Sn Substitution Research Articles

Precisely tuning Ge substitution for efficient solution-processed Cu2ZnSn(S, Se)4 solar cells**Project supported by the Joint Talent Cultivation Funds of NSFC-HN (Grant No. U1604138), the National Natural Science Foundation of China (Grant Nos. 21603058 and 51702085), the Innovation Research Team of Science and Technology in Henan Province, China (Grant No. 17IRTSTHN028), the Science and Technology Innovation Talents in Universities of Henan

The kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have yielded a prospective conversion efficiency among all thin-film photovoltaic technology. However, its further development is still hindered by the lower open-circuit voltage (), and the non-ideal bandgap of the absorber is an important factor affecting this issue. The substitution of Sn with Ge provides a unique ability to engineer the bandgap of the absorber film. Herein, a simple precursor solution approach was successfully developed to fabricate Cu2Zn(SnyGe1−y)(SxSe1−x)4 (CZTGSSe) solar cells. By precisely adjusting the Ge content in a small range, the and are enhanced simultaneously. Benefitting from the optimized bandgap and the maintained spike structure and light absorption, the 10% Ge/(Ge+Sn) content device with a bandgap of approximately 1.1 eV yields the highest efficiency of 9.36%. This further indicates that a precisely controlled Ge content could further improve the cell performance for efficient CZTGSSe solar cells.

Tuning antiferromagnetic exchange interaction for spontaneous exchange bias in MnNiSnSi system

Based on almost all the data from the literature on spontaneous exchange bias (SEB), it is expected that the system will show SEB if it meets two conditions simultaneously: (i) there are the coexistence and competition of antiferromagnetic (AFM) and ferromagnetic (FM) interactions and (ii) AFM interaction should dominate but not be too strong in this competition. In order to verify this view, a systematic study on SEB has been performed in this work. Mn50Ni40Sn10 with strong FM interaction and without SEB is chosen as the mother composition, and the negative chemical pressure is introduced by the substitution of Sn by Si to enhance AFM interaction. It is found that a long-range FM ordering window is closed, and a long-range AFM ordering window is opened. As a result, SEB is triggered and a continuous tuning of the spontaneous exchange bias field (HSEB) from 0 Oe to 1300 Oe has been realized in a Mn50Ni40Sn10−xSix system by the enhanced AFM interaction.

Antibacterial and physicochemical properties of co‐sputtered CuSn thin films

Copper‐tin thin films (CT TFs) were deposited on p‐type Si(100) by radio frequency (RF) magnetron co‐sputtering method. The atomic ratio of Cu and Sn showed complementary tendency with various RF powers on metal targets. Antibacterial test was conducted with Gram‐negative Escherichia coli. The ratio of Cu and Sn ions and the contact time with E. coli affected the antibacterial efficiency. Increasing the ratio of Cu ions and contact time showed higher antibacterial activity. Cu20Sn6 called as bronze structure, metallic Cu, and copper oxide phases were identified from X‐ray diffraction data after sterilization. The lattice strain that was changed due to the substitution of Cu and Sn was also calculated. The surface morphology of CT TFs was entirely grown to round shape when the dominant element was Sn. But, as the content of Cu increased, the surface morphology was changed from ball shape to sharp column shape. When fixed contact time, the intensities of Cu 2p increased but the intensities of Sn 3d decreased as increasing the atomic ratio of Cu. The oxidation of Cu was more sharply progressed as the RF power on Cu target increased. When fixed CT TFs, the intensities of Cu 2p were consistent but the intensities of Sn 3d3/2 decreased as increasing contact time between CT TF and E. coli.

Self-organized lattice-matched epitaxy of Si1−xSnx alloys on (001)-oriented Si, Ge, and InP substrates

The crystal growth of single-crystalline Si1−xSnx layers with various Sn contents and analytical comparisons of their fundamental physical properties are strongly desired for next-generation group-IV electronics. In the present study, Si1−xSnx layers with varying Sn contents (1%−40%) were grown on various substrates [(001)-oriented Si, Ge, or InP] by solid-phase epitaxy. Crystallographic and composition analyses indicated that the grown Si1−xSnx layers were nearly lattice-matched to the substrates. When grown on Si, Ge, and InP substrates, the substitutional Sn contents were ∼1%, ∼20%, and ∼40%, respectively. Hard X-ray photoelectron spectroscopy revealed a valence-band offset resulting from the Sn substitution. The offset exhibited an upward-bowing tendency when plotted against the Sn content. The Si0.78Sn0.22/n-type Ge junction displayed rectifying diode characteristics with the ideality factor of 1.2.

Experimental and theoretical approaches for magnetic, superconducting and structural characterization of Bi1.75Pb0.25Sr2Ca2Cu3-xSnxO10+y glass ceramics

In this work, the effect of the partial substitution of Sn for Cu on structural, electrical and magnetic properties in the superconducting ceramic glass Bi1.75Pb0.25Sr2Ca2Cu3-xSnxO10+y system (x=0, 0.1, 0.5) has been examined. The structural characterization of samples produced by glass-ceramic technique were done by X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. The electrical and magnetic properties were determined by resistance-temperature (R-T) measurement and magnetization-magnetic field measurement (M-H) in the low temperature by using vibrating sample magnetometer (VSM), respectively. From the results of R-T measurement, the value of critical temperature (Tcoffset) has been decreased from 98 K to 73 K with increasing Sn- concentration. The critical current density has also been decreased with increasing magnetic field intensity. It has been observed from M-H plots that it was decreased with increasing the value of temperature. We have observed from M-H curves that the area size of the hysteresis curve decreases with increasing the value of temperature.

Formation of high-Sn content polycrystalline GeSn films by pulsed laser annealing on co-sputtered amorphous GeSn on Ge substrate**Project supported by the National Natural Science Foundation of China (Grant No. 61474094) and the National Basic Research Program of China (GrantNo. 2013CB632103).

Polycrystalline Ge1−x (poly-Ge1−xSnx) alloy thin films with high Sn content (> 10%) were fabricated by cosputtering amorphous GeSn (a-GeSn) on Ge (100) wafers and subsequently pulsed laser annealing with laser energy density in the range of 250 mJ/cm2 to 550 mJ/cm2. High quality poly-crystal Ge0.90Sn0.10 and Ge0.82Sn0.18 films with average grain sizes of 94 nm and 54 nm were obtained, respectively. Sn segregation at the grain boundaries makes Sn content in the poly-GeSn alloys slightly less than that in the corresponding primary a-GeSn. The crystalline grain size is reduced with the increase of the laser energy density or higher Sn content in the primary a-GeSn films due to the booming of nucleation numbers. The Raman peak shift of Ge–Ge mode in the poly crystalline GeSn can be attributed to Sn substitution, strain, and disorder. The dependence of Raman peak shift of the Ge–Ge mode caused by strain and disorder in GeSn films on full-width at half-maximum (FWHM) is well quantified by a linear relationship, which provides an effective method to evaluate the quality of poly-Ge1−xSnx by Raman spectra.

Tunable long persistent luminescence in the second near-infrared window via crystal field control

Construction of an active composite as a biomarker with deeper tissue penetration and higher signal-to-noise ratio (SNR) is of great importance for the application in bioimaging. Here, we report a strategy for tuning the emission bandwidth and intensity via crystal field control in long persistent phosphors (LPPs). Ni2+-doped Zn1+ySnyGa2−x−2yO4 phosphors, with a tunable emission band peaking from 1270 to 1430 nm in the second near-infrared (NIR) window, have been successfully prepared. Such featured materials have the advantages of low absorption and scattering as well as more efficient tissue penetration. The emission spectra can be controlled by tailoring the local crystal field around the activator precisely via substitution of Zn and Sn for Ga. Moreover, with high resolution and weak light disturbance, these developed multi-band afterglow phosphors exhibit great application potential in advanced optical imaging.

Stanniferous magnetite composition from the Haobugao skarn Fe–Zn deposit, southern Great Xing'an Range: Implication for mineral depositional mechanism

The Great Xing'an Range in north‐eastern China hosts numerous super‐large Ag–Pb–Zn deposits and some Fe–Sn deposits. The Mesozoic Haobugao Fe–Zn polymetallic skarn deposit in the southern Great Xing'an Range is contemporaneous with the regional Ag–Pb–Zn mineralization. Numerous ore bodies are hosted in the Lower Permian carbonate strata or along the contact with the Early Cretaceous granite. According to the field and systematic petrography and mineralography research, the Haobugao mineralization phases are divided into 3 paragenetic stages: prograde stage, retrograde stage, and sulphide stage. Magnetite mainly occurred in the retrograde stage and replaced the anhydrous skarn minerals (e.g., garnet and diopside). Two types of magnetite (Mag1 and Mag2), including 6 subtypes, can be distinguished based on the scanning electron microscopy and back scattered electron images. Electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometer analysis were used to determine major and trace elements in different types of magnetite. Mag1 has higher Ti and V concentrations than Mag2, indicating a relatively higher depositional temperature. Mag1 also contains relatively higher Mg and Mn concentrations, coupled with much lower Si and Al concentrations, which reflects a low fluid/rock ratio at the site of Mag1 deposition. Element variation features of Mag1 and Mag2 reveal that the Haobugao mineralization fluids gradually evolved from high‐temperature and low fluid/rock ratio fluids to relatively low‐temperature and high fluid/rock ratio fluids. However, electron probe microanalysis data of Mag2 display significantly higher Sn concentrations (up to 2.82 wt.%) than that in Mag1, which indicates that Sn can be incorporated into magnetite crystal lattice. We propose a possible substitution mechanism of Sn4+ + Mn2+ = 2Fe3+, supported by the strongly positive correlation between Sn4+ and Mn2+, whereby a substitution of Sn4+ for Fe3+ in octahedral sites of magnetite requires a compensatory substitution of Mn2+ for Fe3+ to maintain the charge balance.

Ti1-Sn O2 nanofilms: Layer-by-layer deposition with extended Sn solubility and characterization

Abstract High quality rutile Ti 1- x Sn x O 2 nanofilms were successfully grown in a layer-by-layer mode at a moderately low temperature of 400 °C using pulsed laser deposition (PLD). High solid solubility of up to x = 0.216 has been achieved in the Ti 1- x Sn x O 2 films despite theoretical prediction by Density functional theory (DFT) of large formation energy (∼5.64 eV) required for the substitutional alloy to exist at such high Sn concentration. The resultant films have smooth interfaces and step-terraced surfaces with well controlled stoichiometry and are optically transparent. Sn L 3 -edge Extended X-ray absorption fine structure (EXAFS) reveals the substitution of Sn 4+ in the Ti 4+ lattice sites of TiO 2 . The lattice spacing along [110] increases linearly with increment in x due to substitution of Sn 4+ ions in the Ti lattice sites of the Ti 1- x Sn x O 2 films. X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering (RBS) show that Sn is uniformly distributed on the surface and in the bulk of the films. These results are crucial when considering Ti 1- x Sn x O 2 with suitable composition for making TiO 2 based quantum structures in advanced optoelectronic devices and solar energy materials, where high-quality crystalline thin film-substrates are important.

Tuned thermoelectric transport properties of Co2.0Sb1.6Se2.4 and Co2.0Sb1.5M0.1Se2.4 (M=Zn, Sn): Compounds with high phonon scattering

Thermoelectric (TE) materials can directly switch waste-heat into useful electric energy and evident significant role to future energy management. In recent years, Sb based chalcogenides have been widely studied due to their excellent TE performance. Based on this, the present work focuses on preparation, crystal structure determination and thermoelectric studies of the new Co-Sb-Se ternary system. The obtained needle shaped single crystal specimens of Co-Sb-Se phase are subjected to single crystal diffraction studies, the refinement of crystal data reveals that the material adopts FeAs2 type orthorhombic structure [Marcasite, space group Pnnm (58); Pearson symbol = oP6, a = 4.9864(3) Å b = 5.9657(3) Å c = 3.6933(2) Å]. It is noticed that the pristine Co2.0Sb1.6Se2.4 exhibits merely low thermal conductivity value (∼1.0 Wm−1K−1 at 300 K and ∼0.7 Wm−1K−1 at 657 K) due to severe phonon scattering among Sb/Se disordered lattices, analogously the compound shows poor electrical transport properties i.e. low power factor (σS2). Hence suitable structural modification is carried out to improve power factor values of the compound. Effect of Zn and Sn substitution in the pristine Co2.0Sb1.6Se2.4 system has been potentially analyzed. The qualitative and quantitative structural analyses of the compounds were assessed by Rietveld refinement technique. As expected, upon substitution of Zn and Sn atoms, the σS2 values of the samples considerably increased. Additionally, the compounds exhibit ultra low thermal conductivity ∼0.5 Wm−1K−1 at 657 K via phonon scattering by point defects, which originates reduction in lattice thermal conductivity due to mass and strain fluctuations among the host (Sb/Se disordered site) and guest atoms. Therefore, the low thermal conductivity together with enhanced electrical transport properties result in higher thermoelectric figure of merit (ZT) for Co2Sb1.5Zn0.1Se2.4 and Co2Sb1.5Sn0.1Se2.4 than that of pristine Co2Sb1.6Se2.4 with an optimal carrier concentration. As a result, a peak ZT value of ∼0.5 is found in Co2Sb1.5Zn0.1Se2.4 compound at 657 K which is analogous to the state-of-the-art thermoelectric materials based on ternary chalcogenides.

Nonlinear polarization responses of ZrO2-based thin films fabricated by chemical solution deposition

The nonlinear polarization responses of ZrO2-based thin films were investigated. Y, Ce, Ti, and Sn were used as substitutes in ZrO2 thin films by chemical solution deposition. A pure ZrO2 film and the ZrO2 film with 1% Y substitution showed constricted polarization–electric field (P–E) curves. In contrast, the ZrO2 film with 5% Y substitution showed a linear P–E curve. The dielectric constants of the pure ZrO2 film and the ZrO2 film with 1% Y substitution increased by 7 and 11%, respectively, under an applied electric field of 2.5 MV/cm. The nonlinearity of the polarization responses was decreased by Ce substitution and Ti substitution. The ZrO2 films with Sn substitution showed narrow P–E curves. The dielectric constant of the ZrO2 film with 10% Sn substitution increased by 13% under an applied electric field of 3 MV/cm. These dielectric constant increases originate from electric-field-induced phase transitions of ZrO2-based thin films.

Phase Segregation Behavior of Two-Dimensional Transition Metal Dichalcogenide Binary Alloys Induced by Dissimilar Substitution

Transition metal dichalcogenide (TMD) alloys form a broad class of two-dimensional (2D) layered materials with tunable bandgaps leading to interesting optoelectronic applications. In the bottom-up approach of building these atomically thin materials, atomic doping plays a crucial role. Here we demonstrate a single step CVD (chemical vapor deposition) growth procedure for obtaining binary alloys and heterostructures by tuning atomic composition. We show that a minute doping of tin during the growth phase of the Mo1–xWxS2 alloy system leads to formation of lateral and vertical heterostructure growth. High angle annular dark field scanning transmission electron microscopy (HAADF-STEM) imaging and density functional theory (DFT) calculations also support the modified stacking and growth mechanism due to the nonisomorphous Sn substitution. Our experiments demonstrate the possibility of growing heterostructures of TMD alloys whose spectral responses can be desirably tuned for various optoelectronic applications.

(Invited) Growth and Applications of Si1-xSnx Thin Films

Toward creation of a direct gap group-IV semiconductor, we have developed a new method of growing Si1-xSnx layers with various Sn content including a very high Sn content around 40% by using solid phase epitaxy. Crystallographic analyses indicate that grown Si1−xSnx layers are nearly lattice-matched to the substrates, specifically, the substitutional Sn contents of ~20 and ~40% are achieved for case of growth on (001)-oriented Ge and InP substrates, respectively. Although band structure of the Si0.6Sn0.4 layers grown on InP is still indirect band gap, the difference between the indirect and direct band gap energies decreases from 3.01 (Si) to 0.14 eV (Si0.6Sn0.4) following Sn substitution.

Structural, optical and magnetic properties of Sn doped ZnS nano powders prepared by solid state reaction

Tin doped ZnS powders (Zn1−xSnxS, x = 0.00, 0.02, 0.05&0.08) were synthesized by a simple Solid state reaction and were characterized by Powder X-ray diffractometer (XRD), UV–Vis–NIR diffuse reflectance spectrophotometer, fluorescence spectrophotometer, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The XRD studies revealed that no change in crystal structure was observed by the substitution of Sn into ZnS lattice. The crystallite size was calculated by Scherrer's formula and found that the crystallize size of Sn doped ZnS powders were in the range of 35–45nm. From the diffused reflectance spectra, the band gap values of Zn1−xSnxS powders were estimated, and they were found to be in the range of 3.53–3.58eV. The pure ZnS particles showed higher optical absorption in visible region than that of Sn doped ZnS nano particles. The Photoluminescence (PL) spectra of Zn1−xSnxS powders were recorded in the range of 400–700nm with an excitation wavelength of 360nm. The Zn1−xSnxS powders exhibited ferromagnetism at low temperature (100K) and super paramagnetism at room temperature (300K). The strength of magnetization increased with increase of Sn doping concentration from 0.015emu/g to 0.18emu/g, when x increased from 0.00–0.05.

Preparation and characterization of (Co0:3Zn0:7)(Ti1–xSnx)Nb2O8microwave dielectric ceramics

AbstractZn0.7Co0.3(Ti1-xSnx)Nb2O8(x = 0.1, 0.15, 0.2, 0.25, 0.3, 0.35) microwave ceramics were prepared by traditional solidstate reaction method. The influences of Sn substituted for Ti on the phase constitution, crystal structure and microwave dielectric properties of Zn0.7Co0.3(Ti1-xSnx)Nb2O8ceramics were discussed. The XRD patterns revealed the main phase of ZnTiNb2O8and little content of Zn0.17Ti0.5Nb0.33O2secondary phase. With further substitution of Sn, the lattice constant, volume and apparent density of the ceramics increased, the ceramic structure reached a maximal compactness at x = 0.2 which was shown on SEM. Tremendous improvement of Q × f and a declining trend of Ɛrand τfwere obtained with increasing x value. Appropriate substitution value (x = 0.10) would ensure excellent microwave dielectric properties (Ɛr= 34.1, Q × f = 40562 GHz, τf=-5 ppm/°C) of the ceramics sintered at 1080 °C.

Sn-doped Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials for lithium-ion batteries with enhanced electrochemical performance

Sn-doped Li-rich layered oxides of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 have been synthesized via a sol-gel method, and their microstructure and electrochemical performance have been studied. The addition of Sn4+ ions has no distinct influence on the crystal structure of the materials. After doped with an appropriate amount of Sn4+, the electrochemical performance of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 cathode materials is significantly enhanced. The optimal electrochemical performance is obtained at x = 0.01. The Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode delivers a high initial discharge capacity of 268.9 mAh g−1 with an initial coulombic efficiency of 76.5% and a reversible capacity of 199.8 mAh g−1 at 0.1 C with capacity retention of 75.2% after 100 cycles. In addition, the Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode exhibits the superior rate capability with discharge capacities of 239.8, 198.6, 164.4, 133.4, and 88.8 mAh g−1 at 0.2, 0.5, 1, 2, and 5 C, respectively, which are much higher than those of Li1.2Mn0.54Ni0.13Co0.13O2 (196.2, 153.5, 117.5, 92.7, and 43.8 mAh g−1 at 0.2, 0.5, 1, 2, and 5 C, respectively). The substitution of Sn4+ for Mn4+ enlarges the Li+ diffusion channels due to its larger ionic radius compared to Mn4+ and enhances the structural stability of Li-rich oxides, leading to the improved electrochemical performance in the Sn-doped Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials.

Preparation and study of the thermoelectric properties of Fe2TiSn1–x Si x Heusler alloys

Polycrystalline alloys Fe2TiSn1–x Si x (0 ≤ x ≤ 1) theoretically predicted as highly efficient thermoelectric materials are experimentally studied. Structural studies show that the partial substitution of Sn with Si results in the formation of a multiphase state in samples with x > 0. Impurity phases in general lead to a significant decrease in the Seebeck coefficient and an increase in the thermal conductivity of Fe2TiSn1–x Si x samples, which does not allow consideration of these materials as promising thermoelectrics.

Investigation of Band Structure of ZrNiSn1-xGax Semiconductor Solid Solution

The mechanism of simultaneous generation of donor-acceptor pairs in ZrNiSn1-xGax semiconductor solid solution is established. The modeled distribution of atoms in the crystal lattice of ZrNiSn1-xGax showed that the speed of movement of Fermi level εF, obtained from the band structure calculations is in agreement with experimental extracted from lnρ(1/T) dependencies. It is shown that with substitution of Sn (5s25p2) with Ga (4s24p1) atoms in 4b crystallographic site both acceptor and donor (vacancies in 4b site) defects are generated.

Combustion Synthesis of MAX Phase Solid Solution Ti<sub>3</sub>(Al,Sn)C<sub>2</sub>

Formation of the Ti3(Al,Sn)C2 solid solutions was studied by combustion synthesis from elemental powder compacts with Al4C3 and TiC additions. Combustion temperatures of 1590–1700 °C and flame-front speeds of 14.2–18.8 mm/s were measured for the Al4C3-added samples. Due to the dilution effect of TiC, the combustion temperature and flame velocity were significantly reduced to 1220–1280 °C and 7.1–9.6 mm/s, respectively, for the TiC-adopted samples. The XRD analysis indicated that MAX solid solutions Ti3(Al1–xSnx)C2 with x = 0.2, 0.4, and 0.6 were produced from the Al4C3-adopted samples. Because of the low reaction temperature, the extent of Sn substitution for Al in Ti3(Al1–ySny)C2 was narrowed down to y = 0.4 for the TiC-containing samples. The as-synthesized Ti3(Al,Sn)C2 grains were plate-like and closely stacked into a laminated microstructure.

The effect of low Sn doping on the dielectric and electrocaloric properties of ferroelectric ceramics Ba0.95Sr0.05Ti0.95Zr0.05O3

Ba0,95Sr0,05(Ti0,95Zr0,05)1-xSnxO3 (x = 0 and x = 0.025) ceramics were prepared by solid state method. We have systematically studied the effects of a low quantity of Sn substitution on the crystal structure, dielectric and electrocaloric properties. X-ray diffraction shows that the symmetry of the two compositions x = 0 (BSTZ) and x = 0.025 (BSTZS) is both tetragonal with a space group P4mm and orthorhombic with Pmmm space group. Dielectric measurements show that Sn doping significantly reduces the Curie temperature from 392 K for BSTZ to 364 K for BSTZS. A typical hysteresis loops were observed for the investigated compositions and they were confirmed the ferroelectric-to-paraelectric transition phase. Finally electrocaloric effect in lead-free BSTZ and BSTZS ceramics is studied using an indirect method from the thermal variation of P-E hysteresis loops using the Maxwell relation. In the composition x = 0, the electrocaloric temperature ΔT was about 0.048 K. The addition of a low quantity of tin (Sn) ions in the matrix of Ba0,95Sr0,05(Ti0,95Zr0,05) has been able to increase the electrocaloric temperature until ΔT reached 0.095 K to a field E = 1 kV/mm.