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Determination of Phonon Deformation Potentials in Carbon-Doped Silicon
摘要： Carbon-doped silicon (Si:C) is used as a stressor to the channel of n-type metal oxide semiconductor field-effect-transistor (MOSFET). In this study, we determined PDPs, phonon deformation potentials, (p and q) of Si:C to realize evaluation of anisotropic biaxial stress by using water-immersion Raman spectroscopy. Raman peak shift in longitudinal and transverse optical (LO and TO) phonon modes were measured by water-immersion Raman spectroscopy. Furthermore, in-plane and out-of-plane strain were measured by X-ray diffraction (XRD). Based on the Raman shift and the in-plane strain, p and q in each sample were derived. As a result, it took a different value from pure-Si, and the PDPs tended to increase as the C concentration increased.
关键词： phonon deformation potentials,strain evaluation,Carbon-doped silicon,X-ray diffraction,water-immersion Raman spectroscopy
更新于2025-09-23 15:21:01
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Effects of 2-Amino-4,6-Dimethoxypyrimidine on PVDF/KI/I2-Based Solid Polymer Electrolytes for Dye-Sensitized Solar Cell Application
摘要： In this work, we have investigated the effects of 2-amino-4,6-dimethoxypyrimidine on polyvinylidene fluoride/potassium iodide/iodine (PVDF/KI/I2) in dye-sensitized solar cells (DSSC). Different weight ratios (0%, 10%, 20%, 30%, 40% and 50%) of 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based solid polymer electrolytes (SPEs) were prepared by solution-casting method. The prepared 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPEs were characterized by powder x-ray diffraction (PXRD) analysis, AC impedance analysis and scanning electron microscopy (SEM) analysis. The crystallinity of 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPEs was confirmed by PXRD measurement. The ionic conductivity of 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPEs was calculated using AC impedance analysis. The ionic conductivity values of different weight ratios (0%, 10%, 20%, 30%, 40% and 50%) of 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPEs are 5.50 × 10?6 S cm?1, 1.74 × 10?5 S cm?1, 4.91 × 10?5 S cm?1, 2.04 × 10?5 S cm?1, 1.58 × 10?5 S cm?1 and 1.04 × 10?5 S cm?1, respectively. Ionic conductivity studies revealed that the 20% 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPE showed the highest ionic conductivity value. The SEM images show the surface morphology of 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPEs. The power conversion efficiency (PCE) of DSSCs utilizing different weight ratios (0%, 10%, 20%, 30%, 40% and 50%) of 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPEs are 1.4%, 2.0%, 2.5%, 2.3%, 1.9% and 1.6%, respectively. These results revealed that the DSSC using 20% 2-amino-4,6-dimethoxypyrimidine-doped PVDF/KI/I2-based SPE exhibited the highest PCE.
关键词： crystalline nature,Powder x-ray diffraction,ionic conductivity,2-amino-4,6-dimethoxypyrimidine,solid polymer electrolyte
更新于2025-09-23 15:21:01
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Small fatigue crack growth behavior of Ti-6Al-4V produced via selective laser melting: In situ characterization of a 3D crack tip interactions with defects
摘要： Small fatigue crack growth (SFCG) behavior is examined for additively manufactured Ti-6Al-4V specimens with optimal and trial build conditions (representing an increased degree of defects) through a combination of in situ tomography and in situ energy dispersive X-ray diffraction. The results showed slower crack growth rates for the SFCG samples compared to the long cracks (which was not expected). In the case of the trial conditions, the increased levels of porosity deterred crack growth by blunting the crack, as evident by the in situ tomography characterization.
关键词： In situ tomography,Porosity,Energy dispersive X-ray diffraction,Process build conditions,Additive manufacturing
更新于2025-09-23 15:21:01
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Luminescent-center tuning for Ba6Ca3YAlSi6O24:Ce3+, Na+ orthosilicate phosphors
摘要： Ce3+ ion-doped Ba6Ca3YAlSi6O24 phosphors with a charge-compensating Na+ ion were prepared using a solid-state reaction. Ba6Ca3YAlSi6O24 was structurally characterized using synchrotron X-ray powder diffraction. The emission wavelengths of Ce3+ in different Ba2+ and Ca2+ sites with the distortion index of polyhedrons in the host lattice were calculated. The photoluminescence excitation and emission spectra of the Ce3+-activated phosphors were site-selectively monitored; furthermore, the emission quenching as a function of Ce3+ content in the Ba6-2xCexNaxCa3YAlSi6O24 and Ba6Ca3-2xCexNaxYAlSi6O24 (x = 0.01–0.4) was clearly distinguished at relatively high concentrations of the activator. The Gaussian components of the phosphors were exploited by using the Ce3+ ion sites in the host lattice; in addition, the one and two luminescent centers for the Ba6-2xCexNaxCa3YAlSi6O24 and Ba6Ca3-2xCexNaxYAlSi6O24 phosphors, respectively, were identified. The sites of the luminescent centers for the calculated Ba6Ca3-2xCexNaxYAlSi6O24 composition was selectively tuned as the (BaCa)9-2xCexNaxYAlSi6O24 lattice structure.
关键词： orthosilicate,photoluminescence,X-ray diffraction,luminescent center
更新于2025-09-23 15:21:01
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Characterization of Lattice Parameters Gradient of Cu(In1-xGax)Se2 Absorbing Layer in Thin-Film Solar Cell by Glancing Incidence X-Ray Diffraction Technique
摘要： In or Ga gradients in the Cu(In1-xGax)Se2 (CIGS) absorbing layer lead to change the lattice parameters of the absorbing layer, giving rise to the bandgap grading in the absorbing layer which is directly associated with the degree of absorbing ability of the CIGS solar cell. We tried to characterize the depth profile of the lattice parameters of the CIGS absorbing layer using a glancing incidence X-ray diffraction (GIXRD) technique, and then allows to determine the In or Ga gradients in the CIGS absorbing layer, and to investigate the bandgap grading of the CIGS absorbing layer. When the glancing incident angle increased from 0.50 to 5.00°, the a and c lattice parameters of the CIGS absorbing layer gradually decreased from 5.7776(3) to 5.6905(2) ?, and 11.3917(3) to 11.2114(2) ?, respectively. The depth profile of the lattice parameters as a function of the incident angle was consistent with vertical variation in the composition of In or Ga with depth in the absorbing layer. The variation of the lattice parameters was due to the difference between the ionic radius of In and Ga co-occupying at the same crystallographic site. According to the results of the depth profile of the refined parameters using GIXRD data, the bandgap of the CIGS absorber layer was graded over a range of 1.222 to 1.532 eV. This approach nondestructively guess the bandgap depth profile through the refinement of the lattice parameters using GIXRD data on the assumption that the changes of the lattice parameters or unit-cell volume follow a good approximation to Vegard’s law.
关键词： Vegard’s law,Cu(In1-xGax)Se2 absorbing layer,Depth profile,Bandgap grading,Glancing incidence X-ray diffraction technique
更新于2025-09-23 15:21:01
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57Fe M?ssbauer and XRD studies on β-FeSi2 prepared by high energy mechanical attrition
摘要： The evolution of different phases of Fe-Si binary system on milling elemental Fe and Si has been carried out in argon atmosphere at 1000 rpm using the hardened tungsten carbide powders has been studied by x-ray diffractometry and 57Fe M?ssbauer spectroscopy. The milling medium. The sizes of both Fe and Si are found to be less than 50 nm on milling the mixture for 50 min. Metallic α-FeSi2 formation takes place at this stage due to enhanced reactivity caused by reduction in particle size. The semiconducting β-FeSi2 phase along with ε-FeSi and a metastable Fe-Si solid solution are found to be formed on annealing the milled product at 500 °C. A clean semiconducting β-FeSi2 phase forms on milling Fe and Si for 50 minute followed by annealing at 800 °C for 2 hrs.
关键词： M?ssbauer spectroscopy,X-ray diffraction,semiconducting β-FeSi2
更新于2025-09-23 15:21:01
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Facile synthesis of La-doped CdS nanoparticles by microwave assisted co-precipitation technique for optoelectronic application
摘要： Low-cost microwave assisted technique has been applied to produce La-doped CdS nanoparticles and their structural, morphological, optical, Raman, dielectric and electrical studies were carried out. Broad XRD peaks revealed the growth of low-dimension La-doped CdS nanoparticles with wurtzite structure. Spherical shape morphology of synthesized nanostructures was confirmed by SEM analysis. SEM mapping and EDAX analysis showed the elemental composition and successful incorporation of La in CdS matrix. Diffused reflectance spectroscopy was used to determine the energy gaps and it was observed to be reduced from 2.47 to 2.3 eV upon La doping. Vibrational studies on La:CdS nanoparticles displayed longitudinal optical modes. PL studies exhibited improved luminescence for the band to band transition of the CdS nanoparticles. The ε’ values are enhanced in general; though it displayed reduced ε’ values at some concentration owing to reduction of polarization. Enhancement in AC conductivity was observed with increasing La concentration and the studies on the involved conduction mechanism revealed that the hopping motion in prepared nanostructures is translation motion with a quick hopping and the behavior is that of ionic conduction.
关键词： FT-Raman spectroscopy,optical properties,dielectric and electrical properties,X-ray diffraction,SEM/EDX,La:CdS
更新于2025-09-23 15:21:01
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Interfacial structure of SrZr <sub/><i>x</i> </sub> Ti <sub/>1?</sub><sub/><i>x</i> </sub> O <sub/>3</sub> films on Ge
摘要： The interfacial structure of SrZrxTi1?xO3 films grown on semiconducting Ge substrates is investigated by synchrotron X-ray diffraction and first-principles density functional theory. By systematically tuning the Zr content x, the effects of bonding at the interface and epitaxial strain on the physical structure of the film can be distinguished. The interfacial perovskite layers are found to be polarized as a result of cation-anion ionic displacements perpendicular to the perovskite/semiconductor interface. We find a correlation between the observed buckling and valence band offsets at the SrZrxTi1?xO3/Ge interface. The trends in the theoretical valence band offsets as a function of Zr content for the polar structures are in agreement with reported X-ray photoelectron spectroscopy measurements. These results have important implications for the integration of functional oxide materials with established semiconductor based technologies.
关键词： synchrotron X-ray diffraction,density functional theory,valence band offsets,SrZrxTi1?xO3 films,Ge substrates,interfacial structure
更新于2025-09-23 15:21:01
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Coexistence of pressure-induced structural phases in bulk black phosphorus: a combined x-ray diffraction and Raman study up to 18 GPa
摘要： We report a study of the structural phase transitions induced by pressure in bulk black phosphorus by using both synchrotron x-ray diffraction for pressures up to 12.2 GPa and Raman spectroscopy up to 18.2 GPa. Very recently black phosphorus attracted large attention because of the unique properties of few-layers samples (phosphorene), but some basic questions are still open in the case of the bulk system. As concerning the presence of a Raman spectrum above 10 GPa, which should not be observed in an elemental simple cubic system, we propose a new explanation by attributing a key role to the non-hydrostatic conditions occurring in Raman experiments. Finally, a combined analysis of Raman and XRD data allowed us to obtain quantitative information on presence and extent of coexistences between different structural phases from ~5 up to ~15 GPa. This information can have an important role in theoretical studies on pressure-induced structural and electronic phase transitions in black phosphorus.
关键词： high pressure,black phosphorus,x-ray diffraction,Raman spectroscopy,phase transitions
更新于2025-09-23 15:21:01
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Persistence of the R3m Phase in Powder GeTe at High Pressure and High Temperature
摘要： As a phase-change material, rhombohedral GeTe (space group R3m) was believed to transform to the cubic rock-salt phase (B1) at 3–4 GPa, associated with the disappearance of a Peierls distortion. However, using a combination of synchrotron X-ray diffraction and theoretical calculations, we found that the R3m phase persists from ambient pressure up to pressures of about 15.8 GPa, in contrast to previous reports. Neither was the B1 phase observed in a heating X-ray powder diffraction experiment. The spurious transformation from R3m to B1 is caused by changes to the compression ratio of lattice parameters in the R3m phase under high pressure/temperature. These findings provide insight into transitions of phase-change materials, relevant to other materials undergoing displacive transitions under high pressure/temperature.
关键词： structural phase transitions,density-functional theory,high pressure,phase-change materials,high temperature,GeTe,synchrotron X-ray diffraction
更新于2025-09-23 15:21:01