Impurity Doping Research Articles

Electrical Doping in Sc-III-Nitrides: Toward Multifunctional Devices at the Signal Device Level.

A homogeneous integration of various types of devices using a single material platform is an ideal route toward multifunctional devices at the single-device level for miniaturized, fast, and energy-efficient systems. However, such a single material platform is still missing. Scandium-containing III-nitrides (Sc-III-nitrides) are promising, but their electrical doping properties remain unknown. In this work, the electrical doping in Sc-III-nitrides is investigated and optoelectronic devices using Sc-III-nitrides on silicon (Si) are further demonstrated. The material format of the nanowire is used, with magnesium (Mg) serving as the impurity dopant to control the electrical doping. It is discovered that, by adjusting the Mg doping concentrations, the Sc-III-nitrides can be tuned from n-type to p-type. Device application in light-emitting is further demonstrated using the p-type Sc-III-nitrides as the hole injection layer. The performance comparison between devices using the regrown Sc-containing p-type contact layers and non-Sc-containing p-type contact layers indicates the advantage of Sc incorporation in improving the quality of the regrown p-type layer in a device structure. The electrical doping in Sc-III-nitrides demonstrated in this study represents an important step toward a homogeneous integration of different types of devices using a single material platform.

Influence of the Y3Al5O12 on the structure formation and properties of ceramics of the Al2O3 – Y2O3 system

The paper presents results of the study of the structure and physico-mechanical properties of ceramics composits α-Al2O3 + n Y2O3 (n = 0; 0.5; 1; 1.5; 2; 3; 4; 5 wt.%) based on the basis of polymorphic modifications γ+θ-Al2O3 depending on the concentration of the Y2O3 doping impurity and the annealing temperature of the powder mixtures (800 and 900°C). The effect of mutual protection against crystallization was discovered, which results in mutual inhibition of crystallization processes in Al2O3–Y2O3 powder systems. By X-ray diffraction analysis, the formation of a phase of yttrium-aluminum garnet Y3Al5O12 (YAG) in ceramics has been established. The dependence of the mechanical characteristics of the materials under study on the amount and size of the formed phase YAG has been revealed.

Thermovoltaic response in two-layered thin-film zinc oxide structures

A method of measuring the thermovoltaic effect in heterogeneous media with gradient doping impurity distributions producing gradient carrier distributions has been proposed. Iron doped zinc oxide specimens have been produced using ion beam sputtering on thin foil tantalum substrates for thermovoltaic effect measurements, glass-ceramic substrates for Hall measurements and silicon substrates for structural study. The doping impurity concentration хFe in the specimens has been varied from 0.34 to 4.18 at.%. X-ray phase analysis has shown that all the specimens have a hexagonal zinc oxide crystal structure. The films have preferential [002] orientation. The carrier concentration in the experimental specimen layers according Hall data obtained on an ECOPIA 5500 measurement system in a 0.5 T DC magnetic field has varied in the 1016–1020 cm-3 range. The specimens have an n-type conductivity. Thermovoltaic measurements have been carried out for two-layered iron doped zinc oxide specimens with different carrier and iron doping impurity concentrations using the method proposed. The maximum thermovoltaic response (U ~ 80 μV) has been observed in the two-layered thin-film specimen with the carrier concentration difference between the layers (Δn ≈ 2∙103 cm-3). The observed saturation of the thermovoltaic response has been attributed to the establishment of dynamic equilibrium between carrier diffusion from the high carrier concentration layer to the low carrier concentration layer and carrier drift due to internal electric field.

Experimental investigation on the crystal structure and superconductivity of germanium-intercalated 2H–NbSe2 system

We report the structural and superconducting properties of Ge-intercalated 2H–NbSe2 polycrystals. GexNbSe2 samples with nominal 0 ≤ x ≤ 0.1 crystallize in the space group P63/mmc with Ge disorderedly occupying the interlayer Se6 octahedral interstices. Superconducting critical temperature Tc monotonically decreases from 7.2 K in NbSe2 to 4.9 K in Ge0.1NbSe2. Studies on resistivity, magnetization and specific heat derive the superconducting- and normal-state parameters, indicating that the suppression of the two-gap superconductivity is mostly caused by the lowered electron-phonon coupling parameter λe-p and density of states at the Fermi level N(EF). Surprisingly, the upper critical field Hc2 and irreversible field Hirr of the low Ge-level samples are enhanced compared with those of the undoped one, which may ascribe to the electron scattering and vortex pinning by nonmagnetic Ge. This study suggests the feasibility for improving high-field performance by slight impurity doping and advances the understanding of superconductivity in transition-metal dichalcogenides.

(Y3+/Sm3+)-doped and co-doped CoFe2O4 for heterogeneous advanced oxidation process: structural, magneto-optical, and photocatalytic investigations.

The photocatalytic properties of CoFe2O4 nanoparticles were activated by the doping and co-doping of a low level of Y3+ and Sm3+ cations. After optimizing the annealing temperature, 900°C was found to be the optimal temperature for the successful incorporation of Y3+ and Sm3+ into the spinel structure. The purity of our samples annealed at 900°C was confirmed using several characterization methods, including PXRD, SEM, XPS, VSM, FTIR, and Raman spectroscopy. Thus, we were able to increase the photocatalytic degradation of orange G dye from 9.9 to 64.63% for the Sm3+-doped sample, 76.42% for the Y3+-doped sample, and even 85.81% for the co-doped sample under 60min of UV-visible light irradiation. The beneficial effect of samarium and yttrium doping and co-doping is attributed to several factors: the first factor is doped and co-doped rare earth impurities induce distortion in the lattice, the larger the ionic radii of dopant element, the highest is the photocatalytic activity; second factor, upon doping and co-doping of rare earth impurities in the structure of CoFe2O4 leads to the creation of donor state level within the band gap, causing the Fermi energy to shift near the conduction band. Third factor, co-doping produced strong interactions, which accelerated photocarrier mobility and transport; lastly, longer electron-holes lifetime. We have provided a detailed study of the structural, vibrational, and optical properties to support our conclusions.

Properties of phosphorus-boron co-doped c-Si quantum dots/SiNx:H thin film prepared by PECVD in-situ deposition

Co-doping of phosphorus and boron elements into crystalline silicon quantum dot (c-Si QD) is an effective approach for enhancing the photoluminescence (PL) performance. In this paper, we report on the preparation of hydrogenated silicon nitride (SiNx:H) thin films embedded with phosphorus-boron co-doped c-Si QDs via plasma enhanced chemical vapor deposition route. Mixed dilution including hydrogen (H2) and argon (Ar) is applied in the in-situ deposition process for optimizing the deposition process. The P-B co-doped c-Si QD/SiNx:H thin films exhibit a wide range of PL spectra. The emission is greatly improved especially for the short-wavelength light when compared to the SiOx:H thin film containing P-B co-doped c-Si QDs. The effects of H2/Ar flow ratio on the structural and optical characteristics of thin films are systematically investigated through a series of characterizations. Experimental results show that various properties, such as crystallinity, QD size, optical band gap and doping concentrations, are effectively controlled by tuning H2/Ar flow ratio. Based on the red-shift of QCE-related PL peak, the successful P-B co-doping into Si QDs are verified. Finally, a comprehensive discussion has been made to analyze the influence of H2-Ar mixed dilution on the film growth and impurity doping in detail in this paper.

Size-Dependent Isovalent Impurity Doping for Ambipolar Control in Cu3N.

Substitutional doping, involving the replacement of a host with an aliovalent impurity ion, is widely used to attain ambipolar controllability in semiconductors, which is crucial for device application. However, its effectiveness for p-type doping is limited in monovalent cation compounds due to the lack of suitable aliovalent (i.e., zerovalent) impurities. We propose an alternative approach for p- and n-type doping, mediated by the sizes of isovalent alkali metal impurities in Cu(I)-based semiconductors, such as copper nitride with an electron concentration of ∼1015 cm-3. Doping of isovalent Li with a smaller size to interstitial positions improves n-type conductivity, and electron concentration is controllable in the range of 1015 to 1018 cm-3. In contrast, larger isovalent Cs and Rb impurities facilitate p-type conversion, resulting in a hole concentration controllability of 1014 to 1017 cm-3. First-principles calculations indicate that Li is placed as an interstitial impurity acting as a shallow donor in conjunction with the formation of a neutral impurity on Cu defects. As the impurity size increases beyond the capacity of the vacant space, the formation of multiple acceptor-type Cu vacancies is enhanced owing to the repulsion between host Cu+ and Cs+/Rb+ impurities. Consequently, the Cs or Rb impurity is located at the sites of the N accompanied by six neighboring Cu vacancies, forming acceptor defect complexes. This size-dependent isovalent impurity doping scheme opens up an alternative avenue for advancement in optoelectronic devices using monovalent cation-based semiconductors.

Effect of Cr doping on electronic and optical properties of mono/bilayer MoTe2 nanosheets– a first-principles study

The influence of Cr-doping on mono/bilayer MoTe2 nanostructures is studied within the framework of density functional theory (DFT) since doping may be used to effectively tailor the electronic and optical characteristics in a desired manner. Chromium (Cr) seems to modify the electronic properties and energy band gap of MoTe2 considerably. At first, we confirmed the stability of the proposed structure with the support of cohesive formation energy and phonon-band-spectrum. Moreover, doping with Cr on MoTe2 produces a red shift towards far infra-red region in the absorption coefficient, thus making it suitable for far infra-red region applications. Hence, Cr doping is employed in this work. When Cr impurities are substituted in pristine MoTe2 nanostructures, the band structure gets modified. Additionally, the band gap of mono/bilayer MoTe2 nanostructures reduces from 1.143/0.74 eV for pristine MoTe2 to 0.807/0.621 eV for 8 % substitution of Cr. By examining absorption spectra, it was found that the optical characteristics of mono/bilayer MoTe2 changed significantly with doping of Cr impurities. The results of this study provide insight into the band structure, optical, and electronic attributes of mono/bilayer MoTe2 nanostructures that could be further fine-tuned for optoelectronic applications using substitution of Cr impurities.

Enhanced broadband IR absorption and electrical characteristics of silicon variably hyperdoped by sulfur (1018-1021 cm−3) by ion implantation/pulsed laser annealing

Spectral range of crystalline silicon absorption could be extended to near- and even mid-infrared region by its hyperdoping via ion-implantation technology, requiring the following thermal annealing for removing ion-induced defects, recrystallizing the crystalline structure and activating the doping impurity. In this article, the crystalline structure, chemical and electrical characteristics of sulfur-hyperdoped silicon layers with broadly variable impurity concentration (1018-1021 cm−3) and annealed by a nanosecond laser were investigated for the first time by Raman, energy-dispersion x-ray and infrared spectroscopy, as well as by van der Paw and Hall measurements, respectively. The most preferable sulfur concentration for silicon hyperdoping from the point of view of impurity optical and electrical activation was found to be 1020 cm−3.

(Invited) Bulk Traps in Layered 2D Gate Dielectrics

Ultra-thin ferromagnets, when coupled with magnetoelectric or multiferroic materials, could potentially enable highly energy-efficient electric field control of the magnet for use in nanoelectronic memories. Substitutional doping of magnetic impurities in monolayer transition metal dichalcogenides (TMDs) may be a promising way to create 2D ferromagnets but, according to theoretical calculations, require high doping levels (10-20 %) to achieve above room temperature (RT) Curie temperature. Room-temperature ferromagnetism has been reported for very low doping levels (0.1-1%), in conflict with the theoretical calculations, and always in the presence of high concentrations of defects, making it unclear if the dopants alone are responsible for this ferromagnetism. In this work, we use a combination of molecular beam epitaxy (MBE), plan-view TEM, XRD, XPS, Raman, and magnetometry to study iron and vanadium doping in monolayer WSe2. We show that optimally grown monolayers with up to 35% doping and low defect density show no ferromagnetism. Interestingly, ferromagnetism is observed when these monolayers contain a significant amount of selenium vacancies (Sevac), intentionally created via a post-growth heat treatment process, and magnetism is seen to scale with heating time/vacancy concentration. Moreover, even undoped WSe2 shows similar ferromagnetism for Sevac > 1014 cm-2. This ferromagnetism can later be quenched by filling these vacancies via Se annealing. For films with low Se vacancy concentration, TEM analysis reveals significant clustering of the V and Fe dopants which likely suppresses the ferromagnetism predicted by theory - a problem that has previously plagued III-V based dilute magnetic semiconductors as well. We go so far as to claim that all of the above room-temperature ferromagnetism reports in the literature thus far are due to Se vacancies and not magnetic doping.

Impact of Fe doping on the reactivity of γ-dicalcium silicate: Insights from DFT calculations

This study investigates the impact of Fe doping on the reactivity of γ-dicalcium silicate (γ-C2S) using density functional theory (DFT) calculations. We examined isolated point defects and defect complexes in various charge states to assess substitution tendencies. The results reveal that substituting Si with Fe is energetically more favorable than substituting Ca, due to smaller distortions and minimal impact on Fe-O bonds compared to Ca-O bonds. We systematically analyzed the impact of Fe impurities on γ-C2S reactivity through atomic charges, chemical bonds, and ab initio molecular dynamics (AIMD) simulations. On the one hand, Fe strengthens nearby Ca-O bonds, reducing the effective charge of oxygen atoms and inhibiting reactivity. On the other hand, hydroxylation of Fe-O groups, followed by dehydroxylation, decreases the coordination number of certain surface Ca ions, enhancing reactivity. The overall reactivity of Fe-doped γ-C2S balances inhibition and enhancement, depending on the reacting molecules. In pure H2O systems, the inhibitory effect prevails, while in the presence of H2CO3, the enhancement effect dominates. Experimental observations corroborate these findings. This study provides insights into impurity doping mechanisms in calcium silicate minerals.

Tailoring electronic and optical properties of Lutetium pyrosilicate (Lu2Si2O7) through Nd and Tb doping: Insights from DFT+U calculations

In this research paper, we investigate the electronic and optical properties of Lutetium pyrosilicate (Lu2Si2O7, LPS) by Nd and Tb doping using density functional theory (DFT) calculations within the framework of the WIEN2k code. The DFT + U method is employed to account for the strong correlation effects in the rare earth dopants. The analysis of the electronic properties reveals that the materials under investigation exhibit semiconductor behavior. The calculated spin up/dn energy band gaps for pristine, Nd & Tb doping Lu2Si2O7 are determined to be 4.610/4.660 eV, 4.635/5.162 eV, and 5.06/4.45 eV, respectively. Our results reveal that the doping of Nd and Tb impurities leads to the introduction of new electronic states within the band gap of Lu2Si2O7, resulting in a significant modification of the electronic and optical properties. Specifically, we find that the Tb-doped Lu2Si2O7 shows a wide band gap and enhanced optical absorption in the visible region, while the Nd-doped Lu2Si2O7 exhibits a broadened band gap and reduced optical absorption in the visible region. This study can provide a reference for future research and helps to extend the properties of Lu2Si2O7 by Nd and Tb materials into the optical applications.

Development of MnWO4:Ag nanodilute magnetic semiconductors with tunable magnetic and optoelectronic properties

The bandgap engineered MnWO4 nanoparticles doped with Ag were developed using a facile one-pot synthesis method. The impurity doping concentration of Ag was varied from 1 to 5 wt percentages to tune the interactions between manganese tungstate and silver ions to obtain desirable magnetic and optoelectronic properties. The structural properties of the MnWO4 particles with various concentrations of Ag were investigated using X-ray diffraction. The optical properties of the pristine and Ag-doped MnWO4 particles were determined using UV‒Vis and photoluminescence spectroscopy. The impurity concentration-dependent structural transformations and changes in the vibrational modes, lattice dynamics, electronic transitions and optoelectronic properties of the prepared materials were analyzed using Raman spectroscopy. The topology, morphology and elemental analysis of the synthesized nanoparticles were elucidated using HRTEM, SAED, SEM and EDX techniques. The magnetic properties of the MnWO4:Ag nanoparticles were measured using a vibrating sample magnetometer (VSM). The obtained results suggested that Ag-doped MnWO4 nanosystems show enhanced and tunable magnetic properties suitable for nanodilute magnetic semiconductor (nDMS) applications. The presented work opens a range of possibilities for the development of advanced materials with applications in optoelctronics, nanomedicine, energy-efficient electronic devices and energy conversion.

CaCl2 doping effect on optical and structural properties of halide perovskites under ligand assisted reprecipitation synthesis

The high potential of metal halide perovskite (MHP) nanocrystals with the general formula CsPbX3 (X = Cl, Br, and I) has led to the development of easy and cost-effective methods on a daily basis. The room temperature (RT) and open atmosphere ligand-assisted reprecipitation (LARP) methods were utilized to synthesize CsPbBr3 and CsPbBr2I nanocrystals (NCs). CaCl2 was used as a dopant in four different concentrations (0.25, 0.5, 0.75, and 1 % molar) to optimize the optical and electrical properties and to enhance the stability of NCs. The most optimal results were observed with 0.25 % doping for CsPbBr2I and 0.75 % doping for CsPbBr3. XRD and FE-SEM analyses revealed a cubic crystal structure for the synthesized nanocrystals. Dynamic light scattering (DLS) analysis indicated an average size of was 35–70 nm. The introduction of Ca2+ impurity, resulted in increased sizes for 0.75 % doped CsPbBr3 NCs; and increased intensity for 0.25 % doped CsPbBr2I NCs. Optical studies, including UV–vis, Fourier Transform Infrared (FTIR), and photoluminescence spectroscopies were conducted. The bandgap of CsPbBr2I and CsPbBr3 was estimated at 2.60 and 2.75 eV, respectively. The FTIR spectra suggested the effective involvement of the ligand agents oleic acid (OA) and oleylamine (OLA) in synthesis of metal halide perovskite nanocrystals. Photoluminescence spectroscopy demonstrated that the photoluminescence intensity of CsPbBr2I and CsPbBr3 varied with impurity doping, indicating an enhancement of semiconductor electronic properties under Ca2+ doping.

Aftermath of Ag embedding on structural, optical, and supercapacitor electrode attributes of USP-grown CuO thin films

Here, ultrasonic spray pyrolysis method (USP) was utilized to produce pure and silver doped copper oxide nanostructures on glass substrates. Thereafter, several characterization techniques were conducted on the grown samples to delve into their morphological, structural, electrochemical, and optical aspects. The mentioned analyses were carried out by performing x-ray photoelectron spectroscopy, scanning electron microscope, X-ray diffraction, electrochemical impedance spectroscopy, galvostatic charge-discharge, cyclic voltammetry, and UV–visible spectroscopy measurements. Thus, the impact of silver impurity doping on the relevant aspects of host material were recorded as well as the features of unspoiled copper oxide films. Accordingly, the samples, as indicated by X-ray diffraction results, possessed (002) preferential plane orientation of copper oxide material along with the crystallite sizes ranging from 52.52 nm to 75.02 nm due to the imperfections caused by the silver doping. The scanning electron microscope images exhibited that the silver doping did not form significant modifications in the host material morphology where nanowire-like structures observed. The presence of the suggested materials in the films was verified by the x-ray photoelectron spectroscopy. Also, the UV–visible spectroscopy measurements detected that optical absorbance edge and bandgap energy values red shifted as a result of the impurity doping. The electrochemical supercapacitors performances of the silver doped copper oxide nanostructured thin films were inspected by using the GCD, EIS, and CV. The silver doped copper oxide films demonstrated a specific capacitance value of 66 F/g at a current density of 1 A/g in 1 M KOH electrolyte. From Nyquist plot, Rs, Rcor, Rpo, Ccor and Cc were obtained as 2.327 × 103 Ω.cm2, 43.63 × 103 Ω.cm2, 4.580 × 103 Ω.cm2, 111.5 × 10-6 S*s^a. cm-2 and 101.1 × 10-6 S*s^a. cm-2, respectively. The results indicated that the electrochemically synthesized the silver doped copper oxide electrodes can be obtained and developed as an alternative electrode material for supercapacitors (SCs).

Variation of the metal-insulator phase transition temperature in VO2: An overview of some possible implementation methods

The great interest in VO2, which has stimulated a large number of studies and publications in recent decades, is caused by the reversible metal-insulator phase transition (MIT) that occurs at T = 68 °C and is accompanied by the transformation of a low-temperature dielectric (semiconductor) monoclinic phase into a high-temperature metallic phase with a rutile structure. Despite the ongoing discussion about the physical mechanism of this transition, the concomitant rapid change in the electrical and optical characteristics of the material by several orders of magnitude already finds numerous applications in optics, optoelectronics and sensors. At the same time, it became obvious that both the number and performance of the applications of VO2 would greatly increase, if it were possible to decrease the temperature of the phase transition without deterioration of other properties. This issue has become the subject of numerous studies. Mechanical stress and oxygen vacancies in the VO2 lattice, the concentration of free charge carriers, tuned by impurity doping or implantation, have been investigated and discussed as the main factors affecting the transition temperature. In this review, we intend to summarize and analyze the literature data on these ways, primarily those which are most efficient in influencing the transition temperature while maintaining a significant change in the modulation characteristics.

Investigation of TM (TM=Mg, Cu) doping effect on the luminescence performance of CsPbCl3 from a first-principles investigation

The inorganic perovskite CsPbCl3 has raised great concern in recent years due to its great tunability of luminescence properties via impurity doping. However, the blue-emitting mechanism of the impurity-doped CsPbCl3 is unexplored. In this work, we focus on the structural, electronic, and optical properties of CsPb1-x TM x Cl3 (TM=Mg, Cu; x = 0, 0.037, 0.074) based on the first-principles calculations. It is indicated that TM doping decreases the lattice parameter, deforms octahedral structure, and improves the stability of CsPbCl3. The increased direct bandgap values and unique TM energy levels occupation show that the doped systems behave only blue-emitting well. The Mg-s and Cu-3d (eg) states out the bandgaps are close to the valence band edge and conduction band edge respectively, both promoting the carrier radiation recombination. Furthermore, the density of states analyses demonstrates that the enhanced emission of TM-doped CsPbCl3 benefits from the TM different electronic configurations and the different hybridization ways (Mg 3s/Cl 3p, Cu eg/Cl 3p), producing more carriers with increasing x respectively. The obtained optical properties imply that the TM-doped systems exhibit significant optical absorption and high carrier mobilities, promoting excellent luminescence efficiency. Our work explains the blue-emitting mechanism of the TM-doped CsPbCl3, providing a prospective strategy for designing highly efficient blue-emitting devices for optoelectronic applications based on the available parent materials by modulating the bandgap, synergistic relation of impurity energy level and band edge, and optical property.

Performance tweaking of Co3O4 UV radiation detector via zirconium dopant microstructural and photo-electronic engineering

Incorporation of dopant impurities in semiconducting metal oxide nanostructures has been presumed to increase the pace at which photo-induced holes and electrons separate due to possible bandgap engineering and oxygen vacancy modulations. In this study, we have adopted an electrodeposition technique using a three-electrode configuration for the preparation of Co3O4 thin film samples and investigated the effect of Zr as a dopant ion on the UV radiation sensing performance of nanostructured Co3O4 host material via energy band engineering and microstructural modulation. Consistency in optical energy band gap measurements of the deposited Zr-doped Co3O4 (Zr@Co3O4) was unveiled with the aid of two models: Tauc’s and absorption spectrum fitting (ASF) methods. Ag/Zr@Co3O4/ITO/glass UV radiation detector was fabricated and a sample with 3 % Zr-dopant content demonstrated high UV-365 nm detector performance: detectivity, 1.2 ×1011 Jones, and responsivity, 1818 mA W−1, with high cycling stability, attributable to the host's dopant microstructural tailoring, and the enhancement in its electronic charge carrier number and their scattering potentials within the host's band structure, thanks to the synergistic impacts of dopant ion incorporation and UV irradiation.

High-average-power 216 MHz Kerr lens mode-locked Yb:KGW ring laser oscillator for application to laser spectroscopy

We report the development of a ring Yb:KGW laser oscillator with an average power of 4.22 W, a pulse duration of 312 fs at a repetition rate of 216 MHz. The ring laser oscillator is purely Kerr lens mode-locked (KLM) taking advantage of the high nonlinear refractive index of the laser crystal in spite of being pumped by a multimode laser diode. To the best of our knowledge, this is the highest average power obtained from a KLM ring Yb:KGW laser oscillator. Monitoring the repetition rate fluctuations after initial warm-up of the laser cavity, a peak to valley of only 354.28 Hz during 30 min of free-running operation has been achieved. This could make a free-running ring cavity a suitable light source for application to laser spectroscopy. Using the ring laser oscillator, we have measured the absorption of the second overtone of the ν1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ u _1$$\\end{document} mode of NH3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_3$$\\end{document}. We have also measured absorption spectra of the Yb:KGW crystal to evaluate the quality of the crystal affected by the doped impurities.

Mechanism study of synergistic aluminum extraction and purification by ammonium for high-value conversion of secondary aluminum dross

Secondary aluminum dross (SAD) constitutes a significant volume of hazardous solid waste with huge productions. Balancing extraction efficiency and purity within the current resourcing recovery process proves challenging and impedes high-value conversion. Consequently, the NH4HSO4-H2SO4 system was employed in this study to convert SAD into high-purity alumina nanoparticles, and the effect of ammonium was investigated. The results indicated that the leaching rate reached 85.98 % under the optimum conditions (170 °C, [Htot]=12 mol/L, 16/1,6 h); the interaction of NH4+ and H+ with the oxygen atoms on the surface of Al2O3 was demonstrated to enhance the reactivity of the aluminum atoms by DFT calculations. The incorporation of NH4+ also facilitated the separation of aluminum by leveraging the temperature-dependent solubility characteristic of NH4Al(SO4)2. Molecular dynamics simulation revealed that NH4+ inhibits the diffusion rate of Al3+, thereby regulating the doping impurities such as Mg and Ca, and improving the purity of Al2O3 (95.29–99.64 %). Additionally, Nanoscale regulation was executed through the conversion of the NH4AlO(OH)HCO3 precursor and control. The sintering and agglomeration problems brought about by pyrolysis in atmospheres such as H2O and SO3 were avoided. This research provides reference for the high-value utilization of aluminum-containing solid waste.