Increasing Sb Content Research Articles

Study of Structural and Optical Properties of Non-Oxide Se90Cd10–xSbx(2 ≤ x ≤ 8) Chalcogenide Thin Films

Thin films of Se90Cd10–xSbx (2 ≤ x ≤ 8) of thickness 0.4 microns were prepared on ultra-clean glass substrate by thermal evaporation technique. The vacuum level was 10–6 torr. This paper intends to investigate the impact of Sb concentration on the optical characterization. XRD measurement has been done to investigate the Structural characterization of the prepared thin films. XRD result indicates the prepared thin have amorphous nature. To analyze the optical characterization of the thin films the absorption spectra were recorded over 400–1100 nm wavelength range. In the present study the optical absorption follows direct allowed transition. An increase in photon energy causes an increase in absorption coefficient while extinction coefficient has been found to increase with an increase in frequency of the photons i.e., deceases with increase of wavelength. Optical bandgap (Eg) of thin films have been studied and an increase in it has been recorded with increasing Sb concentration.

Investigation of Dielectric Behaviors and a.c. Conduction of a-Se90Cd10–xSbx (2 ≤ x ≤ 8) Chalcogenide Glass

The dielectric relaxation and ac conduction play a vital role to understand the mechanism of conduction. The structure and defects of solid can be determined by dielectric relaxation whereas the nature of defect states and their density of states can be studied by a. c. conductivity. In the present work, we have prepared a novel Se90Cd10–xSbx (2 ≤ x ≤ 8) glass in bulk form by conventional melt quenching technique. The investigation of dielectric behavior and conduction of amorphous Se90Cd10–xSbx (2 ≤ x ≤ 8) of pellets has been studied in the frequency span 5 × 102–1 × 105 Hz at temperature 323 K. It is observed that the dielectric constants (ɛ′) dielectric loss (ɛ″), loss angle (tan (δ)) and AC conductivity (σac) show the frequency dependent behavior. It is also noticed that ɛ′, ɛ″, tan(δ) and σac decreases with increase of Sb concentration in Se90Cd10–xSbx (2 ≤ x ≤ 8) glassy alloys.

Evolution of structural, magnetic, and transport properties in MnBi2−xSbxTe4

Here we report the evolution of structural, magnetic and transport properties in MnBi$_{2-x}$Sb$_x$Te$_4$ (0$\leq x \leq$2) single crystals. MnSb$_2$Te$_4$, isostructural to MnBi$_2$Te$_4$, has the lattice parameters of \textit{a}=4.2445(3)$\AA$ and \textit{c}=40.869(5)$\AA$, respectively. With increasing Sb content in MnBi$_{2-x}$Sb$_x$Te$_4$, the \textit{a}-lattice decreases linearly following the Vegards law while the \textit{c}-lattice shows little compositional dependence. The \textit{a}-lattice contraction occurs by reducing Mn-Te-Mn bond angle while Mn-Te bond length remains nearly constant. The anisotropic magnetic properties suggest an antiferromagnetic order below T$_N$=19\,K for MnSb$_2$Te$_4$ with the magnetic moments aligned along the crystallographic \textit{c}-axis. The antiferromagnetic ordering temperature slightly decreases from 24\,K for MnBi$_2$Te$_4$ to 19\,K for MnSb$_2$Te$_4$. More dramatic change was observed for the critical magnetic fields required for the spin-flop transition and moment saturation. With increasing Sb content, both critical fields decrease and in MnSb$_2$Te$_4$ a small field of 3\,kOe is enough to saturate the moment. In high magnetic fields, the saturation moment shows significant suppression from 3.56$\mu_B$/Mn for MnBi$_2$Te$_4$ to 1.57$\mu_B$/Mn for MnSb$_2$Te$_4$. Data analyses suggest that both the interlayer magnetic interaction and single ion anisotropy decrease with increasing Sb content. The partial substitution of Bi by Sb also dramatically affects the transport properties. A crossover from n-type to p-type conducting behavior is observed around x=0.63. Our results show close correlation between structural, magnetic and transport properties in MnBi$_{2-x}$Sb$_x$Te$_4$ and that partial substitution of Bi by Sb is an effective approach to fine tuning both the magnetism and transport properties of MnBi$_{2-x}$Sb$_x$Te$_4$.

Study the Optical Properties of Undoped and Antimony Doped Tin Oxide Films Prepared by APCVD Technique

In the present study, antimony doped tin oxide (SnO2:Sb) thin films are prepared by atmospheric pressure chemical vapor deposition (APCVD) technique by varying the doping concentration in very small range, 1- 1.4 wt.% at a constant substrate temperature of 480 oC. The effect of Sb-doping concentration on the optical behavior of SnO2 film deposited on glass substrates are analyzed and discussed. Optical measurements showed that the average optical transmittance decreased with increased Sb concentration, and each of absorbance, absorption coefficient and extinction factor were increased in same way and regularly with increasing the concentration of Sb. However the optical reflectance and the refractive index were irregularly increased in same way with increasing the concentration of Sb. A little decrease of energy gap from 3.96 to 4.015 eV with increasing Sb concentration is observed.

Structural and dielectric performance of the Ba(Zn1/3Nb2/3-xSbx)O3 perovskite ceramics

In this work, we have explored the antimony doping effects on the structural and dielectric properties of Ba(Zn1/3Nb2/3)O3 ceramics (BZN). The ceramics displayed perovskite structures with a lattice constant that decreases with increasing Sb content. The antimony solubility limit of the BZN ceramics is Below this limit and in the range of the microstrain, the dislocation density and the stacking faults decreased and the crystallite size increases with increasing Sb content in the composition of BZN. When the limit is exceeded minor phases are predicted by software analysis and confirmed by the experimental techniques. The presence of these phases is also verified by the scanning electron microscopy and energy dispersive x-ray spectroscopy techniques. Increasing the Sb content is observed to decrease the value of the dielectric constant. The Sb doped BZN ceramics exhibits high dielectric quality factors that nominate it for applications in electronics as radio waves resonators.

Effect of Sb Additions on the Creep Behaviour of Bi Containing SAC Alloys

Creep behaviour as well as microstructural evolution resulting from long-term isothermal treatment of cast Sn-3Ag-3Bi-0.5Cu-(0.6–5)Sb solder alloys for electronic packaging applications are investigated. Mechanisms of deformation are evaluated via creep tests conducted at a temperature range of 25–150°C using 7.5–12.5 MPa stress and in-depth scanning electron microscopy analysis. Short primary creep stages (< 1 h), an indication of low work hardening, followed by the secondary creep stage occurred in all conditions. Dislocation processes were found to control creep deformation above 100°C. Increase in Sb content has negligible effect on minimum creep rates but does affect the duration of secondary creep stage. A change in activation energy of creep deformation is determined at temperatures below 100°C.

Optical and transport properties of few quintuple-layers of Bi2-xSbxSe3 nanoflakes synthesized by hydrothermal method

Hydrothermal synthesis as a commonly bottom-up growth method has considerable advantages for manufacturing thermoelectric nanomaterials with advanced thermoelectric properties. However, the hydrothermally synthesized thermoelectric nanostructures often show a low thermoelectric performance due to their low power factor. In this work, we report on using a hydrothermal method for the growth of n-type Bi2-xSbxSe3 nanoflakes with a fixed thickness of ∼16 quintuple-layers. The controlling of the stoichiometric composition, phase purity and crystallinity of the Bi2-xSbxSe3 nanoflakes are demonstrated by the X-ray diffraction, Raman spectroscopy, and high resolution transmission electron microscopy. We further prove that adding of antimony into Bi2Se3 compound mostly influences the in-plane vibration mode. The optical energy gap is sharply increased as the Sb content increases. The effect of the antimony incorporation on the electrical conductivity, Seebeck coefficient and power factor of Bi2-xSbxSe3 nanoflakes is systematically investigated. The Bi1.92Sb0.08Se3 sample is found to have the highest power factor ∼13.17 μW/cm.K2 at 470 K which is much higher than those published for other various nanostructured or bulk Bi2Se3 compounds. The results propose a great prospect for further enhancing the thermoelectric power factor of the Bi2Se3 nanostructures synthesized by this hydrothermal method. Taking into consideration the progress in Bi–Se compounds, the results of this work advocate the promise of Bi–Se nanostructures towards producing high performance thermoelectric devices.

Band-gap engineering, conduction and valence band positions of thermally evaporated amorphous Ge15-x Sbx Se50 Te35 thin films: Influences of Sb upon some optical characterizations and physical parameters

Quaternary chalcogenide Ge15-xSbxSe50Te35, (0.0≤x≤15.0, at. %) thin films are prepared using the thermal evaporation process under the residual vacuum pressure of ≈ 10−3 Pa. The rate of deposition and thicknesses of the film samples are kept constant at 10 nm/s and 200 nm, respectively. X-ray diffraction is employed to examine the amorphous or crystalline structure of films. The absence of sharp and distinct peaks confirms the amorphous nature. The compositional element ratio of all prepared samples is analysed by energy-dispersion X-ray spectroscopy technique. UV–Vis–NIR absorption spectra are used to study the optical parameters of thin films. The values of the absorption coefficient for all film samples are found to be higher than 104 cm −1. The optical band-gap energy is determined both experimentally and theoretically. The band gap is due to the indirect electronic transitions, and the band gap values are found to decrease from 1.047 eV to 0.864 eV with the increase in Sb-ratio. The band-tail width increases from 0.103 eV to 0.258 eV. The optical density, skin effect and extinction coefficient increase with an increase in Sb-content. The positions of the conduction and valence bands, as well as the conduction potentials of all samples, are also evaluated. The Fermi level shifts closer to the valence band and away from the conduction band with increasing Sb content. The chemical bond approach model is applied to study the cohesive energy and average-coordination number of these a-Ge-Sb-Se-Te films. The total number of constraints, floppy modes, cross-linking density, the number of the valence electrons and the number of lone-pair electrons are also investigated. All discussed parameters are found to be strongly dependent on the Sb-content.

Antimony in urine during early pregnancy correlates with increased risk of gestational diabetes mellitus: A prospective cohort study

BackgroundAntimony (Sb) has been associated with type 2 diabetes in previous studies. However, the role of Sb in the incidence of Gestational diabetes mellitus (GDM) remains unclear. ObjectivesWe investigated the association between Sb exposure during early pregnancy and the risk of GDM. MethodsWe performed a prospective study of 2093 pregnant women from the Tongji Maternal and Child Health Cohort (TMCHC). Sb concentrations were measured in urine samples during early pregnancy by ICP-MS. The association between urinary Sb concentration and GDM incidence was assessed using robust Poisson regression model after adjustment for confounders. ResultsThe 95th percentile value of creatinine-corrected Sb (CC-Sb) concentration in the urine of all pregnant women was 1.33 μg/g. The CC-Sb concentrations were significantly higher in women with GDM than those without GDM (median value: 0.49 μg/g vs. 0.38 μg/g, p = 0.001). After adjustment for potential confounders, for each one natural logarithmic unit increase in Sb concentration, there was 29% [adjusted relative risk (RR) = 1.29; 95% confidence interval (CI): 1.06, 1.57] increase in the risk of GDM. Women in the highest tertile for CC-Sb had a 1.92-fold (95% CI: 1.42, 2.60) higher risk of GDM compared with women in the lowest tertile (p-value for trend <0.001). ConclusionTo our knowledge, this is the first research of an association between urinary Sb levels during pregnancy and GDM. Our study suggests that pregnant women with higher Sb exposure levels may have a higher risk of GDM and this association remains consistent even after stratification.

Fabrication and characterization of Ba8Zn(Ta6−xSbx)O24 microwave ceramics

Ba8Zn(Ta6−xSbx)O24 ceramics have been prepared through the solid-state ceramic route. The X-ray diffraction analysis showed the ceramics have hexagonal perovskite structure with space group P63cm. The structure of the system was confirmed using Fourier transform Raman spectroscopy. The microstructure of the sintered pellet was analyzed using scanning electron microscopy. A correlation study is performed between the structure and the measured dielectric properties. The τf values of the samples were reduced from 38.6 to − 1.6 ppm/°C with the increase in Sb concentration. The compositions have good microwave dielectric properties and are suitable for dielectric resonator applications.

Critical behavior of CrTe1-xSbx ferromagnet

The modified Arrott plots and Kouvel-Fisher analysis are used to investigate the critical behavior of CrTe1-xSbx ferromagnetic material near its transition temperature Tc. The Ferro–Paramagnetic transition is found to be a second-order phase transition. For x=0.2, the critical exponents closely follow the Mean Field Model with the estimated values of the exponents: β=0.60±0.03, γ=1.00±0.03 and δ=2.67±0.03. We also found with increasing Sb-concentrations, the critical exponents significantly deviate from the mean field values and gradually shift towards the 3-Dimensional behavior. The deviation may indicate changes in the spin configuration with increasing Sb concentrations.

Band alignment and carrier recombination of InAs/GaAs&amp;lt;sub&amp;gt;1&amp;minus;&amp;lt;/sub&amp;gt;&amp;lt;sub&amp;gt;&amp;lt;italic&amp;gt;x&amp;lt;/italic&amp;gt;&amp;lt;/sub&amp;gt;Sb&amp;lt;sub&amp;gt;&amp;lt;italic&amp;gt;x&amp;lt;/italic&amp;gt;&amp;lt;/sub&amp;gt; quantum dots affected by Sb content

The influences of Sb content on the band structure and carrier recombination dynamics of InAs/GaAs1− x Sb x quantum dots (QDs) have been investigated by both calculation and experimental demonstration. The calculation results using the eight-band model indicated that the band alignment of InAs/GaAs1− x Sb x QDs was type I at low Sb content and changed from type I to type II when Sb content increased from 0.08 to 0.14. During this phase, electrons were still localized in InAs QDs while holes were transferred from InAs QDs to the GaAsSb capping layer gradually, which resulted in the reduction of the overlap of electron and hole wave functions and carrier transition rate. To experimentally prove the calculation results, InAs/GaAs1− x Sb x QDs with various Sb contents were grown by molecular beam epitaxy. The photoluminescence (PL) measurement results confirmed the expected influence of Sb content on the band alignment of InAs/GaAs1− x Sb x QDs. For InAs/GaAs1− x Sb x QDs samples with Sb content of 0.15 and 0.2, the PL peak energy showed a blue shift with increasing excitation power, which is a signature of a type-II band alignment structure. On the other hand, the PL peak energy was independent of excitation power in the samples with Sb content of 0.05 and 0.1. Besides, the redshift with increasing Sb content became stronger and the PL intensity became weaker when Sb content was larger than 0.14. To investigate the carrier transition rate, time-resolved PL measurement was performed. The minority carrier lifetime increased from 0.41 to 14.3 ns when the band alignment of InAs/GaAs1− x Sb x QDs changed from type I to type II, which indicated that carrier recombination was inhibited. InAs/GaAs1− x Sb x QDs with type-II band alignment are preferred for intermediate band solar cells due to longer carrier lifetime resulting from the spatial separation of electrons and holes, which is beneficial to maintain the separation between conduction band, intermediate band and valence band quasi-Fermi levels.

Tuning the optical properties of InAs QDs by means of digitally-alloyed GaAsSb strain reducing layers

In this work, we demonstrate the use of a digitally alloyed GaAsSb as a strain reducing layer (SRL) to tune the optical properties of InAs quantum dots grown on GaAs substrates. The GaAsSb digital alloy was made using a short period GaAs/GaSb superlattice. Increasing the Sb-shutter duty cycle (Sb-SDC) from 0 to 0.35 redshifts the emission wavelength from 1220 nm to 1492 nm at 300 K. The wavelength red shift is attributed mainly to the increased Sb content in the GaAsSb SRL as confirmed by high resolution X-ray diffraction. Power dependent photoluminescence showed a type II band alignment for the samples grown with a Sb-SDC of 0.25 and 0.35. Reversing the growth order of GaAs and GaSb layers and maintaining the same Sb-SDC (0.25) drastically alters the optical properties of the QDs. A large wavelength blue shift of 143 nm and a transformation from a type II to type I emission were observed as a result of GaSb intermixing with InAs QDs.

Achieving wavelength emission beyond the C-band from Type-II InAs-GaAsSb quantum dots grown monolithically on silicon substrate

Abstract The optical quality enhancement of a GaAs template grown on Silicon substrate using InGaAs/GaAs Dislocation Filters (DFs) combined with an annealing step have been assessed optically using Photoluminescence (PL) of embedded InAs/InGaAs QDs within a GaAs matrix. An annealing temperature after the growth of the DFs of 690 °C was shown to be optimum, giving an enhanced PL emission from the embedded InAs QDs in terms of intensity and Full Width at Half Maximum (FWHM). InAs quantum dots capped with GaAsSb grown at different temperatures were grown on the optimized GaAs template on Si. The prepared samples were characterized by PL, Atomic Force Microscopy (AFM), excitation power and dependent PL at 77 K and 300 K. At 77 K, the InAs/GaAsSb grown at 484 °C showed a type II band alignment with an emission wavelength of 1297 nm, which is shorter than the emission obtained from the reference sample, where the GaAsSb-capped dots were grown on GaAs (1357 nm). By reducing the GaAsSb capping layer growth temperatures to 465 °C and 450 °C, the wavelength at 77 K was extended to 1375 nm and 1480 nm respectively, resulting from an increased Sb content in the capping layer. At 300 K, a long wavelength emission of 1623 nm have been achieved.

Influence of alloy engineering on structural and photo detection properties of SbXSn1-XSe2 ternary alloys

In order to exploit effect of Sb incorporation on properties of SnSe2, alloy engineering is performed in SbxSn1-xSe2 (x = 0, 0.1, 0.2, 0.3) ternary compounds. The single crystals are grown by direct vapour transport technique. The elemental composition and purity of as-grown compounds are characterized by EDAX. The optical microscopy and scanning electron microscopy show characteristic morphological features like helical spiral, layered structure, clean surface, etc. on surface of grown crystals. The powder X-ray diffraction shows that the pristine and Sb incorporated samples possess 2H-Hexahonal lattice structure. However, lattice parameters and unitcell volume are changed on incorporation of Sb in SnSe2 structure due to increase in microstrain. The Raman spectroscopy reveals SnSe2-type A1g vibrational mode and the corresponding peak is shifted on lower wavenumber side on increasing Sb content. The results confirm substitution of Sb(+5) on Sn(+4) lattice site in host network. The influence of alloy engineering on photo response is studied. The highest photocurrent of 1.88 μA, responsivity of 43.45 mAW−1, detectivity of 18.25 × 1011 Jones and EQE (%) of 47.28% are observed for X = 0.1 sample.

Effect of Sb incorporation on the structural, optical, morphological and electrical properties of CdSe thin films deposited by electron beam evaporation technique

Cadmium Selenide (CdSe) and antimony (Sb) incorporated CdSe (CdSe:Sb) thin films were deposited by electron beam evaporation technique at various concentration of Sb (5 wt%, 10 wt%, 15 wt% and 20 wt%). The effect of Sb concentration on the properties of CdSe thin films was investigated. Formation of hexagonal crystal structure with preferred growth along [001] direction was confirmed by X-ray diffraction analysis. The interplanar spacing, lattice constant, average crystallite size, strain and dislocation density of CdSe and CdSe:Sb thin films were calculated from X-ray diffraction studies. The crystallite size of CdSe thin film is 40 nm, which is decreased to ~25 nm with increasing Sb concentration in CdSe from 5 wt% to 20 wt% in the source material. Optical transmittance of the CdSe films obtained from UV–Vis spectra is decreased with various amount of Sb incorporation in CdSe film. Direct optical band gap of the film varies in the range of 1.74–2.3 eV as a function of Sb concentration in the source material. Photoluminescence spectra of CdSe:Sb films show near band edge emission at 605 nm and deep trap related emission band at 743 nm. The intensity of the emission bands varies and shows shifts towards the lower wavelength side with increase in Sb concentration. The electrical resistivity is relatively minimum for CdSe:Sb (5 wt%) and further increase in Sb concentration increases the resistivity of the CdSe films.

Modulation of carrier concentration and microstructure for high performance BixSb2-xTe3 thermoelectrics prepared by rapid solidification

In this study, a series of BixSb2-xTe3 were prepared by vacuum melting, melt spinning combined with the plasma activated sintering (SPS) process. The influence of Bi/Sb ratio on the phase composition and thermoelectric properties were systematically discussed. The carrier concentration increases gradually with the increasing Sb content. Due to the optimized carrier concentration while preserving high Seebeck coefficient through adjusting Bi/Sb ratio, Bi0.46Sb1.54Te3 sample obtains the highest power factor of 3.90 mW m−1 K−2 at room temperature. Moreover, the microstructure is effectively modified by adjusting the linear speed of the copper roller, where the average grains size decreases gradually with the increasing speed of melting spinning (MS). The sample synthesized with the MS speed of 20 m/s possesses the widest distribution of grains size spanning from several nanometer to tens of micrometer, which scatters the phonons with wider range of mean free paths, resulting in the lowest lattice thermal conductivity of 0.64 W m−1 K−1 at 350 K. Benefitting from the decreased lattice thermal conductivity and enhanced power factor, a peak ZT value of around 1.2 is obtained at 350 K for the Bi0.46Sb1.54Te3 specimen with the MS speed of 20 m/s.

Polaronic transport in antimony-vanadium tellurate glasses at high temperatures

The ternary bulk glasses of the form (60-x)V2O5-40TeO2-xSb with 0 ≤ x≤15 (in mol%) were prepared by using the standard melt quenching technique. The dc electrical conductivity of the mentioned samples was investigated within the temperature range of 296–408 K. The dc conductivities at 370 K, with values in the range of 4.80 × 10−6–1.08 × 10−4 S cm−1, were found to decrease with increase of Sb content. The experimental temperature-dependency of conductivity and the variation of the pre-exponential factor were interpreted in terms of polaron hopping theory. It founds that within the studied temperature range, the non-adiabatic small polaron hopping (NASPH) mechanism for electrons between different valent states of vanadium ions is applicable. The ratio of wave function decay (tunneling factor α) was found to be 2.26 × 108 cm−1 for samples with x ≥ 8 mol%.

SPUTTER-GROWN Sb-DOPED SILICON NANOCRYSTALS EMBEDDED IN SILICON-RICH CARBIDE FOR Si HETEROJUNCTION SOLAR CELLS

Sb-doped silicon nanocrystals (Si–NCs) films were fabricated by magnetron co-sputtering combined with rapid-thermal annealing. The effects of Sb content on the structural and electrical properties of the films were studied. The dot size increased with the increasing Sb content, and could be correlated to the effect of Sb-induced crystallization. The variation in the concentration of Sb shows a significant impact on the film properties, where as doped with 0.8[Formula: see text]at.% of Sb exhibited major property improvements when compared with other films. By employing Sb-doped Si–NCs films as emitter layers, Si–NCs/monocrystalline silicon heterojunction solar cells were fabricated and the effect of the Sb doping concentration on the photovoltaic properties was studied. It is found that the doping level in the Si–NCs layer is a key factor in determining the short-circuit current density and power conversion efficiency (PCE). With an optimized doping concentration of 0.8[Formula: see text]at.% of Sb, a maximal PCE of 7.10% was obtained. This study indicates that the Sb-doped Si–NCs can be good candidates for all-silicon tandem solar cells.

Growth, phase and electronic structure of RbTiOPO4 crystals doped with antimony

RbTiOPO4 crystals doped with different concentrations of antimony (Sb) (5–15%) were grown by high-temperature solution method. At the bottom of the crucible, a large amount of crystalline particles and a small amount of flaky crystals were obtained. The crystalline phase, chemical composition and electronic structure of the crystals were analyzed by X-ray diffraction (XRD), electron probe microanalyzer (EPMA) and X-ray photoelectron spectroscopy (XPS). The results show that the doped crystals belong to KTP phase when the concentration of Sb is lower. When the doping concentration of Sb is up to 15%, a new phase is generated and a large amount of white flake materials are produced. From the detailed XPS spectra of P 2p, O 1s and Ti 2p3/2, we found that the binding energy difference between the O 1s and P 2p is stable for different doping concentrations: ΔBE (OP) = 398.1 eV. The binding energy difference between the O 1s and Ti 2p3/2 increases firstly and then decreases with increasing Sb content. Compared with pure RTP, the electronic structure of antimony-doped RTP crystals has changed. The ionicity of TiO bond in the crystal increases with the increase of doping concentration when Sb content is no more than 10%. Sb doping has no significant effect on the PO bond property.