Search

A C60-polyglycidyl nitrate (C60-PGN) maleic acid copolymer lead salt was synthesized through two steps using C60-PGN, maleic acid, and lead nitrate as raw materials. The synthesized product was cha...

Metal-halide perovskites have become the most studied material for efficient next-generation solar cells, in part because of the possibility of depositing high quality semiconducting perovskites by simple solution-based methods. However, the majority of solvent systems implemented in literature for deposition of lead halide perovskites are hazardous to handle. Investigation of alternatives perovskite processing methods are hence key to safely upscale the perovskite photovoltaic manufacturing. In this manuscript we use the Hansen theory to find suitable nonhazardous solvents to solubilize two lead salts, PbBr2 and PbI2, used to fabricate the corresponding methylammonium (MA) lead halide perovskite films. The method is based on the use of the Hansen solubility parameters (HSPs) of a lead salt and a solvent to provide insight into whether interactions between them are favorable or not. We first studied the solubility properties of each lead salt (PbBr2 and PbI2) by determining experimentally their Hansen solubility spheres. Using these results, computer simulations allow us to determine compatible nonhazardous solvents with these two compounds in terms of solubility. We further investigated the use of a nonhazardous diester blend polar solvent to deposit MAPbI3 and MAPbBr3 thin films.

Lead salt photoconductors are popular IR photodetectors due to their outstanding performance-to-cost ratio, high room temperature performance (D* > 1E10) and availability of large area detectors. The lead salt photodetector history has been reviewed also recognizing several more recent research developments. The chemical bath deposition technique for production of the lead salt detectors has been outlined, followed by a review of the basics for their characterization. Spectral responses of both PbS and PbSe detectors collected in a wide temperature range and properly corrected have been presented.

The structural properties of various salts of methanetrisulfonic acid (H3mts) are described, spanning the free acid, ammonium and alkali metals (Na, K, Cs), first row transition metals (Cr, Co−Zn), and lead. A number of different coordination modes is found, including unexpected motifs such as the κ3O1,4,7 coordination in the lead salt and anions of the type [M(H2O)4(κ2O1,4-mts)]− (M=Co, Ni, Zn), which do not seem to be persistent in aqueous solution.

Fully converting the lead salt to perovskite is crucial for the performance of the perovskite solar cells via the sequential deposition method. By applying mixture of PbI2 and PbCl2 as the lead salts here, a fast conversion rate was found and a new PbICl phase was involved.

Mid-infrared vertical external cavity surface emitting lasers (VECSEL) were developed for the wavelength range 4 to 5 μm. The devices are based on lead salt materials grown by MBE on BaF2 or Si substrate. The VECSELs are optically pumped with a 1.55 μm wavelength laser. They are operating up to above room temperature. An output power 6 mWp was reached at a temperature of +27°C. The VECSELs are temperature tunable and lasing is observed from ∼4.8 μm at −60°C down to ∼4.2 μm at +40°C heat sink temperature.

A new way to prepare PMMA contain lead salt was presented. This work firstly prepares the material by microemulsion polymerization. The ability of anti-radiation, transmittance ratio and glass transition temperature ( T g ) of the material was characterized. The anti-radiation ability is enhanced with the increasing of lead salt content and the thickness of the material. The transmittance ratio decreased with the content of the lead salt. The glass transition temperature of the material is increased with the lead salt content of the organic glass.

Lead palmitate and stearate did not autoxidise in the presence of water and their saturated solutions did not render water non-corrosive. Lead oleate, linoleate and linolenate autoxidised to give water-soluble inhibitive materials; lead linoleate and linolenate yielded in addition short-chain acids, the lead salts of which were corrosive at the pH of the extracts (4.6). The unsaturated lead salts also yielded water-soluble peroxides, which enabled a given lead salt to inhibit corrosion at a lower concentration.

A simple procedure for transferring PbS and PbSe quantum dots into water is presented, along with characterization of the resulting water-soluble quantum dots. The external surface of the water-soluble quantum dots include carboxylic groups, which will allow target-specific labeling of cells. As a first example, near-infrared fluorescence imaging of human colon cancer cells is demonstrated using these water-soluble near-infrared fluorophores.

The ability of the transition metal complex M(salen)* (M = Ni, Cu) to form Lewis acid−base adducts with lead(II) salts has been explored. The new complexes Pb(Hsal)2(Cu(salen*))2 (1), {Pb(NO3)(Cu(salen*))2}(NO3) (2), Pb(OAc)2(Cu(salen*)) (3), and {Pb(OAc)(Ni(salen*)2}(OAc) (4) (Hsal = O2CC6H4-2-OH, salen* = bis(3-methoxy)salicylideneimine) have been synthesized and characterized spectroscopically and by single-crystal X-ray diffraction. The coordination environment of the lead in the heterobimetallic complex is sensitive both to the initial lead salt and to the transition metal salen complex that is employed in the synthesis. As a result, we have been able to access both 2:1 and 1:1 adducts by varying either the lead salt or the transition metal in the heterobimetallic coordination complex. In all cases, the salen* complex is associated with the lead center via dative interactions of the phenolic oxygen atoms. The relationship between the coordination requirements of the lead and the chemical nature of th...

Nepal situated on the lap of mighty Himalayas is now threatened by heavy metals pollution in her atmosphere, land and river system. The indigenious technology of Nepal heavily depends on the use of mercury in gold plating technique. The mercury vapours are released to the atmosphere, when gold-amalgam smeared untesils and idols are strongly heated. Absence of control mechanism to collect mercury vapours has not only polluted atmosphere but it has also caused health hazard to the workers working in the poorly ventilated workshop. The craftsmen and articians have been victim of mercury poisoining. Another heavy metal that has caused atmospheric pollution in Nepal is lead. The lead containing gasoline used in greater amount in vehicles has released more and more lead in the from of exhaust gas into the atmosphere. The atmospheric pollution has been more acute in Nepal due to the use of lead gasoline in used vehicles. Likewise the river system of the urban areas of Nepal is polluted by heavy metals like cadmium, lead salt, ferrous salt, etc. The effluents of battery industries, leather factories, dye factories are directly dumped into the river system of urban areas. This has killed many aquatic animals of rivers. Thus Nepal is facing the problem of heavy metals pollution in her environment.

(a) Groupe d’Etude des Mate´riaux Optoe´lectroniques, F. S. T. G., BP. 618,40000 Marrakech, Morocco(b) Groupe d’Etude des Semiconducteurs, UMR 5650, Universite´ Montpellier II,Place Euge`ne Bataillon, 34095 Montpellier Cedex 5, France(c) Centre for Electronic Materials and Devices, Imperial College of Science,Technology and Medicine, Exhibition Road, London SW7 2AY, UK(Received July 10, 2001; in revised form October 22, 2001; accepted November 6, 2001)Subject classification: 71.55.Ht; 73.50.Bk; 73.61.Le; S8Hall coefficient measurements on p-type lead salt PbSe and its ternary alloys Pb

PbS/PbI2 nanocomposites were prepared by choosing K[PbI3] as both a lead salt and an iodide precursor and acetone/water as a reaction medium. It was found that the amount of the PbI2 component could be controlled, to some extent, by varying the amount of water used. Further, this simple bicomponent precursor-based synthetic route can be extended to prepare other lead-containing nanocomposites such as Pb3O4/PbI2 and PbSe/PbI2. Because of the heavy-atom effect, PbS/PbI2 nanocomposites exhibited good and composition-dependent electrogenerated chemiluminescence (ECL) performance, demonstrating their potential in the development of novel ECL sensors for analytical and clinical applications. These interesting findings would encourage us to gain deep insight on these phenomena, which could lead to the further development of these new inorganic materials and their applications.

Nanocrystals of PbTe synthesized by the reduction of tellurium powder with sodium borohydride (NaBH4) to produce telluride ions followed by a reaction with a lead salt. Considerable control of the reaction is possible when lead carbonate is used. Dots and rods of PbTe nanocrystals are obtained at different temperatures

Nanocrystals or quantum dots of the IV-VI semiconductors PbS, PbSe, and PbTe provide unique properties for investigating the effects of strong confinement on electrons and phonons. The degree of confinement of charge carriers can be many times stronger than in most II-VI and III-V semiconductors, and lead salt nanostructures may be the only materials in which the electronic energies are determined primarily by quantum confinement. This Account briefly reviews recent research on lead salt quantum dots.

Synthesis, characterization and thermal studies of copper and lead salts of 4-(2,4,6-trinitroanilino) benzoic acid have been carried out. Differential thermal analysis data show that Pb2+ and Cu2+ salts are stable up to 240 and 260°C respectively and then decompose exothermically. Impact sensitivity value (h50) is 77 cm for lead salt and 170 cm for copper salt. Both the salts are found friction insensitive upto 36 kg. The calorimetric values of lead and copper salts are 679 and 839 cal/g, respectively.

The previous work reported from this laboratory (l-5) on the chemical nature of vitamin C has been continued, particularly in the study of the solubility of the active material in organic solvents, leading towards its isolation by crystallization. This paper deals with (a) the precipitation of the active material as the lead salt, and (b) the isolation of a crystalline compound which is active in preventing scurvy in guinea pigs. The properties of this active crystalline substance correspond with those given for the LLhexuronic acid” studied by Szent-Gyorgyi (6-7) as an oxidation-reduction factor in adrenal cortex, oranges, and cabbage. We believe that the two subst.ances are identical, as stated in a previous communication (8).

The quantized states for electrons and holes confined in lead-salt semiconductor quantum wells (QW's) grown on (100) and (111) substrates and the corresponding electric-dipole optical transition energies are calculated analytically, within the envelope function approximation and with the Dimmock two-band $\stackrel{\ensuremath{\rightarrow}}{k}\ensuremath{\cdot}\stackrel{\ensuremath{\rightarrow}}{p}$ model for the bulk. The solution takes into account nonparabolicity, anisotropy, and break of valley and spin degeneracy, due to quantum confinement. Transition energies for different PbTe QW's, calculated as a function of temperature and well width, are shown to give a fair description of the observations of the quantum size effect reported in the literature. Limitations of the spherical and of the parabolic approximations to the electronic structure of the lead-salt QW's are made clear and the Rashba spin-orbit term in the effective Hamiltonian is derived.

We observe that the temperature coefficients of electron-hole pair energies $(dE/dT)$ in PbS and PbSe quantum dots depend strongly on the size of the quantum dot. With decreasing size the temperature coefficient of the lowest electron-hole pair energy ${\mathrm{dE}}_{g}/dT$ decreases by more than an order of magnitude from the bulk value. The weak temperature dependence found in the strong-confinement limit is expected for atomiclike levels, but has not been observed previously in a semiconductor.

In order to investigate plasma membrane Ca2+-ATPase (Ca2+-ATPase) activity in three subsets of microglia/macrophages (microglia in perineuronal regions (perineuronal microglia)), microglia in contact with the parenchymal side of the vascular basal lamina (juxtavascular microglia) and perivascular cells within the basal lamina), we performed an ultracytochemical study using a lead salt technique in rat cerebral cortices. In 60.6% of perineuronal microglia, the cytochemical reaction (CR) for Ca2+-ATPase on the plasma membrane (PM) in the vicinity of neurons was stronger than the CR on the other side of the PM, and deposits of the reaction product (RP) for Ca2+-ATPase had accumulated, reflecting the polarity of Ca2+-ATPase activity. In contrast, in all of juxtavascular microglia and perivascular cells, deposits of the RP were distributed evenly along the PM without polarity. These results suggest that the polarity of the Ca2+-ATPase activity manifests certain functional interactions between perineuronal microglia and neurons.

The effects of carbon black, cupric adipate and RDX on the thermal decomposition behaviour of lead flake in double-base system are investigated by DSC measurement. The results show that the thermal decomposition peak of lead flake decomposition shifts to lower temperature with the addition of carbon black, cupric adipate and RDX, and the exotherm heat of lead flake increases with the addition of carbon black and RDX. DSC results are compared with the burning characteristics of practical plateau propellants, the chemical reactions involving lead salts near the burning surface are assumed. The mechanism of the effects of ballistic modifiers and RDX on the phenomenon of platonization are discussed. Les effets de la suie, de l'adipate de cuivre et du RDX sur la decomposition thermique de flakes de plomb dans les systemes a double base est etudie au moyen de mesures DSC. Les resultats montrent qu'en cas d'addition de suie, d'adipate de cuivre et de RDX, le pic de decomposition thermique des flakes de plomb se deplace vers des temperatures plus basses et qu'en cas d'addition de suie et de RDX, le degagement de chaleur augmente. Les resultats DSC sont compares a la caracteristique de combustion de propergols a plateau. On suppose l'existence de reactions chimiques mettant en jeu des sels de plomb pres de la surface de combustion. On discute de mecanisme des effets de modificateurs balistiques et de RDX sur la formation du plateau. Die Wirkung von Rus, Kupferadipat und RDX auf die thermische Zersetzung von Blei-Flakes in Doublebase-Systemen wird untersucht mittels DSC. Die Ergebnisse zeigen, das bei Zusatz von Rus, Kupferadipat und RDX sich der thermische Zersetzungspeak der Bleizersetzung in den niedrigeren Temperaturbereich verschiebt und das bei Zusatz von Rus und RDX die Warmeentwicklung zunimmt. Die DSC-Ergebnisse werden verglichen mit der Abbrandcharakteristik plateaubildender Treibstoffe; chemische Reaktionen an der Abbrandoberflache unter Einflus der Bleisalze werden angenommen. Der Mechanismus der Wirkung von ballistischen Modifikatoren und von RDX auf die Plateaubildung wird diskutiert.

A catalytic amount of lead is necessary to promote the reduction of a 2-thioxo-4-thiazolidinone to the corresponding 4-thiazolidinone with zinc dust. If sufficient lead (>1000 ppm) is not contained in the commercially supplied zinc dust, a catalytic amount of lead dust or a lead salt may be added to consistently obtain the desired reactivity. Addition of larger amounts (>2 mol %) of lead salts or other metal salts results in a decrease in reactivity. Thallium(I) chloride is also a useful additive for increasing the reactivity of commercial zinc dust which does not contain lead. Identification of the catalytic role of lead allowed development of a robust process for the synthesis of 4-thiazolidinones.

A Lead salt midinfrared quantum-well (QW) laser on [110] orientation is proposed. Theoretical simulations of [110] QW edge-emitting lasers show a 70° temperature increase in continuous-wave operation compared to the conventional [100]-orientated lasers. This is because the gain on [100]-orientated QW structure is significantly increased. Among [100], [111], and [110] orientations, [110]-orientated QW structure offers the highest gain. PbSe∕PbSrSe QW structures were successfully grown on [110]-orientated BaF2 substrate by molecular-beam-epitaxy (MBE). Photoluminescence intensity of [110]-orientated samples was twice as high as that on [111]-orientated BaF2 substrates from the same MBE run.

The application of tunable diode lasers, both lead salt- and GaAs-based, for atmospheric trace gas monitoring is reviewed. The basic features of a typical monitoring system along with more specialized methods are described.

Atomistic sp3d5s* tight-binding theory of PbSe and PbS nanocrystals is developed. It is demonstrated, that the valley splittings of confined electrons and holes strongly and peculiarly depend on the geometry of a nanocrystal. When the nanocrystal lacks a microscopic center of inversion and has T_d symmetry, the splitting is strongly suppressed as compared to the more symmetric nanocrystals with O_h symmetry, having an inversion center., Comment: 5 pages, 4 figures, 1 table

A formalism for determining energy eigenstates of cylindrical lead salt quantum wires in the multiple-band envelope-function approximation is developed. Electron energy dispersion for quantum wire subbands within the conduction and valence bands is found.

Tunable mid‐infrared vertical external cavity surface emitting lasers were developed for the wavelength range around 3.8–3.9 μm and 3.2–3.3 μm, respectively. The devices are based on lead salt materials epitaxially grown by MBE on a Si substrate. The active part consists of PbSe QW in a PbSrSe host layer. Both devices are operated around −20 °C and have output power of several 10 mW. By changing the cavity length, a single mode hop free tuning range up to 80 cm−1 is achieved.

Optical stabilization of tunable lead-salt diode lasers (TDL) in the mid-infrared is presented for the first time. By introducing an external feedback mirror both the linewidth is substantially narrowed and the frequency of the TDL is stabilized and controlled via this mirror in a frequency-offset locked scheme. We achieved narrowing of the linewidth by 1–2 orders of magnitude or better. The TDL is offset-locked to a CO gas laser by a heterodyne technique: the beatnote between the two lasers is used to control the length of the external resonator. By this scheme we gain the capability of absolute frequency measurements with sub-Doppler accuracy. The improved spectral properties of the diode laser provide a new tool for high-resolution molecular spectroscopy in the mid-infrared.