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single crystal
摘要： We have investigated the hyperfine structure in high-resolution broadband optical absorption spectra of a strongly diluted paramagnet 7LiYF4 : Ho3+ (0.1 at. %) in external magnetic fields parallel to the tetragonal symmetry axis of the crystal. Anticrossings in the hyperfine spectral pattern were observed. It is the first direct observation of the hyperfine level anticrossings in optical spectra. Analysis of the spectral envelopes corresponding to transitions between the electron-nuclear sublevels of crystal-field non-Kramers doublets and singlets of the Ho3+ ions, based on the microscopic model of the electronic 4f 10 configuration, allowed us to retrieve information on the hyperfine structure of electronic singlets, nuclear quadroupole interactions, and random lattice strains.
关键词： LiYF4:Ho3+,hyperfine structure,hyperfine interactions,crystal-field,random strains,optical spectra,magnetic fields,anticrossings
更新于2025-09-23 15:23:52
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Room-temperature multiferroic and magnetodielectric properties of SrTiO3/NiFe2O4 composite ceramics
摘要： Various xNiFe2O4 ? (1-x)SrTiO3 (x = 0.04, 0.05, 0.1, 0.2) composite ceramics were prepared using sol–gel method and two-step calcination. The composite ceramics possessed no impurities and exhibited obvious magnetic properties (22.8 emu/g at x = 0.2). The magnetic second phase imposed strain effects on the SrTiO3 matrix to induce ferroelectricity. Strain values of (001) and (110) crystal planes were ~2.9% and ~1.3%. The tetragonal phase transition was evident in the Raman spectra. The remanent and maximum polarizations were 1.4 and 15.8 μC/cm2, respectively, in ceramic with 10 mol.% NiFe2O4. The dielectric permittivity was tuned with 1.6% change rate at 50 kHz and 10000 Oe.
关键词： Phase transition,Ferroelectricity,Strains,SrTiO3,Magnetodielectric
更新于2025-09-23 15:22:29
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Nucleation of Three-Dimensional Ge Islands on a Patterned Si(100) Surface
摘要： The nucleation of three-dimentional Ge islands formed on a pre-patterned Si substrate with an array of round pits is studied. It is found that the Ge islands nucleate within pits with pointed bottoms and along the perimeters of pits with flat bottoms. This effect is determined by the difference between the distributions of elastic strains at the Ge/Si interface for differently shaped pit bottoms. The results of the simulation of growth show that, in the case of pits with pointed bottoms, the most relaxed regions are at the centers of the pit bottoms and the nucleation of islands takes place just in these regions. At the same time, in the case of pits with flat bottoms, the most relaxed regions are shifted from the pit bottoms to the pit edges, resulting in the nucleation of islands along the pit perimeters.
关键词： three-dimensional Ge islands,patterned Si substrate,elastic strains,nucleation,Ge/Si interface
更新于2025-09-23 15:21:01
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Effects of Strains on Thermal Conductivity of Si/Ge Superlattices
摘要： The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics (NEMD) simulation. The thermal conductivities experienced a near linear drop with increasing tensile and compressive strains. It was explained by the fact that the decrease of the phonons velocities and a mass of structural defects generated under strains. Meanwhile, a theoretical calculation based on Modified-Callaway model was performed，and it was found that the theoretical results were in good agreement with the molecular dynamics results.
关键词： nonequilibrium molecular dynamics,thermal conductivity,Si/Ge superlattics,strains
更新于2025-09-23 15:21:01
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Concrete Crack Monitoring Using a Novel Strain Transfer Model for Distributed Fiber Optics Sensors
摘要： In this paper, we study the strain transfer mechanism between a host material and an optical fiber. A new analytical model handling imperfect bonding between layers is proposed. A general expression of the crack-induced strain transfer from fractured concrete material to optical fiber is established in the case of a multilayer system. This new strain transfer model is examined through performing wedge splitting tests on concrete specimens instrumented with embedded and surface-mounted fiber optic cables. The experimental results showed the validity of the crack-induced strain expression fitted to the distributed strains measured using an Optical Backscattering Reflectometry (OBR) system. As a result, precise estimations of the crack openings next to the optical cable location were achieved, as well as the monitoring of the optical cable response through following the strain lag parameter.
关键词： crack,distributed strains,crack opening,wedge splitting test,fiber optics sensors,strain transfer,imperfect bonding,concrete
更新于2025-09-23 15:19:57
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Synthesis and Characterization of Li <sup>+</sup> , Ag <sup>2+</sup> and Cu <sup>2+</sup> metals doped MgO nanostructured in Gel Method
摘要： The MgO nano particles doped with alkali, Nobel and transition metals (Li+, Ag2+, Cu2+) were synthesized by gel method. The structures, morphologies and size of synthesized samples were characterized and confirmed by Powder X-ray diffraction (PXRD), Scanning Electron Microscope (SEM) and High Resolution Transmission Electron Microscope (HR-TEM). The antibacterial activity for pure and doped MgO nano particles were studied against S.auerus. Among the results, the Li+ and Cu2+ doped MgO nano particles are best inhibition against the bacterial strains due to the presence of active oxygen species.
关键词： PXRD,Nanoparticles,MgO,Strains
更新于2025-09-10 09:29:36
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Strain-Tunable Electronic Properties and Band Alignments in GaTe/C2N Heterostructure: a First-Principles Calculation
摘要： Recently, GaTe and C2N monolayers have been successfully synthesized and show fascinating electronic and optical properties. Such hybrid of GaTe with C2N may induce new novel physical properties. In this work, we perform ab initio simulations on the structural, electronic, and optical properties of the GaTe/C2N van der Waals (vdW) heterostructure. Our calculations show that the GaTe/C2N vdW heterostructure is an indirect-gap semiconductor with type-II band alignment, facilitating an effective separation of photogenerated carriers. Intriguingly, it also presents enhanced visible-UV light absorption compared to its components and can be tailored to be a good photocatalyst for water splitting at certain pH by applying vertical strains. Further, we explore specifically the adsorption and decomposition of water molecules on the surface of C2N layer in the heterostructure and the subsequent formation of hydrogen, which reveals the mechanism of photocatalytic hydrogen production on the 2D GaTe/C2N heterostructure. Moreover, it is found that in-plane biaxial strains can induce indirect-direct-indirect, semiconductor-metal, and type II to type I or type III transitions. These interesting results make the GaTe/C2N vdW heterostructure a promising candidate for applications in next generation of multifunctional optoelectronic devices.
关键词： Strains,Density functional theory,Heterostructure,Multifunctional devices,GaTe/C2N
更新于2025-09-10 09:29:36
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Strain induced enhancement of erasable domain wall current in epitaxial BiFeO <sub/>3</sub> thin films
摘要： The characteristic of electronic transport at the ferroelectric domain boundary is intensively studied for the potential application in random access memory due to its unique resistance switching mechanism along with polarization reversal. Such high conductivity in artificially created domain walls is not only affected by the material defect chemistry, such as oxygen vacancies, but also pertinent to the multiple polarization states of the sample. Here, we show the enhanced domain wall current in BiFeO3 thin films that could be obtained by the optimization of epitaxial strains from substrates. The leakage current analysis reveals the electronic transport of domain wall current in line with the space-charge-limited conduction mechanism. It is believed that the uncompensated polarization charge arouses the band bending at the domain boundary, which profoundly affects the wall current. Free carriers are easily concentrated in the domain boundary region for the compensation of the enhanced polarization by the strain, resulting in an abrupt increase of the conductivity.
关键词： ferroelectric domain boundary,BiFeO3 thin films,space-charge-limited conduction,epitaxial strains,electronic transport
更新于2025-09-09 09:28:46
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Dataset of single Mycobacterium tuberculosis bacteria cells with different antibiotic susceptibility obtained by Raman spectroscopy
摘要： This data article contains Raman experimental data, obtained with Horiba Jobin-Yvon LabRam HR800 spectrometer (Japan), which can be used for rapid identification of Mycobacterium tuberculosis (MbT) bacteria (Beijing clade) in vitro. Data present analyzed Raman spectra of bacterial cells with various drug resistances obtained from pulmonary and extra pulmonary samples. Data can provide information about characteristic maxima of different structures in biological cell.
关键词： sensitive drug (SD) strains,multidrug resistance (MDR) strains,spectral data,Mycobacterium tuberculosis,Raman spectroscopy
更新于2025-09-04 15:30:14