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This year marks the 20th anniversary of the discovery of LaAlO3/SrTiO3 (LAO/STO) oxide heterointerfaces. Since their discovery, transition metal oxide (TMO) interfaces have emerged as a fascinating and fast‐growing area of research, offering a variety of unique and exotic physical properties which has provided a strong impetus for the rapid advances and actualization of oxide electronics. This review revisits the fundamental mechanisms accounting for the two‐dimensional (2D) conducting interfaces, and how new models proposed to better account for the unique interfacial effects. Recent breakthroughs in the theoretical and experimental domains of oxide interfaces are also discussed including the detection and investigation of 2D quasiparticle. Moving beyond the well‐known LAO/STO interface, this review delves into other systems where unconventional interfacial superconductivity, interfacial magnetism, and spin polarization are dealt with in greater detail. In terms of device applications, this review proceeds with a treatment on the recent developments in domains including field effect transistors and freestanding heterostructure membranes. By emphasizing the opportunities and challenges of integrating oxide interfaces with existing technologies, the review will end off with an outlook projecting the progress and the trajectory of this research domain in the years to come. [ABSTRACT FROM AUTHOR]

Magnetically coupled resonant wireless power transmission technology (WPT) based on high-temperature superconducting (HTS) coils has gained wide popularity due to its low impedance and high-quality factor Q value characteristics. This technology has greatly improved the energy transfer performance of wireless power transmission (WPT) systems. However, practical applications of conventional WPT, such as wireless charging of autonomous underwater vehicles at mooring points, often encounter spatial misalignment issues due to the complex ocean environment and ocean currents. Nonetheless, few studies have investigated the spatial misalignment of HTS WPT systems, particularly the angular misalignment. This paper presents a solution to address this problem by constructing magnetically coupled resonant wireless energy transmission systems based on HTS coils and copper coils. The study analyzes the relationship between the transmission efficiency of the WPT system and the received power of the load with respect to the spatial orientation of the coil. The performance of the superconducting coil and copper coil WPT systems is compared. The experimental results demonstrate that, under the same spatially misaligned conditions, the WPT system using HTS coils can significantly improve the transmission efficiency and load power compared to the conventional copper WPT system. Moreover, simultaneous adjustment of the lateral misalignment distance and different orientation deflection angles can improve the transmission efficiency and smooth load output power of the high-temperature superconducting WPT system. [ABSTRACT FROM AUTHOR]

The present work reports our efforts to enhance the performance and uniformity for the long tapes of metal–organic deposition YBa2Cu3O7−x (MOD-YBCO) layer on ion-beam-assisted deposition MgO (IBAD-MgO) template. Reflection High-energy electron diffraction (RHEED) is employed to realize the in-situ growth monitor of IBAD-MgO, as well as the correlation between the quantitative RHEED peaks and in-plane texture of Epi-MgO identified by XRD, which is an effective guide to improve the uniformity and performance of long YBCO tapes. In addition, the surface of the LMO layer during the magnetron sputtering process is improved via controlling the O2 flux, and then the critical-current density (Jc) of YBCO films has been improved. By optimizing the texture of the MgO layer and precisely controlling the LMO layer growth conditions, the performance and uniformity of YBCO-coated conductors grown by metal–organic deposition (MOD) have been greatly enhanced. The superconducting current-carrying capacities of 12-mm-wide tapes have upgraded steadily from 400–500 A to 500–550 A in past 3 years. The laminated CC tapes with current-carrying capacities of 150–170 A per 4-mm width show good uniformity and high quality along 500-m length, implying being promising for various commercial power applications. [ABSTRACT FROM AUTHOR]

The perovskite membrane with large particle size, uniform coverage and high quality is the prerequisite for the preparation of efficient and stable perovskite solar cells. Various additives have been used to increase the grain size and improve the film morphology and crystal quality. In this paper, methylammonium chloride (MACl) was proposed to obtain high crystalline quality of ( FAPbI 3) 0. 8 5 ( MAPbBr 3) 0. 1 5 perovskite absorption layer. The results show that the adding ammonium methyl chloride into the precursor of tricationic perovskite not only passivates surface defects to form high-quality and large-grain perovskite films, but also facilitates the formation of pure α -phase FAPbI 3 . Meanwhile, the designed perovskite precursor solutions were used to fabricate mesoporous perovskite solar cells (PSCs). Owing to the perovskite layer consisting of optimized MACl doping, the short-circuit current density (J sc ) of PSCs reaches 23.81 mA/cm2, which is 2.73 mA/cm2 higher than the primary ( FAPbI 3) 0. 8 5 ( MAPbBr 3) 0. 1 5 based on PSCs. The obtained power conversion efficiency (PCE) increases from 13.67% to 17.59%. [ABSTRACT FROM AUTHOR]

The screening current induced in superconductors can passively shield external magnetic fields and hence provide a noise free environment for precision sensors and instruments. This paper presents a novel design employing artificial joint-free REBCO (REBa2Cu3O7-x, RE: rare earths) coils which can economically extend the field shielding space for larger instruments, e.g. clinical equipment. We compared the shielding factors of single, double and multi-coils, and confirmed a coil with Helmholtz construction as the optimal architecture. Due to the zero resistance of the joint-free REBCO coils, the shielding effectiveness reaches 80 dB at the center of coils, shielding 99.99% of the external magnetic field of 10 μT at 1 × 10−5 Hz, and 40 dB (99%) in a greater spherical space of 40 mm in diameter. Additionally, the shielding effectiveness does not decrease in the external magnetic field of 1 nT. Such a low frequency magnetic shielding effect implies promising applications for the present work, such as preventing interference magnetic fields from precision instruments, which generally require field sensitivity as low as the fT · Hz−1/2 range. [ABSTRACT FROM AUTHOR]

LaMnO3−δ (LMO) films with different oxygen contents are deposited on Epi-MgO/IBAD-MgO templates using reactive magnetron sputtering under varying temperatures and atmospheres. Subsequent YBa2Cu3O7−δ (YBCO) films are grown on LMO layers by metal-organic deposition (MOD) method. X-ray diffraction measurements reveal that YBCO texture cannot be further improved when the full width at half maximum (FWHM) values of LMO (011) φ-scans (evaluation on in-plane alignment) and LMO (002) ω-scans (evaluation on out-of-plane alignment) for LMO films are less than 8° and 4°, respectively. Sharp orientation with in-plane FWHM value of <3° for YBCO (103) φ-scan and out-of-plane FWHM value of <1.5° for YBCO (006) ω-scan can typically be achieved in YBCO films. Precise control of growth conditions, especially atmosphere, remains a feasible way to modify the surface of LMO films. It induces changes in oxygen content, lattice structure and surface morphology of LMO, and further affects the epitaxial growth of superconducting layers. Oxygen-deficient LMO with expanded lattice parameters and flat surface can effectively suppress the non-c-axis oriented YBCO, thereby enhancing the current carrying capability. The 500 m long YBCO coated conductors with conditioned LMO layers have an inductive critical current (Ic) ranging from 358 to 437 A/12 mm width with an average value of 398 A/12 mm width. [ABSTRACT FROM AUTHOR]

Blended cathode materials generally suffer from capacity loss impacting on their power performance in lithium-ion batteries. This work reports a systematic study of LiNi1/3Co1/3Mn1/3O2–LiMn2O4 blended materials incorporated with characterizations of particles, calculations of charging-discharging characters, and analysis of cyclic voltammetry. A synergetic effect, a capacity increasing at high discharging rate referring to the linear superposition of blending components, is observed in a wide blending ratio for blended materials. The model analysis of charging-discharging characters shows that LiMn2O4 releases more reversible capacity in the blended materials than when it is alone at the same electrochemical condition. An equivalent circuit model is proposed to interpret the electrochemical behaviors showed in electrochemical impedance spectroscopy. The mechanism of particle synergetic effect is attributed to the compensating property of blending components, which improves the inter-particles diffusibility of Li+, therefore reduces the particle impedance of blended materials promoting rate performance. Over the blending range, the scheme LiNi1/3Co1/3Mn1/3O2/LiMn2O4–Blend (50:50 in mass ratio) shows the best performance and highest capacity increasing. [ABSTRACT FROM AUTHOR]

Polyethyleneimine (PEI) with an amount of -NH2 groups used in precursor solution could effectively reduce Cu2+ volatilization during the pyrolysis process. Thermogravimetric analysis shows that the temperature window of low-temperature pyrolysis for precursor solution with PEI (PEI-YBCO) is widened significantly. The slower pyrolysis process can enrich Cu2+ and improve critical current density (Jc) of PEI-YBCO films. The highest Jc is 3.03 MA/cm2 at 77 K when the amount of PEI is 0.5 g/10 mL and the film thickness is 400 nm. Then the thickness increases from 0.4 to 2.0 μm by changing the coating times. The Jc values of PEI-YBCO films decrease gradually with the thickness increase. However, the critical current (Ic) can be up to 197 A/cm (at 77 K, self-field) and Jc can still keep 1.68 MA/cm2 at 1.2 μm. [ABSTRACT FROM AUTHOR]

Bilayered YDy0.5Ba2Cu3.6O7−δ superconducting films with a thickness of about 1 μ were deposited by metallorganic deposition method, an interlayer of secondary phase of SrZrO3 (SZO) and BaZrO3 (BZO) were inserted. Detailed growth mechanism studies of these structures as well as superconducting properties in different temperatures and magnetic field range (0-5 T) were investigated. Structural analysis showed that bilayer structure changed clearly the growth mechanism of YBCO. The SZO interlayer smoothens the film surface. Magnetic measurements of superconducting properties demonstrated that the critical temperature decreases slightly when both of SZO and BZO interlayer were inserted. This indicates a growing strain effect at the layer interfaces. The critical current densities as well as pining forces of bilayered YDy0.5Ba2Cu3.6O7−δ in the entire applied temperature and magnetic field range were enhanced by the insertion of SZO layer and decreased when BZO layer is introduced. The enhancement of the pinning properties is explained by the dense flux pinning in layered YDyBCO superconductors; this result may give further improvements in the current-carrying capability. [ABSTRACT FROM AUTHOR]

An effective soldering process of second-generation coated conductors (CCs) with low joint resistance was presented by using home-made equipment in the present study. The benefit of preprocessing, i.e., polishing, was proved with respect to the reduced joint resistances based on the voltage–current curves. It is revealed that the joint resistance of 10-8 Ω with an overlapping length as short as 2 cm can be achieved, while the joint resistances would further decrease with increasing the overlapping area, in agreement with Ohm's law. In the case of the overlapping length of 8 cm, the order of nΩ can be achieved for the resistances of solder joints. The heating time in joint fabrication process can be shortened to 1 min without negative effects on joint resistance, speeding up the soldering process largely. The effectiveness was evidenced further by the hard degradation in Ic through the joint part of the studied tapes and the enhanced adhesion between solder layer and Cu layer according to the cross-section observation. Temperature dependence of the joint specimen resistances suggested that the lattice constant of superconducting layer after jointing may be preferable to attain a higher critical temperature than that of original tape. The fragmentation of the superconducting layer and decohesion of the interface between hastelloy/buffer and ceramic layers, not the Cu-solder interface for the joint by external force, implied that the valid soldering was achieved using the present process. [ABSTRACT FROM PUBLISHER]

BaHfO (BHO) has been proposed as a new cap layer material for YBaCuO (YBCO) coated conductors. Highly c-axis oriented BHO cap layer has been deposited on ion-beam assisted deposition-MgO buffered Hastelloy tapes by direct-current-magnetron sputtering method. The epi-growth of BHO films combined with its properties is investigated in details. The degenerated cubic crystal structure of BHO film is confirmed by Raman spectrum analysis. XRD θ-2θ scan, φ-scan and ω-scan reveal an excellent c-axis alignment with good in-plane and out-of-plane textures for BHO cap layers. SEM and AFM investigations show BHO cap layer a dense and crack-free morphology. Subsequently pure c-axis orientation YBCO film was epitaxial grown on such BHO cap layer successfully, shown BaHfO a potential cap layer material for coated conductors. [ABSTRACT FROM AUTHOR]

We report a mild template-free hydrothermal route for selective synthesis of SnO2 hollow microspheres and nano-sheets using SnCl2 and NaOH as initial materials. By switching the solvent from water to ethanol, the formed SnO2 nanostructures changed from nano-sheets to hollow microspheres. The obtained nano-sheets were single crystalline in structure. On the basis of the characterization of intermediate products, the formation of SnO2 hollow microspheres was ascribed to a crystal growth process, while the formation of SnO2 nano-sheets was ascribed to the oxidation of SnO2 sheets during the hydrothermal process. Further characterization of the SnO2 hollow microspheres and nano-sheets by X-ray photoelectron spectroscopy and UV-Vis absorption spectroscopy reveals different optical absorption properties and valence band electronic structures. In addition, the SnO2 nano-sheets and hollow microspheres exhibit different sensing properties. The present work provides a facile and simple template-free method for the synthesis of nano-structured SnO2. [ABSTRACT FROM AUTHOR]

Abstract: Square SnO2 nano-sheets have been successfully synthesized by a template-free hydrothermal method basing on the reaction between SnCl2 and NaOH in ethanol/water solution. The products have been characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. The size and morphology of nano-sheets could be controlled by changing the ratio of ethanol to water. Compared experiments showed that the addition of NaOH was crucial to the formation of SnO2 nano-sheets, and the addition of glycol could induce the formation of cabbage-like structure. The nano-sheets show a strong absorption peak around 330 nm, corresponding to a band gap value of 3.75 eV. This blue shift of the band gap energy was possibly induced by the spatial confinement of excitons in the nano-sheet structures. [Copyright &y& Elsevier]

• The offset characteristics of HTS wireless power transfer (WPT) system was investigated systematically. • The transfer efficiency decreases monotonically with the increase of offset distance. A "flat top" exists in transfer efficiency at short-range radial offset, benefiting the practical applications. • The relationship between load receiving power (LRP) and offset distance is not monotonic. There is an optimal position to reach corresponding maximum LRP. • The HTS WPT system exhibits superior performance in both transfer efficiency and LRP than the copper WPT system. The usage of high-temperature superconducting (HTS) coils in magnetically-coupled resonant wireless power transfer (WPT) systems can considerably improve the transfer efficiency, and hence it attacked great attention. However, there are few studies on offset characteristics in HTS WPT systems. In order to further improve the performance of HTS WPT systems, we have studied experimentally the influences of relative displacement of the coils on the transfer efficiency and load receiving power (LRP) in a magnetically-coupled resonant WPT system. The WPT systems using copper coils and HTS coils were carefully compared. The results show that the transfer efficiency decreases monotonically with the increasing offset. However, there is an optimal position for the LRP to achieve the maximum value. Both the transfer efficiency and LRP of the HTS WPT system are higher than those of the copper WPT system under the same conditions. [ABSTRACT FROM AUTHOR]

It is demonstrated that electrodeposition is a promising cost-effective technique to grow oxide buffer on metallic tapes. The resultant layer of CeO2 shows the biaxial texture of FWHM = 5.5° as well as a smooth surface of RMS = 2.0 nm, and YBa2Cu3O7−δ coated conductor with such a buffer exhibits the critical current density of 1.85 MA cm−2 at 77 K. Of more interest is that the CeO2 film thickness reaches a high value of more than 200 nm without any cracks, while it is very hard to achieve a thickness of more than 70 nm in the conventional vapor deposition methods employed. [ABSTRACT FROM AUTHOR]

Substrate engineering is very significant in the synthesis of the high-temperature superconductor (HTS) coated conductor. Here we design and synthesize several distinct and stable Cerium oxide (CeO 2 ) surface reconstructions which are used to grow epitaxial films of the HTS YBa 2 Cu 3 O 7-δ (YBCO). To identify the influence of annealing and post-annealing surroundings on the nature of nucleation centers, including Ar/5%H 2 , humid Ar/5%H 2 and O 2 in high temperature annealing process, we study the well-controlled structure, surface morphology, crystal constants and surface redox processes of the ceria buffers by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electronic microscopy (FE-SEM), respectively. The ceria film post-annealed under humid Ar/5%H 2 gas shows the best buffer layer properties. Furthermore, the film absorbs more oxygen ions, which appears to contribute to oxygenation of superconductor film. The film is well-suited for ceria model studies as well as a perfect substitute for CeO 2 bulk material. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the preparation of nano-composite W–La2O3 material by freeze-drying and spark plasma sintering (SPS). The thermionic electron emission capability and surface properties of this material have been investigated. The surface compositions and depth profiles of the prepared material were checked “in situ” by means of AES from 298K to 1573K. Nano-composite W–La2O3 material exhibits good electron emission performance: a saturated emission current density of 1.46Acm−2 can be reached at 1673K with a corresponding work function of 2.79eV. The surface analysis results showed that the good emission capability might be related to an about 10nm surface layer contained excess La caused by diffusion of La from bulk material to the surface. [Copyright &y& Elsevier]

Abstract: Sn2O3-based NO gas sensors were fabricated and investigated in this study. The sensor doped by 1.0at.% antimony had a maximal response to NO gas at 473K. The NO gas with a concentration down to 10ppm can be detected by the sensor without any cross sensitivity to the interfering species such as NO2 and CO. The response speed was shortened about 5.7 times after mixing the 10.0wt.% SnO2 nanoparticles into the 1.0at.% Sn2O3:Sb gas sensor, which was resulted from the formation of Sn2O3–SnO2 hetero-junction. This kind of mixed-oxides gas sensor showed good response to NO gas, weak response to NO2 gas and unstable response to CO gas. [Copyright &y& Elsevier]

Owing to its inherent non-trivial geometry, the unique structural motif of the recently discovered kagome topological superconductor AV 3 Sb 5 (A = K, Rb, Cs) is an ideal host of diverse topologically non-trivial phenomena, including giant anomalous Hall conductivity, topological charge order, charge density wave (CDW), and unconventional superconductivity. Despite possessing a normal-state CDW order in the form of topological chiral charge order and diverse superconducting gaps structures, it remains unclear how fundamental atomic-level properties and many-body effects including Fermi surface nesting, electron-phonon coupling, and orbital hybridization contribute to these symmetry-breaking phenomena. Here, the direct participation of the V3d-Sb5p orbital hybridization in mediating the CDW phase transition in CsV 3 Sb 5 is reported. The combination of temperature-dependent X-ray absorption and first-principles studies clearly indicates the inverse Star-of-David structure as the preferred reconstruction in the low-temperature CDW phase. The results highlight the critical role that Sb orbitals play and establish orbital hybridization as the direct mediator of the CDW states and structural transition dynamics in kagome unconventional superconductors. This is a significant step toward the fundamental understanding and control of the emerging correlated phases from the kagome lattice through the orbital interactions and provides promising approaches to novel regimes in unconventional orders and topology., (© 2022 Wiley-VCH GmbH.)

BaHfO 3 (BHO) has been proposed as a new cap layer material for YBa 2 Cu 3 O 7-δ (YBCO) coated conductors. Highly c-axis oriented BHO cap layer has been deposited on ion-beam assisted deposition-MgO buffered Hastelloy tapes by direct-current-magnetron sputtering method. The epi-growth of BHO films combined with its properties is investigated in details. The degenerated cubic crystal structure of BHO film is confirmed by Raman spectrum analysis. XRD θ-2θ scan, φ-scan and ω-scan reveal an excellent c-axis alignment with good in-plane and out-of-plane textures for BHO cap layers. SEM and AFM investigations show BHO cap layer a dense and crack-free morphology. Subsequently pure c-axis orientation YBCO film was epitaxial grown on such BHO cap layer successfully, shown BaHfO 3 a potential cap layer material for coated conductors.