Sn-doped Samples Research Articles

Effects of Sn addition in W-doped Ag paste against electrochemical corrosion and sulfurization

Purpose This study aims to address these challenges by enhancing the resistance of Ag-based pastes to corrosion and sulfurization, thereby improving their performance and weatherability in high-power and high-frequency electronic applications. Design/methodology/approach This study investigates the influence of Sn doping in W-doped Ag paste to enhance resistance against electrochemical corrosion and sulfurization. A systematic examination was conducted using transient liquid phase sintering and solid–liquid inter-diffusion techniques to understand the microstructural and electrochemical properties. Findings This study found that Sn addition in W-doped Ag paste significantly improves its resistance to electrochemical corrosion and sulfurization. The sintering process at 600°C led to the formation of an Ag2WO4 phase at the grain boundaries, which, along with the presence of Sn, effectively inhibited the growth of Ag2WO4 grains. The 0.5% Sn-doped samples exhibited optimal anti-corrosion properties, demonstrating a longer grain boundary length and a passivation effect that significantly reduced the corrosion rate. No Ag2S phase was detected in the weatherability tests, confirming the enhanced durability of the doped samples. Originality/value The findings of this study highlight the potential of Sn-doped Ag-W composites as a promising material for electronic components, particularly in environments prone to sulfurization and corrosion. By improving the anti-corrosion properties and reducing the grain size, this study offers a new approach to extending the lifespan and reliability of electronic devices, making a significant contribution to the development of advanced materials for high-power and high-frequency applications.

Effect of single and dual doping on the thermoelectric properties of FeVSb0.95Sn0.05 and Fe0.95Co0.05VSb0.90Sn0.10 half-Heusler alloys

FeVSb in addition to a set of novel FeVSb0.95Sn0.05 and Fe0.95Co0.05VSb0.90Sn0.10 half-Heusler alloys were fabricated by arc melting followed by induction melting simple methods. Impacts of single Sn-doping and double Co- and Sn-doping on the structural and thermoelectric properties of FeVSb were investigated in this article. Structural and thermoelectric properties of FeVSb, FeVSb0.95Sn0.05 and Fe0.95Co0.05VSb0.90Sn0.10 compounds have been extensively studied in this work. N-type conduction was confirmed for the FeVSb system and for the doped FeVSb0.95Sn0.05 and Fe0.95Co0.05VSb0.90Sn0.10 alloys. The absolute value of Seebeck coefficient for the single Sn-doped sample increased from 127 μV/K to 155 μV/K, with the temperature increasing. Similarly, the Seebeck coefficient of the double Co- and Sn-doped alloy also increased from 40 μV/K to 60 μV/K. The thermoelectric power factor was notably enhanced for the dual doped Fe0.95Co0.05VSb0.90Sn0.10 alloy reaching 14 μW/cm.K2. Lattice thermal conductivity of the single Sn-doped FeVSb0.95Sn0.05 alloy decreased considerably over the whole temperature range. A maximum zT of 0.084 was achieved for FeVSb0.95Sn0.05 alloy at 575 K. The improved figure of merit due to doping is attributed to the phonon scattering at point defects. Sn-doping has significantly reduced thermal conductivity due to the enhanced point-defect and electron–phonon scatterings which contributed to improved thermoelectric figure of merit. Our findings showed also that the room-temperature thermal conductivity is seriously reduced via Sn and Co dual doping leading to higher ZT value for Fe0.95Co0.05VSb0.90Sn0.10 alloy. Promising candidates for further thermoelectric applications could be achieved by Sn-doping and double Co- and Sn-doping.

Various rejuvenation behavior of Cu–Zr–Al-(Sn) metallic glass via deep cryogenic cycling treatment

Deep cryogenic cycling treatment (DCT) has been used to rejuvenate Cu–Zr–Al-(Sn) bulk metallic glasses (BMGs). The thermally treated samples exhibit rejuvenated behaviors characterized by improved enthalpy of relaxation and plasticity. Notably, the degree of rejuvenation varies significantly in Sn-doped samples compared to the Sn-free counterparts. Molecular dynamics simulations reveal that Sn doping leads to a decrease in the peak height of Cu–Zr atom pairs and a significant increase in Zr–Zr atom pairs. The negative mixing heat between Sn and Zr results in the degradation of short-range ordered structures between Cu–Zr, generating the clusters with more Zr atoms and a subsequently more closely packed structure. Such structural modification is associated with the less obvious rejuvenation in Sn-doped samples. Furthermore, the addition of Sn reduces the fraction of polyhedral structures with higher five-fold symmetry, particularly <0, 0, 12, 0>, thereby negatively impacting the rejuvenation behavior during DCT. The changes in microstructure during rejuvenation also influences the shear localization under external shear deformation. The reduction in the proportion of polyhedra with relatively higher five-fold symmetry, such as <0, 0, 12, 0>, leads to a more pronounced activation in local regions. These activated local shear units contribute to the delocalization of shear flow and the initiation of additional shear bands. The present study sheds light on the intricate interplay between Sn doping, microstructural changes, and the resulting mechanical properties in metallic glasses subjected to deep cryogenic cycling.

Study on the Effect of Sn, In, and Se Co-Doping on the Thermoelectric Properties of GeTe.

GeTe and Ge0.99-xIn0.01SnxTe0.94Se0.06 (x = 0, 0.01, 0.03, and 0.06) samples were prepared by vacuum synthesis combined with spark plasma sintering (SPS). The thermoelectric properties of GeTe were coordinated by multiple doping of Sn, In, and Se. In this work, a maximum zT(zT = S2σT/κ) of 0.9 and a power factor (PF = S2σ) of 3.87 μWmm-1 K-2 were obtained in a sample of Ge0.99In0.01Te0.94Se0.06 at 723K. The XRD results at room temperature show that all samples are rhombohedral phase structures. There is a peak (~27°) of the Ge element in GeTe and the sample (x = 0), but it disappears after Sn doping, indicating that Sn doping can promote the dissolution of Ge. The scattering mechanism of the doped samples was calculated by the conductivity ratio method. The results show that phonon scattering Is dominant in all samples, and alloy scattering is enhanced with the increase in the Sn doping amount. In doping can introduce resonance energy levels and increase the Seebeck coefficient, and Se doping can introduce point defects to suppress phonon transmission and reduce lattice thermal conductivity. Therefore, the thermoelectric properties of samples with x = 0 improved. Although Sn doping will promote the dissolution of Ge precipitation, the phase transition of the samples near 580 K deteriorates the thermoelectric properties. The thermoelectric properties of Sn-doped samples improved only at room temperature to ~580 K compared with pure GeTe. The synergistic effect of multi-element doping is a comprehensive reflection of the interaction between elements rather than the sum of all the effects of single-element doping.

Polarized photoluminescence from Sn, Fe, and unintentionally doped β-Ga2O3

In this work, we demonstrate that β-Ga2O3 shows orientation-dependent polarized photoluminescence (PL) emission and give a comprehensive insight into gallium oxide's PL spectral properties. We characterized the polarization and spectral dependencies of both the incident and emitted light for (−201) unintentionally doped (UID) as well as (−201) and (010) Sn-doped and Fe-doped crystals. We observed for UID and Sn-doped samples that the electron to self-trapped hole and native defect-related emission bands are linearly polarized with polarized emission intensities ordered as E || c (and c*) &amp;gt; E || a (and a*) &amp;gt; E || b. Furthermore, the spectral shape of emission does not change between the UID and Sn-doped samples; instead, the Sn-doping quenches the total PL spectral intensity. For Fe-doped samples, polarized red emission caused by unintentional Cr3+ doping generates emission intensities ordered E || b &amp;gt; E || c (and c*) &amp;gt; E || a (and a*). It is also observed that in some circumstances, for some doped crystals, the PL spectra can show variations not only in intensity but also in spectral shape along different polarization directions. As an example, the PL emission band for emission along c is blueshifted relative to that along a in Sn-doped β-Ga2O3.

Antibacterial activity of tin-doped zinc oxide thin films deposited by laser ablation

The main purpose of this research is to assess the potential of doped zinc oxide (ZnO)-based materials in providing antibacterial activity to bioinert implants. Thus, the current study deals with the production and characterization of tin (Sn)-doped ZnO thin films grown by the pulsed laser deposition (PLD) technique. The coprecipitation method was applied for the synthesis of the primary powders, that were subsequently converted into targets. The latter were employed in several deposition experiments, for which the substrate temperature (room temperature and 400 °C) and oxygen pressure (100 and 700 mTorr) were varied in order to elucidate the influence of the processing parameters on the functional properties. Next, the paper covers a full examination of the compositional, structural, optical, and morphological features of ZnO intermediate or final samples. Moreover, the thin films were characterized in terms of antibacterial activity against Escherichia coli (E. coli) gram-negative bacterium, and biocompatibility in the presence of mouse fibroblast cells. The results revealed a finer morphology for the doped target sintered at 1200 °C, consisting of grains several micrometers in size and a large proportion of interconnected pores, as well as the partial integration of Sn in the crystal lattice of ZnO, the rest of the dopant being trapped in a Sn-rich secondary phase (Zn2SnO4). The morphological assessment of the layers obtained by laser ablation revealed the pronounced effect of substrate temperature on the processes of nucleation and crystal growth, namely the occurrence of a denser packing of grains with significant higher dimension. Moreover, a higher oxygen pressure during deposition promoted an increased roughness for the deposited samples. The best antibacterial performance was achieved in the case of Sn-doped samples deposited at 400 °C, which demonstrates the beneficial contribution of the dopant ions.

Corrosion Performance of Sn-Doped AlCrFeNiMn High-Entropy Alloy Synthesized via Arc-Melting Technique

Failure of materials such as steels during engineering applications can result in economic harm; hence, developing new corrosion-resistant materials is critical. In this work, high-grade powders of Al, Cr, Fe, Mn, and Ni were used to synthesize an equimolar AlCrFeNiMn high-entropy alloy (HEA) for potential chemical industry application. The cast alloy's properties were further altered by the addition of 1at%, 3at%, and 5at% tin (Sn) as alloying additives. To assess the impact of Sn on the alloy's resistance to corrosion, potentiodynamic polarization tests were conducted in various acidic and basic environments. Several surface inspection techniques, including scanning electron microscopy (SEM), optical microscopy (OPM), X-ray diffractrometry (XRD), and energy-dispersive X-ray spectroscopy (EDS), were employed to examine the morphological changes and elemental composition of the alloy after it was subjected to corrosive conditions. The nano-indentation machine was used to analyze the materials' nanohardness. TGA analysis was also performed to determine how Sn additions affected the AlCrFeNiMn HEA’s thermal stability. In 0.5 M HCl solution, the Sn-doped alloys demonstrated good corrosion resistance. Their exposure to 0.5 mol/L H2SO4 solution, on the other hand, found to be deleterious to their electrochemical stability. The weight loss of 5 at% Sn-doped samples in 0.5 M H2SO4 solution was found to be substantially reduced. The mass of all the samples stayed constant in 3.5 wt% NaOH solution.

Effect of Sn-substitution on the electrical conductivity of SrFe12-xSnxO19 (0.0 ≤ x ≤ 1.0) hexaferrite

Herein, we present a study about the effect of Sn-substitution on the electrical conductivity of SrFe12O19 hexaferrite synthesized by the solid-state reaction method. For samples containing Sn4+cations, the complex impedance curves showed the existence of conductive processes. The electrical response studied from the equivalent circuit model, provided grain boundary resistance values higher, in one order, in relation to the grain values, which agrees with the Koop model. For the Sn-doped SrM ceramics samples, the conductivity values increase with the dopant cations content. In addition, the Sn4+ cations insertion in the SrM crystal structure contributes to the emergence of two conductive processes: a DC-conductivity process at low frequency and a second frequency-dependent conductive process at high frequency. From the activation energy, the existence of a small polarons tunneling mechanism with long-range mobility and low frequency, that spontaneously occurring with negative activation energy and an electron hopping mechanism that follows a correlated barrier model and activation energy from 0.135 to 0,355 eV were found.

Investigation of Sn Incorporation in β-Ga2O3 Single Crystals and its Effect on Structural and Optical Properties

Undoped and Sn-doped β-Ga2O3 single crystals were grown by optical floating zone technique by varying the doping concentration of Sn from 0.05 wt% to 0.2 wt%. Uniform distribution of the dopant ions was achieved by heat treatment. The crystalline quality and the expansion of the lattice were observed from the PXRD. Raman spectra reveals the incorporation of Sn atoms into the lattice by replacing Ga in the octahedral site. The interplanar distance (d) was calculated as 2.39 Å from the HR-TEM micrographs. The transmittance was found to be decreasing from 80% to 78% as the concentration of Sn increases. The absorption spectra shows a cut off edge around 260 nm for undoped and 270 nm for all Sn doped samples. The bandgap obtained for undoped β-Ga2O3 was 4.36 eV. The doping of 0.05 wt% of Sn decrease the value of bandgap to 4.08 eV, but, for 0.1 wt% and 0.2 wt% Sn an increase in the bandgap value of 4.13 eV and 4.20 eV was observed respectively. The refractive index was found to be 1.96 at 500 nm wavelength. The increase in Sn concentration results in increase of the roughness from 1.116 nm to 3.511 nm.

Band gap engineered Sn-doped bismuth ferrite nanoparticles for visible light induced ultrafast methyl blue degradation

Remediation of water pollution persists as major concern for scientists and industry. Various ceramic based nanomaterials have been used in efficient photocatalytic degradation of different industrial dyes. However, the major factors that restrict efficacy of these systems are requirement of UV source for activating dye degradation process, prolonged time for degradation and lower efficiency. This paves way to development of alternative material systems that can resolve above problems by not only ensuring maximum dye degradation in minimum time in presence of visible light but also reusability in several cycles. In this work, we report visible light driven photocatalytic degradation of methyl blue (MB) using Sn-doped bismuth ferrite (BFO) nanoparticles. Different concentrations (0, 1%, 1.5%, 2%) of Sn-doped BFO nanoparticles were synthesized using facile sol-gel methods. It was observed that 1.5% Sn-doped BFO nanoparticle exhibits highest photocatalytic activity towards MB degradation compared with pure and other doped BFO nanoparticles. 1.5% Sn-doped BFO nanoparticle delineates 70% dye degradation capability within 10 min of irradiation under visible light. 1.5% Sn-doped sample shows 99% degradation capability within 2 h of visible light irradiation while pristine BFO nanoparticles can degrade only 20% under identical conditions. Additionally, 1.5% Sn-doped BFO nanoparticles are also capable of degrading RhB, another important contaminant. The 1.5% Sn-doped BFO nanoparticle could be a promising photocatalyst for efficient degradation of industrial effluents having various dyes. The efficient dye degradation of 1.5% Sn doped BFO nanoparticle has been explained in terms of increased density of surface active sites evident from bulk structural analyses and greater probability of generation of electron-hole pairs on surface by virtue of reduced band gap. A theoretical modelling of band structure has been done to identify surface .OH ions as most effective species to promote dye degradation.

Sn4+ doping enhanced inner electric field for photocatalytic performance promotion of BiOCl based nanoflowers

BiOCl powders with different amounts of Sn doping (0, 5%, 10%, 20% versus molar amount of Bi, denoting as BOC, BOC-S5, BOC-S10, BOC-S20 respectively) were prepared by solvothermal method. Sn doping resultant effect on obtained samples and their photocatalytic performance were studied. All Sn doped BiOCl showed stronger photocatalytic degradation ability towards organic dye RhB compared with undoped one, where BOC-S10 with highest performance behaved 33% higher RhB degradation than BOC. Through relevant experiments and calculations, it’s found that Sn doping stimulated more dispersive electron localization in [Bi2O2]2+ layer, favorable for carrier generation, while introduction of Sn4+ also strengthened the inner polarization along [001] direction, which improved intrinsic inner electric field revulsive carrier separation. Changes on electronic structure promoted carrier generation and transfer, providing higher photocatalytic performance. Photocatalytic reduction of CO2 manifested that Sn doped samples also behaved larger potential on synthesizing CH4 through CO2 reduction and BOC-S10 still exhibited highest performance with CH4 yield 67% higher than BOC. All the results manifested that Sn doping introduced transformation beneficial to promote photocatalytic performance.

Lewis Acid Site Assisted Bifunctional Activity of Tin Doped Gallium Oxide and Its Application in Rechargeable Zn-Air Batteries.

The enhanced safety, superior energy, and power density of rechargeable metal-air batteries make them ideal energy storage systems for application in energy grids and electric vehicles. However, the absence of a cost-effective and stable bifunctional catalyst that can replace expensive platinum (Pt)-based catalyst to promote oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air cathode hinders their broader adaptation. Here, it is demonstrated that Tin (Sn) doped β-gallium oxide (β-Ga2 O3 ) in the bulk form can efficiently catalyze ORR and OER and, hence, be applied as the cathode in Zn-air batteries. The Sn-doped β-Ga2 O3 sample with 15% Sn (Snx =0.15 -Ga2 O3 ) displayed exceptional catalytic activity for a bulk, non-noble metal-based catalyst. When used as a cathode, the excellent electrocatalytic bifunctional activity of Snx =0.15 -Ga2 O3 leads to a prototype Zn-air battery with a high-power density of 138 mW cm-2 and improved cycling stability compared to devices with benchmark Pt-based cathode. The combined experimental and theoretical exploration revealed that the Lewis acid sites in β-Ga2 O3 aid in regulating the electron density distribution on the Sn-doped sites, optimize the adsorption energies of reaction intermediates, and facilitate the formation of critical reaction intermediate (O*), leading to enhanced electrocatalytic activity.

Electrical properties of α-Ga2O3 films grown by halide vapor phase epitaxy on sapphire with α-Cr2O3 buffers

We report on growth and electrical properties of α-Ga2O3 films prepared by halide vapor phase epitaxy (HVPE) at 500 °C on α-Cr2O3 buffers predeposited on sapphire by magnetron sputtering. The α-Cr2O3 buffers showed a wide microcathodoluminescence (MCL) peak near 350 nm corresponding to the α-Cr2O3 bandgap and a sharp MCL line near 700 nm due to the Cr+ intracenter transition. Ohmic contacts to Cr2O3 were made with both Ti/Au or Ni, producing linear current–voltage (I–V) characteristics over a wide temperature range with an activation energy of conductivity of ∼75 meV. The sign of thermoelectric power indicated p-type conductivity of the buffers. Sn-doped, 2-μm-thick α-Ga2O3 films prepared on this buffer by HVPE showed donor ionization energies of 0.2–0.25 eV, while undoped films were resistive with the Fermi level pinned at EC of 0.3 eV. The I–V and capacitance–voltage (C–V) characteristics of Ni Schottky diodes on Sn-doped samples using a Cr2O3 buffer indicated the presence of two face-to-face junctions, one between n-Ga2O3 and p-Cr2O3, the other due to the Ni Schottky diode with n-Ga2O3. The spectral dependence of the photocurrent measured on the structure showed the presence of three major deep traps with optical ionization thresholds near 1.3, 2, and 2.8 eV. Photoinduced current transient spectroscopy spectra of the structures were dominated by deep traps with an ionization energy of 0.95 eV. These experiments suggest another pathway to obtain p–n heterojunctions in the α-Ga2O3 system.

The effect of annealing on the Sn-doped (−201) β-Ga2O3 bulk

Unintentionally-doped (UID) and Sn-doped crystals of (−201) β-Ga2O3 were high-temperature annealed in N2 and O2 atmospheres. Surface morphology and structure properties were investigated to quantify the effect of annealing process on the Sn-doped (−201) β-Ga2O3 bulk. The smooth step structure can be obtained on the surface of UID β-Ga2O3 bulk after annealing, which was absent for Sn-doped bulk. According to high-resolution X-ray diffraction (HRXRD), the crystal quality of Sn-doped Ga2O3 bulk was improved after annealing in O2 atmosphere. However, there was an obvious Sn segregation effect near the surface, detected by secondary ion mass spectrometry (SIMS), which may be responsible for the increase of surface roughness. In addition, the green luminescence (GL) of cathodoluminescence (CL) spectra, related to the gallium vacancies (VGa), were significantly enhanced for Sn-doped samples after 1100 °C annealing. And as the depth of penetration deepened, the ratio of GL to UV increased. It is shown that the formation of VGa-related defect is a dominant process for Sn-doped β-Ga2O3 bulk during high-temperature annealing.

Dense twin and domain boundaries lead to high thermoelectric performance in Sn-doped Cu3SbS4

Exploring high-performance medium-temperature thermoelectric (TE) materials with nontoxicity and low price is of great significance for waste heat recovery. In spite of low price and nontoxicity, the poor intrinsic electrical properties of Cu3SbS4 restrict its potential commercial applications. Herein, intermediate-phase-free Cu3SbS4-based bulks were fabricated by incorporating a sulfurization process between melting and sintering, and the as-formed dense twin and domain boundaries in a Sn-doped Cu3SbS4 system can significantly enhance the electrical conductivity and retain a higher level of the Seebeck coefficient based on the energy filtering effect and band flattening and convergence. The high power factor of ∼13.6 μW cm−1 K−2 and relatively low thermal conductivity are achieved for a 1.5%Sn-doped Cu3SbS4 sample, resulting in a record zT of ∼0.76 at 623 K in Cu3SbS4-based systems. This work develops an effective pathway to synthesize intermediate-phase-free Cu3SbS4-based TE materials and provides an effective strategy for enhancing TE performance in diamond-like semiconductors by interface engineering.

A general approach to the fabrication of Sn-doped TiO2 nanotube arrays with titanium vacancies for supercapacitors

In general, it is more difficult to realize the metal doping of TiO2 in comparison with the nonmetal doping. Currently, metal-doped TiO2 is mainly prepared by hydrothermal treatment, sol–gel method and high-energy ion implantation. However, these methods have some drawbacks such as cumbersome steps and the need for the use of environmentally harmful reagents or expensive equipment. Here, we report a general approach to realize the metal doping in TiO2 nanotube arrays (NTAs) by using low-melting-point metals as dopant sources. As an example, after thermal annealing of the anodized TiO2 NTAs together with tin metal with a lower melting point in argon atmosphere, Sn-doped TiO2 NTAs are successfully achieved. Unlike common TiO2, the as-prepared Sn-doped TiO2 NTAs have structural defects of Ti vacancies, showing p-type conductivity. Moreover, the Sn-doped samples exhibit significantly enhanced supercapacitive performances compared to the undoped counterpart. Especially, the presented doping methodology is conceptually different from the previous works and is much simpler and more effective, which offers a general technique to realize metal doping of TiO2 NTAs.

XPS study of iodine and tin doped Sb2S3 nanostructures affected by non-uniform charging

X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements are used for investigating incorporation of iodine and tin into the stibnite (Sb2S3) lattice, as well as for determining surface composition and structure, respectively. The XRD analysis revealed the visible presence of a single phase, that of pure orthorhombic Sb2S3 structure. XPS survey spectra confirmed the presence of expected elements (Sb, S, Sn and I) at the surface of corresponding samples. Since the bonding identification was hindered by non-uniform charging of samples during acquiring the photoelectron spectra, a novel approach for the analysis of high resolution spectra was proposed and successfully implemented. XPS results showed that surface composition of the non-doped sample coincides with that of the bulk, while doping strongly affects surface of the samples. Sn-doped sample appears to be prone to surface oxidation. The presence of Sb2S3, Sb2O3, SnS2 and Sn(0) phases at the surface was revealed. Strong segregation of antimony was observed in the I-doped Sb2S3 sample. Iodine is also present at the surface in the form of the SbI3 phase, while the detected sulphur signal most probably corresponds to S atoms from unaltered deeper layers.

ZnO a multifunctional material: Physical properties, spectroscopic ellipsometry and surface examination

The investigation reports on the transparent and conducting pure and metal doped zinc oxide (ZnO) thin layer. The layers are ultrasonic sprayed onto microscope glass substrates at 350 °C. The effect of Sn doping level (from 0% to 3%) is discussed in one hand and metal (Al, Cu and Sn) doping effect on the properties in other hand. Spectroscopic ellipsometry, optical, structural and electrical analyses of the as-grown films have been achieved. The (002)-oriented hexagonal wurtzite crystal structure is revealed by X-ray pattern having a grain size of 4.5–15 nm which confirms the nanosized aspect. The UV–VIS–IR spectrophotometer measurements reveal that the as-grown films are highly transparent in the visible and IR ranges (T~90%). A slight influence of dopants on the band gap energy which ranges between 2.24 and 2.29 eV is emphasized. The electrical parameters such as bulk density, resistivity and mobility are measured by Hall measurement system (HMS). The films thickness is estimated by spectroscopic ellipsometry values and found to be of 178–330 nm. The electrical properties confirm an enhancement of bulk density and conductivity within the range − 1.06 × 1012–5.09 × 1013 (cm−3) and 3.2 × 10−5–1.05 × 10−3(1/Ω cm) due to dopants incorporation as predicted. Inversion to p-type is demonstrated in Sn-doped ZnO sample. The nanostructures are observed in 2D scanned AFM views, size are of micro/nanometer and roughness is of 3.39–15 nm.

Charge Carrier Dynamics in Sn-Doped Two-Dimensional Lead Halide Perovskites Studied by Terahertz Spectroscopy

Sn doping is established as an effective approach to promote the light emission properties in in two-dimensional lead-halide perovskites. However, the effect on the charge carrier dynamics is largely unexplored. In this work, we conduct terahertz spectroscopy to study the effects of Sn doping on the charge dynamics in the two-dimensional perovskites PEA2SnxPb1–xI4 (PEA = phenethylammonium) with different doping levels. The spectral dispersion analysis suggests that the early-stage dynamics with lifetime of ∼ 2 ps is contributed by both the transport of hot charge carriers and the polarizability of hot excitons. The long-lived component of first-order charge carrier recombination is dramatically improved when Sn doping increases, which is ascribed to the equilibrium between charge carriers and excitons with smaller bind energies in the higher-level Sn-doped samples. The finding in this work suggests Sn doping is an effective approach to optimize the charge carrier transport in 2D perovskite for potential optoelectronic applications.

Metal-Organic frameworks-derived 2D spindle-like sn-doped Co3O4 porous nanosheets as efficient materials for TEA detection

Abstract Rational construction of two-dimensional (2D) metal-organic frameworks (MOFs) nanomaterials attracts researcher’s much attention due to their unique structural merits. Herein, 2D spindle-like pure and Sn-doped Co3O4 porous nanosheets have been synthesized using 1, 4-dicarboxybenzene (H2BDC) as a ligand acid, and via a simple solvothermal method and following thermal treatment. The structure, morphology and composition of the as-obtained samples are characterized by XRD, FESEM, TEM, XPS, ICP, AFM, UV–vis-NIR, UPS and nitrogen adsorption-desorption measurement. The results show that Sn4+ has been successfully doped into the lattice of Co3O4. The gas sensing properties of pure and Sn-doped Co3O4 porous nanosheets have been systematically analyzed. The 5 at% Sn-doped Co3O4 sample shows high responses of 70.7–100 ppm triethylamine (TEA) at a relatively low working temperature of 180 °C, which are about 11 times than that of pure Co3O4 (6.4). In addition, the 5 at% Sn-doped Co3O4 exhibits rapid response/recovery time (1 s/17 s), excellent anti-humidity properties, good gas selectivity and repeatability as well as superior long-term stability.