This study highlights the importance of electronic hybridizations in the FeO6 octahedral distortion, structural evolution, magnetization, oxidation state and atomic bonding covalency in multiferroic ...(Bi1−xNdx)FeO3 (x = 0–0.10) ceramics as the system approaches the morphotropic phase boundary (MPB). The Rietveld-refinement analysis reveals reductions of bismuth deficiency, oxygen vacancies, and nonpolar Bi2Fe4O9 phase as Nd increases. The piezoresponse domain switching reveals a coexistence of polar ferroelectric rhombohedral and minor orthorhombic (nonpolar) phases. The piezoresponse ferroelectric polarization hysteresis loops are attributed to the reduced leaky conductivity in the Nd-doped compositions. The Fe K- and L2,3-edges synchrotron X-ray absorptions suggest a mixture of Fe3+ and Fe4+ valence states and reduction of the FeO6 octahedral distortion by the A-site Nd substitution. The oxygen K-edge synchrotron X-ray absorptions reveal that the hybridizations of the O 2p–Fe 3d and the O 2p–Bi 6sp orbitals were decreased with increasing Nd content.
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•Reduction of Bi and O vacancies by the A-site rare earth Nd substitution in BiFeO3.•Coexistence of polar ferroelectric rhombohedral and nonpolar orthorhombic phases.•Mixture of Fe3+ and Fe4+ valences and reduction of the FeO6 octahedral distortion.•Important roles of the O 2p–Fe 3d and the O 2p–Bi 6sp orbital hybridizations.
Thermochomic VO2 thin films are fabricated by using high power impulse magnetron sputtering at room temperature. In order to increase the crystallinity and transparency of VO2 thin films, first a ...buffer layer of TiO2 is deposited on the glass substrate. Then TiO2/VO2 stacks are post-annealed at a temperature of 500 °C for 3 min. The transmittance as functions of film thickness and O2/Ar ratio during film deposition is discussed. It is found that the O/V atomic ratio decreases with increasing O2/Ar ratio, which is due to serious inter-diffusion inside stacked layers. At high O2/Ar ratio, columnar-shaped crystals are suggested, which belongs to V2Ti3O9:Si quaternary oxide. The depth profiles of binding energies measured by X-ray photoelectron spectroscopy are compared with different O2/Ar ratios. Good endurance property for a thermal stress cycle of 25 °C/85 °C is obtained under the O2/Ar ratio of 6%. The laminated film shows satisfactory optical properties with an excellent solar regulation efficiency (ΔTsol = 10.4%) and an applicable luminous transmittance (Tlum = 35.2%) in a low-temperature state.
•VO2 films are fabricated by HIPIMS and annealed with a low thermal budget.•Films show good solar regulation efficiency and applicable luminous transmittance.•Good endurance properties are obtained.
Molybdenum oxide (MoOx) thin films are fabricated by plasma-enhanced atomic layer deposition (PEALD) using molybdenum hexacarbonyl Mo(CO)6 as the precursor and oxygen as the reactant. The effect of ...plasma power for oxygen has been investigated on the evolution of film structure. Molybdenum oxide shows the orthorhombic α-MoO3 phase at low powers and gradually changes to the metastable monoclinic β-MoO3 phase as the power continually increases, which is confirmed by Raman spectroscopy. α-MoO3 is two-dimensional (2-D) phase with Pbnm space group, while β-MoO3 film belongs to three-dimensional phase with P21/c. From the observation of scanning electron microscopy (SEM), a rod-like structure has been detected, whereas a bulk-like grain corresponds to a high ratio of β-MoO3 to α-MoO3 phase at higher power of 150 W. Due to better coverage of 2-D layer preventing surface from oxidation, the interfacial layer of α-MoO3 checked from transmission electron microscopy (TEM) shows thinner at low powers when contacting with silicon substrate, which is consistent with the performance of leakage current. The changes in binding energies of Mo 3d and O 1s orbits at different milling depths are compared by different powers. Though the significant amount of Mo4+ oxidation state is shown from x-ray photoelectron spectroscopy (XPS), only α-MoO3 and β-MoO3 crystallites with +6 state of Mo are observed from x-ray diffraction (XRD) patterns. Above phenomenon is due to the structural change caused by the loss of oxygen atoms. Thus, according to the charge transformation and compensation, the defect reaction model can well explain that oxygen vacancies inside films are more prevalent in orthorhombic phase at low plasma power for oxygen of our reduced MoO3-x.
•MoO3 films are fabricated by PEALD and annealed under a low thermal budget.•The effect of rf power on the evolution of film structure is reported.•Oxygen vacancy is studied by the defect reaction model.
In this study, the phase-forming capacity of 0.9Mg0.95Co0.05TiO3-0.1Ca0.6La0.8/3TiO3 dielectric ceramics was improved by mixing multiple sintering aids (ZnO-B2O3) owing to their lower melting point. ...The mixed-phase systems of Ca0.6La0.8/3TiO3-modified Mg0.95Co0.05TiO3 dielectric ceramics were verified using XRD diffraction to ensure that the crystallites of different phases were present. The microstructures of the Ca0.6La0.8/3TiO3-modified Mg0.95Co0.05TiO3 dielectric ceramics were observed via SEM and EDS to investigate the relation between element ratios and grains. It was found that the phase-forming capacity of Ca0.6La0.8/3TiO3-modified Mg0.95Co0.05TiO3 was effectively enhanced, compared with the treatment that did not involve mixing multiple sintering aids (ZnO-B2O3). Additionally, the microwave dielectric performances of Ca0.6La0.8/3TiO3-modified Mg0.95Co0.05TiO3 dielectric ceramics with multiple sintering aids (ZnO-B2O3) strongly depended on the density and morphology of the specimens. When the compositions of 0.9Mg0.95Co0.05TiO3-0.1Ca0.6La0.8/3TiO3 with 1 wt% multiple sintering aids (ZnO-B2O3) showed an εr value of 22.6, a Qf value of 49,000 GHz, and a τf value of −12.8 ppm/°C, the sintering temperature was reduced from 1350 °C to 1150 °C (about 200 °C). When adding a larger amount of multiple sintering aids (ZnO-B2O3), the sintering temperature could be reduced by more than 200 °C. This study may promote the use of Ca0.6La0.8/3TiO3-modified Mg0.95Co0.05TiO3 dielectric ceramics.
The lower phase-forming temperature of magnesium titanate, MgTiO3, means that it can be used to replace magnesium ionswith cobalt ions at 0.05 mole when a mixture of diverse low melting point ...materials as sintering accelerators is employed(single: B2O3, CuO, V2O5, ZnO; binary: ZnO-B2O3). The phase formation of 0.9Mg0.95Co0.05TiO3 - 0.1 Ca0.61Nd0.78/3TiO3 dielectricceramics was verified using XRD diffraction to observe crystallites at different phases. SEM was used to observe the graingrowth of the ceramic system, and the composition ratio of the grain was analyzed via EDS. Compared with 0.9Mg0.95Co0.05TiO3- 0.1 Ca0.61Nd0.78/3TiO3 dielectric ceramics without the addition of a sintering accelerator, the results show that the sinteringtemperature could be effectively decremented, and the results of the binary addition were better than the single result. Themicrowave dielectric performances of 0.9Mg0.95Co0.05TiO3 - 0.1Ca0.61Nd0.78/3TiO3 dielectric ceramics were closely related tothe density and growth of grains experienced by the specimens. When 1 wt% binary sintering accelerators (ZnO-B2O3) wereadded to 0.9Mg0.95Co0.05TiO3-0.1 Ca0.61Nd0.78/3TiO3 dielectric ceramics, they showed an εr value of 21.7, a Qf value of 42,000 GHz,and a τf value of -27.2 ppm/oC; the phase-forming temperature was minimized from 1350 oC to 1150 oC. KCI Citation Count: 0
•A growth temperature of 420°C for decomposition of VO(acac)2 is optimally required.•Thermochromic properties are present by atomic layer deposition with VO(acac)2.•Annealing temperature much ...influences inter-diffusion of atoms on thermochromics.
Thermochromic VO2 thin films are fabricated by atomic layer deposition with vanadyl acetylacetonate as the precursor. The crystallization process has been performed by post-annealing process, i.e. rapid thermal annealing. The effect of annealing temperature on thermochromic properties is investigated. Though the transmittance increases with increasing annealing temperature, a moderate temperature is suggested by the consideration of atomic inter-diffusion between TiO2 and VO2 layers. It is found that an oxygen-deficient phase of V2O3 appears at low annealing temperatures, while an oxygen-ambient phase of V2O5 presents at high temperatures. Additionally, a ternary compound, Ti3V6O17 is dominant beyond 700°C. The crystalline behavior of monoclinic phase of VO2 and Ti3V6O17 observed from the X-ray diffraction pattern is further examined by high resolution transmission electron microscope. The depth profiling in binding energies of V 2p, O 1s and Ti 2p orbits are compared.
Nanoscale domains and structural disorder are important phenomena in lead-free rare-earth-substituted bismuth ferrite in the vicinity of the morphotropic phase boundary (MPB). This work highlights ...substitution-driven transitions in (Bi1-xPrx)FeO3 (x = 0.05–0.25) polycrystalline ceramics from ferroelectric (FE) rhombohedral R3c to antiferroelectric (AFE) orthorhombic Pbam, then nonpolar orthorhombic Pnma phases as the system crosses over the MPB, identified by the 12{ooo}, 12(011), 14{111}, and 12{100} electron superlattice diffraction patterns. Enhanced ferromagnetic (FM) magnetizations near the MPB may result from a minor Fe4+ valence state and structural disorder. Sequential temperature-dependent phase transitions were observed and the orthorhombic Pnma phase becomes a dominant phase upon heating. The decreased O 2p–Fe 3d orbital hybridization plays a critical role for substitution-driven and thermally-activated structural transitions in the vicinity of the MPB.
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•Substitution-driven structural evolution in (Bi1-xPrx)FeO3 ceramics near the MPB.•Thermal structural transition from rhombohedral R3c to orthorhombic Pnma phase.•Important role of O 2p–Fe 3d orbital hybridization for structural evolution.•Correlation between enhanced ferromagnetism and Fe4+ valence state.
Lung cancer is relatively rare in young patients as the median age at diagnosis is 65-70 years. The main objective of this nationwide study was to investigate the characteristics of young lung cancer ...in Taiwan, especially the relationships among smoking behavior, epidermal growth factor receptor (EGFR) mutation, and age. The National Taiwan Lung Cancer Registry, a database contain detailed cancer statistics, was analyzed in this study for the period 2011-2012. Young lung cancer was defined as age ⦠45 years. There were 21,536 lung cancer patients (13,187 men and 8349 women). Among these patients, 1074 (5.0%) were in the younger group, and 20,462 patients (95.0%) were in the older group. Female gender (48.8% versus 38.2%, P < 0.001), never-smokers (47.3% versus 43.8%, P = 0.015), and adenocarcinoma (70.4% versus 58.1%, P < 0.001) were more frequent in the younger group. While the EGFR mutation rate was lower in the younger group (52.5% versus 60.6%, P = 0.001), the primary site of lung cancer and stage distribution were not significantly different. If only adenocarcinoma patients were included in the analysis, female gender, older age, and never-smokers were more likely to have EGFR mutation. In conclusion, lung cancer in young patients (⦠45 year-old) was associated with unique characteristics, with greater percentages of female patients, adenocarcinoma, and never-smokers and a lower EGFR mutation rate compared with older patients.
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