Zn Ag Research Articles

Synthesis of hierarchical Ag2ZnGeO4 hollow spheres for enhanced photocatalytic property

An Ag(2)ZnGeO(4) photocatalyst was fabricated by ion-exchange reaction between amorphous Zn(2)GeO(4) suspension and Ag(+) solutions. The Ostwald ripening effect induced the formation of hierarchical hollow spheres. Compared with the reference bulk Ag(2)ZnGeO(4), the hierarchical Ag(2)ZnGeO(4) hollow spheres showed enhanced photocatalytic activity.

Formation and microstructure of nanoporous silver by dealloying rapidly solidified Zn–Ag alloys

The electrochemical dealloying of rapidly solidified (RS) Zn–Ag alloys in a 5wt.% HCl solution and 1M NaCl solution has been investigated using electrochemical measurements and microstructural analysis. The results show that the electrochemical properties of the RS Zn–Ag alloys are associated not only with the alloy composition, but with the phase constitution of the alloys. Nanoporous silver (NPS) ribbons can be fabricated through potentiostatically dealloying the RS Zn–Ag alloys in both solutions. Moreover, a minor difference in the applied potential has a significant influence on the dealloying process and formation of NPS. The critical potential and polarization behavior of the Zn–Ag alloys have also been discussed, as well as surface diffusion of Ag adatoms.

The environmental impact of Aguilar mine on the heavy metal concentrations of the Yacoraite River, Jujuy Province, NW Argentina

The Yacoraite River and its tributaries run down the eastern slope of the Aguilar Range. It is one of the tributaries of the Rio Grande, located in Quebrada de Humahuaca, a UNESCO World Heritage site. The Aguilar underground mine (Pb–Ag–Zn) is located in the upper reaches of the Yacoraite River drainage basin. The aim of this work is to characterize the presence of heavy metals in water and sediments of the Yacoraite River and to identify their sources. The analysis shows the seasonal variation of heavy metals concentration in water and their relation with the World Health Organization (WHO) limits established for human consumption. The Yacoraite basin is naturally anomalous in some metals and some elements, such as As which is controlled by the chemical composition of regional lithology. During the wet season, Al, Co, Mo and Pb concentrations in water samples are higher than during the dry season; in addition, these metals are also higher than WHO limit values. High enrichment factors for Ba, Mo, Pb, Zn and Cd were found in Casa Grande stream, indicating the direct influence of the mining activities. Cd, Pb and Zn are present in the Aguilar ore minerals, such as sphalerite and galena. Sediments collected during the dry season show a drastic increase in the concentration of As, Pb, Ba, Zn, Cd and Mn. The Müller geo-accumulation index in Casa Grande indicates that it is a highly polluted stream. The concentrations of As, Pb, Ba, Zn, Cd are also high in Yacoraite River: Security Quality Guidelines indicates toxicity. A decrease in enrichment factors and geo-accumulation indices observed in sediments indicates the occurrence of precipitation/adsorption processes in the river to restore the equilibrium composition. Strict environmental controls in Aguilar Mine are necessary to avoid the uncontrolled input of toxic metals in Casa Grande stream and Yacoraite River.

Preparation and properties of p-type Ag-doped ZnMgO thin films by pulsed laser deposition

We report on p-type Ag-doped ZnMgO thin films prepared on quartz substrates by pulsed laser deposition. The effects of substrate temperature on the structural, electrical and optical properties of the films are investigated in detail. All the films we obtained have a preferred orientation with the c-axis perpendicular to the substrates. Secondary ion mass spectroscopy and X-ray photoelectron spectroscopy measurements confirm that Ag has been incorporated into the films and principally occupies Zn site in the state of Ag + ion and acts as an acceptor. An acceptable p-type conduction, with a resistivity of 24.96 Ω cm, a Hall mobility of 0.32 cm 2 V −1 s −1, and a hole concentration of 7.89 × 10 17 cm −3 at room temperature, was obtained for the film grown at the optimal substrate temperature of 400 °C. The formation of good p-type conduction in this film might be due to a combined effect of the increase of substitutional-Ag (Ag Zn) density and the suppression of the oxygen-related defects. The p-type conduction of Ag-doped ZnMgO film is further confirmed by a rectifying Ag-doped ZnMgO/i-ZnO/Al-doped ZnMgO heterojunction.

Mineral system analysis of the Mt Isa–McArthur River region, Northern Australia

The Mt Isa–McArthur region is renowned for a range of commodities and deposit types of world-class proportions. The region is described here in the context of a ‘mineral system,’ through consideration of processes that operate across a range of scales, from geodynamics and crustal architecture, to fluid sources, pathways, drivers and depositional processes. The objective is to improve targeting of Pb–Zn, Cu and Cu–Au deposits. Repeated extension and high heat flow characterise much of the history prior to 1640 Ma. The pre-Barramundi Orogeny (pre-1.87 Ga) metamorphic basement was the substrate on which a volcanic arc developed, focussed along the Kalkadoon-Leichhardt Belt. This is related to an inferred east-directed subduction between 1870 and 1850 Ma. From 1755 to 1640 Ma, three successive volcano-sedimentary basins developed, the Leichhardt, Calvert and Isa Superbasins, in an interpreted distal back-arc environment. The Isan Orogeny, from 1640 to 1490 Ma, overlapped with Isa Superbasin sedimentation, suggesting a transition from back-arc to a foreland basin setting. Most crustal thickening occurred in the Eastern Fold Belt, an area earlier characterised by thinned crust and deep marine environments. This region was deformed into nappe-like structures with high-temperature–low-pressure regional metamorphism and associated granites; the latter are absent from the Western Fold Belt. Metal deposition mainly occurred late in the history, with all known (and preserved) major base metal occurrences either hosted by Isa Superbasin rocks or formed during the Isan Orogeny. Earlier superbasins were potential fluid source regions. Sedimentary formation waters, metamorphic and magmatic fluids were present at prospect scale, while meteoric and possibly mantle sources are also implicated. The spatial distribution of metallogenic associations (i.e. iron oxide–copper–gold, Pb–Zn–Ag, U, Au) across the inlier may result from differences in the geodynamic make-up and evolution of the pre-1.87 Ga tectonic elements. Penetrative faults are interpreted as predominantly steeply dipping and to have acted as pathways for fluids, both in extension and compression. Fluid mixing was a potentially significant ore deposit control. Examples are drawn from the Ernest Henry iron oxide–copper–gold-related hydrothermal breccias in the east and from the Mt Isa Copper deposit in the west. Stress switching during late-stage deformation appears to have triggered a fluid mixing event that led to formation of the major copper deposits.

Synthetic Studies toward a Biomimetic Linear Precursor of Hirsutellones

In this paper we describe our efforts to synthesize the polyunsaturated part of a putative linear precursor of hirsutellones from (R)-citronellal, characterized by a terminal (E,Z,E)-triene alcohol. The geometry of this last moiety was installed by the alkyne reduction of an ene-yne-ene, under the Boland conditions [Zn(Ag,Cu), MeOH]. Under these conditions, we found that the presence of a diol functionality at the opposite of the linear chain, facing the alkyne, was necessary for the success of the reduction, an effect attributed to the chelation of an activated zinc species. Then one-pot diol cleavage-Wittig olefination allowed for further functionalization into a valuable α,β-unsaturated ester or Weinreb amide.

Electrical properties and Raman scattering investigation of Ag doped ZnO thin films

Ag-doped ZnO thin films were deposited on quartz glass substrates by a radio-frequency (RF) magnetron sputtering technique at room temperature (RT). The influence of Ag doping content on the electrical and Raman scattering properties of ZnO films were systematically investigated by Hall measurement system and Raman scattering spectrum. Two additional local vibrational modes (LVMs) at 230.0 and 394.5 cm −1 induced by Ag dopant in ZnO:Ag films were observed by Raman analyses at RT, corresponding to Ag atoms located at O sites (LV M Zn−Ag) and Zn sites (LV M Ag−O) in ZnO lattice. Moreover, we further studied the effect of donor Ag O and acceptor Ag Zn defects on the electrical properties of ZnO:Ag films. The results indicate that O-rich condition is preferred to suppress the formation of Ag O defects and enhance Ag Zn defects. The p-type ZnO:Ag film was achieved by properly optimizing the annealing conditions under O-rich condition.

Mesozoic molybdenum deposits in the east Qinling–Dabie orogenic belt: Characteristics and tectonic settings

The East Qinling–Dabie orogenic belt accommodates the largest Mo ore district in the world. It contains 8.43 Mt of proven Mo metal reserves which accounts for 66% of the total proven Chinese Mo reserves. The Mo ore district includes 24 deposits and 12 occurrences, with four major types of Mo mineral systems, i.e., porphyry, porphyry-skarn, skarn and hydrothermal veins. The latter can be further subdivided into quartz vein and carbonatite vein types. Although Mo mineralization in the belt began in the Paleoproterozoic (1680 ± 24 to 2044 ± 14 Ma), all economically significant deposits were formed during the Mesozoic. Re/Os dating of molybdenite has shown that there are three episodes of Mo mineralization, i.e., Late Triassic (233–221 Ma), Late Jurassic to Early Cretaceous (148–138 Ma) and Early to middle Cretaceous (131–112 Ma). Late Triassic Mo deposits developed as molybdenite–quartz veins and carbonatite vein types. Stable isotope systematics (C, O, S) and high contents of Re and Sr indicate that the carbonatite Mo veins are mantle-derived. Porphyry and porphyry–skarn Mo mineral deposits were formed in the Late Jurassic to Early Cretaceous and Early to middle Cretaceous. The Late Jurassic to Early Cretaceous granite porphyries that are associated with the Mo deposits usually occupy less than 1.5 km 2 at the surface and are situated in the East Qinling area, far west of China's continental margin. On the other hand, the Early to middle Cretaceous batholiths and granite porphyries, , with associated Mo deposits are located in the Dabieshan area and eastern part of the East Qinling area. The Late Jurassic to Early Creataceous granitoids and related Mo deposits possibly formed in a back-arc extensional setting of the Eurasian continental margin, which was probably triggered by the oblique subduction of the Izanagi plate. The Early to middle Cretaceous batholiths and granite porphyries are linked to the tectonic regime of lithospheric thinning, asthenospheric upwelling and partial melting of the crust, induced by a change in Izanagi Plate motion parallel to the continent margin. In the East Qinling–Dabie belt there are vein type Pb–Zn–Ag deposits surrounding porphyry and/or porphyry–skarn Mo (W) deposits, forming well defined ore clusters. The same spatial arrangement (i.e., porphyry Mo stockworks and outlying Pb–Zn–Ag ore veins) is also observed at the deposit scale. Thus, Mo porphyry stockworks and distal polymetallic veins belong to the same ore system and may reflect an outward temperature decrease from the highly fractionated granite plutons. Both, porphyry stockworks and polymetallic veins, can be used as vectors for further prospecting.

Wetting behaviour and interfacial microstructure of Sn–Ag–Zn solder alloys on nickel coated aluminium substrates

Wetting behaviours of two lead free solders (Sn–2·625Ag–2·25Zn and Sn–1·75Ag–4·5Zn) on nickel coated aluminium substrates were investigated. Sn–2·625Ag–2·25Zn exhibited better wettability compared to Sn–1·75Ag–4·5Zn solder. Contact angles of the solders increased with increasing roughness of the substrate. The Young–Dupre equation was used to evaluate the work of adhesion of solder on the substrate. Sn–2·625Ag–2·25Zn solder exhibited higher work of adhesion than Sn–1·75Ag–4·5Zn. A thin continuous layer of Ni3Sn was detected at the interface between Sn–2·625Ag–2·25Zn solder and nickel coated Al substrate. Sn–1·75Ag–4·5Zn solder exhibited scallop intermetallic compounds (IMCs) growing into the solder field as well as a thin continuous IMC in some cases. Ni3Sn and Ni3Sn4 IMCs were observed at the interface of Sn–1·75Ag–4·5Zn solder and nickel coated Al.

Mineral potential targeting and resource assessment based on 3D geological modeling in Luanchuan region, China

In this paper, we used 3D modeling and nonlinear methods (fractal, multifractal, and probabilistic neural networks (PNN)) for regional mineral potential mapping and quantitative assessment for porphyry and skarn-type Mo deposits and hydrothermal vein-type Pb–Zn–Ag deposits in the Luanchuan region, China. A 3D geological model was constructed from various geological maps, cross sections, boreholes, and gravity and magnetic data. Geological features associated with mineralization were extracted using the 3D geological model and metallogenic models of porphyry and skarn-type Mo and Pb–Zn–Ag deposits. The multifractal method, principal component analysis, and power spectrum–area method were used to separate regional variability from local variability in the geochemical data. A 2.5D forward modeling of gravity and magnetic data was carried out to define the geometry, depth, and physical properties of geological bodies at depth. 3D visualization of the results assisted in understanding the spatial relations between the deposits and the other geological bodies (e.g., igneous intrusions). The PNN method was applied to represent and integrate multiple anomalies for mineral potential modeling. The concentration–area fractal method was used to classify the PNN mineral potential model. Three levels (ground surface and two subsurface horizontal planes) of mineral potential models were evaluated for undiscovered Mo and Pb–Zn–Ag deposits. Validation of the results shows that 3D modeling was useful for not only accurately extracting geological features but also for predicting potential mineral targets and evaluating mineral resources. The mineral potential targets identified consist of eight Mo potential targets and 15 Pb–Zn–Ag potential targets. Based on grade–tonnage data from the known Mo and Pb–Zn–Ag deposits and the results of 3D modeling, estimated potential resources of each of these types of deposits are 10.8 and 153.1 Mt (Pb+Zn is 152.9 Mt and Ag is 0.92 Mt), respectively.

Paleomagnetism of the Mt Isa Zn–Pb–Cu–Ag and George Fisher Zn–Pb–Ag deposits, Australia

Paleomagnetic results are reported for the Mt Isa Zn–Pb–Cu–Ag and George Fisher Zn–Pb–Ag black-shale-hosted deposits in northwestern Queensland, Australia. Both deposits are hosted in greenschist facies carbonaceous and dolomitic siltstones, mudstones and shales of the ca 1655 Ma Urquhart Shale Formation of the Mt Isa Group. Lead model ages for both deposits are ca 1655 Ma, and an Ar–Ar biotite age for Cu mineralisation at Mt Isa is ca 1523 Ma. Paleomagnetic and rock magnetic analyses of 333 specimens (28 sites) isolate, excluding modern hematite, a stable characteristic remanent magnetisation (ChRM) carried mainly by single- or pseudosingle-domain pyrrhotite for Zn–Pb–Ag ore specimens and pyrrhotite and/or titanomagnetite for Cu ore specimens. A paleomagnetic fold test shows that the ChRM postdates D3 deformation of the ca 1595 to 1500 Ma Isan orogeny, yielding a Mesoproterozoic paleopole at ca 1505 Ma on the northern Australian apparent polar wander path, thereby providing a minimum age for the ores and an age for greenschist metamorphism during the last major metamorphic peak of the Isan orogeny in the Mt Isa inlier.

Silver–base metal epithermal vein and listwaenite types of deposit Crnac, Rogozna Mts., Kosovo. Part I: Ore mineral geochemistry and sulfur isotope study

Pb–Zn–Ag vein and listwaenite types of mineralization in Crnac deposit, Western Vardar zone, were deposited within several stages: (i) the pre-ore stage comprises pyrite, arsenopyrite, pyrrhotite, quartz, kaolinite and is followed by magnetite–pyrite; (ii) the syn-ore stage is composed of galena, sphalerite, tetrahedrite and stefanite; and (iii) the post-ore stage is composed of carbonates, pyrite, arsenopyrite and minor galena. The vein type mineralization is hosted by Jurassic amphibolites and veins terminate within overlying serpentinites. Mineralized listwaenites are developed along the serpentinite–amphibolite interface. The reserves are estimated to 1.7 Mt of ore containing in average 7.6% lead, 2.9% zinc, and 102 g/t silver. Sulfides from the pre- and syn-mineralization assemblage of the vein- and listwaenite-types of mineralization from the Crnac Pb–Zn–Ag deposit have been analyzed using microprobe, crush-leachates and sulfur isotopes. The pre-ore assemblage precipitated under high sulfur fugacities ( f(S 2) = 10 − 8 –10 − 6 bar) from temperatures ranging between 350 °C and 380 °C. Most likely water–rock reactions, boiling and/or increase of pH caused an increase of δ 34S of pyrite toward upper levels within the deposit. The decomposition of pre-ore pyrrhotite to a pyrite-magnetite mixture occurred at a fugacity of sulfur from f(S 2) = 8.7 × 10 − 10 to 9.6 × 10 − 9 bar and fugacity of oxygen from f(O 2) = 2.4 × 10 − 30 to 3.1 × 10 − 28 bars, indicating a contribution of an oxidizing fluid, i.e. meteoric water during pre-ore stages of hydrothermal activity. The crystallization temperatures obtained by the sphalerite-galena isotope geothermometer range from 230 to 310 °C. The δ 34S values of pre- and syn-ore sulfides (pyrite, galena, sphalerite, δ 34S = 0.3–5.9‰) point to magmatic sulfur. Values of δ 34S of galena and sphalerite are decreasing upwards due to precipitation of early formed sulfide minerals. Post-ore assemblage precipitated at temperature below 190 °C. Based on data presented above, we assume two fluid sources: (i) a magmatic source, supported by sulfur isotopic compositions within pre- and syn-ore minerals and a high mol% of fluorine found within pre- and syn-ore leachates, and (ii) a meteoric source, deduced by coincident pyrite–magnetite intergrowth, sulfur isotopic trends within syn-ore minerals and decrease of crystallization temperatures from the pre-ore stage (380–350 °C), towards the syn-ore (310–215 °C) and post-ore stages (< 190 °C). Post-ore fluids are Na–Ca–Mg–K–Li chlorine rich and were modified via water–rock reactions. Simple mineral assemblage and sphalerite composition range from 1.5 to 10.1 mol% of FeS catalog Crnac to a group of intermediate sulfidation epithermal deposit.

Glucose-mediated solution–solid route for easy synthesis of Ag/ZnO particles with superior photocatalytic activity and photostability

In this paper, we report an effective glucose-assisted solution–solid process for preparing Ag/ZnO photocatalyst with excellent photocatalytic performance. The solution–solid route included first formation of a glucose–Zn–Ag precursor containing Zn and Ag source in glucose framework (solution-phase stage) and subsequent heat treatment of the precursor to obtain Ag/ZnO particles (solid-phase stage). Ag/ZnO particles could be prepared on large scale through this solution–solid process (about 1.5 g for each time synthesis and could be easily scaled up). Also, the result of photocatalytic test indicates that the material exhibits superior photocatalytic activity for the photodegradation of organic dye Rhodamine B. Notably, no obvious loss of catalytic activity was observed after ten cycles, indicating the excellent photostability of Ag/ZnO particles.

LEAD-ANTIMONY SULFOSALTS FROM TUSCANY (ITALY). XI. THE NEW MINERAL SPECIES PARASTERRYITE, Ag4Pb20(Sb14.5As9.5) 24S58, AND ASSOCIATED STERRYITE, Cu(Ag,Cu)3Pb19(Sb,As)22(As-As)S56, FROM THE POLLONE MINE, TUSCANY, ITALY

The new mineral species parasterryite has been discovered in the Pollone barite – pyrite – (Pb–Zn–Ag) deposit at Valdicastello Carducci, near Pietrasanta, in the Apuan Alps, Tuscany, Italy. It forms acicular crystals up to 4 × 0.3 mm in vugs in quartz–barite veins. Sterryite (second world occurrence) also is present. The associated sulfides and sulfosalts are pyrite, sphalerite and various Sb–As sulfosalts. Parasterryite is black and metallic. Under the microscope, it is white with weak pleochroism; anisotropism is distinct, with greenish and brownish tints. Data on maximum and minimum reflectances for the COM wavelengths are [λ (nm), R air , R oil (%)]: 470: 35.1, 40.8 and 19.4, 22.2, 546: 33.5, 39.3 and 19.3, 21.7, 589: 32.7, 38.2 and 18.7, 21.1, 650: 31.4, 36.5 and 17.3, 19.5. Hardness VHN 10 = 238 kg/mm 2 . An electron-microprobe analysis gave (in wt.%, mean result of 32 spot analyses): Cu 0.09(2), Ag 4.36(6), Hg 0.15(2), Pb 47.00(18), Sb 19.57(30), As 7.73(21), S 20.56(7), total 99.46(23). A single-crystal X-ray study of parasterryite indicates monoclinic symmetry, space group P 2 1 / c , with a 8.3965(5), b 27.9540(4), c 43.8840(13) A, β 90.061(12)°, V = 10300(3) A 3 . The main powder-diffraction lines [ d in A( I )( hkl )] are: 3.62(100)(075, 0112, 234, 234), 3.42(45) (244, 244), 3.35(95)(0113), 3.23(65)(078), 3.01(45)(239, 239), 2.945(85)(088), 2.885(80), 1.916(45). The name parasterryite reflects its close structural relationship with sterryite. Sterryite is more abundant than parasterryite. Electron-microprobe analyses of two samples gave: 1) Sb-rich sterryite (wt.%): Cu 1.27(1), Ag 2.19(11), Hg 0.55(5), Tl 0.56(8), Pb 44.76(25), Bi 0.26(7), Sb 24.71(11), As 5.33(9), S 20.47(11), total 100.10(39), and 2) Sb-poor sterryite: Cu 0.73(4), Ag 4.12(13), Pb 44.58(16), Sb 20.84(22), As 8.27(12), S 20.92(7), total 99.47(15). The unit cell of Sb-rich sterryite is: a 8.1891(1), b 28.5294(13), c 42.98(2) A, β 94.896(8)°, V = 10005(5) A 3 (space group P 2 1 / n ). It presents a powder diagram close to that of sterryite from Madoc, Ontario, the type locality. The crystal structures of sterryite and parasterryite (not described here) are very similar, and represent a limiting case of homeotypy; they are also expanded homologues of owyheeite. The structural formula of parasterryite is based on 48 cations and 58 S, ideally Ag 4 Pb 20 (Sb 14.5 As 9.5 ) ∑24 S 58 ( Z = 4). The structural formula of sterryite is based on 47 cations and 56 S, with an (As–As) 4+ dimer [ d (As–As) = 2.64 A] and a specific Cu site, ideally Cu(Ag,Cu) 3 Pb 19 (Sb,As) 22 (As–As)S 56 ( Z = 4). The presence of the As–As dimer in sterryite indicates its formation with a lower f (S 2 ) than parasterryite, which may also explain the formation of some rare Pb–Sb–As sulfosalts at Madoc.

Tailoring polymer–TiO2 film properties by presence of metal (Ag, Cu, Zn) species: Optimization of antimicrobial properties

Presence of metallic Ag or oxidic Cu and Zn species on an anatase surface is shown to allow drastic improvement of the disinfection capability of polymer-based TiO2-containing nanocomposite films against both gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacteria and upon both ultraviolet and visible light excitations. The inorganic incorporation to the polymer matrix is reached without alteration of the main physico-chemical (structural and thermal) characteristics of the organic component. Irrespective of the excitation wavelength, the disinfection capability improvement is observed for Ag and Zn promoted film materials but not for the Cu-containing composite. A study of the optical properties attempts to interpret the biocidal enhancement observed in presence of such Ag, Cu, and Zn-containing species at inorganic–organic interfaces.

Ca–Mg–Zn–(Ag) bulk metallic glasses prepared by unidirectional quenching

We fabricated ternary Ca–Mg–Zn and quaternary Ca–Mg–Zn–Ag bulk metallic glasses with diameter of 7 mm by unidirectional quenching into water-cooled Ga–In–Sn liquid alloys. It was suggested that the electromagnetic stirring caused by induction eddy current facilitated the glass formation. Glass forming ability of Ca 62.5Mg 17.5Zn 20− x Ag x ( x = 0, 1, 3, 5, 7, 9) system was dependent on Ag content. It was found that in the system the in-situ formed crystalline phases enhanced the second-stage crystallization, whereas there seemed no contribution to the third-stage crystallization.

Determination of solid–liquid interfacial energy for a solid Sn in equilibrium with a Sn–Ag–Zn eutectic liquid

The equilibrated grain boundary groove shapes for a solid Sn in equilibrium with a Sn–Ag–Zn eutectic liquid were observed in a linear temperature gradient by using a Bridgman type directional solidification apparatus. The Gibbs–Thomson coefficient, solid–liquid interfacial energy and grain boundary energy for a solid Sn in equilibrium with a Sn–Ag–Zn eutectic liquid were determined to be (8.21 ± 0.7) × 10 −8 Km, (116.2 ± 15.1) × 10 −3 J m −2 and (228.1 ± 34.2) × 10 −3 J m −2, respectively from observed grain boundary groove shapes. A comparison of present results with the previous experimental and theoretical results for similar solids in equilibrium with the different liquid was also made.

Assessment of the diffusional mobilities in the face-centred cubic Ag–Zn alloys

Based on the available thermodynamic information and diffusion coefficient data of the Ag–Zn binary system, the atomic mobilities of Ag and Zn in face-centred cubic (fcc) Ag–Zn alloys have been assessed as a function of temperature and composition in terms of the CALPHAD method using the DICTRA software package. Optimized mobility parameters are presented. Comparisons between the calculated and measured diffusion coefficients show that most of the experimental information can be satisfactorily reproduced in the present work. The obtained mobility parameters can also predict reasonable concentration profiles of the diffusion zone in the binary Ag–Zn diffusion couples.

Wetting Behaviour and Evolution of Microstructure of Sn–Ag–Zn Solders on Copper Substrates with Different Surface Textures

Abstract The effect of surface roughness on wetting behaviour and evolution of microstructure of two lead-free solders (Sn-2.625Ag-2.25Zn and Sn-1.75Ag-4.5Zn) on copper substrate was investigated. Both solders exhibited good wettability on copper substrates having rough surface and lower wettabilty on smooth surfaces. The contact angles of solders decreased linearly with increase in surface roughness of the substrate. The exponential power law, ϕ=exp(−Kτn), was used to model the relaxation behaviour of solders. A high intermetallic growth was observed at the interface particularly on copper substrates with rough surface texture. A thin continuous interface showing scallop intermetallic compounds (IMC) was obtained on smooth surfaces. With an increase in surface roughness, the IMC morphology changed from scallop shaped to needle type at the Sn-2.625Ag-2.25Zn solder/substrate interface and nodular to plate like IMCs for Sn-1.75Ag-4.5Zn solder matrix.

Effect of solidification parameters on the microstructure of Sn-3.7Ag-0.9Zn solder

In this work, Sn–Ag–Zn alloy of eutectic composition (Sn-3.7wt.%Ag-0.9wt.%Zn) was directionally solidified upward at a constant temperature gradient ( G = 4.33 K/mm) in a wide range of growth rates ( V = 3.38–220.12 μm/s) and a constant growth rate ( V = 11.52 μm/s) with different temperature gradients ( G = 4.33–12.41 K/mm) using a Bridgman type directional solidification furnace. The microstructure was observed to be a rod Ag 3Sn structure in the matrix of β–Sn from the directionally solidified Sn-3.7wt.%Ag-0.9wt.%Zn samples. The values of eutectic spacing ( λ) were measured from transverse section of samples. The dependency of eutectic spacing on the growth rate ( V) and temperature gradient ( G) were determined with linear regression analysis. The dependency of λ on the values of V and G were found to be λ = 10.42 V − 0.53 and λ = 0.27 G − 0.48 , respectively. The values of bulk growth were also determined to be λ 2 V = 86.39 μm 3/s by using the measured values of λ and V. The results obtained in present work were compared with the previous similar experimental results obtained for binary and ternary alloys.