Zn Impurities Research Articles

Jewelry Morocco septaria. Gemological characteristics and mineral composition

Background. Septaria, comprising calcareous-clay nodules with calcite veins, are widely used as jewelry and ornamental materials. Septaria from Morocco represented on the world and Russian markets of jewelry and ornamental stones remain gemologically and mineralogically underexplored. In this article, the gemological characteristics and mineral composition of Morocco septaria, as well as the conditions of their formation, are described for the first time.Aim. To determine the gemological characteristics and mineral composition of Morocco septaria, as well as their formation conditions. To conduct their comparison with septaria from other regions of the world.Materials and methods. The author studied the assortment of Morocco septaria presented at international and Russian exhibitions. A collection (15 samples) representing the main decorative septarium varieties was compiled. The materials underwent determination of microhardness, density, luminescence (10 samples), optical-petrographic analysis (4 sections), quantitative determination of mineral and chemical composition (2 samples), electron probe studies (2 samples).Results. The septaria were found to consist of (wt %): quartz — 38, goethite — 16, chlorite (shamosite) — 28, kaolinite — 6, siderite — 5, dolomite — 4, calcite — 1, pyrite, zeolite, apatite, hydrosludes less than 1. Dispersed inclusions of leucoxene, barite, and microcline were discovered. The septarium veins consisted mainly of dolomite, quartz, chlorite with inclusions of siderite, calcite and pyrite. The Zn, Sr, and Ba impurities ranged within 0.01—0.05 wt %, while Cr, V, Ni, Cu, Rb, Zr, Y, and Pb ranged within 0.001—0.01 wt %. The mineral composition of the studied Morocco septaria was found to differ significantly from that of septaria in other regions of the world, where calcite plays a decisive role.Conclusion. Morocco septaria of small size (from 2 to 6 cm) are used as interior decorations and jewelry cabochons. The mineral and chemical (including micro-inclusions and impurities) composition of Morocco septaria was established for the first time, which allows their identification. The mineral composition of the septaria under study is associated with the regional low-temperature metamorphism, which altered the original, predominantly calcite composition.

Effect of in-situ Zn doping on suppression of phase separation in InxAl1−xAs epitaxial layer on InP(001) grown by MOCVD

The effect of Zn impurities on the surface morphology evolution and phase separation behavior of the InAlAs layer on InP(001) substrates is investigated using metal organic chemical vapor deposition (MOCVD). The phase separation of InAlAs occurs at a relatively low growth temperature (T < 620 °C), accompanied by surface roughening and bandgap lowering. According to the microstructural analyses, indium (In) and aluminum (Al) atoms have high reactivity with In-rich or Al-rich columns in a certain growth region. The addition of Zn impurities during InAlAs growth at the phase-separating temperature results in the suppression of phase separation, which can be attributed to a high probability of Zn incorporation into the sites, which generates an In-rich and Al-rich phase column in the phase-separated InAlAs layer. Based on atomic force microscopy (AFM) and high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) analysis, we classify four types of InAlAs surface morphology as a function of the growth temperature and flow rate of Zn impurities.

Impurity-related defect complexes-mediated ferromagnetism and impurity band hopping conduction in a highly compensated Zn-doped SnO2

We reported the ferromagnetism (FM) and electrical transport properties induced by donor-acceptor compensated defect complexes and related impurity bands in highly compensated Zn-doped SnO2 thin films. Various characterizations were used to study the optical, electrical, luminescent, and magnetic properties of SnO2 films with Zn dopants. Comparing with the paramagnetic nature of undoped n-type SnO2, we observed a room temperature d0 FM in the highly compensated and p-type Zn-doped SnO2 films with a low conductivity of ∼10−3 Scm−1, suggesting a strong correlation between ferromagnetism and the donor-acceptor compensation. The coercive field, remanent and saturation magnetization for the Zn-doped SnO2 film at 300 K are 310 Oe, 0.8 emu/cm3, and 2.6 emu/cm3, respectively. A detailed analysis for temperature-dependent resistivity indicates that the electrical conduction behavior of Zn-doped SnO2 at low temperatures follows the variable range hopping mechanism proposed by Mott and confirms that impurity bands occur at the Fermi level. As the concentration of Zn dopants increases, the fitting Mott temperature gradually rises, suggesting the contribution of Zn impurities to form the impurity bands where the carriers are localized. First-principles calculations reveal that the Zn substituting Sn site (ZnSn) defect with a low formation energy is responsible for the transformation of the charge carrier type. Furthermore, the oxygen vacancy (VO) between two nearest-neighbor ZnSn defects can stabilize the ferromagnetic coupling and form Mott's variable range hopping conduction derived from the localized carriers in the compensated impurity bands. Our results are of significance for the better understanding of the physical mechanisms underlying the effects of impurity/defect bands on the magnetic and electrical properties of the SnO2 with Zn dopants.

Recovery of AZ91D magnesium alloy waste by vacuum gasification - Directed condensation

Magnesium alloys, known as "green engineering material in the 21st world" and "revolutionary medical metal material", have been widely used. However, in the process of production and consumption, a large amount of waste is generated, which not only pollutes the environment, but also wastes secondary resources. Therefore, the vacuum gasification - directed condensation method was adopted in this study, and the waste of AZ91D magnesium alloy was taken as the representative for recovery. The vapor pressure and separation coefficient of main metal magnesium and impurity were calculated. The three-phase diagram of magnesium and mechanism of molecular motion under vacuum was analyzed to determine vacuum vaporization process for the recovery of magnesium scrap, and the distribution of volatile condensing heat field of volatile impurity Zn and Mg was simulated. The effects of system pressure, temperature and holding time on the purity of recycled magnesium alloy were investigated experimentally. The results show that the optimal experimental conditions were pressure 100 Pa, distillation temperature 1073 K, condensation temperature 873 K and holding time of 60 min. The final purity of magnesium can reach 99.96%. This study provides a good theoretical and practical basis for the vacuum recovery of complex magnesium alloy waste.

Introduction of deep level impurities, S, Se, and Zn, into Si wafers for high-temperature operation of a Si qubit

To realize high-temperature operation of Si qubits, deep impurity levels with large confinement energy, which are hardly thermally excited, were introduced into Si wafers. Group II impurity Zn and group VI impurities S and Se, which are known to form deep levels, were introduced into the Si substrates by ion implantation. These samples were analyzed for concentration-depth profiles, energy level depths, and absence of defects. To introduce deep impurities into thin channels such as 50 nm thick Si, we found impurity introduction conditions such that the concentration depth profiles had maximum values at less than 50 nm from the Si surface. Then, the formation of the deep levels and absence of defects were experimentally examined. Using the conditions to introduce deep impurities into the Si wafer obtained from the experiments, single-electron transport at room temperature, high-temperature operation of qubit, and room-temperature quantum magnetic sensors are promising.

Specific features of the microimpurity composition of chrome-spinel inclusions in diamonds from kimberlites of Sakha-Yakutia

Specific features of the microimpurity composition of chrome-spinel inclusions in 323 diamond crystals from eight kimberlite pipes of two diamond-bearing regions of Yakutia were revealed by microprobe analysis. Processed data on their content of the Ni, Zn, V, Mn, and Si impurities are presented. It is shown that chrome-spinels in diamonds from the kimberlite pipes of the different regions are characterized by different contents of the impurity elements. The revealed differences in the composition of chrome spinel inclusions in the diamonds, as well as in the defect-impurity composition of the hosting diamonds, from the different, including neighboring, kimberlite pipes of Yakutia, are evidence of a local heterogeneity in the mantle composition within a certain kimberlite field. These data confirm the opinion of most researchers on heterogeneity of the mantle composition in different regions of the Yakutian diamondiferous province.

Study of the Possibility of Recycling of Technogenic Hafnium during Electron Beam Refining

The possibility of removing metallic (such as Zr, Fe, Cr, and Zn) impurities and non-metallic (such as [O] and C) impurities from technogenic hafnium through single and double refining in the conditions of electron beam melting (EBM) has been studied. The influence of thermodynamic and kinetic parameters on the degree of removal of these impurities from the base metal under vacuum conditions and within a temperature interval of 2500 K to 3100 K is defined. The relative volatility of metal impurities and the stability of the oxides and carbides present in the base metal are evaluated. The possibility for complete removal of Fe, Cr, Zn, [O], and C during EBM is shown. In the case of double refining, at a temperature of 2700 K for 20 min, the maximum degree of removal of Zr is 46.8%, the achieved highest hafnium purity is 99.004%, and the overall effectiveness of the refining of hafnium from impurities is 53%. There is a correlation between the degree of removal of Zr and the micro-hardness of the Hf ingots obtained after EBM. The weight losses vary in the ranges of 1.5-5.8% and 1-8% under the studied single and double refining processes, respectively.

Impurity properties in phosphorene: First-principles calculations and comparisons

Based on first-principles calculations within the generalized gradient approximation (GGA) and the hybrid functional (HSE06) frameworks, the properties of dozens of impurities in phosphorene have been systematically investigated and compared. The adsorbed Li, Na and K impurities have low formation energies and create defect states near the conduction band minimum of phosphorene, thus they are promising donors. The adsorbed Ga, In, Cu and Ag impurities also act as donors but have high formation energies, making them hard to be formed in equilibrium conditions. Group-II and group-VIII impurities introduce defect states in the energy gap far away from the band edges, while the adsorbed Zn, Cd and group-VI impurities produce no defect states in the gap region. According to the GGA results, the substitutional group-IV impurities create defect states near the valence band maximum, but in the HSE06 calculations these states shift deeply into the energy gap, rendering the impurities hard to be activated. Among the group-VI and group-VII impurities, only the adsorbed O, F and Cl have low formation energy. The formation energy of the same group impurities monotonously decreases or increases with the impurity-atom’s location in the periodic table of elements.

Identification of a nematic pair density wave state in Bi2Sr2CaCu2O8+x

Electron-pair density wave (PDW) states are now an intense focus of research in the field of cuprate correlated superconductivity. PDWs exhibit periodically modulating superconductive electron pairing that can be visualized directly using scanned Josephson tunneling microscopy (SJTM). Although from theory, intertwining the d-wave superconducting (DSC) and PDW order parameters allows a plethora of global electron-pair orders to appear, which one actually occurs in the various cuprates is unknown. Here, we use SJTM to visualize the interplay of PDW and DSC states in Bi2Sr2CaCu2O8+x at a carrier density where the charge density wave modulations are virtually nonexistent. Simultaneous visualization of their amplitudes reveals that the intertwined PDW and DSC are mutually attractive states. Then, by separately imaging the electron-pair density modulations of the two orthogonal PDWs, we discover a robust nematic PDW state. Its spatial arrangement entails Ising domains of opposite nematicity, each consisting primarily of unidirectional and lattice commensurate electron-pair density modulations. Further, we demonstrate by direct imaging that the scattering resonances identifying Zn impurity atom sites occur predominantly within boundaries between these domains. This implies that the nematic PDW state is pinned by Zn atoms, as was recently proposed [Lozano etal., Phys. Rev. B 103, L020502 (2021)]. Taken in combination, these data indicate that the PDW in Bi2Sr2CaCu2O8+x is a vestigial nematic pair density wave state [Agterberg etal. Phys. Rev. B 91, 054502 (2015); Wardh and Granath arXiv:2203.08250].

Changes in the Structural Parameters and Effective Magnetic Moment of Eu2−xCexCuO4+α−δ by Zn Substitution

The effect of nonmagnetic Zn impurities on the structural parameters and effective magnetic moment of electron-doped superconducting cuprates Eu2−xCexCu1−yZnyO4+α−δ (ECCZO) with x = 0.10 and 0.15 and y = 0 and 0.01 has been investigated using XRD and SQUID measurements. From XRD measurements, it is found that the lattice parameter of c and the Cu-O bond length increase with increasing y. The crystallite size of ECCZO samples was relatively smaller than the sample without impurities determined by the Debye–Scherrer equation and the W-H Plot method. Changes in the lattice parameters of c and Cu-O bond length can affect the appearance of superconductivity (Tc). The smaller the value of the lattice parameter of c and the Cu-O bond length causes the distance between the conducting layer and the charge reservoir to be close enough so that the charge transfer process becomes easier. From the magnetic susceptibility measurement, paramagnetic characteristics were observed for samples with x = 0.10. Meanwhile, for samples with x = 0.15, diamagnetic characteristics can be identified in sample with y = 0. The onset of Tc was observed around 11 K, as indicated by a change from paramagnetic to diamagnetic characteristics. The superconductivity phase disappears with y = 0.01. The effective magnetic moments in samples with y = 0 are smaller than those in samples with y = 0.01. The effective magnetic moment in ECCZO can be contributed by Cu2+. When the amount of Cu2+ decreases due to the addition of nonmagnetic Zn2+ atoms, the overall effective magnetic moment value also decreases. Another possibility that causes a decrease in the value of the magnetic moment of the ECCZO is the existence of stripe-pinning model, which results in suppressed superconductivity by Zn.

Theoretical insight into the enhancement of longer-wavelength light absorption in silicon solar cell with multilevel impurities

In this article, we theoretically demonstrate multilevel impurity photovoltaic effect in an efficient silicon dual-homojunction solar cell that ensures an extended absorption of longer wavelength light. Along with suitable contact work functions (Ni and Ta as anode and cathode, respectively), three impurity energy levels from acceptor type impurities (One from Tl and two from Zn) have been introduced in the energy gap of the absorber layer of the solar cell. The simulations have been performed with Solar Cell Capacitance Simulator (SCAPS-1D) program. The pristine Si solar cell shows a PCE of 25.4% with JSC = 37.99 mA/cm2, VOC = 0.780 V and FF = 85.76%. While the incorporation of Tl impurity level alone provides a PCE of 33.4%, with JSC = 51.56 mA/cm2, VOC = 0.789 V and FF = 82.03%, respectively. The PCE of the solar cell further enhances to 35.4% with an elevation of the short circuit current by 3.76 mA/cm2 due to the inclusion of Zn impurity into the optimized structure. This increment of the JSC and hence PCE is evolved from the longer wavelength light absorption due to impurity-assisted two-step photon upconversion in the solar cell.

Recovery of Lanthanum from Aqueous Solutions by Crystallization as Lanthanum Sodium Sulfate Double Salt

The recovery of rare earth elements from spent nickel-metal hydride batteries by hydrometallurgical processing has become increasingly important in recent years. The present work investigated the effect of temperature, systems of adding the reactant, the molar ratio of sodium and lanthanum, and the initial concentration of six sulfate impurities (Ni, Co, Al, Mn, Fe, and Zn) on the crystallization of the monohydrate of sodium lanthanum sulfate double salt (NaLa(SO4)2·H2O) crystals from synthetic leachate solutions. The sodium sulfate reactant was added as an acidic solution by pumping or batchwise as a solid anhydrate salt to a pregnant lanthanum sulfate solution. Compared to precipitation with acidic sodium sulfate solution, precipitation with solid sodium sulfate yielded smaller single crystals, a greater tendency to form aggregates, and lower crystal purity. The lowest overall impurity and highest lanthanum quantity in crystals were obtained by semi-batch reactant adding performance of Na2SO4 solution at 70°C with Na/La molar ratio of 3. Real-time monitoring of the count rates of different chord length fractions clearly showed the influence of crystallization temperature on the precipitation kinetics.

Preparation Process and Quality Characterization of High Density Fine Grain Osmium Target for Coated Cathode

High quality osmium targets are the key influence in improving the emission performance, lifetime and reliability of M-type cathodes. In this experiment, oxidative distillation was used to prepare osmium powder with a purity greater than 99.99%. The effect of hydrogen sintering and hot pressing sintering processes on the densities and grain size of the targets was investigated. The results show that the oxidation distillation process can effectively separate Os from Si, Fe, Ni, Zn and other impurity elements, and the purity of osmium powder prepared by multiple oxidation distillation was not less than 99.99%. Both hydrogen sintering and hot pressing sintering processes can be used to obtain osmium targets with a density of not less than 95%. However, the sintering temperature and time used in the hot pressing sintering process under pressure assistance are significantly lower than those of hydrogen sintering, which is more conducive to inhibiting grain growth during the high densification sintering process. By optimizing the parameters of the hot pressing sintering process, the sintering temperature of 1500°C and the holding time of 1.5h resulted in an osmium target with a density of 99.11% and a grain size of ≤12. XPS analysis of the highly dense fine crystalline osmium targets prepared by hot pressing sintering showed that the C and O mass fractions on the surface of the targets were 0.85% and 4.43% respectively, and the C and O contents gradually decreased with increasing etching depth. The above highly dense and fine crystalline osmium targets can be used in the M-type cathode standard coating process to obtain high purity, dense and strong bonded osmium films.

Mineralogical and Chemical Changes after Reduction Roasting of Xinjiang Iron Ore, China

The mineralogical and chemical changes in Chinese Xinjiang iron ore containing impurities, lead, and zinc as a result of reduction roasting were studied via chemical analysis, optical microscopy, X-ray fluorescence (XRF), electron probe microanalysis (EPMA), and energy-dispersive spectroscopy (EDS). Analysis showed that hematite was the main iron-bearing mineral, with small amounts of magnetite and iron silicate; lead impurities were mainly lead oxide and lead–iron alum, while zinc oxide was the main zinc impurity. X-ray fluorescence analysis for raw samples indicated the presence of quartz, hematite, magnetite, chlorite, calcite, and dolomite. The results of the analysis of roasted samples showed an increase in hematite at temperatures of 750 °C and 950 °C, while the elemental iron increased at a temperature of 1200 °C, along with the conversion of galena to lead oxide and sphalerite to zinc oxide, with a stable quartz ratio. The chemical analysis of the raw sample showed that the TFe grade of the sample was 47.04%, while the contents of harmful Pb and Zn impurities were 0.39% and 0.30%, respectively, both of which exceed the index (less than 0.10%) required by the iron industry for raw materials. The content of harmful sulfur impurities was also high, at 1.19%, which needs to be eliminated or reduced. The results of EPMA and EDS analysis of pre-roasting raw samples showed that chemical compositions vary in different locations in the hematite, magnetite, sphalerite, and galena micro-zones. It has also been observed that quartz is mostly diffused with magnetite and hematite, and sulfur appears in small quantities in most regions. The analysis after roasting showed that the percentages of lead, zinc, and sulfur impurities decreased by a large rate. It is clear that the roasting process plays a major role in removing impurities such as sulfur, which appears in a small percentage after the roasting process, and also helps in oxidizing the impurities of lead and zinc, which helps in removing them.

Zn-doped CdS/CdSe as efficient strategy to enhance the photovoltaic performance of quantum dot sensitized solar cells

Metal ion doping is a suitable approach for optimizing quantum dots (QDs), which can change the recombination dynamics and charge separation of QDs via creating electronic states within their band gap, and improve their optical and electrical properties. In this work, the transition metal Zn-doped CdS and CdSe QDs are performed by SILAR (successive ionic layer adsorption and reaction) method. And the sensitized solar cells (QDSSCs) based on the Zn-doped CdS and CdSe QDs are assembled. The effect of Zn-doping concentration on the optical properties and charge carrier transport characteristics of photoanodes is investigated. Based on these QDs sensitized TiO2 photoanodes, the assembled QDSSCs with Zn-dopant of a molar concentration of 1.6 mol % exhibited a maximum power conversion efficiency (PCE) of 5.59 %, which is increased by 26.76 % in comparison with that of the QDSSC (4.41%) without Zn-doping. The significantly enhanced PCE of QDSSCs was attributed to improved current density and open-circuit voltage, particularly arising from enhanced light absorbance by narrowing the band gap with the midgap states and upshift of Fermi level promoted by the high electrons concentration due to the ionization of Zn impurities. In addition, the Zn-doping contributes to attenuation of the interfacial charge recombination rate and prolongs the electron lifetime, resulting in more efficient charge collection in QDSSCs.

Separation behavior of As, Zn and Cd trace impurities in the deep vacuum purification process of refined lead

Environmentally friendly vacuum distillation has been employed to purify refined lead (99.996%), aiming to separate low-boiling point trace impurities of As, Zn and Cd in refined lead and to provide a foundation for the preparation of high-purity lead (5 N) and ultrapure lead (6 N). In this paper, the low-boiling point trace impurities As, Zn and Cd in refined lead are removed by low-temperature vacuum distillation (LTVD). Detailed analysis of the initial and purified lead was performed by glow discharge mass spectrometry (GDMS) to reveal that Cd and Zn were evaporated as volatiles and were removed from the refined lead in a crucible. Correspondingly, the contents of Zn and Cd impurities decreased from 4 ppmw and 1 ppmw to 0.006 ppmw and 0.01 ppmw, respectively. In contrast to the removal efficiencies of Zn and Cd by LTVD, the removal efficiency of As impurities is only 4%. To cope with this, a novel high-temperature pyrolysis-zone condensation (HTP-ZC) vacuum purification process is proposed for further As separation. The HTP-ZC results indicate that As, Cd and Zn are condensed as residues and removed in the condensation stage. Removal efficiencies of 99.96% for As, 99.98% for Zn, and approximately 100% for Cd were achieved. This approach, with huge industrialization potential, pushes the direct yield of the product to 90% and effectively removes trace impurities with low boiling points, such as As, Cd and Zn, in refined lead. The proposed HTP-ZC process has the potential to stably, cleanly and efficiently produce high-purity lead and ultrapure lead.

Минеральный состав руд, использовавшихся на укрепленном поселении бронзового века Устье-I (Южное Зауралье)

At the fortified settlement of the Bronze Age, Ustye-I (South Trans-Urals), metal products of copper, arsenic and tin bronzes, numerous fragments of metallurgical slags, as well as fragments of copper ores have been discovered. According to the results of early studies, pure copper predominates among metal items (53.4% of finds), but also a significant part contains an admixture of arsenic (25.4% of finds), tin (13.6% of finds) and both components simultaneously (7.6% of finds). Several alloying components of the samples are simultaneously found in slags: Pb (50% of cases), As (49% of cases), Zn (40% of cases), Bi (38% of cases), Sn (7% of cases), Ni (4% of cases), Sb (1% of cases). To identify the relationship between the incoming raw materials and the received metal, 15 ore samples were examined. The ores studied are ‘gravelly’ clasts with a size of 5 mm to several centimeters, and ‘sandy’ ores with a size of 2–3 mm. According to their mineral composition, ores are subdivided into malachite, azurite, and limonite. The main copper minerals are malachite and azurite; chrysocolla is found occasionally, chalcopyrite, cuprite are rarely found. Copper is bound to Fe- and Mn-hydroxides. We have identified copper slag fragments in ‘sandy’ ores. In all types of ores, natural alloying components are very rare and are represented by Pb and Zn. These elements can form their own minerals (mottramit, a mineral of the plumbogummite family) or act as an impurity to malachite (up to 0.62 wt% ZnO), azurite (up to 1.12 ZnO and up to 2.37 PbO), iron hydroxides (up to 2.66 ZnO and up to 2.02 PbO) or manganese hydroxides (up to 0.41 ZnO and up to 9.48 PbO). No As and Sn impurities were found. The presence of numerous fragments of brown iron ore at the settlement, the close location of copper mines indicates that the settlers were engaged in the extraction and processing of copper ore. The widespread occurrence of ores, consisting mainly of malachite and azurite, indicates that the ores were mined from the upper parts of the oxidation zone, and the metal smelted from these ores must correspond to pure copper. The distribution of Pb and Zn impurities indicates that some of the copper ores originate from the oxidation zones of pyrite ores or deposits of other formational types with a similar ore composition. The difference in the compositions of the ores found at the settlement and the compositions of slag and metal is associated with several sources of ores. The sources of copper ores could be mines located near the settlement. Arsenic-bearing ores could have come from mines in adjacent areas. Tin ores were brought in as a result of trans-regional exchange with the Central Asian region.

Effects of Zn impurity on the photoluminescence properties of InP quantum dots

Heavy-metal-free indium phosphide (InP)-based quantum dots (QDs) have attracted much attention as materials for display applications. Methods such as introducing Zn in the core of InP QDs and passivating wide band-gap materials have been used to improve the luminescent properties of InP QDs. Herein, we investigated the photophysical properties of the In(Zn)P core QDs with the influence of the Zn additive on the InP QDs. The near band edge photoluminescence (PL) of the In(Zn)P QDs was spectrally asymmetric in shape, with a redshifted side peak originating from a Zn impurity that induced shallow defect sites, resulting in PL linewidth broadening. The shallow trap emission of the In(Zn)P QDs disappeared after the overcoating of the ZnSeS passivated the shell layers, and the PL linewidth of In(Zn)P/ZnSeS (core/shell) QDs was solely determined by the band-edge excitonic energy distribution caused by the size dispersion in ensemble QD systems. We expect that the understanding the photophysical properties of In(Zn)P-based QDs future strategies to narrow the ensemble emission line of the InP-based QD synthesis.

EVALUATION OF 68Ge/68Ga GENERATOR PRE-ELUTION EFFICIENCY ON METALLIC IMPURITIES IN THE COMPOSITION OF 68GaPSMA-11 RADIOPHARMACEUTICAL IN NUCLEAR MEDICINE PET CHEMISTRY

Objective: The presence of metallic impurities can pose a serious concern due to their interaction with receptor-specific biomolecules that require the highest possible specific activity, especially in radioactive labeling. There are studies in which Zn and other toxic metal pollution increases if the generator is not used for a long time. In this study the effect of pre-elution on chemical and radiochemical impurities in the synthesis product was investigated. Material and Methods: In the study, 68GaPSMA-11 labeling was performed with the generator eluate that was not used for one month (sample 1). A blank elution was taken 24 hours after using the generator (sample 2). In the next 24 hours, the second 68GaPS-MA-11 labeling was performed (sample 3). Six hours after this labeling, another 68GaPSMA-11 synthesis was performed (sample 4). Eluates were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results: Results was reported as a table in μg/ml. 68Ge levels determined at 0.018 ppm, 0.012 ppm and 0.009 ppm levels in the labeled products were determined below the pharmacopoeia limits. Zn(II) impurities were found as 0.625 ppm in the labeling performed without generator pre-elution. In generator pre-eluted labelings; Zn(II) impurities were determined as 0.133 ppm and 0.108 ppm.&nbsp;Conclusion: Pre-elution of the generator prior to synthesis does not seem to be a chemical requirement other than zinc pollution. 68GaPSMA-11 can be pre-eluted for high labeling efficiency, but it is thought that pre-elution is not significant in terms of chemical and radiochemical contamination.

Zn-Induced Defect Complexity for the High Thermoelectric Performance of n-Type PbTe Compounds.

Although defect engineering is the core strategy to improve thermoelectric properties, there are limited methods to effectively modulate the designed defects. Herein, we demonstrate that a high ZT value of 1.36 at 775 K and a high average ZT value of 0.99 in the temperature range from 300 to 825 K are realized in Zn-containing PbTe by designing complex defects. By combining first-principles calculations and experiments, we show that Zn atoms occupy both Pb sites and interstitial sites in PbTe and couple with each other. The contraction stress induced via substitutional Zn on Pb sites alleviates the swelling stress by Zn atoms occupying the interstitial sites and promotes the solubility of interstitial Zn atoms in the structure of PbTe. The stabilization of Zn impurity as a complex defect extends the region of PbTe phase stability toward Pb0.995Zn0.02Te, while the solid solution region in the other direction of the ternary phase diagram is much smaller. The evolution of defects in PbTe was further explicitly corroborated by aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM) and positron annihilation measurement. The Zn atoms compensate the Pb vacancies (VPb) and Zn interstitials (Zni) significantly improve the electron concentration, producing a high carrier mobility of 1467.7 cm2 V-1 s-1 for the Pb0.995Zn0.02Te sample. A high power factor of 4.11 mW m-1 K-2 is achieved for the Pb0.995Zn0.02Te sample at 306 K. This work provides new insights into understanding the nature and evolution of the defects in n-type PbTe as well as improving the electronic and thermal transport properties toward higher thermoelectric performance.