectic alloys

Surface tension and density measurement of liquid Bi₅₆Pb₄₄, Bi₄₃Sn₅₇ and Bi₄₆Pb₂₉Sn₂₅ eutectic alloys was carried out by using the large drop method over the temperature range of 380–750 K. The regular solution model has been used in conjunction with Butler's equation to calculate the surface tension of binary and ternary alloys of the Bi–Pb–Sn system, while the surface tension of ternary alloys has also been predicted by using geometric models. The new experimental results were compared with the calculated values of the surface tension as well as with the data available in the literature.     

The thermoelectric power in AgxTiS2 and AgxNiPS3. Part II. The ionic component of the thermoelectric power

The EMF of the isothermal cells: Ag/AgI/Ag_xTiS₂: 0<x<1, T=150–200°C/Ag_xNiPS₃: 0<x<3, T=150–350°C has been measured. From the EMF-x curves the existence ranges of the 2-phase (stage I and II) regions ?0.16<x<0.32 for the Ag/Ag_xTiS₂ system at 190°C; 0.20 < x < 0.50 and 1 < x < 2 for the Ag/Ag_xNiPS₃ system at 400°C - have been determined. The results are sustained by X-ray diffraction and electrical conductivity measurements. From the EMF-T curves the partial enthalpy (ΔH?_Ag) and entropy (ΔS?_Ag) of dissolution of silver in the Ag_xSSE (solid solution electrode) materials were obtained. In the case of Ag_xTiS₂, ΔH?_Ag has a low absolute value, while ΔS?_Ag is distinctly positive. The EMF of the Ag/Ag_xNiPS₃ system also has a positive temperature coefficient. Furthermore, the ionic component of the thermoelectric power, ΔE/ΔT, of the thermogalvanic cells: Ag/AgI/Ag_xSSE/AgI/Ag Ag_xTiS₂: 0 < x < 1, T = 150–200°C( T ) (T+ΔT) Ag_xNiPS₃: 0 < x < 1, T= 150–350°C has been measured. The kinetically important heat of transport of silver ions in the Ag_xSSE materials has been determined in two ways: first from the dependence of the ionic Seebeck coefficient (?_Ag+) on reciprocal temperature; and second from direct calculation, using the data for ?_Ag+ and ΔS?_Ag. The heat of transport is much smaller than the activation enthalpy for Ag⁺-conduction, indicating a high ionic polaron binding energy in these materials.     

p型Ag0.5(Pb8－xSnx)In0.5Te10化合物的制备及其热电性能

采用高温熔融缓冷和放电等离子烧结工艺制备了p型Ag_0.5(Pb_8-xSn_x)In_0.5Te₁₀五元化合物.研究了Sn含量对化合物载流子传输特性及热电性能的影响规律.结果表明：在Ag_0.5(Pb_8-xSn_x)In_0.5Te₁₀(x 关键词： 0.5(Pb_8-xSn_x)In_0.5Te₁₀')" href="#">Ag_0.5(Pb_8-xSn_x)In_0.5Te₁₀ 合成 载流子 热电性能     

Phase relations and optical properties of semiconducting ternary sulfides in the system Cu–Sn–S

The ternary system Cu–Sn–S was re-investigated and the phase diagram Cu₂S–SnS₂ studied in detail by differential thermal analysis and X-ray diffractometry. Three phases of composition Cu₄SnS₄, Cu₂SnS₃ and Cu₂Sn_3+xS_7+2x(0≤×≤1) were found exhibiting melting points at 833, 856 and 803 °C, respectively. Ellipsometric and diffuse reflectance measurements revealed that the latter two sulfides possess a fundamental band gap of 0.93 eV followed by a higher transitions. For the first time it could be demonstrated that Cu₂Sn₃S₇ has semiconducting properties and an absorption coefficients of the order 10⁵ cm⁻¹.     

Magneto-crystalline properties of BaFe12−2x M x Sn x O19 (M = Sn, Ni, Zn) ferrite powders

BaFe_12?2x M _x Sn _x O₁₉ compounds, where M?=?Sn²⁺, Ni²⁺ or Zn²⁺ ions, were synthesized by mechanical milling and partially by citrate precursor methods. Analysis of magneto-crystalline structure has been carried out by Mössbauer spectroscopy. The Sn⁴⁺ ions replace Fe³⁺ ions on 2b and slightly on 2a?+?4f₁ sites, Zn²⁺ ions strongly prefer 4f₁ sites, Sn²⁺ ions prefer 4f₁ sites too and Ni²⁺ ions occupy 4f₂ and 12k or 2a sites. The magnetic properties were evaluated by the vibrating sample magnetometry and the thermomagnetic analysis. A large variation of the intrinsic coercivity H _c (330 to 78 kA/m) and of temperature coefficient of coercivity of ΔH _c /Δ? (0.39 to 0.22 kA/m°C) were achieved as a function of the (Zn–Sn) and (Sn–Sn) substitutions, respectively. The Curie temperature T _c decreased with the (Ni–Sn) substitution from 447 to 399°C.     

Correlation between structural and giant magnetoresistance properties of Fe–Ag nanogranular films

Fe _x Ag_1?x granular thin-films, with the atomic Fe concentration, x, ranging from 0 up to 0.5, were deposited by dc magnetron co-sputtering. The giant magnetoresistance (GMR) intensity is maximum at x _I  = 0.32, while the maximum of GMR efficiency, γ, i.e., the change of GMR intensity for a unit change of reduced squared magnetization, is observed at x _γ = 0.26. Owing to the spin-dependent scattering features, the GMR intensity and γ depend on both the concentration and the arrangement of the magnetic material. Therefore, to explain the difference between x _I and x _γ and to understand how the structural properties affect the magnetoresistive behaviour, we performed magnetization, Mössbauer and X-ray diffraction measurements as a function of x. X-ray data indicate that the granular films exhibit three different regimes: for x < 0.2, they can be described as a Fe–Ag solid solution; for 0.2 < x < 0.32 the Fe–Ag solid solution is still observed and very small Fe precipitates are found; finally, for x > 0.32, a Fe–Ag saturated solid solution is detected, containing bcc Fe clusters whose size is about 10 nm. Differently, for all the concentrations, magnetization data show the presence of Fe precipitates, whose size increases with x, and the Mössbauer investigation confirms this picture. We find that the samples grown at x = x _γ display the finest Fe dispersion within the Ag matrix, as the Fe–Ag solid solution is nearly at saturation and the Fe cluster size is of the order of a few nanometers; this arrangement possibly maximizes the magnetic/non-magnetic interface extension thus enhancing the GMR efficiency. If x is slightly increased, the increase in total Fe content compensates the GMR efficiency reduction, so the GMR intensity maximum is observed.     

Synthesis and characterization of highly conductive Sn–Ag bimetallic nanoparticles for printed electronics

To synthesize low-cost, highly conductive metal nanoparticles for inkjet printing materials, we synthesized Sn–Ag bimetallic nanoparticles using a polyol process with poly(vinyl pyrrolidone). Because a surface oxidation layer forms on Sn nanoparticles, various compositions of Sn–xAg [x = 0, 20, 40, 60, 80, 100 (wt%)] nanoparticles were synthesized and characterized for the purpose of removing the β-Sn phase. The results of XPS, TEM, and XRD analyses confirm that the formation of a bimetallic phase, such as Ag₄Sn or Ag₃Sn, hinders the β-Sn phase and, consequently, leads to the removal of the surface oxidation layer. To measure the sheet resistance of various compositions of Sn–Ag nanoparticles, we made the ink that contains Sn–Ag by dispersing 10 wt% of Sn–Ag nanoparticles in methanol. The sheet resistance is decreased by the conductive Sn–Ag phases, such as the fcc, Ag₄Sn, and Ag₃Sn phases, but sharply increased by the low-conductive Sn nanoparticles and the surface oxidation layer on the Sn nanoparticles. The sheet resistance results confirm that 80Ag20Sn and 60Ag40Sn bimetallic nanoparticles are suitable candidates for inkjet printing materials.     

Structural,electronic and magnetic properties of negative thermal expansion material Mn3Cu1−xSnxN

We have investigated the structural, electronic and magnetic properties of Mn₃Cu_1?xSn_xN(x=0, 0.5) using first-principles density functional theory within the generalized gradient approximation (GGA) + U schemes. The crystal structure of the compounds is tetragonal crystal for x=0 while it is a cubic crystal for x=0.5. Our spin-polarized calculations give a metallic ground state for the x= 0, 0.5 in agreement with experiments. From the charge density and density of states(DOS), the coupling between Sn 5p with Mn 3d and spin geometrical frustration effect are the main reasons for magnetic transition in Mn₃Cu_1?xSn_xN.     

Flux-driven cellular precipitation in open system to form porous Cu3Sn

Recently, a new morphology of porous Cu₃Sn with lamellar structure is observed. Several possible explanations of the formation are proposed and compared. The most reasonable one seems to be the one based on a theory of flux-driven cellular precipitation in open system. Outflux of Sn from Cu₆Sn₅ generates simultaneously supersaturation with vacancies and with copper leading to the eutectoid-like transformation β → α + γ (where γ is void). The transformation is complete due to a complete outflux of Sn from the Cu₆Sn₅ phase. Simple formulae for prediction of the lamellar structure parameters and the propagation velocity are obtained and compared reasonably with experimental data. The suggested model can be interpreted as one more case of the flux-driven phase transformations in open systems.