Lead Sulfide Crystals Research Articles

Sulfide‐Inhibiting Growth of Lead Sulfide Rods Array Film from Micron to Nano for NIR Photodetector

In general, the growth rate of lead sulfide (PbS) crystals in the solution is fast, and it is difficult to obtain nanosized structure films without the presence of inhibitors. Herein, highly crystalline 1D single‐crystal PbS nanorods array on the graphene substrate is prepared in the solution containing a high‐concentration sulfur ion as the inhibitors by electrochemical atomic layer epitaxy (ECALE) method. Meanwhile, the diameter of the PbS array from micrometers to nanometers can be controlled by adjusting the ratio of lead and sulfur. Through polarization studies on graphene substrates, the critical role of Au–thiolate in the vertical growth of PbS nanorod is controlled. Finally, the PbS array–graphene heterostructure photodetector presents an extraordinary photoresponsivity in 1.55 μm at room temperature.

Shape Controllable Preparation of PbS Crystal by a Simple Solvothermal Method

Hierarchical eight-arm, star-shaped lead sulfide (PbS) crystals have been successfully synthesized by a simple hydrothermal method. When pyridine was used as solvent, candy-like PbS crystal was obtained. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform-infrared (FT-IR) measurements.

Synthesis and photophysics of leadsulphide nanocrystallites

Nanoparticles of lead sulphide have been stabilized in the presence of excess Pb2+ in aqueous basic medium by a simple chemical route of synthesis. These PbS nanoparticles were synthesized very conveniently at room temperature using hexametaphosphate as stabilizer. These nanoparticles have an absorption extending into the NIR region. A significant quantum confinement effect made the bandgap of lead sulphide nanoparticles produce a blue shift from 0.41 eV to about 1.5 eV. The size and morphology of the particles were studied by TEM. Particles were relatively small sized (about 6 nm) having narrow size distribution. XRD data analysis indicate that the product is a mixture of PbS, PbO and Pb(OH)2. Both XRD pattern and HRTEM images confirm the crystalline structure of lead sulphide crystals. IR spectroscopy indicates the formation of PbS. PbS nanoparticles were fairly stable and could be stored for about three weeks at room temperature and for about two months at 5°C without agglomeration. These particles were photoactive and sensitized the reaction of aniline by light leading to the formation of azobenzene.

Perfect peony-like PbS films in situ synthesized on flexible lead foils

Peony-like lead sulfide films were in situ fabricated on flexible lead foils for the first time. When only ethylenediamine was used as solvent, peony-like lead sulfide crystals were synthesized uniformly on a large scale. By changing the volume ratio of ethylenediamine to ethanol, lead sulfide films with cube-, rod- and flower-like morphologies were also obtained. Detail study indicated that ethylenediamine played a key role in the formation of the peony-like PbS films. The peony-like films with three-dimensional microstructures exhibited superior absorbance properties and might have potential applications in solar cells.

Aminocaproic acid mixed methanolic lead–thiourea complex precursor and its thermal decomposition to star-shaped lead sulfide crystals

In this work, we present for the first time a simple synthetic route to fabricate a controlled lead sulfide (PbS) structure using amino acid mixed precursor. High yield star-shaped PbS crystals were developed by solvothermal synthesis technique using an environment friendly aminocaproic acid (ACA) mixed methanolic Pb–TU complex precursor at 170°C for 20h. The mechanism leading to these star-shaped PbS crystals was discussed. The as-synthesized PbS crystals were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR). The obtained results show that the synthesized star-shaped PbS crystals were exempt of impurities and were crystalline with cubic phase. Finally, the FTIR study indicates that molecules were bounded on the surface of PbS crystal via nitrogen lone pair of the amino head groups.

Studying of quantum-size effects origination in semiconducting lead sulfide nanocrystals

Lead sulfide (PbS) crystals with sizes from 20 to 500 nm were deposited in chemical bath from an alkaline solution (CBD method). The morphology of specimens was studied using high resolution scanning electron microscopy (HRSEM). Influence of crystallite sizes on the electronic structure was studied with X-ray photoelectron spectroscopy (XPS) and high resolution electrons energy losses spectroscopy (HREELS). The work function was measured with a Kelvin probe microscopy in air.

PbS crystals with clover‐like structure: Preparation, characterization, optical properties and influencing factors

AbstractA new and simple route to synthesize Lead sulfide (PbS) crystals with the clover‐like structure was described in the current paper. PbS was prepared in a simple aqueous solution employing (CH3COO)2Pb and thiourea as the initial materials under 130 W microwave irradiation. No any surfactant or template including organic polyamines with N‐chelation property was needed. The phase and composition of the product were identified by X‐ray powder diffraction (XRD) and X‐ray photoelectron spectra (XPS). TEM observation showed that the product with the six‐petal flower‐shaped structures was obtained, but SEM observation confirmed the clover‐like structure of the product; and the six‐petal flowers were formed via the overlap of two clovers revolved 60° around the center of the flower. Some factors affected the shape of the final product were studied and the optical properties of PbS crystals with the clover‐like structure were measured. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

SIMS and SIMS imaging studies of adsorbed dialkyl dithiophosphinates on PbS crystal surfaces

Secondary Ion Mass Spectrometry (SIMS) has been used to study the surfaces of natural galena (lead sulfide) crystals treated with a homologous series of dialkyl dithiophosphinates. The semiquantitative adsorption data, as a function of pH, obtained from the near static SIMS measurements using the fragment ions attributable to the dithiophosphinates are consistent with that expected from actual mineral flotation data. Imaging experiments using reagent fragment ions under non-static SIMS conditions allowed mapping of dithiophosphinate species on crystal faces of galena. Contrary to what might be expected, non-uniform dithiophosphinate adsorption was observed. The very high sensitivity relative to other surface analytical techniques, and the imaging capability of SIMS, make it a valuable tool to study monolayer and submonolayer adsorption of surfactants on solids.

Epitaxial formation of lead sulfide crystals under arachidic acid monolayers

Lead sulfide (PbS) particulate films composed of highly oriented, equilateral-triangular crystals have been in situ generated by the exposure of arachidic acid (AA)-monolayer-coated aqueous lead nitrate [Pb(NO 3 ) 2 ] solutions to hydrogen sulfide (H 2 S). The AA-coated PbS particulate films, at different stage in their growth, were transferred to solid substrates and characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), and electron diffraction measurements

Electron microscopic study of the morphology of lead sulphide and silver sulphide crystals obtained by the silica gel crystal growth technique

An electron microscopic study has been performed of the morphological changes in PbS and Ag2S crystals during their growth by the silica gel technique in different inorganic acidic gel media using U-tubes. The formation and growth of the PbS and Ag2S crystals were followed by a binocular lens and an optical microscope. The morphological changes of the PbS crystals obtained in an HCl gel medium were the same as those observed for the Ag2S crystals in HClO4 and HNO3 gels. The sequence began with the formation of single crystals showing dendritic growth, and was followed by growth along the [100] direction. The changes were remarkably different for PbS crystals obtained in HClO4 and HNO3 gel media. Whereas the first steps also involved the formation of dendritic crystals, subsequently the crystals grew along [111]. Therefore, morphological changes are due to different nucleus formation and growth rates, which depend on the nature and concentration of the acidic medium. The most perfect cubic structure is obtained for the slowest rate.These changes were confirmed by electron microscopy, and the compounds obtained were identified by X-ray diffraction. Using these techniques it was observed that PbS and Ag2S crystals grew independently in gels which diffused thioacetamide and a mixture of Pb and Ag ions, instead of yielding PbS-containing AgI ions as an impurity.

Characterization and growth of lead sulfide whiskers

The structure and morphology of whiskers grown on an Al-spiral coil inside the nozzle of a kerosene burner were investigated using transmission electron microscopy. The whiskers were formed of lead sulfide crystals with axes along 〈001〉 direction and encapsulated in an amorphous carbon sheath. High-resolution imaging revealed the arrangements of rows of lead atoms in the PbS crystal. The growth of PbS whiskers following the vapour-liquid-solid (VLS) growth mechanism is discussed.

Microhardness of as-grown and annealed lead sulphide crystals

The results of the measurement of Vickers microhardness of {100} faces of synthetic lead sulphide crystals are reported. It was found that, for loads lower than ∼60g, the microhardness value depends on the applied load, the duration of indentation, and on the density of dislocations in the crystals, but that at higher loads the microhardness is independent of the applied load and is dependent on the dislocation density in the crystals. Furthermore, an influence of the adsorption of water on the microhardness of the crystals was observed. The observations are discussed in terms of the existence of a distorted zone near the crystal-medium interface, a concept originally advanced by Berzinaet al. Finally, this concept of the distorted zone is briefly compared with more recent approaches of microhardness.

Semiconducting Characteristics of Galena Electrodes: Relationship to Mineral Flotation

Electrochemical, interfacial capacitance, and surface photovoltage (SPV) measurements have been used in a study of oxygen reduction and xanthate chemisorption on in situ cleaved natural and synthetic lead sulfide crystals. Electrodes cleaved in nitrogen‐sparged 0.1M sodium tetraborate assume the flatband potential, , at the instant of cleavage, and thus the cleavage potential decreases with increasing bulk electron concentration. Highly n‐type electrodes have a cleavage potential of ≃−0.6V (SCE), and highly p‐type electrodes have a value of ≃−0.2V (SCE). The space charge is readily varied by applied potentials in the range −0.2 to −0.6V. This Bureau of Mines, U.S. Department of the Interior, report discusses the effect of the variable space‐charge layer on oxygen reduction and xanthate chemisorption.

ChemInform Abstract: INFLUENCE OF SEMICONDUCTING CHARACTER OF SYNTHETIC LEAD(II) SULFIDE CRYSTALS ON THEIR CORROSION IN NITRIC ACID

Chemischer InformationsdienstVolume 13, Issue 4 Physical Inorganic Chemistry ChemInform Abstract: INFLUENCE OF SEMICONDUCTING CHARACTER OF SYNTHETIC LEAD(II) SULFIDE CRYSTALS ON THEIR CORROSION IN NITRIC ACID C. GUTIERREZ, C. GUTIERREZSearch for more papers by this author C. GUTIERREZ, C. GUTIERREZSearch for more papers by this author First published: January 26, 1982 https://doi.org/10.1002/chin.198204026Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue4January 26, 1982 RelatedInformation

Electrochemical behavior of the surface of lead sulfide crystals as revealed by potentiodynamic, reflectance, and rotating-electrode studies

Interest in the surface electrochemistry of lead sulfide arises from studies of the mechanism of flotation of such minerals as galena by means of addition agents such as xanthate in the presence of oxygen. In the present work, cyclic-voltammetry and individual linear potentiodynamic sweep experiments have been conducted over various potential ranges at polished galena crystal electrodes and corresponding determinations of relative reflectance changes, Δ R/ R, have been made over the same ranges of potential in order to establish the electrochemical surface processes which arise. The overall anodic/cathodic cycle can be repeated reproducibly but the processes within it are not reversible. Two main regions of oxidation of the PbS surface arise in the potential range −0.45 to +0.40 V vs H 2 electrode. Rotating PbS disk experiments indicate the role of formation of a solution-soluble species in the first potential range of electroactivity of PbS from −0.45 to −0.05 V E H. Evidence is given that this species is the S 2− ion which subsequently becomes oxidized to another species that changes the surface properties of PbS as indicated by Δ R/ R measurements. In the second potential range, −0.05 to +0.4 V E H, oxidation of the surface to Pb(OH) 2 occurs in a process that is little influenced by stirring but is affected by species generated in the first region. The Δ R/ R experiments enable surface processes which involve Faradaic film formation and reduction to be distinguished from those involving formation and reduction of solution-soluble species generated from the PbS surface during the potential cycling. Various mechanisms for the anodic and cathodic reactions observed, and for the film-forming processes, are tentatively proposed.

The observation of ring formation in the growth of lead sulfide crystals in polyacrylamide gels

The so-called “ring formation” during the growth of PbS in polycarylamide gels is demonstrated and discussed.

Halogen vapor deposition of chalcogenide crystals: Lead sulfide

n-type single crystals of lead sulfide, PbS, have been grown by a novel chemical vapor deposition method of potential importance for growing a variety of chalcogenide crystals. A reduced-pressure flowing system was developed based on the following chemical reactions: Pb+Cl2→PbCl2 and PbCl2+H2S→PbS+2HCl. Additional Cl2 is used for fine control of the growth rate. The optimal growth conditions are a temperature of 650 to 750°C and a pressure of 8 Torr. Important to the furnace design is a quartz concentric gas injection arrangement which prevents premature mixing and reacting of the gases. n-type single crystals of PbS having carrier concentrations of the order of 1019 cm−3 and Hall mobilities of 600 cm2/V sec at 300°K and as high as 14 000 cm2/V sec at 77°K have been grown. An isothermal anneal at 850°C for 15 days will convert the crystals to p type. Possible extensions of the technique to mixed lead-tin salts, including tellurides and selenides, and to other chalcogenides are discussed.

The growth of group II–VI crystals in gels

Experiments relating to the gel-growth of selected group II–VI semiconductor compounds in single crystal form are described. Single lead sulphide crystals with relatively low etch pits density and a size of 1-1.5 mm have been grown in silica gels. α-mercuric sulphide crystals, 0.1-0.15 mm in size have been successfully grown in polyacrylamide gels. The growth of cadmium sulphide crystals has resulted in either spherulites or dendrites depending mainly upon the cadmium ion source used. The experimental problems associated with the successful growth of cadmium, zinc, lead and copper selenides and tellurides are discussed, and the specific proposed solutions are described. Experiments on the growth of selenides have resulted in excessive nucleation and the successful growth of these crystals, therefore, depends on a better control of supersaturation in the growth systems. Attempts to grow single telluride crystals of Cd, Zn, and Pb were unsuccessful.

The Diffusion of Lead and Bismuth into Single Crystals of Undoped and Bismuth-Doped Lead Sulfide at 700°C

The simultaneous diffusion of 210Pb and 210Bi into undoped single crystals of lead sulfide and single crystals doped with 4×1018 and 4×1019 bismuth atoms/cm3 has been studied as a function of deviations from stoichiometry at 700°C. The diffusion coefficients for lead and for bismuth were identical. The identical values of the lead and bismuth diffusion coefficients suggest that Coulombic attraction between VPb′ and BiPb is negligible. Although the addition of 4×1018 atoms of bismuth to lead sulfide does not change the diffusion coefficients of 210Pb and of 210Bi relative to undoped lead sulfide for −6.5<log sulfur pressure (logps2) <0.0, the addition of 4×1019 atoms of bismuth does. This result and other evidence indicates a higher concentration of native lattice defects than previously considered. For logps2>−3.9, the diffusion coefficients in undoped and lightly doped (4×1018 Bi) material are proportional to ¼ logps2. Because the concentration of singly ionized cation vacancies is also proportional to ¼ logps2, it is concluded that the singly ionized cation vacancy is the predominant defect through which 210Pb and 210Bi diffuse and may be the majority cation defect in lead sulfide at 700°C. For a logps2<−3.9, the diffusion coefficients are independent of composition presumably because the as-grown crystals contain microprecipitates of lead which dissolve extremely slowly under low sulfur pressures. Hence, these crystals contained essentially a constant concentration of defects.

The growth of single crystals of lead sulphide in silica gels at ambient temperatures - preliminary characterization and effect of various organic compounds as sulphide ion donors

The use of thioacetamide as sulphide ion donor for the growth of lead sulphide single crystals in silica gels at ambient temperatures is discussed. Data are presented on the chemical purity and certain pertinent electronic properties of the gel grown lead sulphide crystals. Other organo-sulphur compounds are experimentally evaluated as possible sulphide ion donors and compared with thioacetamide which compound has given the best results to date.