Sb Doping Research Articles

Improving thermoelectric properties of ZrPtSn-based half-Heusler compound by Sb doping

Improving thermoelectric properties of ZrPtSn-based half-Heusler compound by Sb doping

Antimony doped SnO2 nanowire@C core–shell structure as a high-performance anode material for lithium-ion battery

SnO2 is considered as one of the high specific capacity anode materials for Lithium-ion batteries. However, the low electrical conductivity of SnO2 limits its applications. This manuscript reports a simple and efficient approach for the synthesis of Sb-doped SnO2 nanowires (NWs) core and carbon shell structure which effectively enhances the electrical conductivity and electrochemical performance of SnO2 nanostructures. Sb doping was performed during the vapor-liquid-solid synthesis of SnO2 NWs in a horizontal furnace. Subsequently, carbon nanolayer was coated on the NWs using the DC Plasma Enhanced Chemical Vapor Deposition approach. The carbon-coated shell improves the Solid-Electrolyte Interphase stability and alleviates the volume expansion of the anode electrode during charging and discharging. The Sb-doped SnO2 core carbon shell anode showed the superior specific capacity of 585 mAhg−1 after 100 cycles at the current density of 100 mA g−1, compared to the pure SnO2 NWs electrode. The cycle stability evaluation revealed that the discharge capacity of pure SnO2 NWs and Sb doped SnO2 NWs electrodes were dropped to 52 and 152 mAh g−1 after100th cycles. The process of Sb doping and carbon nano shielding of SnO2 nanostructures is proposed for noticeable improvement of the anode performance for SnO2 based materials.

The effect of the change in the amount of Sb doping in ZnO nanorods for hydrogen gas sensors

In this study, pure and variable content Sb doped ZnO nanorods (NRs) were grown by a simple spray pyrolysis method successfully. Structural analysis has showed that all the films are indicating preferential dominant c-axis (002) plane from x-ray diffraction (XRD) measurements. It is observed that Sb doping does not result in changes in lattice parameter indicating no lattice distortion. Raman measurements has indicated Sb doping related modes in ZnO NRs especially defect related. SEM images has shown uniform hexagonal close packing NR structures uniformly distributed throughout the film. X-ray photoelectron spectroscopy (XPS) has displayed lower incorporation of the Sb from the precursor to the Sb doped NRs. Hydrogen gas sensor performances of these NRs has investigated. 5.0 wt% Sb doped ZnO NR sample has showed outstanding response with 23-fold response to 10 ppm hydrogen gas level at 250 °C.

Epitaxial growth and properties study of p-type doped ZnO:Sb by PLD

Abstract Undoped and antimony (Sb) doped ZnO films were synthesized on sapphire (0001) substrates using Pulsed Laser Deposition (PLD) method. Structural and morphological studies proved the good crystallinity of the ZnO films with c-axis (0002) orientation growth. The substitution of Sb in ZnO lattice was proved from the analysis of XPS data. Interestingly, it was important that the presence of Sb5+ ions opened the way for the apparition of the complex acceptor (SbZn–2VZn) level with high stability. The decrease in the value of the band gap Eg with Sb doping evidenced the creation of energy levels related to such complex acceptor. From the study of photoluminescence (PL) at low temperatures, it was shown the dominant emission is related to free electron transition from neutral acceptor (e, A0), indicating the conductivity conversion from n to p with Sb doping. The reproducibility and stability of p-type conduction from the ZnO:Sb3% films were evaluated by Hall measurements. As application, ZnO homojunction device was carefully made and shows rectifying current-voltage (I–V) characteristics, typical to perfect diode. Thus, the prepared ZnO–Sb films are promising for application in optoelectronic field.

Effect of Sb doping on the photocatalytic performance of Z-scheme TiO2NRA/SnO2/potassium titanate heterojunction and its photocatalytic mechanism

Firstly, Sb–SnO2/potassium titanate (Sb–SnO2/K4TiO4 (KTO)) was fabricated by a sol-gel method, and then TiO2 nanorod arrays were grown on the surface of Sb–SnO2/KTO by a hydrothermal method (TiO2NRA/Sb–SnO2/KTO). The photocatalytic activity was evaluated by degrading tetracycline hydrochloride (TCH). The prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), ultraviolet–visible diffuse reflectance spectrometer (UV–Vis), and X-ray photoelectron spectroscopic characterizations (XPS). The results show that the Z-scheme heterojunction formed between SnO2/KTO and TiO2 can enhance the range of light response. With the doping of Sb, the conductivity of the composite is enhanced, which is advantageous to the transfer of electron and the low recombination rate of electron-hole pairs. Thus, the doping of Sb is effective to improve the photocatalytic performance. Our work demonstrates the optimal doping amount of Sb is 5%. The degradation efficiency of TCH concentration can reach 95.6% after 2 h and TiO2NRA/Sb–SnO2/KTO shows good reusability.

PH-dependent doping level and optical performance of antimony-doped tin oxide nanocrystals as nanofillers of spectrally selective coating for energy-efficient windows

The optimal pH value of the titration endpoint remains uncertain for the synthesis of antimony-doped tin oxide by the co-precipitation method. In this study, the influence of the pH titration endpoint on doping level and optical performance was systematically studied. The phase composition, microstructure, the valence state of Sb ions and thermodynamic behaviors of antimony-doped tin oxide were comprehensively investigated. The UV–Vis–NIR transmittance spectra of ATO glass and SEM images of ATO coating were also studied. When the pH value of the titration endpoint was 6, the measured doping ratio of Sb was 10.81% which was close to the initial Sb doping level of 10%. In the meanwhile, the content of Sb5+ ions also reached the maximum value of 76.4%. Especially, the spectrally selective coating exhibited optimally spectral selectivity with the average visible light transmittance of 77.24% and the average near-infrared shielding ratio of 80.06% respectively. The results show that the doping level and optical properties of antimony-doped tin oxide certainly relied on the pH value of the titration endpoint. It is of great significance to scale up the production of antimony-doped tin oxide with superior near-infrared shielding performance and promote its practical application in the field of energy-efficient glazing.

Observation of Dirac-like surface state bands on the top surface of BiSe

Weak topological insulators (TIs) host non-trivial topological surface state bands (SSBs) at the side surface of the crystal while the top (001) surface can be topologically either dark or light. In our detailed angle-resolved photoelectron spectroscopy (ARPES) study we found Dirac-like linearly dispersive SSBs on the (001) surface of BiSe and Sb-doped (8%) BiSe. The lower part of the SSBs buries deep in the bulk valence band (BVB) and the overlap region between the SSBs and BVB increases significantly with Sb doping. These results highlight the role of the interlayer coupling between the Bi bilayer and the Bi2Se3 quintuple layer (QL). Furthermore, in the overlap region the SSBs deviate from the Dirac-like linear dispersion. Interestingly, we observed a large intensity imbalance ) in the SSBs located at the positive and negative directions. This asymmetry pattern ) gradually reverses to ) as the excitation energy scans from low (14 eV) to high (34 eV) values. The observed photon energy-dependent intensity variation could be a signature of the mixing between the spin and the orbit texture of the SSBs.

Improved thermoelectric performance of GeTe via efficient yttrium doping

Optimization of the carrier concentration by doping/alloying is a key prerequisite for improving thermoelectric performance. In reality, it is, however, challenging to identify effective dopants in some specific systems. Herein, we discovered that Y doping significantly reduced the carrier concentration, enhanced the power factor, and, therefore, boosted thermoelectric performance. The high Y-doping efficiency had origin in the fact that the compensating effect due to Ge vacancies was weaker in comparison to other dopants in GeTe because the slightly increased rhombohedral interaxial angle suggested that the Ge-vacancy concentration would not be altered dramatically. In addition, first-principles calculations revealed that Y doping did not induce significant modifications on the band structure, consistent with electrical transport measurement results. Moreover, Bi doping was found to be more powerful than Sb doping to further increase electrical resistivity and to enhance performance in which the highest peak ZT ∼ 1.8 together with a high average ZT ∼ 1.1 from 300 K to 723 K was achieved. Our work not only highlighted the efficacy of Y doping in enhancing the thermoelectric performance of the GeTe system but also developed advanced GeTe-based materials for power generation applications.

Enhancement of spin-orbit coupling in Dirac semimetal Cd3As2 films by Sb doping

We present a study on magnetotransport in films of the topological Dirac semimetal Cd$_{3}$As$_{2}$ doped with Sb grown by molecular beam epitaxy. In our weak antilocalization analysis, we find a significant enhancement of the spin-orbit scattering rate, indicating that Sb doping leads to a strong increase of the pristine band-inversion energy. We discuss possible origins of this large enhancement by comparing Sb-doped Cd$_{3}$As$_{2}$ with other compound semiconductors. Sb-doped Cd$_{3}$As$_{2}$ will be a suitable system for further investigations and functionalization of topological Dirac semimetals.

Boosting the thermoelectric performance of GeTe by manipulating the phase transition temperature via Sb doping

With rising Sb content, the crystal symmetry of Sb-doped GeTe elevates by lowing phase transition temperature, thus leading to superior thermoelectric properties. A ZTmax of ∼1.8 at 773 K and ZTave of ∼1.1 can be obtained in Ge0.9Sb0.1Te.

Enhancing the Thermoelectric Performance of Mg2Sn Single Crystals via Point Defect Engineering and Sb Doping.

Mg2Sn is a potential thermoelectric (TE) material that exhibits environmental compatibility. In this study, we fabricated Sb-doped Mg2Sn (Mg2Sn1-xSbx) single-crystal ingots and demonstrated the enhancement of TE performance via point defect engineering and Sb doping. The Mg2Sn1-xSbx single-crystal ingots exhibited considerably enhanced electrical conductivity because of the donor-doping effect in addition to high carrier mobility. Moreover, the Mg2Sn1-xSbx single-crystal ingots contained Mg vacancy (VMg) as a point defect. The introduced VMg and doped Sb atoms formed nanostructures, both acting as phonon-scattering centers. Consequently, lower lattice thermal conductivity was achieved for the Mg2Sn1-xSbx single-crystal ingots compared with polycrystalline counterparts. Owing to the significant enhancement in the electrical conductivity and the reduction in the lattice thermal conductivity, the maximum power factor of 5.1(4) × 10-3 W/(K2 m) and the maximum dimensionless figure of merit of 0.72(5) were achieved for the Mg2Sn0.99Sb0.01 single-crystal ingot, which are higher than those of single-phase Mg2Sn1-xSb polycrystals.

Improvement of the dust removal performance of a high-transmittance SnO2–SiO2 film by Sb doping

Dust on outdoor glass will significantly reduce glass transmittance in various applications and even damage solar cell panels. Here, the effects of Sb doping on the structure and photoelectric properties of a Sb-doped SnO2–SiO2 (ATO-SiO2) film prepared on a glass substrate with a sol-gel method and the dust removal performance of the resulting film were studied. The results show that the Sb-doped SnO2–SiO2 film consists of a SnO2 tetragonal rutile phase, but the doped Sb decreases the sample crystallinity. With an increase in the Sb doping concentration, two lattice parameters of the ATO-SiO2 film, a and c, show “M"-shaped changes. The nanoparticle size first decreases and subsequently increases when the Sb doping concentration is over 6 mol%. The transmittance of the substrate glass coated with this film in the visible wavelength range (380–780 nm) decreases from 86.3% to 82.7%. The square resistance first decreases and subsequently increases, while the dust removal performance first increases and subsequently decreases. At a 12 mol% Sb doping concentration, the square resistance is minimal (4.64 × 106 Ω/□). The maximal dust removal performance is 64%.

Double Charge Polarity Switching in Sb‐Doped SnSe with Switchable Substitution Sites

AbstractTin mono‐selenide (SnSe) is one of the most promising thermoelectric materials; however, it experiences difficulty in controlling the carrier polarity, which is inevitable for realizing p‐n homojunction devices. Herein, double switching of charge polarity in (Sn1−xSbx)Se by varying x is reported; pure SnSe shows p‐type conduction, whereas the polarity of (Sn1−xSbx)Se switches to n‐type conduction for 0.005 < x < 0.05, and then re‐switches to p‐type conduction for x > 0.05. The major Sb substitution site switches from the Se (SbSe) to Sn site (SbSn) with increasing x. SbSn (Sb3+ at Sn2+) works as a donor, but SbSe (Sb3− at Se2−) does not produce a hole because of the Sb–Sb dimer formation. The mechanism of double polarity switching is explained by native p‐type conduction in pure SnSe due to Sn‐vacancy formation, whereas (Sn1−xSbx)Se exhibits n‐type behavior due to conduction through the SbSe impurity band formed above the valence band maximum, and finally re‐switches to weak p‐type, where the Fermi level approaches the midgap level between the SbSe band and conduction band minimum. Clarification of the Sb doping mechanism will provide a crucial guide for developing more sophisticated doping routes for SnSe and high‐performance energy‐related devices.

A two-dimensional electron gas based on a 5s oxide with high room-temperature mobility and strain sensitivity

The coupling of optical and electronic degrees of freedom together with quantum confinement in low-dimensional electron systems is particularly interesting for achieving exotic functionalities in strongly correlated oxide electronics. Recently, high room-temperature mobility has been achieved for a large bandgap transparent oxide – BaSnO3 upon extrinsic La or Sb doping, which has excited significant research attention. In this work, we report the realization of a two-dimensional electron gas (2DEG) on the surface of transparent BaSnO3 via oxygen vacancy creation, which exhibits a high carrier density of ~7.72 × 1014 cm−2 and a high room-temperature mobility of ~18 cm2·V−1·s−1. Such a 2DEG is rather sensitive to strain and a less than 0.1% in-plane biaxial compressive strain leads to a giant resistance enhancement of ~350% (more than 540 kΩ/□) at room temperature. Thus, this work creates a new path to exploring the physics of low-dimensional oxide electronics and devices applicable at room temperature.

Inserting an intermediate band in Cu- and Ag-based Kesterite compounds by Sb doping: A first-principles study

Intermediate band solar cells(IBSCs) have attracted much attention owing to the ideal three-photon absorption by one absorber. Here, we have investigated Sb-doped Cu2ZnSnS4(CZTS), Cu2ZnGeS4(CZGS), Ag2ZnSnS4(AZTS) and Ag2ZnGeS4(AZGS) as the absorber for IBSCs by first-principles calculation. After doping Sb at Sn or Ge site, an isolated and half-filled intermediate band has been inserted in the main band gaps of all of the four Kesterite compounds, which mainly consists of Sb-s and S-p states. The absorption coefficients of the doped samples are greatly enhanced in visible light region and can cover the solar radiation spectrum effectively owing to the three-photon absorption with the help of intermediate band. Based on the calculation on defect formation energy, we have found the suitable chemical potential condition and gotten the minimums of defect formation energies for Sb doping at Sn or Ge site. Finally, Sb-doped AZTS as the promising absorber candidate for IBSCs has been proposed.

Structural and optical properties of undoped and antimony-doped lead telluride thin films

Undoped and antimony-doped lead telluride (Sb-doped PbTe) thin films were deposited onto borosilicate and fluorine-doped tin oxide (FTO) glass substrates by a spray pyrolysis method. The structural and optical properties were investigated. The X-ray diffraction (XRD) patterns indicate that PbTe and PbTe:Sb on both substrates had a cubic structure. Sb doping yields a decrease in lattice constant and crystallite size of PbTe. The onset (Egonset) and direct (Egdi)optical band gap increases with Sb incorporation into the PbTe lattice. The Egonset and Egdi values were in the range of 1.17–1.22 eV and 1.40–1.53 eV for each condition, respectively. Defects and disorders in the PbTe lattice were also performed due to Sb incorporation into both neighboring vacancies of the Pb and Te atoms.

Compositional Fluctuations Locked by Athermal Transformation Yielding High Thermoelectric Performance in GeTe.

Phase transition in thermoelectric (TE) material is a double-edged sword-it is undesired for device operation in applications, but the fluctuations near an electronic instability are favorable. Here, Sb doping is used to elicit a spontaneous composition fluctuation showing uphill diffusion in GeTe that is otherwise suspended by diffusionless athermal cubic-to-rhombohedral phase transition at around 700 K. The interplay between these two phase transitions yields exquisite composition fluctuations and a coexistence of cubic and rhombohedral phases in favor of exceptional figures-of-merit zT. Specifically, alloying GeTe by Sb2 Te3 significantly suppresses the thermal conductivity while retaining eligible carrier concentration over a wide composition range, resulting in high zT values of >2.6. These results not only attest to the efficacy of using phase transition in manipulating the microstructures of GeTe-based materials but also open up a new thermodynamic route to develop higher performance TE materials in general.

Enhanced nonlinear absorption coefficient and low optical limiting threshold of NiO nanocomposite films

In order to enhance the optical nonlinearity of the nickel oxide, NiO nanoparticles doped with Cr/Sb were synthesized by hydrothermal method. Their nanocomposite films which have nanoparticles and polymer forms were produced by spin coating method. Structural measurements revealed that all of the nanoparticles are in cubic structure with crystallite size between 10.3 nm and 17.3 nm. TEM images of the annealed nanoparticles confirmed the particle sizes found from XRD pattern. Open Aperture Z-scan technique was used to estimate the nonlinear absorption characteristics of the nanocomposite films. Nonlinear absorption coefficient of nanocomposite films was found to be 1.84 × 10−4 cm/W and increased to 7.45 × 10-4 cm/W and 4.18 × 10−4 cm/W with Cr and Sb doping. Nanocomposite films have low optical limiting threshold values between 8.65 mJ/cm2 and 2.24 mJ/cm2. These results suggested that the NiO, NiO:Cr and NiO:Sb nanocomposite films can be good candidate for optoelectronic applications especially as an optical limiter due to their low optical limiting thresholds.

Influence of antimony on the structural, electronic, mechanical, and anisotropic properties of cubic barium stannate

Throughout this study, we have investigated Sb doping’s effects on the physical metallurgy of perovskite BaSnO3 by employing the first-principles calculations based on the density functional theory (DFT). We observed an increasing trend of lattice constants with an increasing doping concentration of Sb on perovskite BaSnO3. The calculated formation enthalpy and elastic constants ensured the structural stability of our system even under varied doping of Sb. Our band structure calculations suggested that it would be possible to tune the band structure of BaSnO3 by partially substituting Sb at the Sn-site, which reduced the band gap at low doping levels and transformed the compound from semiconducting to metallic at Sb ≥ 12.5%. The mechanical properties exhibited the prominent effects of Sb doping. In addition, the anisotropy of our system was significantly dependent on the elastic constant Cij and varied as the doping concentration of Sb is increased. Therefore, our simulation outputs clearly illustrated the importance of taking into account the Sb doping influence on the physical properties of BaSnO3 perovskite material.

Investigation of local structures and electronic states of Sb-doped Mg2Si by fluorescence XAFS and HAXPES

To clarify the origin of the figure of merit in the thermoelectric material Mg2Si, we performed extended x-ray absorption fine structure (EXAFS) analysis and hard x-ray photoelectron spectroscopy (HAXPES). We elucidate the local structures and electronic states of Mg2Si, especially focusing on the contribution of doped Sb. EXAFS analysis revealed that Sb substituted Si and that the nearest neighbor distance expanded around Sb. Furthermore, HAXPES confirmed the formation of density of states near the Fermi level by co-doping with 0.5% Zn and 0.5% Sb. The comparison of the experimental and theoretical results suggested that the density of states at the Fermi level was due to the tail of the conduction band, and it was filled by the electrons provided by doped Sb. From a microscopic viewpoint, the results obtained in this study suitably explain why Sb doping increases electrical conductivity and decreases thermal conductivity in Mg2Si, as reported in a previous study.