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Nanoscale temperature measurement during temperature controlled in situ TEM using Al plasmon nanothermometry
摘要： Over recent years, the advent of microelectromechanical system (MEMS)-type microheaters has pushed the limits of temperature controlled in situ transmission electron microscopy (TEM). In particular, by enabling the observation of the structure of materials in their application environments, temperature controlled TEM provides unprecedented insights into the link between the properties of materials and their structure in real-world problems, a clear knowledge of which is necessary for rational development of functional materials with new or improved properties. While temperature is the key parameter in such experiments, accessing the precise temperature of the sample at the nanoscale during observations still remains challenging. In the present work, we have applied aluminium plasmon nanothermometry technique that monitors the temperature dependence of the volume plasmon of Al nanospheres using electron energy loss spectroscopy for in situ local temperature determination over a MEMS microheater. With access to local temperatures between room temperature to 550°C, we have assessed the spatial and temporal stabilities of the microheater when it operates at different setpoint temperatures both under vacuum and in the presence of a static H2 gas environment. Temperature comparisons performed under the two environments show discrepancies between local and setpoint temperatures.
关键词： in situ transmission electron microscopy,electron energy loss spectroscopy,volume expansion of metal,local temperature determination,volume plasmons shift
更新于2025-09-12 10:27:22
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Diffusion of Oxygen and Nitrogen into Titanium under Laser Irradiation in Air
摘要： This paper examines the dynamic interactions between pure titanium and ambient air under transient laser processing conditions. The microstructures and composition distributions of the reaction products on and within the titanium samples are reported, which lead to the estimation of high-temperature diffusion coefficients for nitrogen and oxygen into the titanium substrate. In-situ synchrotron X-ray diffraction testing is conducted to reveal the high temperature reaction steps between titanium and air. The formation mechanisms of both titanium nitrides and titanium oxides are discussed.
关键词： titanium oxidation,titanium nitridation,synchrotron X-ray diffraction.,in-situ phase transformation,laser irradiation
更新于2025-09-12 10:27:22
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Structural evolution of fused silica below the glass-transition temperature revealed by in-situ neutron total scattering
摘要： The common belief that glass structure is completely frozen-in at room temperature is challenged at both macroscopic and atomic scales. Here, we demonstrate an analytical method to elucidate the fine details of a continuous structural change of fused silica (FS) at temperatures below the glass-transition temperature using in-situ neutron total scattering. We find that the SiO4 tetrahedron expands through the entire temperature range with a local coefficient of thermal expansion of 9.1 × 10?6 K?1, while the average medium-range distance, derived from the first sharp diffraction peak of the structure factor, expands at a rate of 21 × 10?6 K?1. Such an expansion difference reflects glass-structure changes within the "rigid-unit mode" model, where each tetrahedron behaves as a rigid unit and the flexible rotations between rigid units lead to more than two times higher medium-range thermal expansion. We further demonstrate that such rotations change the shape of individual rings, leading to a measurable change in the first sharp diffraction peak (FSDP). This study paves the way to measure the structural changes of other silicate glasses, especially through the glass transition.
关键词： Structural change of fused silica,Short- and medium-range structure,In-situ neutron total scattering,First sharp diffraction peak,Rigid-unit mode
更新于2025-09-12 10:27:22
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In-situ stress modulated ferroelectric photovoltaic effect in cluster-assembled TbFe <sub/>2</sub> /Bi <sub/>5</sub> Ti <sub/>3</sub> FeO <sub/>15</sub> heterostructural films
摘要： TbFe2/Bi5Ti3FeO15 heterostructural ?lms were prepared by inserting cluster-assembled TbFe2 microdiscs into a Bi5Ti3FeO15 matrix using low energy cluster beam deposition combined with sol-gel methods. The phase structure, ferroelectric properties, bandgap, photovoltaic spectral response, and performances of the ferroelectric photovoltaic effect were modulated by the in situ stress driven by magnetostriction of TbFe2 clusters under external magnetic ?elds. The short-circuit current, open-circuit voltage, and power conversation ef?cient increase with the in situ stress, reaching 0.026 mA/cm2, 9.5 V, and 5.88 (cid:2) 10(cid:3)2%, respectively, under a maximum in-stress of 0.075 GPa. So the high open-circuit voltage above bandgap is attributed to the distinct bandgap shifting and the effective separation of photogenerated electron-hole pairs derived from the in situ stress induced large built-in ?eld. The in situ stress dominated symmetry breaking contributes to the improvement of the power conversation coef?cient. The in situ dynamic internal stress provides a high ef?cient approach to modulate and improve ferroelectric photovoltaic effects.
关键词： magnetostriction,in situ stress,ferroelectric photovoltaic effect,bandgap shifting,TbFe2/Bi5Ti3FeO15 heterostructural films
更新于2025-09-12 10:27:22
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Plasmonic Microneedle Arrays for in situ Sensing with Surface-Enhanced Raman Spectroscopy (SERS)
摘要： Surface-enhanced Raman spectroscopy (SERS) is a sensitive, chemically specific, and short-time response probing method with significant potential in biomedical sensing. This paper reports the integration of SERS with microneedle arrays as a minimally invasive platform for chemical sensing, with a particular view towards sensing in interstitial fluid (ISF). Microneedle arrays were fabricated from a commercial polymeric adhesive and coated with plasmonically active gold nanorods that were functionalized with the pH-sensitive molecule 4-mercaptobenzoic acid. This sensor can quantitate pH over a range of 5 to 9 and can detect pH levels in an agar gel skin phantom and in human skin in situ. The sensor array is stable and mechanically robust in that it exhibits no loss in SERS activity after multiple punches through an agar gel skin phantom and human skin or after a month-long incubation in phosphate-buffered saline. This work is the first to integrate SERS-active nanoparticles with polymeric microneedle arrays and to demonstrate in situ sensing with this platform.
关键词： SERS,agar gel skin phantom,pH in situ sensing,human skin,Plasmonic microneedle arrays
更新于2025-09-12 10:27:22
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Exploring the Ti-5553 phase transformations utilizing in-situ high-temperature laser-scanning confocal microscopy
摘要： Recently, the β metastable Ti-5553 alloy has attracted significant interest owing to the possibility of achieving excellent mechanical properties. In this study, for the first time, the Ti-5553 phase transformations were investigated using high-temperature laser-scanning confocal microscopy (HT-LSCM). During a continuous heating of an aged sample, the α phase dissolution was not clearly visible owing to the remaining grooves of former grain and interphase boundaries. However, a continuous cooling from the β field showed that the α phase precipitation started preferentially at grain boundaries. With the increase in cooling rate, the α precipitates became more refined and the supercooling necessary to promote allotriomorphic precipitation increased. At a cooling rate of 100 °C min-1, no α phase was observed in the analyzed field of view. A higher oxygen content was suggested to contribute to the microstructural differences between the free surface and bulk. The volume fraction of the α phase was lower than that obtained on the original surface at cooling rates of 5, 25, and 50 °C min-1, while only minor differences were observed at cooling rates of 100 and 250 °C min-1. The α phase precipitation was analyzed in detail. The HT-LSCM technique can be a useful method for the analyses of solid-state phase transformations in Ti alloys.
关键词： Titanium,In-situ,Ti-5553 alloy,HT-LSCM,Phase transformation,Microstructure
更新于2025-09-12 10:27:22
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Coherent Vibrational Spectroscopy of Electrochemical Interfaces with Plasmonic Nano-gratings
摘要： The fundamental understanding of electrochemistry urges accurate knowledge of all interfacial properties at the molecular-level, but the retrieval of such information is a real challenge. Optical spectroscopies facilitated by surface plasmon enhancement can shed light on this field, yet past studies relied on either highly inhomogeneous “hot spots”, or planar plasmon modes with limited enhancement. Here we report an in situ sum-frequency vibrational spectroscopy scheme using plasmonic nano-gratings, which enable strong, coherent surface plasmon excitation even on planar electrodes. With two classical reactions, the gold oxidation and pyridine adsorption in water, we demonstrate the realization of coherent vibrational spectroscopy in the strong absorption region, revealing the polar orientation and ordering of interfacial species that are crucial toward the mechanistic understanding of electrochemical phenomena.
关键词： field enhancement,surface plasmon resonance,molecular-level information,in situ spectroelectrochemistry,electrode/electrolyte interfaces
更新于2025-09-12 10:27:22
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In situ thermal conversion of graphene oxide films to reduced graphene oxide films for efficient dye-sensitized solar cells
摘要： Severe aggregation of reduced graphene oxide nanosheets and their weak adhesion to the conductive substrate largely restricts the electrocatalytic property. To overcome this flaw, we propose a simple strategy for fabrication of efficient reduced graphene oxide film through in-situ thermal conversion of graphene oxide film that is first adsorbed onto the conductive substrate. As compared to the reduced graphene oxide film prepared from the direct adsorption of reduced graphene oxide nanosheets, the reduced graphene oxide film obtained from the in-situ thermal conversion of graphene oxide film exhibits much higher electrocatalytic activity on the reduction of I3? due to the stronger adhesion to the conductive substrate and better film quality without aggregation. The thermal-converted reduced graphene oxide cathode produces much higher power conversion efficiency (6.35%) than that (1.20%) for the directly adsorbed reduced graphene oxide cathode. This work opens up a new avenue for preparation of simple and low-cost cathodes.
关键词： Reduced graphene oxide,Counter electrode,Graphene oxide,In situ thermal conversion,Dye-sensitized solar cell
更新于2025-09-12 10:27:22
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Stress-controlled decomposition routes in cubic AlCrN films assessed by in-situ high-temperature high-energy grazing incidence transmission X-ray diffraction
摘要： The dependence of decomposition routes on intrinsic microstructure and stress in nanocrystalline transition metal nitrides is not yet fully understood. In this contribution, three Al0.7Cr0.3N thin films with residual stress magnitudes of ?3510, ?4660 and ?5930 MPa in the as-deposited state were in-situ characterized in the range of 25–1100 °C using in-situ synchrotron high-temperature high-energy grazing-incidence-transmission X-ray diffraction and temperature evolutions of phases, coefficients of thermal expansion, structural defects, texture as well as residual, thermal and intrinsic stresses were evaluated. The multi-parameter experimental data indicate a complex intrinsic stress and phase changes governed by a microstructure recovery and phase transformations taking place above the deposition temperature. Though the decomposition temperatures of metastable cubic Al0.7Cr0.3N phase in the range of 698–914 °C are inversely proportional to the magnitudes of deposition temperatures, the decomposition process itself starts at the same stress level of ~?4300 MPa in all three films. This phenomenon indicates that the particular compressive stress level functions as an energy threshold at which the diffusion driven formation of hexagonal Al(Cr)N phase is initiated, provided sufficient temperature is applied. In summary, the unique synchrotron experimental setup indicated that residual stresses play a decisive role in the decomposition routes of nanocrystalline transition metal nitrides.
关键词： thin films,AlCrN,phase decomposition,thermal expansion,microstructure,in-situ XRD,residual stress
更新于2025-09-12 10:27:22
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Unusually Dispersed AgI Quantum Dots For Efficient HTL-free CH3NH3PbI3 Photovoltaics
摘要： The utilization of quantum dots (QDs) to improve the performance of perovskite solar cells (PSCs) is attracting much attention due to their unique optical and electronic properties. Most of QDs have to be prepared in advance and then incorporated into the perovskite hosts, which could not ensure the maintenance of their QD characteristics. In this work, we intelligently developed an in-situ preparation strategy to disperse AgI QDs homogeneously in perovskite host for MAPbI3:AgI(QDs) cross blended layer directly on ITO via a common and convenient spin-coating process. We combine transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and Raman techniques to demonstrate the cross blended MAPbI3:AgI (QDs) structure in the final perovskite devices. Furthermore, a series of simply inverted ITO/MAPbI3:AgI(QDs)/PCBM/Ag devices have been designed and fabricated. The photovoltaic performance of these solar cells show significantly improved short-circuit current density (Jsc) and a champion power conversion efficiency (PCE) of 16.41% even without a hole transport layer (HTL). The current technique induced the crystal growth toward high quality perovskite films with homogeneous structure, good crystallinity, less grain boundaries and defects, increased optical path length and uniform thickness for better solar cell performance. Besides, the impact of the current strategy also lies in a accommodation effect of the hole collection at the ITO side induced by AgI QDs, which modifies the Fermi level of perovskite films, leading to significantly decreased level difference in Fermi level/work function between the perovskite layer and ITO substrates by UPS analysis. More importantly, the charge carrier dynamics of such novel MAPbI3:AgI (QDs) structures were also scrutinized by transient photovoltage (TSPV) analysis.
关键词： in-situ preparation,AgI,quantum dots,MAPbI3:AgI,cross blended structure
更新于2025-09-12 10:27:22