Sn Doping Concentration Research Articles

The figure of merit improvement of (Sn, Co)–ZnO sprayed thin films for optoelectronic applications

Nanocrystalline zinc oxide (ZnO) has garnered significant attention from researchers and industries due to its superior properties as an optoelectronic material, particularly in solar cells as a transparent electrode. Doping, especially with tin (Sn) and co-doping with tin and cobalt (Co), can refine its optoelectronic properties. In this manuscript, we report on the optoelectronic properties of undoped ZnO thin films, as well as those doped with Sn and/or Co, elaborated using a simple chemical pneumatic spray pyrolysis method on glass substrates. A 1 % Sn doping concentration was used, with Co doping concentrations of 0 %, 0.5 %, and 1 %. The effects of Sn and/or Co doping concentration on the structure, morphology, optical, and electrical properties of nanocrystalline ZnO were studied using X-ray diffractometer (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FESEM), UV–Vis–NIR spectroscopy and Hall effect measurements. All the films studied exhibit wurtzite ZnO structures with a predominant (002) orientation and no secondary phase, as confirmed by X-ray diffraction (XRD) analysis. The Raman spectroscopy also reveals the presence of a wurtzite structure in all the films. The FESEM images reveal the kind and concentration of the dopants significantly influenced the surface morphology of the films. The elemental analysis with energy dispersive X-ray analysis (EDS) analysis successfully detected the doping of Sn and Co. The analysis of UV–Vis spectroscopy provide that the optical band gap for the undoped ZnO film is 3.25 eV. This band gap increases upon doping and co-doping, reaching a peak value of 3.30 eV for the Sn:Co (1 %:0.5 %) co-doped ZnO film. The ZnO film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 1.95 × 10−2 Ω cm for the film (1%Sn, 0.5 % Co)–ZnO. The highest figure of merit (FOM) achieved is 1.41 × 10−4 Ω−1 for a ZnO thin film co-doped with (1 % Sn, 0.5 % Co). The existence of (1 % Sn, 0.5 % Co) film with improved optical gap, low electrical resistivity and high FOM supports its use in transparent conductive oxide applications.

Preparation, characterization, and antibacterial activity of Ni, Sn co-doped ZnO nanoparticles: Effect of Sn doping concentration

Ni, Sn co-doped ZnO nanoparticles have been prepared by chemical method at room temperature. The effects of Sn on the structural, morphological, optical, electrical, and anti-microbial properties of the prepared nanoparticles have been evaluated and discussed. The crystallite size and the unit cell properties have been influenced by the doping concentration of Sn. The addition of Sn enhances the texture coefficient of the nanoparticles. The optical band gap of the material is blue-shifted as the doping concentration of Sn increases. The prepared nanoparticles have high hole concentration than electron concentration. The nanoparticles became more transparent at high doping concentrations. The effect of Sn concentration against E. coli, S. aureus, and P. aeruginosa has been evaluated.

Study of rectifying properties and true Ohmic contact on Sn doped V2O5 thin films deposited by spray pyrolysis method

In this paper, V2O5 thin-films were deposited on glass substrates by using the ultrasonically nebulized spray pyrolysis technique. Doping concentration of 1 %, 2 %, and 7 % of Sn, in V2O5 thin-films is studied by using metal–semiconductor-metal (MSM) based device structure. X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM) were used to analyze the surface morphology of the thin films. The XRD spectroscopic analysis shows the crystal size of above-mentioned samples, to be respectively 39 nm, 58 nm, 60 nm and 72 nm. The FESEM images showed the enhancement of crystal size with increase in Sn doping concentration. The optical properties of Sn doping on V2O5 thin film were studied by using UV–Vis spectrometer. The UV–Vis spectroscopic analysis shows that the absorption coefficient values decrease with increase in concentration of Sn metal doping in V2O5 thin film. The activation energies of all thin-film samples were calculated from Arrhenius plots and were found to be 0.938 eV, 1.101 eV, 1.11 eV and 1.169 eV, respectively, for all the thin-film samples mentioned above. The MSM based structure was fabricated by using a shadow mask and thermal evaporation. Later, the I-V characteristics of all the thin films were obtained by using semiconductor parameter analyzed at a biased voltage between −50 V and + 50 V with a step size of 1 V. Rectification ratio of the V2O5 films is significantly enhanced as the doping concentration increases. It was found that the rectification ratio of undoped V2O5 thin films increased linearly from 1.018 to 1.059 with an increase in temperature from room temperature to 130 °C. Similar trend was followed for 1 % (from 1.079 to 1.198), 2 % (from 1.081 to 1.224) and 7 % (from 1.095 to 1.311) Sn doped films. These results show the potential application of V2O5 thin films in the field of optoelectronics and thin film gas sensors.

Wavelength Tunable Infrared Perfect Absorption in Plasmonic Nanocrystal Monolayers.

The ability to efficiently absorb light in ultrathin (subwavelength) layers is essential for modern electro-optic devices, including detectors, sensors, and nonlinear modulators. Tailoring these ultrathin films' spectral, spatial, and polarimetric properties is highly desirable for many, if not all, of the above applications. Doing so, however, often requires costly lithographic techniques or exotic materials, limiting scalability. Here we propose, demonstrate, and analyze a mid-infrared absorber architecture leveraging monolayer films of nanoplasmonic colloidal tin-doped indium oxide nanocrystals (ITO NCs). We fabricate a series of ITO NC monolayer films using the liquid-air interface method; by synthetically varying the Sn dopant concentration in the NCs, we achieve spectrally selective perfect absorption tunable between wavelengths of two and five micrometers. We achieve monolayer thickness-controlled coupling strength tuning by varying NC size, allowing access to different coupling regimes. Furthermore, we synthesize a bilayer film that enables broadband absorption covering the entire midwave IR region (λ = 3-5 μm). We demonstrate a scalable platform, with perfect absorption in monolayer films only hundredths of a wavelength in thickness, enabling strong light-matter interaction, with potential applications for molecular detection and ultrafast nonlinear optical applications.

Chemically prepared p-type Sn doped ZnO nanoparticles: Synthesis, characterization and its antibacterial properties

The undoped and transition metal doped ZnO nanoparticles are prepared by the chemical precipitation method. Transition metal Sn is chosen as the dopant. The doping concentration of Sn is varied from 0 % to 15 % and the effects of the doping concentration of Sn on structural, optical and antibacterial properties are discussed. The increasing Sn doping concentration increases crystallite size and reduces the strain of the nanoparticles. The band gap is red-shifted due to the addition of Sn. Irrespective of the doping concentration, the hole concentration is larger than the electron concentration. The observed Hall coefficient is in the order of 10−8 m3 C−1, and it decreases non-linearity as the Sn concentration increases. The refractive index also depends on the doping concentration. The doping of Sn enhanced the zone of inhibition against E. coli, S. aureus, and P. aeruginosa. It has been observed that the ZnO nanoparticles doped with Sn have impressive antibacterial activity against both Gram-positive and Gram-negative bacteria.

Crystal growth and thermoelectric properties of Sn-doped Bi2Se3

We have studied the crystal growth of SnxBi2Se3 (x = 0 ∼ 0.75) and examined the effect of Sn doping on the structure and thermoelectric properties of Bi2Se3. All the crystal samples of SnxBi2Se3 were synthesized using a direct melt-growth. The results indicated that when the Sn doping content was ≤ 0.3, some Sn atoms were incorporated into the interlayers of Bi2Se3, thereby increasing the carrier concentration. In the intermediate to the high-temperature range, Sn doping improved the electrical conductivity of Bi2Se3, resulting in overall good performance in the power factor(PF). All the doped samples exhibited good ZT (a dimensionless figure of merit) in the intermediate to the high-temperature range, especially with the doping sample of x = 0.3 showing a maximum ZT value of 0.2 at 835 K.

Unraveling the injection barrier between electrode and organic layer in OLED device: A theoretical prediction model

This study developed a new prediction model for hole injection barriers. Based on the electronegativity equalized model (EEM), the vacuum level shift in the adjacent layers was further considered in this model. In addition, the variation in ΦITO, which is dependent on the doping concentration of Sn, was considered as one of the determinants for predicting the hole injection barrier (HIB) between ITO and the organic layer. Further, the effect of p-dopants on the HTL energy level was also introduced in this model. The predicted HIBs of various anode/organic junctions were quantitatively and qualitatively consistent with UPS experiments. We believe that the developed EEM model can aid in determining the appropriate HTL/HIL organic materials without tremendous effort and time costs.

Preparation and characterization of Sn doped NiO thin films by sol–gel spin coating technique

Nickel Oxide (NiO), being a wide energy bandgap semiconductor, exhibit excellent optical, electrical and magnetic characteristics and show great application potential in various technological applications. Doping with suitable dopant is known to further enhance the intrinsic properties of NiO. Pristine and Sn-doped (2, 4, 6 and 8 mol%) nano-crystalline NiO films are deposited onto the substrates (glass) using conventional sol–gel spin coating technique. Detailed structural, optical, and photoluminescence properties are examined to comprehend the consequences of Sn doping in NiO host matrix. The XRD results reveal the formation of single phased, polycrystalline films that have cubic face-centered structure of NiO. The crystallinity and size of crystal found decreasing as increasing the Sn doping concentration. The vibrational stretching modes of Ni-O absorption band are observed from the FTIR spectra with wave number of 550–750 cm−1. The UV–visible transmittance results show that, the prepared samples of pure, 2 mol% and 4 mol%Sn doped NiO exhibit 75%transmittance within the visible region and which decreases with raise in concentration of Sn. Further, the optical bandgap of the films is evaluated using the Tauc’s relations and the optical energy bandgap values are found to be 3.47, 3.51, 3.52, 3.50 and 3.44 eV for pristine, 2 mol%,4 mol%, 6 mol%, and 8 mol% Sn doped films, respectively. The results offered that the structural and optical properties can be tailored by varying concentration of dopant; these films are the potential candidates for gas sensing and optoelectronic device applications.

Effects of Sn doping on piezoelectric power generation and energy density of flexible BaTiO3 thin films

Ferroelectric thin films find applications in numerous areas, including sensors and energy storage devices. To address the toxicity associated with thin films such as Pb(Zr,Ti)O3, developing Pb-free ferroelectric thin films with enhanced physical properties is necessary. Herein, the piezoelectric power generation and energy density of Sn-doped BaTiO3 (SBTO) thin films with varying Sn doping concentrations were studied. Polycrystalline SBTO thin films with Sn doping concentrations of 0%, 5%, 10%, and 15% were deposited on flexible Pt/mica substrates with a preferential (111) orientation. The SBTO thin film with a Sn doping concentration of 5% exhibited the highest remanent polarization (Pr) in the ferroelectric hysteresis loop. In contrast, the SBTO thin films with Sn doping concentrations of 10% and 15% exhibited reduced Pr owing to the formation of 90° domains. The lowest Pr was observed for the SBTO thin film with 15% Sn. With an increase in the Sn doping concentration, the piezoelectric coefficient (d33) increased due to the formation of a-domains. Owing to the high concentration of a domain, the SBTO thin film with 15% Sn exhibited the highest d33 and consequently, the highest piezoelectric power generation voltage. Moreover, the minimum Pr of the film with 15% Sn facilitated an increase in energy density and efficiency.

Infrared Plasmonic Metamaterials Based on Transparent Nanoparticle Films of In2O3:Sn for Solar-Thermal Shielding Applications.

Three-dimensional nanoparticle (NP) assemblies show interesting optical responses that differ from naturally occurring materials, such as metals, oxides, and semiconductors. In this study, we investigate the optical response of thin films comprising Sn:In2O3 NPs (ITO NP films) based on the correlation between complex permittivity and infrared (IR) reflectance for solar-thermal shielding applications. IR ellipsometry measurements are conducted to clarify the presence of Lorentz resonances in plasmonic metamaterials. The Lorentz resonances are correlated to the electric field strength at interparticle gaps by varying the Sn dopant concentration, as confirmed using finite-difference time-domain (FDTD) simulations. High solar-thermal shielding performance was obtained owing to selective near-IR reflection based on strong Lorentz resonances as the ITO NP films were electrically polarizable but magnetically inactive. Thermal shielding efficiency was demonstrated via a comparison of the air temperature change in a simulated box used as a model house. Additionally, we demonstrate the significance of NP packing density on the enhancement of the near-IR reflectance. The role of interparticle spacing for high near-IR reflectance was revealed by comparing effective medium approximation analyses and FDTD simulations. This relationship was also demonstrated by the reduction of solar-thermal shielding performance when using aggregated ITO NPs. Our work confirmed that the control of complex permittivity in plasmonic metamaterials must be considered in the structural design of transparent and reflective materials for solar-thermal shielding applications.

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.

Effect of Sn concentration on the structural, morphological and thermoelectric transport properties of zinc Stannates thin films

This study aimed to set suitable Tin dopant concentration in ZnO based thin films to get optimal structural, morphological and thermoelectric properties. The samples under investigation were prepared by thermal evaporation technique using stoichiometric ratios of Zn and Sn powders. X-ray diffractograms showed that all grown samples are fully c-axis oriented but increasing Sn concentration caused a blue shift in XRD peak position. Raman spectrum of ZTO nanoparticles has confirmed the perfect wurtzite structure having an intense E2 mode. It was further showed that with increasing crystallite size, the frequency of E2 (highest peak) phonon mode decreases whereas its line width increases. The Seebeck coefficient has maximum value (800 μV/K) for un-doped sample while the value of electrical conductivity (5.2 S/cm) has maximum value for sample having Sn concentration 4%. This behavior of thermoelectric properties can be understood by the fact that Sn doping concentration increases the free carrier concentration in the host crystal of ZnO which resulted in the reduction of Seebeck coefficient and enhancement of electrical conductivity. This argument was further highlighted by the SEM measurements.

Long-lasting stability and low-concentration SO2 gas detection aptitude of Sn-doped alumina sensors

The Sn-doping effect on the SO2 gas sensing properties has been investigated by a resistance-based measurement method. During structural analysis, the undoped aluminium oxide (Al2O3) nanoparticles display a rhombohedral phase and the Sn-doped nanoparticles reveal the orthorhombic phase which causes a diffraction shift to a higher angle. From the surface analysis, particles expose dense microstructure, which is further enhanced by doping. High-resolution scanning microscopy images confirm a non-identical orientation of particles, suggesting polycrystalline nature. Besides, the particles are interconnected through one-by-one approach by forming a necklace of bead-like structure. The optical spectroscopy measurement endows a decrease in absorption intensity followed by an increase in bandgap with increasing Sn-doping concentration (SnxAl2-xO3). In sensor investigation, Sn-doped sensor senses the SO2 gas more efficiently even at low and higher concentrations i.e. from 10 to 300 ppm. The sensor adduces an elevated sensitivity of 78.14% at 300 ppm. In addition, the sensor adsorbs the gas molecules within 17 s, depicting a fast response time. As a result of the greater sensitivity, assistive technology such as pre-concentration is no longer required. The Sn-doped sensor bestows 96.83% reproducibility, showing a practical importance.

Multi-Layered Sol–Gel Spin-Coated CuO Nanofilm Characteristic Enhancement by Sn Doping Concentration

CuO films, with their many features, attract special attention for applications in various optoelectronics. In their pristine form, CuO films suffer from low conductivity, which limits their application. Modification, especially by doping, is thus needed. The effects of tin (Sn) doping on the structure, morphology, and optical and, more importantly, electrical properties of multi-layered copper oxide (CuO) films deposited onto tin-doped indium oxide (ITO)/glass substrates by sol–gel spin coating are examined here. The multi-layered films were characterized with X-ray diffraction (XRD), atomic force microscopy (AFM), electronic absorption (UV-Visible) spectra, and four probe methods. The results confirmed the substitution of Cu2+ ions by Sn4+ ions in the CuO crystallites without altering their monoclinic structure. The measured crystallite size values decreased with increased doping concentration, indicating increased imperfection. This applies to both 5- and 10-layered CuO films. The doping concentration affected other film characteristics, namely, surface morphology and electrical conductivity, in each layered film. Among various systems, the 10-layered film, with 1.5 at% Sn, exhibited optimal properties in terms of higher uniformity (mean square root surface roughness 41 nm) and higher conductivity (50.3 × 10−3·Ω−1·cm−1).

Modulated carrier concentration and enhanced seebeck coefficient of Ge2Sb2Te5 thin films by Sn doping

We introduced Sn as a potential dopant in Ge2Sb2Te5 films to improve the thermoelectric performance. A systematic study of the thermoelectric properties of Sn doped Ge2Sb2Te5 films is presented. The effects of Sn doping content on chemical bonds were studied and Sn element was verified to combine with Te. The generation of additional LDOS peaks and the flatting of conduction band in Sn doped system promote the optimization of Ge2Sb2Te5's carrier concentration near the Fermi level and enhance its seebeck coefficient. The carrier concentration is optimized through occupation of Ge cation vacancies by Sn and formation of SnTe antistie defect. The adjustment of carrier concentration and carrier effective mass accounts for the decrease in resistivity and the increase in seebeck coefficient. A competitively high-power factor of 0.7 mW/K2m was reached in 20 W Sn doped amorphous film at 323 K and a maximal PF value of 1.88 mW/K2m was achieved in 50 W Sn doped crystalline film at 723 K. This work reveals that Sn doping contributes to the improvement of the thermoelectric properties of the Ge2Sb2Te5 films.

Investigating the Role of Surface Depletion in Governing Electron-Transfer Events in Colloidal Plasmonic Nanocrystals

Doped metal oxide nanocrystals (NCs) attract immense attention because of their ability to exhibit a localized surface plasmon resonance (LSPR) that can be tuned extensively across the infrared region of the electromagnetic spectrum. LSPR tunability triggered through compositional and morphological changes during synthesis (size, shape, and doping percentage) is becoming well-established, while the principles underlying dynamic, postsynthetic modulation of LSPR are not as well understood. Recent reports have suggested that the presence of a depletion layer on the NC surface may be instrumental in governing the LSPR modulation of doped metal oxide NCs. Here, we employ postsynthetic electron transfer to colloidal Sn-doped In2O3 NCs with varying sizes and Sn doping concentrations to investigate the role of the depletion layer in LSPR modulation. By measuring the maximum change in the LSPR frequency after NC reduction, we determine that a large initial volume fraction of the depletion layer in NCs results in a broad modulation of the LSPR energy and intensity. Utilizing a mathematical Drude fitting model, we track the changes in the electron density and the depletion-layer volume fraction throughout the chemical doping process, offering fundamental insights into the intrinsic NC response resulting from such electron-transfer events. We observe that the maximum change in electron density that can be induced through chemical doping is independent of Sn concentration, and subsequently, the maximum total electron density in the presence of excess reductant is independent of the NC diameter and is dependent only on the as-synthesized Sn doping concentration. This study establishes the central role that surface depletion plays in the electronic changes occurring in the NCs during postsynthetic doping, and the results will be instrumental in advancing the understanding of optical and electrical properties of different colloidal plasmonic NCs.

Effect of Sn doping concentration on the oxidation of Al-containing MAX phase (Ti3AlC2) combining simulation with experiment

Sn doping is usually adopted to prepare Ti3AlC2 in mass production because it can reduce the synthesis temperature while increasing the phase purity. However, excessive Sn doping usually deteriorates the oxidation resistance of Ti3AlC2. Therefore, an appropriate Sn doping concentration is a vital issue. In this work, the effect of Sn doping concentration on the oxidation behavior of Ti3AlC2 was systematically investigated by combining theoretical calculations and experimental methods. Density function theory calculations suggest that the oxygen adsorption mechanisms for the (001) surface of Ti3AlC2 with and without Sn doping are similar, and Ti-O bonds are always preferentially formed. The molecular dynamics simulation further indicates that Al atoms have a faster diffusion rate during the oxidation process. Therefore, a continuous Al2O3 layer can form rapidly at high temperature. Nevertheless, when the Sn doping concentration exceeds 10 mol%, the continuity of the Al2O3 layer is destroyed, thereby impairing the oxidation resistance of Ti3AlC2. Furthermore, oxidation experiments verify the above results. The oxidation mechanisms of Ti3AlC2 with different Sn doping concentrations are also proposed.

Sn doping effect on NiO hollow nanofibers based gas sensors about the humidity dependence for triethylamine detection

• Hollow Sn-doped NiO nanofibers are synthesized through a facile electrospinning approach. • The Sn-doped NiO sensor with suitable Sn content (6 at%) shows the highest gas response to triethylamine. • Sn doping concentrations can significantly influence the resistance of sensors in air and in target gas under different RH. • The resistances of the sensor change slightly in target gas under different RH with suitable Sn doping content (6 at%). High stable triethylamine gas sensors under different relative humidity are highly desirable in order to correctly detect the concentrations of target gas. In this study, a series of Sn-doped NiO hollow nanofibers were prepared through a facile electrospinning process followed by heat treatment. Sn doping could inhibit the crystal growth, and the crystal sizes would decrease with the increase of Sn doping concentration. Gas sensing investigation indicates that Sn doping could significantly enhance the gas response towards triethylamine at a relative low temperature. Especially, the gas sensor exhibits the highest response to triethylamine when the doping content of Sn reaches to 6 at%. The response value is about 16.6–100 ppm triethylamine, and it is ∼9.2 times higher than that of pure NiO nanofibers at the same operating temperature. In addition, the resistances of the gas sensors with different doping contents of Sn would change differently in air or in target gas under variable relative humidity. The resistances in target gas are almost unchanged with the increase of relative humidity with the Sn doping content of 6 at%. It is reasonable to speculate that Sn doping can heavily alter the surface state of NiO nanofibers, which is beneficial for the improvement of the gas response and humidity dependence properties.

Tuning of zinc oxide temperature sensing and optical absorption properties by tin heavy-doping

This paper presents the feasibility of tin (Sn) heavily doped zinc oxide (ZnO) thin film as an active layer for a microbolometer and the effect of this Sn heavily doping on the structural, optical and electrothermal properties of Sn-doped ZnO (SnxZn1-xO) thin films. The SnxZn1-xO thin films were deposited on substrates using an RF/DC co-sputtering method at room temperature with different Sn dopant concentrations %, x (x = 0.22, 0.26 and 0.32). It was found that the optical and electro-thermal properties were strongly affected by Sn doping. The result revealed an increase in the visible and infrared radiation absorption and electrical conductivity with increasing Sn doping whereas the temperature coefficient of resistance (TCR) decreases. A maximum TCR value of 1.9%/K with a sheet resistance (Rs) of 233 kΩ/□ was observed with 0.22 Sn doping concentration. The result proved that the Sn doping could help to decrease the TCR temperature dependence and the sheet-resistance of ZnO thin film as well as increasing its IR radiation absorption that makes it a strong candidate for the active layer of microbolometer.

Sn doped ZnMn2O4 microspheres with excellent electrochemical performance and high cycle stability

Sn-doping ZnMn2O4 (Sn-ZMO) porous microspheres with shell structure were synthesized by utilizing SnO as Sn source. The effect of Sn content on its structure, morphology, and performance was investigated. Sn doping can increase the crystal plane spacing of ZnMn2O4 (ZMO) microspheres and enhance the electrochemical performance of ZMO materialis. When the Sn-doping content is 0.5%, the specific capacitance of Sn-ZMO microspheres is 18.5% higher than that of pure ZMO microsphere, which reaches 530 F/g under the current density of 1 A/g. Furthermore, the cycle stability has a significant promotion. 77% of the capacity is maintained after 2000 cycles under the scan rate of 20 mV/s. The enhancement in electrochemical performance is attributed to form a spherical shell with a certain thickness after ZMO microsphere were doped by Sn atom, in which the spherical shell can suppresses the volume expansion during the charge-discharge process.