Binary Pb Research Articles

Nanoscale insight into the domain structures of high Curie point Pb(In1/2Nb1/2)O3-PbTiO3 single crystal

Recently high-Curie point relaxor ferroelectric single crystals represented by the binary (1-x)Pb(In1/2Nb1/2)O3-xPbTiO3 (PINT, PINTx) and ternary Pb(Mg1/3Nb2/3)O3–Pb(In1/2Nb1/2)O3-PbTiO3 (PMN-PIN-PT) attracted much attention. In order to given an insight into the domain structures for these high Curie temperature Tc single crystals, in this work, PINT single crystal, grown by a modified Bridgeman method, was studied by piezoresponse force microscopy (PFM). Results indicated that the PINTx single crystal exhibited strip-like long-range-order ferroelectric domain structures at room temperature with x across the morphotropic phase boundary ranging from 0.28 to 0.42. The electric-field induced domain evolution was performed to give an insight into the local poling behavior for rhombohedral compositions PINT0.28 and PINT0.34 (with giant piezoelectric strain response). The temperature-dependent PFM results indicated that the PINT single crystal exhibited good temperature stability in nanoscale and clear domain patterns could still be observed above the Tc.

Effect of soil fulvic and humic acid on binding of Pb to goethite–water interface: Linear additivity and volume fractions of HS in the Stern layer

The effects of soil fulvic (JGFA) and humic acid (JGHA) on Pb binding to goethite were investigated with batch experiments and modeling. The CD-MUSIC and NICA-Donnan model could describe the Pb binding to, respectively, the binary Pb–goethite and Pb–HS systems. The adsorption of humic substances (HS) on goethite strongly depended on pH and was promoted by Pb binding. The mass amount of adsorbed JGFA (mg/g) was smaller than that of JGHA, but when expressed in number of particles/nm2 the JGFA adsorption was higher. At low pH and low initial Pb concentration the linear additivity rule always underestimated Pb adsorption to goethite–HS complex, which was caused by the strong effect of adsorbed HS on the electrostatic potentials in the Stern layer region. At other conditions except the 450mg/L JGHA in the 0.5mmol/L Pb system the additivity rule predicted the experimental results reasonably well, and at high pH nearly all Pb is bound to goethite. At the same mass adsorbed, the effect of JGFA on Pb adsorption to goethite is stronger than that of JGHA, due to the fact that the JGFA particles were primarily adsorbed in the Stern layer, whereas JGHA particles were present in both Stern layer and diffuse layer. Therefore, the electrostatic potential profile of the goethite-JGFA complex is considerably different from that of goethite-JGHA complex and affects Pb binding strongly.

Numerical simulation of macrosegregation during solidification of binary alloys

Macrosegregation as a consequence of solidification of a binary Pb–48 wt% Sn alloy in two-dimensional rectangle cavity was investigated by two-phase model instead of the common used continuum model. The macroscopic transport of mass, momentum, species and energy was coupled with the microscopic descriptions of grain nucleation and growth. The mathematic equations of the two-phase model were discretized on staggered grids and solved by the finite volume method. The final tin concentrations along different heights over the bottom face were compared with the experiment measurements. Simulations with different microstructure parameters (second dendrite arm spacing (SDAS)) were conducted to ascertain the influence of microstructure on the final macrosegregation. The results show that with the decrease in SDAS value, the drag force as the resistance to relative motion between solid and liquid phase increases, and the macrosegregation during solidification is alleviated.

Removal of Binary Metal (Nickel and Lead) Ions from Aqueous Solution Using Natural and Modified Clinoptilolite

In this study, adsorption of binary metal (Ni(II) and Pb(II)) ions from aqueous solution by using natural (NC), acid-modified (AC) and base-modified (BC) clinoptilolite were investigated to determine the effects of adsorbent dosage, metal solution’s pH and initial metal solution concentration. From the adsorption studies, the optimum dosage of adsorbent was found to be 2.0g for all adsorbents (NC, AC and BC) specifically for removal of Pb(II). In contrast, optimum dosage of for removal of Ni(II) was found to be 2.0g for NC and 4.0g for both AC and BC, respectively. The average pH for Ni(II) and Pb(II) ion solutions were 6. It was further observed that, the percentage removal of Ni(II) was largely influenced by the presence of lead due to the preference of Pb2+ ions by the natural and modified clinoptilolites.

Viscosity of liquid binary Pb–Zn alloys in the miscibility gap region

The shear viscosity studies were performed for the liquid Pb–Zn monotectic system over a wide temperature range using an oscillating-cup viscometer, with special attention to the critical point (CP) region. The critical parameters describing the peculiarities of the viscosity behavior in the vicinity of CP are evaluated. The data analysis is based on the dynamic theory of phase transitions and the viscosity equation, which takes into account a spatial dispersion of the systems near their critical temperatures. The results are compared with available data for immiscible dielectric solutions.

Minimization of pyroelectric effects in relaxor-PbTiO3 crystals for piezoelectric sensors

To minimize pyroelectric effects while keeping high piezoelectric effects in relaxor-PbTiO3 single crystals, the crystallographic orientation dependence of the pyroelectric and piezoelectric coefficients were investigated for binary (1 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT), ternary (1 − x − y)Pb(In1/2Nb1/2)O3–yPb(Mg1/3Nb2/3)O3–xPbTiO3 (PIN–PMN–PT) and Mn-doped PIN–PMN–PT single crystals with the “4R” multidomain state. The secondary pyroelectric coefficients were calculated from the thermodynamic inter-relationship between the piezoelectric, elastic, and thermal expansion coefficients, being on the order of (1.16–1.23) × 10−4 C m−2 K−1 for binary crystals and (0.97–2.03) × 10−4 C m−2 K−1 for ternary ones. The primary pyroelectric coefficients were –(6.73–6.84) × 10−4 C m−2 K−1 and −(5.44–6.43) × 10−4 C m−2 K−1 for binary and ternary crystals, respectively. The pyroelectric coefficients could be reduced by matrix rotation, but at the cost of decreasing longitudinal piezoelectric coefficients d33. Of particular interest is that the maximum piezoelectric coefficients d24∗ at θ = ±55o and d34∗ at θ = ±35o by a counterclockwise rotation of θ about the X axis (θ is the rotation angle about the coordinate axes), or d15∗ at θ = ±55o, and d35∗ at θ = ±35o by a counterclockwise rotation the Y axis, were found on the order of 3000 pC N−1. The corresponding pyroelectric coefficients could be reduced by ∼20%. The reduced pyroelectric coefficients that can contribute to decrease undesirable output signals, together with the high piezoelectric coefficients, enable relaxor-PT crystals as favorable candidates for high-sensitivity piezoelectric sensors.

Primary and secondary pyroelectric coefficients of rhombohedral and tetragonal single-domain relaxor-PbTiO3 single crystals

The primary and secondary pyroelectric coefficients were determined for binary (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-PT) and ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PIN-PMN-PT) relaxor-PT single crystals. The secondary pyroelectric coefficients were calculated from the thermodynamic inter-relationship between the piezoelectric, elastic, and thermal expansion coefficients. Poling along [111] and [001] directions resulted in single-domain state of “1R” and “1T” and a macroscopic symmetry of 3m and 4mm for rhombohedral (x = 0.28) and tetragonal (x = 0.42) crystals, respectively, enabling relatively large values of pyroelectric coefficients p ≥ 5.7 × 10−4 C/m2 K. The calculated results show that the secondary pyroelectric coefficients are in the range of (−0.62 ∼ −1.06) × 10−4 C/m2 K for rhombohedral crystals and (0.70 ∼ 1.14) × 10−4 C/m2 K for tetragonal crystals, significantly lower than that of primary pyroelectric coefficients, which is important for thermal directional and imaging applications. In contrast, high d15 piezoelectric coefficients (>2000 pC/N), together with zero pyroelectric coefficients in thickness shear crystals, also makes them promising candidates for piezoelectric sensors where thermal noise is undesirable.

Analysis of lead(II) retention from single salt and binary aqueous solutions by a polyamide nanofiltration membrane: Experimental results and modelling

The present paper reports the performance of a polyamide thin-film composite NF membrane (AFC 80) in the removal of highly polluting and toxic Pb(II) ions from single salt and binary aqueous solutions simulating real wastewaters. The effect of the operating variables (pH, transmembrane pressure and feed solution concentration) on the separation process was investigated. It was observed that the rejection of lead ions slightly increases with increasing the transmembrane pressure and slightly decreases with increasing the metal concentration in feed at constant pH of aqueous solutions. The maximum rejection of lead ions in single salt solution was 99.44% for a feed solution containing 50mg Pb/L at pH 5.7. In binary Pb–Cd aqueous solutions the metals rejections are higher than 98.5% for concentrations in the 15–80mg/L range, and the rejection order follows the order of metals hydration energies. The optimum operating conditions selected were: transmembrane pressure in 10–30bars range, feed solutions (polluted wastewaters) at pH 5.7 containing 50–80mg metal/L. The Spiegler–Kedem model ensures a very good description and prediction of the NF processes under study for a wide concentrations range. The model parameters showed that the transport mechanism of the solute is mainly convective, being almost totally hindered by the size of the metal ions which finally determine the salts retention. The AFC 80 membrane proved to be able to perform an effective removal of lead, and also of cadmium and nitrate ions, in very mild and economically advantageous conditions, leading to wastewaters suitable to be discharged into the environment. The structural characteristics of the AFC 80 membrane (effective pore radius and the thickness to porosity ratio) were estimated from uncharged solutes rejection experiments. The charge properties of the membrane surface were assessed by measuring the tangential streaming potential. It was found that the membrane becomes positively charged in lead nitrate solution, and this behaviour was attributed to adsorption of lead ions on the membrane surface. The membrane characteristics thus determined were correlated with the results of lead separation experiments and with the Spiegler–Kedem model parameters.

Thermal-independent properties of PIN-PMN-PT single-crystal linear-array ultrasonic transducers.

In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In(1/2)Nb(1/2))-Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PIN-PMN-PT) and binary Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PMNPT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a -6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising.

PH-Specific Hydrothermal Assembly of Binary and Ternary Pb(II)-(O,N-Carboxylic Acid) Metal Organic Framework Compounds: Correlation of Aqueous Solution Speciation with Variable Dimensionality Solid-State Lattice Architecture and Spectroscopic Signatures

Hydrothermal pH-specific reactivity in the binary/ternary systems of Pb(II) with the carboxylic acids N-hydroxyethyl-iminodiacetic acid (Heida), 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (Dpot), and 1,10-phenanthroline (Phen) afforded the new well-defined crystalline compounds [Pb(Heida)](n)·nH(2)O(1), [Pb(Phen)(Heida)]·4H(2)O(2), and [Pb(3)(NO(3))(Dpot)](n)(3). All compounds were characterized by elemental analysis, FT-IR, solution or/and solid-state NMR, and single-crystal X-ray diffraction. The structures in 1-2 reveal the presence of a Pb(II) center coordinated to one Heida ligand, with 1 exhibiting a two-dimensional (2D) lattice extending to a three-dimensional (3D) one through H-bonding interactions. The concurrent aqueous speciation study of the binary Pb(II)-Heida system projects species complementing the synthetic efforts, thereby lending credence to a global structural speciation strategy in investigating binary/ternary Pb(II)-Heida/Phen systems. The involvement of Phen in 2 projects the significance of nature and reactivity potential of N-aromatic chelators, disrupting the binary lattice in 1 and influencing the nature of the ultimately arising ternary 3D lattice. 3 is a ternary coordination polymer, where Pb(II)-Dpot coordination leads to a 2D metal-organic-framework material with unique architecture. The collective physicochemical properties of 1-3 formulate the salient features of variable dimensionality metal-organic-framework lattices in binary/ternary Pb(II)-(hydroxy-carboxylate) structures, based on which new Pb(II) materials with distinct architecture and spectroscopic signature can be rationally designed and pursued synthetically.

Extracellular Polymeric Substances from Bacillus subtilis Associated with Minerals Modify the Extent and Rate of Heavy Metal Sorption

Extracellular polymeric substances (EPS) are an important source of organic matter in soil. Once released by microorganisms, a portion may be sorbed to mineral surfaces, thereby altering the mineral̀s ability to immobilize heavy metals. EPS from Bacillus subtilis were reacted with Ca-saturated bentonite and ferrihydrite in 0.01 M KCl at pH 5.0 to follow the preferential uptake of EPS-C, -N, and -P. The sorption kinetics of Pb(2+), Cu(2+), and Zn(2+) to the resulting EPS-mineral composites was studied in single and binary metal batch experiments ([metal](total) = 50 μM, pH 5.0). Bentonite sorbed much more EPS-C (18.5 mg g(-1)) than ferrihydrite (7.9 mg g(-1)). During sorption, EPS were chemically and size fractionated with bentonite favoring the uptake of low-molecular weight components and EPS-N, and ferrihydrite selectively retaining high-molecular weight and P-rich components. Surface area and pore size measurements by N(2) gas adsorption at 77 K indicated that EPS altered the structure of mineral-EPS associations by inducing partial disaggregation of bentonite and aggregation of ferrihydrite. Whereas mineral-bound EPS increased the extent and rate of Pb(2+), Cu(2+), and Zn(2+) sorption for bentonite, either no effect or a decrease in metal uptake was observed for ferrihydrite. The extent of sorption always followed the order Pb(2+) > Cu(2+) > Zn(2+), which also prevailed in binary Pb(2+)/Cu(2+) systems. In consequence, sorption of EPS to different minerals may have contrasting consequences for the immobilization of heavy metals in natural environments by inducing mineral-specific alterations of the pore size distribution and, thus, of available sorption sites.

Making practical use of the pseudo-element concept: an efficient way to ternary intermetalloid clusters by an isoelectronic Pb−–Bi combination

Syntheses of [K([2.2.2]crypt)](+) salts of binary Pb-Bi Zintl anions and their reaction with ZnPh(2) or Ni(cod)(2), yielding ternary intermetalloid Ni-Pb-Bi or Zn-Pb-Bi clusters, proved the use of binary precursors with fully isoelectronic atoms as an efficient and thus valuable synthetic approach to this class of clusters. (207)Pb NMR and ESI mass spectra provided insight into the solution behavior of the binary or ternary cages.

Field stability of piezoelectric shear properties in PIN-PMN-PT crystals under large drive field.

The coercive fields (E(C)) of Pb(In₀.₅Nb₀.₅)O₃-Pb(Mg(¹/₃)Nb(²/₃)O₃-PbTiO₃ (PIN-PMN-PT) ternary single crystals were found to be 5 kV/cm, double the value of binary Pb(Mg(¹/₃)Nb(²/₃)O₃-PbTiO₃ (PMNT) crystals, further increased to 6 to 9 kV/cm using Mn modifications. In addition to an increased EC, the acceptor modification resulted in the developed internal bias (E(int)), on the order of ~1 kV/cm. The piezoelectric shear properties of unmodified and Mn-modified PIN-PMN-PT crystals with various domain configurations were investigated. The shear piezoelectric coefficients and electromechanical coupling factors for different domain configurations were found to be >2000 pC/N and >0.85, respectively, with slightly reduced properties observed in Mn-modified tetragonal crystals. Fatigue/cycling tests performed on shearmode samples as a function of ac drive field level demonstrated that the allowable ac field levels (the maximum applied ac field before the occurrence of depolarization) were only ~2 kV/cm for unmodified crystals, less than half of their coercive field. Allowable ac drive levels were on the order of 4 to 6 kV/cm for Mn-modified crystals with rhombohedral/orthorhombic phase, further increased to 5 to 8 kV/cm in tetragonal crystals, because of their higher coercive fields. It is of particular interest that the allowable ac drive field level for Mn-modified crystals was found to be ≥ 60% of their coercive fields, because of the developed E(int), induced by the acceptor-oxygen vacancy defect dipoles.

Accumulation and quantitative estimates of airborne lead for a wild plant ( Aster subulatus)

Foliar uptake of airborne lead is one of the pathways for Pb accumulation in plant organs. However, the approximate contributions of airborne Pb to plant organs are still unclear. In the present study, aerosols (nine-stage size-segregated aerosols and total suspended particulates), a wild plant species ( Aster subulatus) and the corresponding soils were collected and Pb contents and isotopic ratios in these samples were analyzed. Average concentration of Pb was 96.5 ± 63.5 ng m −3 in total suspended particulates (TSP) and 20.4 ± 5.5 ng m −3 in the fine fractions of size-segregated aerosols (SSA) (<2.1 μm), higher than that in the coarser fractions (>2.1 μm) (6.38 ± 3.71 ng m −3). Enrichment factors show that aerosols and soils suffered from anthropogenic inputs and the fine fractions of the size-segregated aerosols enriched more Pb than the coarse fractions. The order of Pb contents in A. subulatus was roots > leaves > stems. The linear relationship of Pb isotope ratios ( 206Pb/ 207Pb and 208Pb/ 206Pb) among soil, plant and aerosol samples were found. Based on the simple binary Pb isotopic model using the mean 206Pb/ 207Pb ratios in TSP and in SSA, the approximate contributions of airborne Pb into plant leaves were 72.2% and 65.1%, respectively, suggesting that airborne Pb is the most important source for the Pb accumulation in leaves. So the combination of Pb isotope tracing and the simple binary Pb isotope model can assess the contribution of airborne Pb into plant leaves and may be of interest for risk assessment of the exposure to airborne Pb contamination.

Thermodynamic investigation of the Pb – Sb system

The enthalpies of mixing of lead – antimony alloys were determined at 973 K in the range 0.2 < X Sb < 0.6 by direct liquid–liquid reaction calorimetry (DLLRC). The results are compared with data of the literature. The mixing enthalpies in the Pb – Sb liquid phase are weakly negative over the entire investigated concentration range with a minimum at Δ mix H m = −70 J mol −1 at X Sb = 0.4. In addition, the Pb – Sb phase diagram on the Pb-rich side was revised using differential scanning calorimetry (DSC). The coordinates of the eutectic point have been ensured. An optimization of the binary Pb – Sb system was finally performed. The calculated phase diagram and thermodynamic functions agree well with experimental data.

Characterization of Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric crystal with enhanced phase transition temperatures

The full set of material constants for relaxor-based ternary single crystals Pb(In(12)Nb(12))O(3)-Pb(Mg(13)Nb(23))O(3)-PbTiO(3) (PIN-PMN-PT) were determined and compared to binary Pb(Mg(13)Nb(23))O(3)-PbTiO(3) (PMNT) crystals. The Curie temperature for rhombohedral compositions of PIN-PMN-PT was found to be in the range of 160-200 degrees C with ferroelectric rhombohedral to tetragonal phase transition on the order of 120-130 degrees C, more than 30 degrees C higher than that found for PMNT. The piezoelectric coefficients (d(33)) were in the range of 1100-1500 pCN, with electromechanical coupling factors (k(33)) about 89%-92% comparable to PMNT crystals. The coercive field of the ternary crystal was found to be 5.5 kVcm, double the value of the binary counterparts. The dielectric behavior under varying dc bias exhibited a similar trend as observed in PMNT with a much broader usage temperature range. Together with its enhanced field induced phase transition level, the ternary PIN-PMN-PT crystals are promising candidates for high temperature and high drive transducer applications.

Temperature dependence of the dielectric, piezoelectric, and elastic constants for Pb(Mg1∕3Nb2∕3)O3–PbZrO3–PbTiO3 piezocrystals

Pb ( Mg 1 ∕ 3 Nb 2 ∕ 3 ) O 3 – Pb Zr O 3 – Pb Ti O 3 (PMN-PZT) ferroelectric single crystals were grown successfully using the solid state crystal growth method. The crystals were found to exhibit higher Curie temperatures TCs and ferroelectric phase transition temperatures TR-Ts when compared to the binary Pb(Mg1∕3Nb2∕3)O3–PbTiO3 system. Specifically the composition 0.4Pb(Mg1∕3Nb2∕3)O3–0.25PbZrO3–0.35PbTiO3 which lies close to the rhombohedral-tetragonal morphotropic phase boundary, was investigated. The full set of materials constants, including elastic (c and s), piezoelectric (d, g, e, and h), and dielectric permittivity (ε∕ε0), were determined using the IEEE standards as a function of temperature ranging between 25 and 100°C. The electromechanical coupling factors k33 and k32 were found to be 93.3% and 93.5%, respectively, with corresponding piezoelectric coefficients d33 and d32 on the order of 1530 and −1440pC∕N. Together with high phase transition temperatures (TC of 216°C and TR-T on the order of 144°C) and high coercive field EC ∼4.6kV∕cm, make PMN-PZT single crystals promising candidates for high temperature actuator and transducer applications.

Effect of Cu(II), Cd(II) and Zn(II) on Pb(II) biosorption by algae Gelidium-derived materials

Biosorption of Pb(II), Cu(II), Cd(II) and Zn(II) from binary metal solutions onto the algae Gelidium sesquipedale, an algal industrial waste and a waste-based composite material was investigated at pH 5.3, in a batch system. Binary Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II) solutions have been tested. For the same equilibrium concentrations of both metal ions (1 mmol l −1), approximately 66, 85 and 86% of the total uptake capacity of the biosorbents is taken by lead ions in the systems Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II), respectively. Two-metal results were fitted to a discrete and a continuous model, showing the inhibition of the primary metal biosorption by the co-cation. The model parameters suggest that Cd(II) and Zn(II) have the same decreasing effect on the Pb(II) uptake capacity. The uptake of Pb(II) was highly sensitive to the presence of Cu(II). From the discrete model it was possible to obtain the Langmuir affinity constant for Pb(II) biosorption. The presence of the co-cations decreases the apparent affinity of Pb(II). The experimental results were successfully fitted by the continuous model, at different pH values, for each biosorbent. The following sequence for the equilibrium affinity constants was found: Pb > Cu > Cd ≈ Zn.

Structural Insights into the Coordination and Extraction of Pb(II) by Disulfonamide Ligands Derived from o-Phenylenediamine

The o-phenylenediamine-derived disulfonamide ligands 1 and 2 complex and efficiently extract Pb(II) from water into 1,2-dichloroethane via ion-exchange, in combination with 2,2'-bipyridine (97.5% and 95.0%, respectively, for 1:1 ligand-to-Pb ratios). The corresponding Pb(II)-sulfonamido binary complexes of ligands 1 and 2 (3 and 4, respectively), and ternary complexes with 2,2'-bipyridine (5 and 6, respectively), were isolated and characterized. (1)H NMR spectra of the organic phases after extraction show the formation of ternary Pb-sulfonamido-bipy complexes. X-ray characterization of 3, 4, and the ternary complex 5 consistently demonstrates four primary coordination sites and a stereochemically active lone pair on Pb. The X-ray structure of 3 shows a pseudo trigonal bipyramidal configuration on Pb, with the lone pair occupying one of the equatorial sites, and the formation of an unusual "hemidirected" coordination polymer via axial S=O-Pb coordination. The same axial S=O-Pb coordination pattern with two DMSO molecules is observed in the structure of 4.[2(CH(3))(2)SO)], thus rationalizing the high solubility of the binary complexes in strongly coordinating solvents. In contrast, the X-ray structure of the ternary complex 5 reveals a distorted four-coordinate configuration with only weak S=O-Pb coordination leading to dimer formation, thus explaining its higher solubility in weakly coordinating solvents. FT-IR spectroscopy confirms the X-ray data, since the ligand nu(S)(=)(O) stretching frequencies shift to lower values in the binary Pb(II)-sulfonamido complexes and are again altered upon formation of the ternary Pb(II)-sulfonamido-bipy complexes, as would be expected for 2,2'-bipy complexation and hindered S=O-Pb coordination.

Microscopic structure of liquid lead–potassium alloys: Neutron-diffraction and molecular-dynamics investigation

Static structure factors, S( Q), for liquid Pb–K alloys obtained by neutron diffraction and molecular-dynamics simulation are presented. Pure lead and the binary Pb–K system for potassium concentrations of 5, 14, 22, and 25 at% are investigated at 660 K. A satisfactory agreement of the experimental data and simulated results is obtained. It is found that the characteristic prepeak of S( Q) at Q∼1 Å −1 disappears for alloys with potassium concentration less than ∼10 at%. Possible cluster configurations in the Pb–K alloys are revealed.