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Structural and conduction behaviour of (BaSr)0.5TiO3 modified in BFO perovskite
摘要： The multiferroic ceramic (BiBa0.5Sr0.5)0.5 (Fe0.5Ti0.5) O3 (BFO-BST) is prepared in an economic way by conventional solid state reaction route and its different behaviours are studied and reported. The X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM) investigations have confirmed single phase forming by the compound. Full proof reitveld analysis has been used for structural refinement. XRD pattern of the sample it is inferred that the observed peaks and calculated peaks are well matched with each other having minimum deviation. The density of the compound is quiet high as calculated by above analysis as well as from SEM image. Dielectric behaviour of the compound has been analyzed through the variation of dielectric constant with frequency while the electrical behaviour is studied through the complex impedance and modulus analysis. Additionally, verification of Jonscher's power law from ac conductivity study gives the detail findings about electrical behaviour of the material.
关键词： Modulus,Ceramic,X-ray diffraction,Impedance
更新于2025-09-23 15:23:52
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Radiative characteristics of Voronoi open-cell foams made from semitransparent media
摘要： The radiative characterization of open-cell foams made from semitransparent solids is more complex than that made from opaque media. This study aims to understand how the component radiative properties and structural parameters of such open-cell foams affect their radiative characteristics. A radiative transfer model was established in the limit of geometric optics for the radiative characterization of a family of numerically generated Voronoi foams with open cells. It considers the reflection and refraction at the solid surface and the transmission, absorption and scattering process inside the solid phase. It is found that when the solid phase is in reality partially transparent, the opaque solid assumption will lead to inaccurate outcomes. Strongly scattering solid phase may cause much radiative energy to be rejected via reflection behavior, which will weaken the absorptive capability of the foam sheets as radiation absorbers. In addition, the radiative transfer model established was applied in three popular ceramic foams (alumina, silicon carbide and zirconia). The model shows advances in the field of analyzing and explaining the spectral radiative characteristics of ceramic foams. The present work can provide useful guidance when open-cell foams made from semitransparent media become potential candidates for thermal applications.
关键词： Voronoi tessellation,Radiative characterization,Ceramic foam,Semitransparent
更新于2025-09-23 15:23:52
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External irradiation with heavy ions of neodymium silicate apatite ceramics and glass-ceramics
摘要： This work aims at comparing the damage induced in the Nd silicate apatite ceramic (Ca2Nd8(SiO4)6O2) by medium energy (ME) and swift heavy ion (SHI) irradiations to evaluate the effects of nuclear collisions and intense electronic excitations for ME ions and SHI ions respectively. The macroscopic induced changes were studied as a function of the fluence by swelling and hardness measurements, whereas structural modifications were followed by X-ray diffraction, Raman spectroscopy and grazing incidence EXAFS (Nd L3-edge). At ME (1.9e6.75 MeV Au ions), radiation-induced amorphization occurred above 6.22 (cid:1) 1013 Au/cm2 associated with a volume expansion of about 8% and a drop of 37% in hardness. At SHI (90 MeV Xe ions or 35 MeV Ar ions), similar macroscopic and structural changes were observed. The electronic stopping power threshold of Nd silicate apatite for amorphization was assessed at about Se ? 5 keV/nm. As apatite crystals containing actinides could be present in rare-earths rich nuclear glasses, SHI irradiation with Xe (995 MeV) ions was also used to damage the Nd silicate apatite crystals dispersed in a soda-lime aluminoborosilicate simplified nuclear glass over a depth of about 60 mm, to evaluate the possible formation of cracks in the residual glass due to crystals swelling. In spite of apatite crystals amorphization under SHI irradiation in the glass-ceramics, no cracking was observed in the glassy phase even close to the biggest crystals which could be explained by strain relaxation in the glass due to plastic deformation (creep) induced by SHI ion beam.
关键词： Amorphization,Glass-ceramic,Neodymium silicate apatite,Heavy ions irradiation
更新于2025-09-23 15:23:52
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Fabrication and mid-infrared property of Er:CaF2 transparent ceramics
摘要： High doped Er:CaF2 transparent ceramics (up to 10.0 at.%) were fabricated by hot pressing nanopowders which were synthesized by co-precipitation method. The composition and micrographs of the powders were characterized. The mid-infrared emission spectra and lifetimes of the 4I13/2 energy level of Er:CaF2 transparent ceramics were investigated for the first time. The mechanisms of energy transfer processes based on the emission spectra of different wavelengths were discussed. The enhanced 2.7 μm emission intensity and the reductions of near-infrared fluorescence lifetimes were observed indicating that the high concentrations of Er3+ ions are beneficial to overcome the self-termination effect and realize 2.7 μm laser output. It can be seen from these results that high concentrations Er-doped CaF2 transparent ceramics can be considered as promising host materials for the applications of mid-infrared lasers.
关键词： Transparent ceramic,Mid-infrared,Luminescence lifetime,Nanoparticle
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Characterization of Multilayered Ceramic Capacitors via Piezoelectric Force Microscopy
摘要： The coupling between an electrical and mechanical response in a material is a fundamental property that provides functionality to a variety of applications ranging from sensors and actuators to energy harvesting and biology. Most materials exhibit electromechanical coupling in nanometer-sized domains. Therefore, to understand the relationship between structure and function of these materials, characterization on the nanoscale is required. This property can be directly measured in a non-destructive manner using piezoelectric force microscopy (PFM), a mode that comes standard in all atomic force microscopes (AFMs) from Park Systems. Additionally, PFM can be used as a spectroscopic tool to evaluate switching of piezoelectric domains. Here we demonstrate the utility of PFM for failure analysis of a multilayered ceramic capacitor. Correlative imaging of topography and electrical signals revealed discontinuous structures in the device that likely had a direct effect on device performance. Spectroscopy was also performed at a specific piezoelectric region to measure domain properties, such as the electric field required to flip the polarization direction (coercive voltage).
关键词： topography,atomic force microscopy,multilayered ceramic capacitor,electromechanics,piezoelectric microscopy,polarization,failure analysis
更新于2025-09-23 15:23:52
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Photoluminescence, scintillation and TSL properties of Eu-doped Al2O3 transparent ceramics synthesized by spark plasma sintering method
摘要： We synthesized Al2O3 transparent ceramics doped with different concentrations of Eu (0.001, 0.01, 0.1 and 1.0%) by the spark plasma sintering (SPS) method, and then we investigated their photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) properties. In the PL, the samples showed a broad emission peak at 400 nm due to the 5d-4f transitions of Eu2+ and several sharp emission peaks across 550–750 nm due to the 4f-4f transitions of Eu3+ and the 3d-3d transitions of Cr3+ impurity ion. In addition to these peaks over 550–750 nm, in scintillation, the samples exhibited two broad peaks over 300–400 nm possibly due to not the 5d-4f transitions of Eu2+ but F and F+ centers. In TSL, the glow curve consisted of peaks at approximately 100, 160, 210 and 320 °C. The TSL intensity of the 0.001% Eu-doped sample was the highest, and the TSL response was confirmed to be linear to irradiated X-ray dose in the range from 0.1 to 1000 mGy.
关键词： Transparent ceramic,Scintillator,Eu,Dosimeter,Al2O3
更新于2025-09-23 15:23:52
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Multifunctional BaTiO <sub/>3</sub> -(Bi <sub/>0.5</sub> Na <sub/>0.5</sub> )TiO <sub/>3</sub> -based MLCC with high energy storage properties and temperature stability
摘要： BaTiO3-(Bi0.5Na0.5)TiO3 (BTBNT)-based multilayer ceramic capacitor (MLCC) chips with the inner electrodes being Ag0.6/Pd0.4 are prepared by a roll-to-roll casting method. The BTBNT-based MLCC chips with ten-dielectric layers can be sintered very well at a low temperature of 1130°C via two step sintering (TSS). X-ray diffraction (XRD) and transmission electron microscope (TEM) results show that MLCC chips are a core-shell structure with two phases coexistence. The core exhibits a tetragonal phase at room temperature and then gradually changes into a cubic phase when the temperature increases above Tc (175°C). While, the shell exhibits a pseudocubic phase at all tested temperature from 25°C to 500°C. BTBNT-based MLCC chips exhibit a broad temperature stability and meet the requirement of Electronic Industries Association (EIA) X9R specifications. In terms of energy storage performance, a large discharge energy density of 3.33 J/cm3 can be obtained at 175°C under the applied electric field of 480 kV/cm. Among all tested temperature ranging from -50°C to 200°C, the energy efficiency of all chips is higher than 80%, even under a high applied electric field. The experimental results indicate that this novel BTBNT-based X9R MLCCs can be one of the most promising candidates for energy storage applications, especially operated in high temperature.
关键词： Energy storage,X9R,Two-step sintering (TSS),Core-shell structure,Multilayer ceramic capacitor (MLCC)
更新于2025-09-23 15:23:52
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22.2: <i>Invited Paper:</i> Sputtered Molybdenum-Oxide for Anti-Reflection Layers in Displays: Optical Properties and Thermal Stability
摘要： Molybdenum (Mo) is commonly used for thin film transistor (TFT) metallization in displays. Apart from its outstanding electronic and adhesive properties in the metallic form, it also possesses stable oxidation states, including sub-stoichiometric oxides. Depending on the amount of oxygen, the properties can be widely tuned and oxygen-deficient MoO3-y films can be electrical conducting and optically absorbing, making them suitable candidates for integration as low-reflection coatings for on/in cell touch, black matrix on array, narrow bezel, or TFT metallization. Deposition of these oxides by fully reactive sputtering from metal targets implies several problems such as lateral inhomogeneities on large substrates (>G5) and difficult control of oxygen flow. To avoid these obstacles, DC-sputtering from ceramic Molybdenum oxide targets without the addition of oxygen gas is proposed. In our work, we show the non-reactive DC-sputtering of MoOx:TaOx in a stable and reliable process with deposition rates of up to 180 nm/min. Further on, the electrical, optical, and structural properties of the resulting films are studied. The reflectance of light from external sources and the resulting color impression of the dark layer coatings is investigated on different substrates. The color coordinates of the film can be tuned by the layer thickness, the type of covered metal layer (e.g. Cu, Al, Mo), as well as composition of the oxide. From a process stability point of view, we discuss changes during additional annealing steps, and show structural changes at elevated temperatures.
关键词： Ceramic Target,Molybdenum,Sputter Deposition,Low Reflectance,Narrow Bezel,Oxide
更新于2025-09-23 15:23:52
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Up-conversion Luminescence Properties of Er3+/Yb3+ Co-Doped Oxyfluoride Glass Ceramic
摘要： Er3+/Yb3+ co-doped glass ceramic samples were prepared by melt-quenching method utilizing nominal composition 52SiO2-8Na2CO3-16Al2O3-33NaF-3LuF3-0.15Yb2O3-0.03Er2O3 (in mol%). The spectral characteristic was studied based on Judd-Ofelt theory. Spectrum intensity parameters Ωλ(λ=2,4,6) were calculated on the basis of the absorption spectrum. The theoretical and experimental oscillator strengths were calculated according to the spectrum intensity parameters, and the root mean square deviation (δrms) of glass ceramic sample was 4.28x10-6. The parameters such as transition probability, decay branching ratios and level lifetime of Er3+ were obtained. Lifetimes of metastable level 4I13/2 and 4I11/2 in as-prepared samples are respectively 11.64 and 13.61ms which are suitable for up-conversion intermediate levels. Decay branching ratio of 4I13/2→4I15/2 is nearly 100% in Er3+/Yb3+ co-doped oxyfluoride glass ceramic samples which can be used to produce 1543nm laser. Under the excitation of 980 nm diode laser, up-conversion luminescence is observed at the wavelength of 549nm and (653, 664) nm, corresponding to the radiative transitions of Er3+: 4S3/2→4I15/2 and 4F9/2→4I15/2, respectively. The numbers of absorbed photons in the transition process of Er3+/Yb3+ co-doped oxyfluoride glass ceramic samples are estimated at 1.99 and 2.06 respectively according to the relationship between the up-conversion transmitting power and the 980 nm LD laser power. It is determined that the transition process of Er3+/Yb3+ co-doped oxyfluoride glass ceramic samples is two-photon absorption process.
关键词： Glass ceramic,Two-photon absorption,Up-conversion,Judd-Ofelt theory
更新于2025-09-23 15:23:52
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High quality factor cold sintered Li2MoO4BaFe12O19 composites for microwave applications
摘要： Ceramics-ceramic composites (1-x)Li2MoO4-xBaFe12O19 (LMO-BF12, 0.00≤x≤0.15) have been cold sintered at 120oC and their structure and properties characterized. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that compositions were dual phase and had a dense microstructure. Composites in the xBF12-(1-x)LMO (0.0≤x≤0.15) series resonated at MW frequencies (~6GHz) with 5.6≤e r≤5.8 and Qf =16,000-22,000 GHz, despite the black colour of compositions with x > 0. The permeability of the composites was measured in the X band (~8 GHz) and showed an increase from 0.94 (x=0.05) to 1.02 (x=0.15). Finite element modelling revealed that the volume fraction of BF12 dictates the conductivity of the material, with a percolation threshold at 10 vol.% BF12 but changes in e r as a function of x were readily explained using a series mixing model. In summary, these composites are considered suitable for the fabrication of dual mode or enhanced bandwidth microstrip patch antennas.
关键词： Finite element modeling (FEM),Composite,Cold sintering process,Dielectric,Ceramic material
更新于2025-09-23 15:23:52