Low Lead Content Research Articles

High-entropy perovskite quantum dots of rare earth synergy with excellent luminescence stability via high-energy ball milling

The problem of low stability and high lead content limit the commercial development of halide perovskite. In this paper, the high-energy ball milling is used to rapidly and efficiently synthesize high-entropy Cs(Pb1/5Mn1/5Ni1/5Zn1/5Yb1/5)Cl3 quantum dots (QDs), the introduction of high-entropy and rare earth ions reduces lead content, increases mixing entropy, and synergistically enhances the photoluminescence (PL) intensity and stability of QDs with other ions. Because the increase of entropy enhances the stability, the QDs still have 70 % PL intensity after 60 days of placement. After the QDs are exposed to the ultraviolet lamp for 8 hours, the PL intensity maintains at 67.1 % due to the loss of ligand. Ionic bonds are easily broken in water, so after soaking in water for 8 hours, the PL intensity of the QDs keeps at 32 %. The thermal stability of QDs is maintained well because of physical and chemical stability of rare earth ions. Since ethanol dissolves the ligands on the surface of the QDs, the non-radiative recombination is enhanced, so the PL intensity of QDs remains at 59 % after soaking for 8 hours. This paper provides a new way that further enhances the stability and solves high lead content of all-inorganic perovskite materials.

Entropy-Driven Strongly Confined Low-Toxicity Pure-Red Perovskite Quantum Dots for Spectrally Stable Light-Emitting Diodes.

Spectrally stable pure-red perovskite quantum dots (QDs) with low lead content are essential for high-definition displays but are difficult to synthesize due to QD self-purification. Here, we make use of entropy-driven quantum-confined pure-red perovskite QDs to fabricate light-emitting diodes (LEDs) that have low toxicity and are efficient and spectrum-stable. Based on experimental data and first-principles calculations, multiple element alloying results in a 60% reduction in lead content while improving QD entropy to promote crystal stability. Entropy-driven QDs exhibit photoluminescence with 100% quantum yields and single-exponential decay lifetimes without alteration of their morphology or crystal structure. The pure-red LEDs utilizing entropy-driven QDs have spectrally stable electroluminescence, achieving a brightness of 4932 cd/m2, a maximum external quantum efficiency of over 20%, and a 15-fold longer operational lifetime than the CsPbI3 QD-based LEDs. These achievements demonstrate that entropy-driven QDs can mitigate local compositional heterogeneity and ion migration.

Low lead inorganic Zn-based mixed-halide perovskites CsPb0.625Zn0.375I3−β X β (X = Cl or Br) for energy generation with 23.5% efficiency

Hybrid perovskite (HP) solar cells have garnered significant attention in recent years for their excellent light absorption, long carrier lifetime, and high diffusion length, resulting in high power conversion efficiency and superior optical performance compared to silicon solar cells. However, the organic component in HP solar cells is vulnerable to thermal variations and the presence of lead (Pb) poses a threat to the environment. To address these issues, this work proposes the use of all-inorganic halide perovskite (IHP) materials with low lead content as the absorber layer in four different perovskite solar cell configurations: CsPb0.625Zn0.375I2Br, CsPb0.625Zn0.375IBr2, CsPb0.625Zn0.375I2Cl, CsPb0.625Zn0.375ICl2. In addition, owing to the consideration novel IHP materials, it is important to identify the appropriate properties of transport layers since conventional transport layers are best suited to conventional organic–inorganic halide perovskites and may not work well with proposed IHP. Therefore, the appropriate electron transport layer (ETL) has also been investigated through optimization of electron affinity (4.0 eV − 4.23 eV), mobility (0.004 cm2/Vs to 4 cm2/Vs), and donor doping density (1015 cm−3 to 1018 cm−3). The device performance has been further analysed and optimized by varying the active layer thickness. The selected ETL is then combined with the absorber layers to evaluate performance. The effect of varying the thickness of the absorption layer is observed in all four device arrangements. Simulation results show that CsPb0.625Zn0.375ICl2 performed best among the mentioned absorber materials, with a power conversion efficiency of 23.5% with ETL parameters of 4.00 eV (electron affinity, χ), 4 cm2/Vs (electron mobility, μ n), 1×1018 cm−3 (donor doping density, Nd) and absorber layer thickness of 500 nm. Proposed work may open a window for the development of a new class of environment friendly and stable perovskite solar cells in future.

Trace element levels and bio-active compounds in ethanolic leaf extract of Chrysophyllum albidum characterised using gas chromatography – mass spectrometry

Aim and objectivesChrysophyllum albidum, also known as Africa star apple, has so many ethnobotanical uses in African healing system. Thus, a study that reveals possible trace elements and its phytochemical profile will give an essential insight to the bioactivity profile of the plant. The study was to identify the trace elements and the bioactive compounds present in Chrysophyllum albidum (C. albidum) leaf extract Materials and methodsThe ethanol leaf extract of Chrysophyllum albidum was evaluated for trace elements using an Atomic Absorption Spectrophotometry (ASS) while the chemical composition was analysed using Gas Chromatography-Mass Spectrometry (GC/MS). The identification of phytoconstituents using GC/MS was based on the instrument library, peak area and retention time. ResultThe ethanol leaf extract of C. albidum showed a high content of potassium, calcium, magnesium and sodium, while relative low content of manganese, iron, copper, zinc, lead and nickel. Total of 30 peaks representing 30 identified compounds were recorded in the GC/MS analysis. These include a variety of heterocyclic compounds such as fatty acids, organic compounds, esters, and disaccharides etc. The major constituents of the extract were: Sucrose (37.45%), followed by 1,2,3-Propanetriol,1-acetate (7.86%), di-Glyceraldehyde dimer (5.70%), 1-(3-Benzyl-2-thioureido)−1-deoxy-beta-d glucopyranose 2,3,4,6-tetraacetate (4.53%), 4 H-Pyran-4-one, 2,3-dihydro-3, 5-dihydroxy-6-methyl- (4.49%), 3-Deoxy-d-Mannoic lactone (3.14%), Glycerine (3.04%) and minor compounds that are less than 3%. ConclusionThe elemental composition of the leaf extract of C. albidum may be influenced by the environmental factors such as soil composition surrounding the plant’s roots, while a variety of bioactive compounds with diverse biological activities were present. Hence, the plant have a potential pharmacological activities.

Cavitation of some copper alloys for naval propellers: electrolyte effect

Efficient shipping is becoming more challenging, not only because of the increasing demand for this means of transport, the performance requirements and the optimisation of resources, but also because of the environmental constraints. Cavitation is a harmful phenomenon that can affect different systems of a ship such as pumps, valves, impellers, pipes, etc., but is particularly known for its effect on propellers, associated with loss of power and even impairment of structural integrity. The mechanical effect of cavitation on metallic materials is in general superimposed by corrosion and may thus lead to a synergistic degradation phenomenon. In this work, the cavitation behaviour and the potential synergistic effect with corrosion was evaluated for three widely used copper-based alloys, NAB (Nickel Aluminium Bronze), MAB (Manganese Aluminium Bronze), and a brass (low lead content) using three types of water: natural seawater, synthetic seawater and synthetic brackish water. Experiments were carried out in an ultrasonic bath, followed by structural surface characterisation. The main result is that MAB is most susceptible to both, general surface damage and deep localized attack. This is attributed to its poor ability in regenerating the protective layer, the area ratio of their phases and the high hardness of the κ-phase, in combination with high mechanical stresses during impacts affecting the grain boundaries. Moreover, natural seawater was found to increase cavitation, attributable to the dispersion of micro-particles, while brackish water with its content of sulfidic species was found to promote the strongest synergy between corrosion and cavitation.

Bioaccumulation of trace elements in vegetables grown in various anthropogenic conditions

Hazardous compounds accumulate in plants and animals as a result of anthropogenic impact. Trace elements, such as heavy metals, move up in the system of snow – soil – water – plant – animal. When contaminants accumulate in plants that serve as animal feed, they eventually accumulate in the animals that consume the feed because heavy metals usually enter living organisms via digestive tract, i.e., with food.
 In 2003–2021, we studied fodder plants grown and harvested by urban zoological organizations, e.g., zoos, nature corners, etc. This research covered the Central Federal District represented by the cities of Moscow, Ivanovo, Yaroslavl, and Uglich. The empirical part of the study relied on a combination of modern ecological, biochemical, and statistical methods. A KVANT-2AT atomic absorption spectrometer was used to define the trace elements and their quantities.
 Broccoli proved to be the most resistant feed vegetable to all the toxic elements in this study. Kohlrabi, sweet potato, and dill had low content of lead and cadmium, while garlic was highly resistant to cadmium and arsenic. Spinach, fennel, potatoes, beets, and bell peppers, which were used as fodder in metropolis conditions, exceeded the maximal permissible concentration of heavy metals. The samples obtained from the Moscow Zoo contained by 1.98 times more zinc, by 1.06 times more copper, and by 89.47 times more lead than average. The samples from Ivanovo accumulated the greatest extent of iron, which exceeded the average level by 3.26 times. The vegetables from Uglich and Ivanovo had the lowest concentration of zinc, which was by 67.86 and 62.70% below the average, respectively. The samples from Yaroslavl contained by 33.08% less copper. In 2003–2021, feed vegetables grown in the Central Federal District had an average increase in zinc, copper, and lead by 1.13, 1.45, and 2.80 times, respectively. The level of iron stayed almost the same throughout 2018–2021, while that of arsenic gradually decreased in concentration. The accumulation level of zinc, copper, iron, and arsenic in feed vegetables appeared to depend on the concentration of their water-soluble metal forms in the soil.
 Therefore, forage agriculture in urban areas requires constant chemical and toxicological tests to prevent contaminated feed from entering animal diet.

Synthesis and Characterization of a New Ferroelectric with Low Lead Content, a High Curie Temperature, and a High Piezoelectric Response

AbstractA new solid solution (1−x)Bi(Fe2/8Ti3/8Mg3/8)O3–(x)PbTiO3 (BFTM‐PT) is synthesized and the electromechanical properties are measured. This system is defined as a low‐lead material with ferroelectric/piezoelectric behavior and a morphotropic phase boundary (MPB) that leads to enhanced properties. The MPB is located between x = 0.30 and 0.35 and coincides with a structural phase transition and a sharp increase in the piezoelectric response. The system demonstrates ferroelectric hysteresis where x = 0.325 displays the best properties with a maximum polarization of 39 µC cm−2 and a remnant polarization of 26 µC cm−2. The range of compositions has high Curie temperature (Tc), ranging from 625–650 °C. Materials with a Tc above 400 °C typically have a low d33 of <50 pC N−1 at room temperature. However, BFTM‐PT has a higher d33 that most other compositions with a Tc in this range, with the highest being 145 pC N−1 for x = 0.375. The d33 drops off above 100 °C, but doping studies can be done in the future to stabilize the piezoelectric response at higher temperatures. These outstanding properties open the possibility of new transducer applications, in particular ones requiring high temperature and high power.

Metal of the "Cimmerian elite" of the North Caucasus ( on the materials of tomb 3 of the Terese burial ground)

The article publishes the results of a study of bronze items from tomb 3 of the Terese burial ground (Central North Caucasus, Karachay-Cherkessia), one of the richest burials of the Koban culture of the Central North Caucasus during the Cimmerian campaigns in Transcaucasia and Western Asia.A typological analysis of the bridle accessories of a number of imported metal items from this complex shows that the burial belongs to a war-horseman of the late 8th centuryBC, who participated in military campaigns in Transcaucasia. ED XRF analysis reveals the main alloy groups used for production of the bridle and harness attachments from the Terese tomb 3 (26 samples) and Fars burial ground (2 samples). Tin bronzes and lead-tin bronzes with low, middle, and high tin concentration and a relatively low lead content clearly dominated the Terese selection. Lost wax casting into investment clay moulds was the main manufacturing technique. The Pb-isotope data of 23 samples obtained by MC-ICP-MS reveals the different sources of copper and lead as well as the recycling of scrap metal. Polymetallic ores of the Sadonsky ore field, located in North Ossetia was considered as one of the possible ore sources. Within the framework of the studied samples, arsenic bronze was recorded only as part of the inlay of two pins, originating from the Central Georgia which were probably made to order by a highly qualified Transcaucasian jeweller.

Demonstration of better superconducting performance in a solder with low lead content

Lead-free SnIn solders are promising for superconducting magnet applications. However, their superconducting properties are not as good as lead solders. In order to improve the superconducting performance of the Sn–In solders, researchers have investigated the superconducting properties of ternary systems such as Sn–In–Bi for solder joints. In this study, powders of Pb, Nb, AgCu and grapheme nano pellets in the ratios of 0.5–5 wt% have been added into SnIn (35:65) to investigate their microstructural, thermal and superconducting properties. The added materials enhance the superconducting properties. We find that even low Pb additions show a dramatic improvement in superconducting properties, with an increase in both T c and J c values of up to 6.35 K and 1.47 × 104 A m−2, respectively. This shows that much lower Pb content superconducting solders can be effective and could be used to replace the PbBi solder commonly used with the superconducting properties T c =8.4 K, H C2 = 1.77 T, H C = 0.0909 T.

Achieving highly efficient and stable MAPbI3 planar solar cell by embedding Cs+, Fe2+, and Cd2+ metal inorganic cations in perovskite structure

Perovskite solar cells (PSCs) have been attracted the attention of many researchers due to their high conversion efficiency, low manufacturing cost, easy manufacturing steps, high light absorption, and the possibility of changing the photo electronic properties by modifying the chemical structure. Despite the mentioned advantages, the low stability of PSCs and toxicity of lead in the perovskite layer were the challenging issues in this field. In this regard, the use of mixed cation and mixed halide perovskite compounds with high crystal quality, efficiency, and stability has attracted enormous attention. In this project, Fe2+, Cd2+, and Cs+ cations with various contents (Fe2+ + Cd2+: 5% and 10%; Cs+: 5% and 10%) were partially replaced the Pb2+ and CH3NH3+ cations, respectively in the MAPbI3 perovskite structure through a two-step process using spin-coating. The as-synthesized [CsyMA1-yPb1-a-bFeaCdbI3-2aCl2a], (a+b): 5, 10%, y: 5, 10%) perovskites were characterized with X-ray diffraction (XRD), grazing incidence X-ray diffraction (GIXRD), and field emission scanning electron microscopy (FESEM). The optical properties of prepared compounds were investigated by ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectroscopy. The photovoltaic behavior as well as stability of solar cells containing MAPbI3, [CsyMA1-yPb1-a-bFeaCdbI3-2aCl2a], (a+b): 5%, y: 5%), and [CsyMA1-yPb1-a-bFeaCdbI3-2aCl2a], (a+b): 10%, y: 10%) perovskites as active layers were evaluated by current density-voltage (I–V) under AM1.5G illumination.Results showed that partial substitution of CH3NH3+ cations with Cs+ and Pb2+ cations with Fe2+ + Cd2+ in the CH3NH3PbI3 structure improved crystallinity and photovoltaic parameters. The average power conversion efficiency (PCE) of six solar cell containing [CsyMA1-yPb1-a-bFeaCdbI3-2aCl2a], (a+b): 10%, y: 10%) perovskite layer was 21.04% which was 1.03 and 1.21 times higher than that cells containing [CsyMA1-yPb1-a-bFeaCdbI3-2aCl2a], (a+b): 5%, y: 5%) and MAPbI3, respectively.The electrochemical impedance spectroscopy (EIS) was utilized to study the charge transfer resistance (Rct) and recombination resistance (Rrec) of prepared solar cells. The Rct and Rrec values of fabricated solar cell were decreased and increased, respectively in the presence of Fe2+, Cd2+, and Cs+ inorganic cations. As a result, the [CsyMA1-yPb1-a-bFeaCdbI3-2aCl2a] perovskites can be considered as the appropriate candidate with high efficiency, stability, and low lead content in the planar perovskite solar cells.

Technosol rehabilitation strategies drive soil physico-chemical properties and fauna diversity on a former coking plant area

Anthropic activities such as mining, resource extraction or transformation profoundly modify ecosystems and may lead to Technosol formation. Post-industrial areas are examples of potentially degraded lands, due to soil contamination with metals or organic pollutants, as well as soil structure damage. Soil biodiversity being closely involved in many soil functions such as organic matter decomposition, formation and stabilization of soil structure, the recovery of degraded soil functions partly depends on soil fauna colonization. However, the relationship between Technosol abiotic parameters and soil fauna colonization is still to be disentangled. In an attempt to fill this gap, we studied a former coking plant area in north-eastern France, composed of Technosols resulting from coking plant embankments or thermally-treated industrial soils and compared them with two local soils considered as references. We hypothesized that the taxonomic and trophic diversity of Technosol-dwelling invertebrates would be more diverse and abundant in the soils with the higher soil physico-chemical quality (i.e higher fertility and lower pollutions levels). To test this hypothesis, we studied four Technosols that were settled following two different rehabilitation strategies within the same post-industrial area and we compared them with two local soils of reference using nested ANOVAs as well as multivariate analyses of soil abiotic parameters and soil fauna community indices, both within the soil and on its surface.The results on physico-chemical analyses showed that the substrates used for Technosol rehabilitation were impoverished in clay content when compared with local soils of reference (4.1 to 7.8-fold) and enriched in sandy materials. The use of coking plant by-products for Technosol implementation have led to poor chemical quality, with low nutrient content but high organic carbon content (41 to 51%) resulting from the use of coal and correlated with the higher lead concentration in the area. The use of thermally-treated industrial soil has led to more fertile Technosols with significantly lower lead content. Meso and macrofauna densities did not vary significantly between the Technosols and the local reference soils. Both Technosol-dwelling fauna trophic and taxonomic community compositions were impacted by the rehabilitation strategy. Few to no earthworms were found in Technosols (mean up to 16 ind.m−2) compared to the local soils of reference (mean of 118.4 and 201.6 ind.m−2). Conversely, Technosols resulting from coking plant embankments and thermally-treated industrial soils were dominated by epigeic soil fauna with an intense activity of soil surface macro-saprophages and micro-arthropods, as well as Formicidae. Our results suggest that the use of technogenic elements in the rehabilitation of post-industrial area led to the development of specific soil invertebrate communities, different from the reference. The gap between the high level of activity of epigeic organisms that we found on Technosols and the low trophic diversity of the litter and soil-dwelling communities suggest that the soil fauna community on a former coking plant is driven rather by soil physico-chemical properties than by colonization constraints.

ЕCOLOGICAL STATE OF SOILS IN IRSHAVA AND KAMIANSKE UNITED TERRITORIAL COMMUNITIES

Soil is the main means of production in agriculture. One of the main dominant factors of transformation and deterioration of soils is human economic activity. The plowing of agricultural lands, depletion of soil cover, industrial pollution, excessive degradation are among them. Reducing the area of agricultural lands directly affects agriculture and leads to lower yields. It can cause an environmental and economic crisis, both in a particular region and in the country as a whole. Therefore, the study of the state of agricultural lands years is paid more and more attention and is an urgent task of researchers in recent.
 The article is devoted to the study of the current ecological condition of soils in Irshava and Kamianske united territorial communities, Zakarpattia region. The assessment was performed on the following indicators: the content of humus, microelements (Zn, Pb), nitrogen, phosphorus, potassium, acidity, nitrates, nitrites. The obtained results showed that exceeding the maximum allowable concentrations in the selected soil samples for any of the elements (Zn, Pb) is not observed. The highest value of the eco-pollutants content was set for the Irshava city, especially for areas close to the road. In addition, it should also be taken into account that the intensive use of lands for agriculture with the introduction of mineral and traditional organic fertilizers in medium doses increases the level of heavy metals in soils. The studied soils have the low content of total lead: from 11.6 to 18.1 mg / kg. This value of Pb concentration in the samples is caused by the relationship between fixed forms of ecopolyutant and humus content. Humus content in studied areas equals 0,75 – 1,45% and corresponds to the low supply of soils with organic matter and the composition of soil-formed rocks.
 The soils of these areas were found to have a medium acid pH of 4,6-5,04 and correspond to a low humus content, obviously due to the high level of the agricultural lands plowing and a decrease in the amount of the organic fertilizers. But in general, the soils of this farm are fit for growing fruit crops.
 Keywords: soil, degradation; soil cover; soil fertility; degradation processes; soil protection; heavy metals; humus; soil quality deterioration; land protection.

Investigation of structural and enhanced piezoelectric properties in low lead content Na0.5Bi0.5TiO3-BaTiO3-PbTiO3 system

Through this work the authors report the structural, ferroelectric, and piezoelectric properties of PbTiO3 modified ceramics: (1–2x)Na0.5Bi0.5TiO3-xBaTiO3-xPbTiO3: (1–2x)NBT-xBT-xPT with x = 0.01, 0.03, 0.05, 0.07 and 0.09. The X-ray diffraction analysis of (1–2x)NBT-xBT-xPT revealed the existence of monoclinic (M) phase for x = 0.01 and 0.03 with the presence of ½(311) superlattice reflection, which acts as a structural bridge between the Rhombohedral (R) and Tetragonal (T) phases. Phase transition from M to T phase was observed at x = 0.03 which is supported by the presence of (002)/(200) splitting in the diffraction pattern. The measured mean grain size and density for x = 0.03 was 5.7 µm and 5.834 g/cm3 respectively, which was the maximum compared to other compositions. The chemical state of elements in the ternary system is found out using the X-ray photoelectron spectroscopy. A diffuse phase transition is perceived from the temperature dependent dielectric studies for x ≤ 0.03, while this diffusiveness decreases for x > 0.03 with the increase in concentration of substituents. Besides, the ferroelectric (FE) to relaxor (RE) transition, TFR is also diminished in higher concentration of BT and PT. A well saturated ferroelectric hysteresis loop with saturation polarization (Ps) and remnant polarisation (Pr) values of 35 and 32 µC/cm2 respectively is achieved for x = 0.03. Under an applied field of 48 kV/cm, a unipolar strain value of 0.26% is achieved for the same composition with a piezoelectric charge co-efficient (d33*) of 541 pm/V. The superior piezoelectric performance shown by (1–2x)NBT-xBT-xPT with a very low lead content of 3 mol%, which is at the proximity of M-T phase transition is explained using the polarisation rotation mechanism, that occurs in conjunction between polar-polar phases. The flat free energy profile that exists at the phase boundaries, eases the rotation of the polarisation vector and hence the piezoelectric constant. Also, a larger grain size will also relieve the polarisation rotation.

Numerical simulations of 22% efficient all-perovskite tandem solar cell utilizing lead-free and low lead content halide perovskites

Lead-free or low lead content perovskite materials are explored in photovoltaic (PV) devices to mitigate the challenges of toxic lead-based halides. However, the conversion efficiency from such materials is far below compared to its counterparts. Therefore, to make a humble contribution in the development of lead-free or low lead content perovskite solar cells (PSCs) for future thin-film PV technology, a simulation study of tin (Sn) and Pb mixed halide (MAPb0.5Sn0.5I3, 1.22 eV) PSC is carried out in this manuscript. The device is further optimized in terms of transport layer and thickness variation to get 15.1% conversion efficiency. Moreover, the optimized narrow bandgap halide based device is further deployed in the monolithic tandem configuration with lead-free wide bandgap (1.82 eV) halide, i.e. Cs2AgBi0.75Sb0.25Br6, 1.82 eV (WBH) PSC, to mitigate the thermalization as well as transparent E g losses. Filtered spectrum, current matching, and construction of tandem J–V curve at the current matching point are utilized to design the tandem solar cell under consideration. Tandem device delivered short current density, J SC (15.21 mA cm−2), open-circuit voltage, V OC (1.95 V), fill factor, FF (74.09%) and power conversion efficiency, PCE (21.97%). The performance of the devices considered in this work is found to be in good approximation with experimental work.

Lead-lean and MA-free perovskite solar cells with an efficiency over 20%

<h2>Summary</h2> Tin-lead perovskite solar cells (Sn-Pb PSCs) with low band gap (1.2–1.4 eV) are expected to achieve the maximum-power conversion efficiency (PCE) of single-junction devices given by the Shockley-Queisser limit. However, over 40 mol % Pb²⁺ is necessary to suppress the oxidation of Sn²⁺, which causes serious p-type self-doping. Here, we propose a new galvanic displacement reaction (GDR) method, through using lead powder as lead source and reductant simultaneously to resolve the above-mentioned issue. Lead powder could fully reduce Sn⁴⁺, but not Sn²⁺, in precursor, meanwhile suppressing the formation of iodide in film. Finally, Sn-Pb PSCs with low lead content and highest efficiency for MA-free-based devices (PCE: 18.34% for 8.5 mol % Pb²⁺, 20.01% for 18.7 mol % Pb²⁺) were realized. The unencapsulated devices retained unchanged or 81% of the original efficiency after storing for 2,352 h or tracking at maximum-power point (MPP) for 700 h in N₂ atmosphere (O₂ ≤ 50 ppm).

گرانیتوئیدهای پهنه سنندج-سیرجان متعلق به سری ایلمینیت (نوع S)، همزاد با کوه زایی سیمیرین (178-160 میلیون سال پیش): بررسی علت عدم تشکیل کانی سازی قلع پورفیری

Introduction The granitic rocks are divided into magnetite and ilmenite series (Ishihara 1977), coinciding spatially with the I-type (eNdi0; (87Sr/86Sr)i~0.704-0.706) and S-type granites (eNdi 0.707, N-MORB normalized patterns with enrichment in Low- and High Field Strength Elements (LFSE and HFSE) and depletion in P and Ti contents, chondrite-normalized patterns with flat heavy rare earth elements (HREE) patterns, magnetic susceptibility 4 km, regional metamorphism at ​​green schist facies (and amphibolite) following Cimmerian orogeny, low (Eu/Eu)N (reducing conditions), magnetic susceptibility 0.707) show that, unlike previous studies, these granitoids are S-type granitoids formed by melting the continental crust in a collisional zone. Therefore, tin mineralization might probably occurred in connection with them. However, there is ample evidence of the absence of tin mineralization by the magma that forms these S-type granitoids, that are including the lack of hydrothermal fluids and consequently mineralization potential (due to the absence of alteration minerals in ASTER satellite images), low content of tin, copper, lead and zinc elements in these granitoids Sanandaj-Sirjan Zone and associated river sediments, (Eu/Eu)N value > 0.2, Rb/Sr 200 ppm, as well as the geological, geophysical and geochemical similarities to barren S-type (ilmenite series) granitoids in Lut block (in Najmabad, Sorkh kuh to Shah kuh areas) which have formed in a continental collision system during the Cimmerian orogeny. References Ahadnejad, V., Valizadeh, M., Deevsalar, R. and Rezaei-kahkhaei, M., 2011. Age and geotectonic position of the Malayer granitoids: Implication for plutonism in the Sanandaj-Sirjan Zone, W Iran. Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen, 261(1): 61–75. https://doi.org/10.1127/0077-7749/2011/0149 Bayati, M., Esmaeily, D., Maghdour-mashhour, R., Li, X. and Stern, R.J., 2017. Geochemistry and petrogenesis of Kolah-Ghazi granitoids of Iran: Insights into the Jurassic Sanandaj-Sirjan magmatic arc. Chemie der Erde- Geochemistry, 77(2): 281–302. https://doi.org/10.1016/j.chemer.2017.02.003 Esna-Ashari, A., Tiepolo, M., Valizadeh, M., Hassanzadeh, J. and Sepahi, A., 2012. Geochemistry and zircon U–Pb geochronology of Aligoodarz granitoid complex, Sanandaj-Sirjan Zone, Iran. Journal of Asian Earth Sciences, 43(1): 11–22. https://doi.org/10.1016/j.jseaes.2011.09.001 Ishihara, S., 1977. The Magnetite-series and Ilmenite-series Granitic Rocks. Mining Geology, 27(145): 293–305. https://doi.org/10.11456/shigenchishitsu1951.27.293 Khalaji, A.A., Esmaeily, D. and Valizadeh, M. V., 2007. Petrology and geochemistry of the granitoid complex of Boroujerd, Sanandaj-Sirjan Zone, Western Iran. Journal of Asian Earth Sciences, 29(5-6): 859–877. https://doi.org/10.1016/j.jseaes.2006.06.005 Neiva, A.M.R., 2002. Portuguese granites associated with Sn-W and Au mineralizations. Bulletin of the Geological Society of Finland, 74: 79–101. https://doi.org/10.17741/bgsf/74.1-2.003 Shahbazi, H., Siebel, W., Pourmoafee, M., Ghorbani, M., Sepahi, A.A., Shang, C.K. and Abedini, M.V., 2010. Geochemistry and U – Pb zircon geochronology of the Alvand plutonic complex in Sanandaj – Sirjan Zone (Iran): New evidence for Jurassic magmatism. Journal of Asian Earth Sciences, 39(6): 668–683. https://doi.org/10.1016/j.jseaes.2010.04.014 Takahashi, M., Aramaki, S. and Ishihara, S., 1980. Magnetite-Series/Ilmenite Series vs. I-type/S-type granitoids, Granitic Magmatism and related mineralization. Mining Geology, Special Issue, 8: 13–28. Tahmasbi, Z., Castro, A., Khalili, M., Khalaji, A.A. and De, J., 2010. Petrologic and geochemical constraints on the origin of Astaneh pluton, Zagros. Journal of Asian Earth Sciences, 39(3): 81–96. https://doi.org/10.1016/j.jseaes.2010.03.001 Zheng, W., Mao, J., Zhao, C., Zhang, Z., Xiao, W., Ji, W., Majidifard, M.R., Rezaeian, M., Talebian, M., Xiang, D., Chen, L., Wan, B., Ao, S. and Esmaeili, R., 2018. Geochemistry, zircon U-Pb and Hf isotope for granitoids, NW Sanandaj-Sirjan zone, Iran: Implications for Mesozoic-Cenozoic episodic magmatism during Neo-Tethyan lithospheric subduction. Gondwana Research, 62: 227–245. https://doi.org/10.1016/j.gr.2018.04.002

Electronic structure modulation of Pb0.6Sn0.4Te via zinc doping and its effect on the thermoelectric properties

Striking a balance between the high performance and detrimental environmental toxicity of PbTe materials in thermoelectrics (TE) has become a necessity in the current situation. In this context, improving the performance of materials with lower lead content to the level of PbTe is crucial. Herein, we engineer the electronic structure of Pb0.6Sn0.4Te, a well-known TCI but a poor TE material by doping Zn. The first principles calculation reveal that Zn doping introduces multiple electronic valleys while simultaneously opening the band gap of Pb0.6Sn0.4Te. Higher power factor with lower thermal conductivity is predicted by the transport property calculations in the doped material. The resonance level introduced along with features of hyper-convergence of the valence bands leads to improved Seebeck co-efficient throughout the studied temperature range. An experimental figure of merit, ZT of ~1.57 at 840 K promises us a TE material applicable for a broad temperature range for future energy applications.

Lead isotope and trace element analysis of the Wuzhu coins from Doujiaqiao hoard, Tianjin City, North China

The minting of coins in almost all societies is related to the central authority. The evolution of the central government's control over the coinage power in the Han Dynasty (202 BC-220 AD) of ancient China reflects the rise and decline of the central authority. Unfortunately, there is no historical record referring to the condition of coinage material management in the HD. Thus, in this paper, XRF, metallography, MC-ICP-MS and ICP-AES were used to study the alloy composition, microstructure, lead isotope and trace element characteristics of 11 Wuzhu (五铢) coins of the Eastern Han Dynasty (25-220 AD) from the Doujiaqiao hoard, Tianjin city, North China. The XRF results showed that there were two kinds of alloy in these coins: one group with high lead content more than 7.6 wt.%, while the other with low lead content less than 1.9 wt.%. And all of these samples had tin content less than 2.9 wt.%. The metallography results indicated that all of these samples were cast, while one sample showed annealing signs. According to the lead isotopic ratios, the lead material of the five high-lead coins had two different provenances: the Yangtze and the Southern China geochemical province. In addition, the copper material of the other six low-lead coins may be derived from several different copper mines. Furthermore, the data of trace elements confirmed that the copper source of the EHD coins in the Doujiaqiao hoard came from different mines, which is consistent with the lead isotope analysis results and further indicates that the copper and lead mines for coinage might be exploited by several local authorities in the EHD.

Comparative study of the Bi(Ni0.5Zr0.5)O3-PbTiO3 and Bi(Mg0.5Zr0.5)O3-PbTiO3 piezoelectric materials for energy harvesters

ABSTRACT In this study, piezoelectric properties of 0.4Bi(Ni0.5Zr0.5)O3–0.6PbTiO3 (BNZ-PT) and 0.4Bi(Mg0.5Zr0.5)O3–0.6PbTiO3 (BMZ-PT) ceramics were investigated and compared with those of Pb(Zr,Ti)O3 in energy harvester applications. Their piezoelectric properties are comparable with those of Pb(Zr,Ti)O3 based materials, although they have lower lead contents. By optimizing the sintering temperature, the piezoelectric charge coefficients (d33) were improved to 438 and 351 pC/N for 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively, whereas the piezoelectric voltage coefficients (g33) were improved to 25.02 × 10−3∙V∙m/N and 28.37 × 10−3∙V∙m/N for 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively. The generated energies were estimated by measuring the generated output voltages. Generated energy densities of 1.67 and 1.01 mJ/cm3 were obtained from 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively. The optimum sintering conditions were found by observing the changes in the piezoelectric constant, dielectric constant, and density as a function of the sintering temperature.

Determination of the elemental composition of historical glasses using a portable X-ray fluorescence analyzer

Historical glasses are complex multicomponent systems that can be modeled by restricting their composition to three or four most important main components and considering the other ones as additives. We present an analysis of glass samples in K 2 O – CaO – SiO 2 system, some of them contain sodium along with potassium and small amounts of different additives (oxides of iron, antimony, arsenic, manganese). Study of the aforementioned objects does not provide for their removal outside the museum storage areas, which substantially limits the range of the methods to be used for their analysis. We have demonstrated the possibility of using a portable X-ray fluorescence analyzer in determination of the compositions of historical glasses, including objects of cultural heritage, the study of which can only be carried out by non-destructive methods of analysis. Determination of compositions of silicate glasses that do not contain lead or with a low lead content is considered. The proposed procedure suggests using the programs for fundamental parameters to determine the elemental composition of the glass with subsequent recalculation of the content of elements into oxides, which makes it possible to estimate the oxygen content in the sample. The content of the other light elements that cannot be determined by an XRF-analyzer used (elements with atomic numbers less than 13) is determined as follows. The literature data indicate that the objects under study do not contain lithium, boron, carbon, nitrogen and fluorine. Magnesium was not specially introduced into the composition of historical glasses, but appeared only as an admixture to limestone or potash thus providing only a semi-quantitative estimation of the magnesium content from the known experimental value of the potassium and calcium content and recalculation to oxides. We determined the sodium oxide content in glass by the difference subtracting the content of all oxides from 100%. Although this technique provides only estimation of the sodium content in glass, it is important in answering the question of whether sodium was added to glass specially or entered it as an impurity in potash.