SrTiO3 Material Research Articles

Enhancing Electrochemical Performance of Si@CNT Anode by Integrating SrTiO3 Material for High-Capacity Lithium-Ion Batteries

Silicon (Si) has attracted worldwide attention for its ultrahigh theoretical storage capacity (4200 mA h g−1), low mass density (2.33 g cm−3), low operating potential (0.4 V vs. Li/Li+), abundant reserves, environmentally benign nature, and low cost. It is a promising high-energy-density anode material for next-generation lithium-ion batteries (LIBs), offering a replacement for graphite anodes owing to the escalating energy demands in booming automobile and energy storage applications. Unfortunately, the commercialization of silicon anodes is stringently hindered by large volume expansion during lithiation–delithiation, the unstable and detrimental growth of electrode/electrolyte interface layers, sluggish Li-ion diffusion, poor rate performance, and inherently low ion/electron conductivity. These present major safety challenges lead to quick capacity degradation in LIBs. Herein, we present the synergistic effects of nanostructured silicon and SrTiO3 (STO) for use as anodes in Li-ion batteries. Si and STO nanoparticles were incorporated into a multiwalled carbon nanotube (CNT) matrix using a planetary ball-milling process. The mechanical stress resulting from the expansion of Si was transferred via the CNT matrix to the STO. We discovered that the introduction of STO can improve the electrochemical performance of Si/CNT nanocomposite anodes. Experimental measurements and electrochemical impedance spectroscopy provide evidence for the enhanced mobility of Li-ions facilitated by STO. Hence, incorporating STO into the Si@CNT anode yields promising results, exhibiting a high initial Coulombic efficiency of approximately 85%, a reversible specific capacity of ~800 mA h g−1 after 100 cycles at 100 mA g−1, and a high-rate capability of 1400 mA g−1 with a capacity of 800 mA h g−1. Interestingly, it exhibits a capacity of 350 mAh g−1 after 1000 lithiation and delithiation cycles at a high rate of 600 mA hg−1. This result unveils and sheds light on the design of a scalable method for manufacturing Si anodes for next-generation LIBs.

Efficient nitrite determination by electrochemical approach in liquid phase with ultrasonically prepared gold-nanoparticle-conjugated conducting polymer nanocomposites.

An electrochemical nitrite sensor probe is introduced herein using a modified flat glassy carbon electrode (GCE) and SrTiO3 material doped with spherical-shaped gold nanoparticles (Au-NPs) and polypyrrole carbon (PPyC) at a pH of 7.0 in a phosphate buffer solution. The nanocomposites (NCs) containing Au-NPs, PPyC, and SrTiO3 were synthesized by ultrasonication, and their properties were thoroughly characterized through structural, elemental, optical, and morphological analyses with various conventional spectroscopic methods, such as field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller method. The peak currents due to nitrite oxidation were characterized in detail and analyzed using conventional cyclic voltammetry (CV) as well as differential pulse voltammetry (DPV) under ambient conditions. The sensor response increased significantly from 0.15 to 1.5mM of nitrite ions, and the sensor was fabricated by coating a conducting agent (PEDOT:PSS) on the GCE to obtain the Au-NPs/PPyC/SrTiO3 NCs/PEDOT:PSS/GCE probe. The sensor's sensitivity was determined as 0.5μA/μM∙cm2 from the ratio of the slope of the linear detection range by considering the active surface area (0.0316cm2) of the flat GCE. In addition, the limit of detection was determined as 20.00 ± 1.00 µM, which was found to be satisfactory. The sensor's stability, pH optimization, and reliability were also evaluated in these analyses. Overall, the sensor results were found to be satisfactory. Real environmental samples were then analyzed to evaluate the sensor's reliability through DPV, and the results showed that the proposed novel electrochemical sensor holds great promise for mitigating water contamination in the real samples with the lab-made Au-NPs/PPyC/SrTiO3 NC. Thus, this study provides valuable insights for improving sensors for broad environmental monitoring applications using the electrochemical approach.

Improvement of thermoelectric properties of xNb:(1-x)SrTiO3 composite ceramics by high-pressure high-temperature synthesis

The high stability and low cost are considered comparative advantages of the SrTiO3 chalcogenide oxide thermoelectric material. However, the pure SrTiO3 material is characterized by low electrical conductivity and high thermal conductivity, which could eventually lead to poor overall thermoelectric performance, and limit its application in the field of high temperature thermoelectricity. The development of composite-based metal materials with SrTiO3 by using suitable methods is arising as the most promising approach to improve their electrical properties. Along these lines, in this work, xNb: (1-x) SrTiO3 composite ceramics were successfully synthesized by using the high temperature and high-pressure (HPHT) method. The Nb powder was oxidized into various niobium oxides exhibiting their own thermoelectric properties under HPHT conditions to optimize the thermoelectric properties of the Nb/SrTiO3 composites. From our analysis, it was demonstrated that with the increase of the Nb powder content, the electrical properties were significantly improved. In addition, the fabricated Nb/SrTiO3 composite ceramics possessed a special “pore” microstructure, which significantly reduced the thermal conductivity of the material. In this work, the physical phase, microscopic morphology, and thermoelectric properties of the synthesized samples were also systematically tested and analyzed, and the maximum zT value of 0.28@973 K was obtained for the final sample with x = 0.4. The implementation of the HPHT method for the preparation of chalcogenide oxide composite ceramics provides valuable insights for the improvement of their thermoelectric properties.

Experimental investigation of structural, morphological, and optical characteristics of SrTiO3 nanoparticles using a shock tube for photocatalytic applications

Abstract We investigated the role of dynamic shock waves in perovskite SrTiO3 (STO) material. XRD, FE-SEM, EDAX, FTIR, UV-DRS, XPS, and Raman spectroscopy were all used to examine the title material. When perovskite sample was loaded with shocks, its diffraction pattern did not show any crystal structure changes. The FE-SEM results suggest that the grain size increased linearly with the number of shocks. We used energy-dispersive X-ray spectroscopy to perform elemental analysis; results confirmed that SrTiO3 NPs were indeed present. Although the impulse of the shock wave changed the optical characteristics, it did not affect the molecular structure. To find the optical band gap energies of untreated and shocked NPs, Tauc plot relationships were used. The band-gap energies got smaller as the shock pulse became more substantial. The impact of shock waves caused oxygen vacancies and surface defects, lowering band gap energy. The test for photocatalytic testing showed that SrTiO3 NPs that are loaded with shock waves worked much better when they were exposed to visible light. The characteristics, including stress, strain, and bond length, were found to significantly influence photocatalytic applications. In addition, attempts were made to provide a viewpoint for future study. Overall, the objective of this research was to provide valuable insights for experts engaged in the field of SrTiO3.

In Tandem Control of La-Doping and CuO-Heterojunction on SrTiO3 Perovskite by Double-Nozzle Flame Spray Pyrolysis: Selective H2 vs. CH4 Photocatalytic Production from H2O/CH3OH.

ABO3 perovskites offer versatile photoactive nano-templates that can be optimized towards specific technologies, either by means of doping or via heterojunction engineering. SrTiO3 is a well-studied perovskite photocatalyst, with a highly reducing conduction-band edge. Herein we present a Double-Nozzle Flame Spray Pyrolysis (DN-FSP) technology for the synthesis of high crystallinity SrTiO3 nanoparticles with controlled La-doping in tandem with SrTiO3/CuO-heterojunction formation. So-produced La:SrTiO3/CuO nanocatalysts were optimized for photocatalysis of H2O/CH3OH mixtures by varying the La-doping level in the range from 0.25 to 0.9%. We find that, in absence of CuO, the 0.9La:SrTiO3 material achieved maximal efficient photocatalytic H2 production, i.e., 12 mmol g-1 h-1. Introduction of CuO on La:SrTiO3 enhanced selective production of methane CH4. The optimized 0.25La:SrTiO3/0.5%CuO catalyst achieved photocatalytic CH4 production of 1.5 mmol g-1 h-1. Based on XRD, XRF, XPS, BET, and UV-Vis/DRS data, we discuss the photophysical basis of these trends and attribute them to the effect of La atoms in the SrTiO3 lattice regarding the H2-production, plus the effect of interfacial CuO on the promotion of CH4 production. Technology-wise this work is among the first to exemplify the potential of DN-FSP for scalable production of complex nanomaterials such as La:SrTiO3/CuO with a diligent control of doping and heterojunction in a single-step synthesis.

Effects of Sintering Temperature and Holding Times on the Microstructure and Chemical Bond of Strontium Titanate (SrTiO3)

Strontium Titanate (SrTiO3) is one attractive material studied. In this study, SrTiO3 has been fabricated via the co-precipitation technique. The samples were sintered at 800°C and 900°C with holding times of 2 h and 4 h for each temperature. The purposes of this study were to synthesize SrTiO3 material using co-precipitation technique and to observe the microstructure and chemical bonds of the SrTiO3 as the variations of the sintering temperatures and holding times. According to the X-Ray Diffraction (XRD) results, the sintering temperatures and holding times influenced the intensity values and peak broadening. The alteration in both parameters consequently changed the crystallite size and lattice strain of the SrTiO3 material. Furthermore, the Fourier Transform Infrared (FTIR) results validated the SrTiO3 material by existence of Sr-Ti-O chemical bonds. Also, the absorption peaks of O-H, C-H, and C=O chemical bonds in the SrTiO3 declined due to the higher temperature and longer holding time demonstrating impurities declined. Therefore, according to this study, the sintering temperature of 900°C and the holding time of 4 h was the best parameter for fabricating SrTiO3 powder.

Graphene/SrTiO3 interface-based UV photodetectors with high responsivity* *Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFF0104801 and 2018YFB0406601) and the National Natural Science Foundation of China (Grant Nos. 61804012 and 11721404).

Strontium titanate (SrTiO3), which is a crucial perovskite oxide with a direct energy band gap of 3.2 eV, holds great promise for ultraviolet (UV) photodetection. However, the response performance of the conventional SrTiO3-based photodetectors is limited by the large relative dielectric constant of the material, which reduces the internal electric field for electron-hole pair separation to form a current collected by electrodes. Recently, graphene/semiconductor hybrid photodetectors by van-der-Waals heteroepitaxy method demonstrate ultrahigh sensitivity, which is benefit from the interface junction architecture and then prolonged lifetime of photoexcited carriers. Here, a graphene/SrTiO3 interface-based photodetector is demonstrated with an ultrahigh responsivity of 1.2 × 106 A/W at the wavelength of 325 nm and ∼ 2.4 × 104 A/W at 261 nm. The corresponding response time is in the order of ∼ ms. Compared with graphene/GaN interface junction-based hybrid photodetectors, ∼ 2 orders of magnitude improvement of the ultrahigh responsivity originates from a gain mechanism which correlates with the large work function difference induced long photo-carrier lifetime as well as the low background carrier density. The performance of high responsivity and fast response speed facilitates SrTiO3 material for further efforts seeking practical applications.

Photocatalytic Overall Water Splitting by SrTiO3 with Surface Oxygen Vacancies.

Strontium Titanate has a typical perovskite structure with advantages of low cost and photochemical stability. However, the wide bandgap and rapid recombination of electrons and holes limited its application in photocatalysis. In this work, a SrTiO3 material with surface oxygen vacancies was synthesized via carbon reduction under a high temperature. It was successfully applied for photocatalytic overall water splitting to produce clean hydrogen energy under visible light irradiation without any sacrificial reagent for the first time. The photocatalytic overall water splitting ability of the as-prepared SrTiO3-C950 is attributed to the surface oxygen vacancies that can make suitable energy levels for visible light response, improving the separation and transfer efficiency of photogenerated carriers.

Significant Improvement in Electrical Conductivity and Figure of Merit of Nanoarchitectured Porous SrTiO3 by La Doping Optimization.

SrTiO3 is a well-studied n-type metal oxide based thermoelectric (TE) material. In this work, the first-principles calculation of La-doped SrTiO3 has been performed using the density functional theory. In addition, high TE properties of bulk SrTiO3 material have been achieved by introducing nanoscale porosity and optimizing carrier concentration by La doping. The X-ray diffraction, atomic resolution scanning transmission electron microscopy imaging, and energy-dispersive X-ray spectrometry results show that La has been doped successfully into the lattice. The scanning electron microscopy images confirm that all the samples have nearly similar nanoscale porosities. The significant enhancement of electrical conductivity over the broad temperature range has been observed through optimization of La doping. Additionally, the samples possess very low thermal conductivity, which is speculated because of the nanoscale porosity of the samples. Because of this dual mechanism of doping optimization and nanoscale porosity, there is a remarkable improvement in power factor, 1 mW/m2K from 650 to 800 K, and figure of merit, zT of 0.26 at 850 K, of the sample, 22 at. % La-doped SrTiO3.

Effect of ceria concentration of Strontium titanate on the structural, optical, dielectric and electrical properties

The present investigation, pure and ceria (CeO2) doped strontium titanate (SrTiO3) powders have been synthesized by the solid-state reaction method. In addition, the effect of ceria (0, 1, and 3%) on the variation of crystallite size, crystalline nature, surface particle shape, optical absorption, optical band gap, dielectric constant, dielectric loss and electric conductivity of SrTiO3 material through physico-chemical characterization like powder X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), UV–Visible spectra and impedance spectroscopy have been investigated. The powder XRD display confirms the evolution of the single phase with cubic structure of SrTiO3 material. Further, we confirmed the formation of strontium titanate material through spectral studies like Fourier Transforms Infrared (FTIR), Raman spectrum and Energy dispersive X-rays studies. X-rays photoelectron spectroscopy (XPS) explains the surface chemical elements and their binding energy of pure and 3% ceria doped strontium titanate. The optical band gap values of SrTiO3 decreases emphasized a red shift with increasing the ceria concentration. Dielectric constant, dielectric loss and electrical conductivity of pure and ceria doped SrTiO3 have been comparatively discussed in detail.

Continuum thermodynamics of unusual domain evolution-induced toughening effect in nanocracked strontium titanate

This work is concerned with the analysis of both unusual mechanical and electric behaviors of nanoscale pre-cracked incipient ferroelectric of SrTiO3 at room temperature. A nonlinear thermodynamic model based on the Ginzburg-Landau theory is thus constructed and employed, which takes into account the appropriate mechanical boundary conditions, the electromechanical coupling between the polarization and the mechanical strain, and the self-strains of the ferroelastic and ferroelectric phase transformations. A large toughening effect is explored as a consequence of a softening nonlinear mechanical behavior, which characterizes for nanoscale SrTiO3, despite of the brittleness of bulk SrTiO3 ceramic. Depending upon applied strain, the large toughening and nonlinear mechanical behavior are attributed to unusual domain evolution of strain-induced polarization from the crack tip, in which a local-to-global transition of ferroelectric phase takes place from polarization vortex to hybrid structure of vortex and stripe domains, and finally to stripe domain structure with Néel type domain walls. Here, we also show the great importance of cross-coupling between the ferroelectric polarization and mechanical strain as it intrinsically leads to the local-to-global transition of ferroelectric phase. More interestingly, such cross-coupling additionally scatters the concentrated stress near the crack tip to Néel type domain walls. The present findings shed light on the crucial role of mechanical strain in controlling both the size and topology of polarization structures in nanoscale SrTiO3. Our numerical results also provide an insight into the vital role of strain-induced polarization for the toughness and strength of SrTiO3 material. Based on our study, the applicability of the present results to other incipient ferroelectrics such as CaTiO3, EuTiO3, and KTaO3 with the same mechanism would be interesting and possible.

Designing Au Surface-Modified Nanoporous-Single-Crystalline SrTiO3 to Optimize Diffusion of Surface Plasmon Resonance-Induce Photoelectron toward Enhanced Visible-Light Photoactivity

Nanoporous single-crystalline SrTiO3 is fabricated at a low temperature of 60 °C via a novel approach of sol-gel alkali-dissolution-exothermal reaction. The plasmon-active metal Au is loaded on the nanoporous single-crystalline SrTiO3 material to construct a new kind of plasmonic photocatalyst. Due to the single-crystalline nature and the space confinement effect of pores for Au growing, not only the promoted diffusion efficiency of surface plasmon resonance (SPR)-induce photoelectron is achieved, but also the diffusion region are well optimized via changing the loading amount of Au. Therefore, an optimal sample with 4.8 wt % Au loading exhibits a more than 40-fold photoactivity enhancement under visible-light irradiation compared to the common nanosized SrTiO3 (a commercially available sample) loaded with 5.3 wt % Au which was prepared under the same condition. Furthermore, combining the special nanostructure of Au surface-modified nanoporous-single-crystalline SrTiO3 with photocatalytic properties, estimation of the diffusion mean free path of SPR-induce photoelectron can be achieved. This study proposes an alternative approach to enhance the photoactivity of plasmonic photocatalyst via fine designing the semiconductor substrate.

Effect of Crystal Growth Direction on Domain Structure of Mn-Doped (Na,K)NbO3 Crystal

Single crystals of (Na0.55K0.45)(Nb0.995Mn0.005)O3 have been grown by a floating zone method in N2 and decompression atmosphere to avoid alkaline metal volatilization on the SrTiO3 material base. The variation of their ferroelectric domain structure and the chemical composition of the grown crystal in the growth direction were evaluated. In the crystal grown in N2 atmosphere, the Na and K are not distributed homogeneously. In addition, the phase transition temperature TC and TO–T showed different values between the grown crystal and raw material. By using laser scanning confocal microscope, the domain structures of the grown crystal revealed random patterns in the initial growth stage and lamellar patterns in the progressing crystal growth. In decompression atmosphere, the TC and TO–T values of the grown crystal were similar to those of the raw material and the domain structures showed a constant domain size. The electrical property of the crystal became stable and the domain structure was easily switched against applied electrical field because the oriented lamellar domain was created during cooling of the crystal.

Structure and dielectric properties of (Sr1−1.5xBix)TiO3 thin films

Bismuth doped SrTiO3 material has shown very interesting phenomena. Dielectric and ferroelectric relaxations have been recently reported in bismuth doped SrTiO3 ceramics in the lower temperature range. Thin films of bismuth doped SrTiO3 [(Sr1−1.5xBix)TiO3] (x=0.0,0.05,0.10) have been prepared by a sol-gel method and investigated in this work. The phases and surface morphologies of thin films were analyzed to assess the structures and crystallization. The structure of the thin films is revealed as a cubic perovskite structure with no other phase detected. The dielectric properties and dielectric tunability of (Sr1−1.5xBix)TiO3 thin films have been studied as a function of doping amount of bismuth and discussed in detail.

Microstructure and dielectric properties of Li2CO3 doped 0.7(Ba,Sr)TiO3–0.3MgO ceramics

Microstructure and dielectric properties of Li2CO3 doped 0.7(Ba,Sr)TiO3–0.3MgO ceramics for the low temperature sintering and microwave applications will be presented. In these days, low temperature sintering process has been widely spread out for the integrated electronic modules for the communication systems such as front-end modules, antenna modules, and switching modules. We have added Li2CO3 and MgO to (Ba,Sr)TiO3 material to reduce the sintering temperature and improve dielectric properties such as loss tangent, and frequency dispersion.In this paper, we have discussed the crystalline properties, dielectric properties, and the microstructures of Li2CO3 doped 0.7(Ba,Sr)TiO3–0.3MgO ceramics. No pyro phase was observed in the X-ray diffraction method. Very weak frequency dispersion (<0.7%) of dielectric permittivity was observed from the 1kHz to 1MHz range. We found that the grain size of BST is around 2μm, while the grain size of Li2CO3 dope 0.7BST–0.3MgO is around 4μm from the SEM analysis.

Interpretation of surface textural changes in SrTiO3 ex‐oxalate samples using XPS and IR spectroscopies

AbstractXPS, IR and x‐ray diffraction (XRD) have been used to study high‐surface‐area ‘ex‐oxalate’ polycrystalline SrTiO3 materials. Changes of surface area and pore size distribution are induced during lixiviation with a 0.1 M HCl solution, which removes carbonate impurities. The study shows the presence in the original sample of a microcrystalline SrCO3 phase at its surface and isolated CO species, these latter remaining even after outgassing at 773 K for 15 h. However, a complete elimination of the SrCO3 and other carbonate species at the surface is achieved by heating the acid‐lixiviated sample at 773 K, although carbonate species still remain in the bulk of the SrTiO3 material after this treatment. The usefulness of the combined use of XPS and IR for the characterization of surface and bulk species in this type of powdered material is pointed out during this study.