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Effect of SrTiO <sub/>3</sub> oxygen vacancies on the conductivity of LaTiO <sub/>3</sub> /SrTiO <sub/>3</sub> heterostructures
摘要： In this work, we report the formation of a conductive layer through oxygen vacancies in an underlying SrTiO3 (STO) layer due to the growth of LaTiO3 (LTO) and the resulting LTO thickness-dependent conductivity of the LTO/STO system. Crystalline LTO films were grown by molecular beam epitaxy on TiO2-terminated STO(001) single-crystal substrates and 8-unit-cell (u.c.) STO template layers grown on Ge(001), under partial pressures of molecular oxygen ranging from 10?10 to 10?7 Torr. Film crystallinity was studied by in situ reflection high-energy electron diffraction, ex situ X-ray diffraction, and ex situ transmission electron microscopy. Film composition and the existence of oxygen vacancies were confirmed by in situ X-ray photoelectron spectroscopy. LTO films grown on STO substrates at oxygen partial pressures of 10?10 Torr were optimally oxidized (1:1:3 La:Ti:O). However, LTO films grown on 8-u.c. templates of STO on Ge with oxygen partial pressures less than 10?7 Torr showed extensive reduction of the Ti oxide and desorption of Sr/SrO in the STO layer. LTO films began to over-oxidize when grown on STO single-crystal substrates at oxygen partial pressures greater than 10?10 Torr but were nearly optimally oxidized when grown on STO templates on Ge at oxygen partial pressures of 10?7 Torr. Electrical characterization showed a dependence of conductivity on the thickness of the LTO films, with sheet carrier densities reaching ～5 × 1016 cm?2 for 20-u.c. (8-nm-thick) LTO/STO grown at 10?10 Torr of oxygen, suggesting that significant conduction occurred throughout the STO substrate due to the formation of oxygen vacancies.
关键词： oxygen vacancies,conductivity,SrTiO3,molecular beam epitaxy,LaTiO3/SrTiO3 heterostructures
更新于2025-09-10 09:29:36
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Structure, dielectric behaviours, enhanced polarization responses and energy storage properties in (1???x)SrTiO3–xBi(Mg1/2Ti1/2)O3 ceramics
摘要： In this work, ceramics of (1 ? x)SrTiO3–xBi(Mg1/2Ti1/2)O3 (ST–BMT, x = 0.05–0.5) were successfully prepared. A single-phase perovskite structure is formed for all the compositions. The average structure is cubic at room temperature. The Raman analysis suggests that the 5 mol% BMT addition might cause the existence of the local tetragonal distortions at room temperature. All the compositions display a frequency-dependent and highly diffused dielectric anomaly. The BMT addition can effectively shift the freezing temperature (Tf), from ~ 32 K for x = 0.1 up to ~ 240 K for x = 0.5. The compositions with x = 0.4 and 0.5 show a small change in the relative permittivity (Δε′/??′373 K < ± 15% at 1 kHz) and keep low values of the dielectric loss (tanδ < 0.01 for x = 0.01 at 1 kHz) in the temperature range of 373–523 K. The BMT addition induces an enhancement of the polarization maxima. Among the compositions, 0.7ST–0.3BMT shows the optimum energy storage performance (Wrec, 0.78 J/cm3).
关键词： ceramics,energy storage,dielectric behaviour,SrTiO3,Bi(Mg1/2Ti1/2)O3
更新于2025-09-10 09:29:36
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Assembly of surface-defect single-crystalline strontium titanate nanocubes acting as molecular bricks onto surface-defect single-crystalline titanium dioxide (B) nanorods for efficient visible-light-driven photocatalytic performance
摘要： Ti3+ self-doped single-crystalline SrTiO3(cid:1)x nanocubes acting as molecular bricks are successfully assembled onto Ti3+ self-doping single-crystalline TiO2(cid:1)x(B) nanorods through an effortless two-step hydrothermal process coupled with an in situ solid-state chemical reduction method. SrTiO3(cid:1)x nanocubes act as molecular bricks, which are uniformly assembled onto the surface of TiO2(cid:1)x(B) nanorods due to lattice matching. The band gap of the resultant SrTiO3(cid:1)x/TiO2(cid:1)x(B) sample is (cid:3)2.97 eV, which exhibits excellent photocatalytic performance for the reduction of Cr(VI) and hydrogen production under visible light. The apparent rate constant k value for the photocatalytic reaction of SrTiO3(cid:1)x/TiO2(cid:1)x(B) for Cr(VI) reduction is (cid:3)8 times higher than that of white TiO2(B). The photocatalytic hydrogen production rate for SrTiO3(cid:1)x/TiO2(cid:1)x(B) is (cid:3)160.2 lmol g(cid:1)1 h(cid:1)1, which is (cid:3)5 times higher than that of white TiO2(B). The enhanced photocatalytic activity can be considered to be caused by a synergetic effect of heterojunction formation and the introduction of Ti3+ self-doping, which can not only facilitate the separation of photogenerated charge carriers between TiO2(cid:1)x(B) and SrTiO3(cid:1)x, but also broaden the photoresponse from the UV to visible-light region.
关键词： Photocatalysis,Heterojunction,Ti3+ self-doping,TiO2(B),SrTiO3
更新于2025-09-10 09:29:36
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Synthesis, Characterization of g-C3N4/SrTiO3 Heterojunctions and Photocatalytic Activity for Organic Pollutants Degradation
摘要： Perovskite-structure SrTiO3 (STO) and graphitic carbon nitride (g-C3N4, CN) have attracted considerable attention in photocatalytic technology due to their unique properties, but also suffer from some drawbacks. The development of composite photocatalysts that combine properties of the individual semiconductors with enhanced charge separation is the current major trend in the photocatalysis field. In this study, SrTiO3/g-C3N4 (CNSTO) composites with different ratios (10, 20, 30, 40 and 50% g-C3N4) were prepared with a sonication mixing method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 porosimetry, Fourrier transform infra-red spectroscopy (FT-IR), UV-Vis diffuse reflectance (DRS) and dynamic light scattering (DLS). STO spherical particles were successfully loaded on the g-C3N4 planes forming heterojunction composite materials. The photocatalytic activity was tested against the degradation of methylene blue (MB) dye under simulated solar light (SSL) irradiation following first-order kinetics. The photocatalytic activity followed the trend: 20CNSTO > 30CNSTO > 40CNSTO > 50CNSTO ≈ 10CNSTO, in accordance with the amount of ?OH radicals determined by fluorescence spectroscopy. A Z-scheme mechanism was proposed for the enhanced photocatalytic degradation of MB as evidenced by trapping experiments with scavengers. Finally, significant stability and reusability was exhibited, indicating that such composites are of potential interest for photocatalytic treatments under sunlight irradiation.
关键词： composites,heterojunction,Z-scheme,g-C3N4/SrTiO3,photocatalysis
更新于2025-09-10 09:29:36
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Review of photoresponsive properties at SrTiO <sub/>3</sub> -based heterointerfaces
摘要： The two-dimensional electron gas at SrTiO3-based heterointerfaces has received a great deal of attention in recent years owing to their potential for the exploration of emergent physics and the next generation of electronics. One of the most fascinating aspects in this system is that the light, as a powerful external perturbation, can modify its transport properties. Recent studies have reported that SrTiO3-based heterointerfaces exhibit the persistent photoconductivity and can be tuned by the surface and interface engineering. These researches not only reveal the intrinsic physical mechanisms in the photoresponsive process, but also highlight the ability to be used as a tool for novel all-oxide optical devices. This review mainly contraposes the studies of photoresponse at SrTiO3-based heterointerfaces.
关键词： persistent photoconductivity (PPC),complex oxides,two-dimensional electron gas,LaAlO3/SrTiO3 heterointerfaces
更新于2025-09-10 09:29:36
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Structure and properties of Mn3O4 thin films grown on single crystal substrates by chemical vapor deposition
摘要： Mn3O4 thin films were fabricated on SrTiO3(111) and Y3Al5O12(100) substrates by chemical vapor deposition (CVD) under O2 atmospheres, starting from a fluorinated Mn(II) diketonate-diamine adduct. The obtained systems were investigated by a multi-technique characterization in order to elucidate the interplay between preparation conditions and their chemico-physical properties. The results highlighted the formation of phase-pure and homogeneous a -Mn3O4 (haussmannite) films, characterized by a smooth morphology, an appreciable Vis light absorption and structural features directly dependent on the used substrate. The target systems were uniformly doped with fluorine, due to the used Mn compound acting as a single-source precursor for both Mn and F. In addition, magnetic force microscopy measurements revealed the formation of spin domains and long-range magnetic order in the target materials, paving the way to their future implementation as magnetic media toward device integration for data storage.
关键词： Y3Al5O12(100),SrTiO3(111),Mn3O4 thin films,chemical vapor deposition,magnetic materials
更新于2025-09-10 09:29:36
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Effect of the Gamma-Ray Irradiation on the Electric and Optical Properties of SrTiO3 Single Crystals
摘要： We investigated the visible emission property of SrTiO3 (STO) single crystals irradiated with gammy-ray (γ-ray) at various total doses up to 900 kGy. The electric and optical absorption properties of the irradiated STO samples were hardly changed with the γ-ray irradiation, compared with those of un-irradiated STO. In contrast, the visible emission near 550 nm increased with the γ-ray dose increasing. While the development of the visible emission was indicative of the increase of oxygen vacancies inside STO by the γ-ray irradiation, the newly generated oxygen vacancies were not significantly harmful to the electric and optical properties of STO. We concluded that the STO single crystal should have a good tolerance against the damage by the γ-ray irradiation.
关键词： Gamma-ray irradiation,Photoluminescence,Oxygen vacancy,SrTiO3 single crystal
更新于2025-09-10 09:29:36
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First-principles investigation of the interface magnetic anisotropy of Fe/SrTiO<sub>3</sub>
摘要： Interface effects in the magnetic nanostructures play a critical role in the magnetic properties. By using the first-principles density functional theory calculations, we investigate the electronic and magnetic properties of Fe/SrTiO3 interfaces, in which both the nonpolar surface SrTiO3(001) and the polar surface SrTiO3(110) are considered. A particular emphasis is placed on the magnetic anisotropy energy (MAE). Compare MAE of the Fe/SrTiO3 interfaces and the corresponding Fe monolayers, we find the Fe/SrTiO3(001) interface decreases MAE, while the Fe/SrTiO3(110) interface increases MAE. The interface orbital hybridization and orbital magnetic moments are detailly analyzed to understand the different interface magnetic anisotropy. Our investigation indicates that interface engineering can be an effective way to modulate the magnetic properties.
关键词： Fe/SrTiO3 interfaces,interface orbital hybridization,first-principles calculations,magnetic anisotropy energy
更新于2025-09-09 09:28:46
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A Comparative Analysis of BaTiO3/(Ba,Sr)TiO3 and BaTiO3/(Ba,Sr)TiO3/SrTiO3 Artificial Superlattices via Raman Spectroscopy
摘要： BaTiO3/Ba50Sr50TiO3 and BaTiO3/Ba50Sr50TiO3/SrTiO3 superlattices are characterized via Raman spectroscopy. Special attention is paid to a comprehensive analysis of their polarized Raman spectra, especially, within a soft mode (E(1TO)) range. The shift of E(1TO) soft mode is found to be more pronounced for BaTiO3/Ba50Sr50TiO3/SrTiO3 sample than for BaTiO3/Ba50Sr50TiO3, presumably owing to stronger 2D compression of BT layers and abruptly increased temperature of transition from ferroelectric to paraelectric phase.
关键词： BaTiO3/Ba50Sr50TiO3/SrTiO3 ferroelectric superlattices,Raman spectroscopy,soft mode,strain,BaTiO3/Ba50Sr50TiO3
更新于2025-09-09 09:28:46
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Decoration of SrTiO3 nanofibers by BiOI for photocatalytic methyl orange degradation under visible light irradiation
摘要： BiOI decorated electrospun SrTiO3 nanofibers (BE) with a spiky club structure were fabricated using a rapid microwave-assisted solvothermal method. The exposed (102) plane of BiOI preferentially coupled with the electrospun SrTiO3 fibers aiming to achieve charge neutrality. XRD analysis demonstrated that a BE composite coupled with an optimal content of BiOI exhibited few crystal imperfections. The resulting BE samples showed a higher degradation efficiency towards methyl orange dye under visible light irradiation (λ > 400 nm) compared to the individual BiOI and SrTiO3. The BE composite possessed a high degradation rate of 0.015 (kapp, min–1) and a normalized rate constant of 2.46 × 10–3 (kapp/surface area), which was 7.7 and 1120 times higher than those of BiOI and SrTiO3 alone, and a degradation level over 94.6% within 3 h of irradiation under visible light. The high photocatalytic activity could be attributed to the heterostructure formation, p-n junction at the BE interface, high contact between water and dye molecules with the BiOI covered surface, and extended visible light absorption. This work provides an effective approach to produce BE nanofibers for dealing with methyl orange dye and proves that BE composites have the potential to serve as visible-light-driven photocatalysts.
关键词： Visible light irradiation,Photocatalyst,SrTiO3,BiOI,Nanofiber
更新于2025-09-09 09:28:46