High-resolution X-ray diffraction is applied to investigate macro and micro crystal structure changes across different synthesis routes in BNBT4 piezoceramics. Synthetic powders were obtained by ...conventional sol-gel auto combustion and mixed oxides methods; then samples were sintered by combining hot uniaxial pressing and subsequent recrystallization. The crystal structure of the ceramic obtained by sol-gel is rhombohedral (R3c) and the one obtained from mixed oxides is monoclinic (Cc). In the sol-gel case, a poling process produces an intense 001 texture parallel to the polarizing electric field. Poling the mixed oxides ceramics quickly transforms the structure from monoclinic to rhombohedral while texture and anisotropic micro-strains develop further as the poling increases. A correlation between detected structural transformations and variations in selected physical properties is suggested. The anisotropy of the critical temperatures for dielectric and electromechanical depolarization is lower for mixed oxides ceramics than for sol-gel ceramics.
Changes in crystal structure, microstructure and properties of (Bi0.5Na0.5)0.96Ba0.04TiO3 (BNBT4) piezoceramics, as dependent on sample physico-chemical route, are explored via high-resolution synchrotron XRD. Display omitted
•Synchrotron XRD detects crystal structure subtleties induced by synthesis processes.•Poling the mixed oxides ceramic transforms crystals from monoclinic to rhombohedral.•Poling the sol-gel ceramic textures the crystal parallel to the polarizing electric field.•Sol-gel high texture - high dielectric and electromechanical thermal depolarization anisotropy.•Mixed oxides high micro-strain - high electromechanical thermal depolarization delay.
The structural and magnetic properties of Nd0.1Sr0.9FeO3-δ nanoparticles (∼60–70 nm) formed by mechanosynthesis at 800 °C (12 h), which is ∼ 200–600 °C lower than the reported formation ...temperatures of rare earth cation-doped SrFeO3-δ phases, are reported. Both XRD and 57Fe Mӧssbauer spectroscopy show the nanoparticles to be a mixture of the cubic Nd0.1Sr0.9FeO3 and the Fe4+/Fe3+ mixed-valence tetragonal Nd0.1Sr0.9FeO2.875 phases in the ratio of ∼ 45 : 55. XPS data reveal a complex surface composition for the nanoparticles where traces of the initial reactants as well as other SrFeO3-δ phases are detected. The Nd0.1Sr0.9FeO3-δ nanoparticles are found to display superparamagnetism with blocking temperatures of ≥78 K for the Nd0.1Sr0.9FeO3 phase and ∼ 61 K for the Nd0.1Sr0.9FeO2.875 one. The nanoparticles exhibit an antiferromagnetic-to-weak ferromagnetic transition at ∼23 K which is attributed to the combined effects of the helical magnetic structure of Nd0.1Sr0.9FeO3, spin canting in Nd0.1Sr0.9FeO2.875 and doping with the Nd3+cation.
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•Nd0.1Sr0.9FeO3-δ nanoparticles (∼60–70 nm) were formed by mechanosynthesis at 800 °C.•The nanoparticles were found to consist of cubic Nd0.1Sr0.9FeO3 and tetragonal Nd0.1Sr0.9FeO2.875 in the ratio of ∼ 45 : 55.•XPS reveals a complex surface composition where traces of the initial reactants are detected.•The nanoparticles are superparamagnetic with TB ≥78 K and TB∼ 61 K for the cubic phase and tetragonal one, respectively.•An antiferromagnetic-to-weak ferromagnetic transition is observed at ∼23 K.
In this study, nanostructured tungsten trioxide (WO3) thin films were deposited on Indium tin oxide (ITO)-coated glass substrate using electrochemical deposition (ECD). After deposition, the films ...were annealed at 450 °C for 2 h in an air atmosphere. X-ray diffraction (XRD) analysis confirmed that the prepared WO3 thin films have crystalline phases. According to the absorption measurements, the optical bandgap of the WO3 film was calculated as Eg 2.80 eV. Based on the scanning electron microscopy (SEM) images, the surface morphology of the thin films was influenced by deposition conditions. Raman spectroscopy analysis was also used to further examine the structure and chemical compositions of the thin films. The nature of the nanostructured WO3 thin films was studied with Electrochemical Impedance Spectroscopy (EIS) and Tafel. Nyquist, open circuit potential and Bode analysis were used to evaluate structural changing and corrosion behavior of the prepared WO3 thin films. With the help of these measurements and analyzes, the parameters such as solution resistance (Rs), polarization resistance (Rpo), a constant phase element (CPE) and a CPE exponent (n) were calculated as 43.43 Ω cm2, 2.67 × 106 Ω cm2, 18.45 × 10−6 Ω−1 s cm−2, 0.958, respectively. Also, the corrosion features of the WO3 thin films were investigated with the help of tafel measurements and the corrosion potential and current values were calculated as −0.583 V and 5.09 × 10−15 A, respectively. It is thought that the prepared thin film might have the potential to be used industrially with these features.
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•Characterized molecular structure of bituminous coal in northern China systematically.•Samples contains a low degree of ordered microcrystalline units.•The oxygen-containing ...functional groups are rich in bituminous coal.
Bituminous coal is used widely for a variety of applications despite causing a range of problems within processes. The complexity and heterogeneity of the molecular structure of coal is one of the reasons for problems during use. Investigation into the molecular structure of the bituminous coal is reported from using X-ray diffraction (XRD), Raman spectroscopy, and Fourier Transform infrared (FTIR) spectroscopy experiments on four coal samples from coal mines in Northern China. The average lateral sizes (La), stacking heights (Lc) and interlayer spacing (d002) of the coal samples’ crystallite structures derived from the XRD ranged from 25.78 to 27.93 Å, 17.27 to 25.88 Å and 3.40 to 3.52 Å, respectively; and the G-D1, ID1/IG and La of the samples ranged from 245.06 to 249.63 cm−1, 2.18 to 2.48 and 18.16 to 20.64 Å, respectively. The FTIR spectra reveals that coal samples incorporate oxygen-containing functional groups, aliphatic functional groups, aromatic functional groups and hydroxyl functional groups. Results show these four coal samples contained a low degree of ordered microcrystalline units with a low degree of aromatic conformation. The samples have the largest proportion of oxygenated functional groups, followed by aromatic structures, aliphatic structures and hydroxyl groups. Results from this study could inform the ongoing study of molecular structural characteristics of bituminous coal as well as help our understanding of properties such as wettability and pore structure.
Antimony (Sb) has emerged as an attractive anode material for both lithium and sodium ion batteries due to its high theoretical capacity of 660 mA h g−1. In this work, a novel peapod‐like N‐doped ...carbon hollow nanotube encapsulated Sb nanorod composite, the so‐called nanorod‐in‐nanotube structured Sb@N‐C, via a bottom‐up confinement approach is designed and fabricated. The N‐doped‐carbon coating and thermal‐reduction process is monitored by in situ high‐temperature X‐ray diffraction characterization. Due to its advanced structural merits, such as sufficient N‐doping, 1D conductive carbon coating, and substantial inner void space, the Sb@N‐C demonstrates superior lithium/sodium storage performance. For lithium storage, the Sb@N‐C exhibits a high reversible capacity (650.8 mA h g−1 at 0.2 A g−1), excellent long‐term cycling stability (a capacity decay of only 0.022% per cycle for 3000 cycles at 2 A g−1), and ultrahigh rate capability (343.3 mA h g−1 at 20 A g−1). For sodium storage, the Sb@N‐C nanocomposite displays the best long‐term cycle performance among the reported Sb‐based anode materials (a capacity of 345.6 mA h g−1 after 3000 cycles at 2 A g−1) and an impressive rate capability of up to 10 A g−1. The results demonstrate that the Sb@N‐C nanocomposite is a promising anode material for high‐performance lithium/sodium storage.
A novel peapod‐like N doped carbon hollow nanotubes encapsulated Sb nanorods composite anode (Sb@N‐C) is fabricated. The facile thermal‐reduction route is monitored through in‐situ high‐temperature X‐ray diffraction. Sb@N‐C anode exhibits ultra‐high rate capability (343.3 mA h g−1 at 20 A g−1) in lithium‐ion batteries and the reported best long‐term 3000 cycles at 2 A g−1 in sodium‐ion batteries.
In this study, we have used a two step method to eliminate the secondary phases in the CZTS thin films grown by sol-gel technique. In the first step, CZTS thin films were grown on different ...substrates ITO coated glass (ITO), Soda Lime Glass (SLG), multi-crystalline Silicon (m-Si) and crystalline Silicon (c-Si) to investigate the optimal substrate for the growth of CZTS with minimum number of secondary phases. XRD, SEM and Raman spectroscopy measurements suggested that the sample grown on ITO substrate has only ZnS and Cu2S secondary phases meanwhile samples grown on mc-Si and C-Si have a number of secondary phases. Due to its smooth surface and single crystalline nature, ITO facilitates the CZTS growth with minimum secondary phases. Therefore, we have used ITO substrate for the further growth of CZTS thin films in the second set of samples. In the second step the previously grown CZTS/ITO samples were annealed in sulphur atmosphere at 500 °C using a tube furnace for different time durations of 20, 40, 60 and 80 min. The characterization data suggested that ZnS secondary phase was still present in the samples which are annealed for 20–60 min while other secondary phase (Cu2S) was eliminated. Finally the ZnS phase also vanished when the annealing time duration was increased to 80 min. The disappearing of secondary phases was maybe due to suppressing the off-stiochiometric composition by increasing the sulpurizing time.
Purpose of this study is to investigate effect of gadolinium (Gd) content of GdxFe2O3(100-x), (x = 0, 5, 10, 20) composite system on structural, thermal, optical and radiation protection of poly ...(vinyl alchool) PVA based nanocomposite film. In this study, Gd doped Fe2O3 nanopowders (with Gd = 0, 5, 10 and 20) were synthesized by spray pyrolysis method. The characterization of these powders have been obtained by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), and Uv–vis spectrometer. After then, GdxFe2O3(100-x)/PVA (x = 0, 5, 10, 20) polymer composite systems were prepared by solution casting technique. The structural, thermal and optical properties of obtained polymer composites have been examined. The irradiation properties of 6 MeV energized X-ray via cLINAC to obtain radiation shielding performance of these different percentage (0, 5, 10, and 20%) Gd doped Fe2O3 PVA thin films were also investigated. By using obtained results, the Linear Attenuation Coefficient (LAC), Half Value Layer (HVL), Tenth Value Layer (TVL), Mass Attenuation Coefficient (MAC). Also, theoretically Zeff value have been calculated. According to all obtained results, it has been seen that the different percentages (0, 5, 10, and 20%) Gd doped Fe2O3 PVA thin films can be used as radiation shielding material.
•Purpose of this study is to investigate effect of gadolinium (Gd) content of GdxFe2O3(100-x), (x=0, 5, 10, 15, 20) composite system on structural, thermal, optical and radiation shielding of poly (vinyl alchool) PVA based nanocomposite film.•The characterization of these powders have been obtained by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), and Uv–vis spectrometer.•The irradiation properties of 6 MeV energized X-ray via cLINAC to obtain radiation shielding performance.•By using obtained results, the Linear Attenuation Coefficient (LAC), Half Value Layer (HVL), Tenth Value Layer(TVL), Mass Attenuation Coefficient(MAC).•Also, theoretically Zeff values have been calculated.
In this study, Al-doped Cu2-xAlxZnSnS4 (x = 0%, 1%, 2%, 3%, and 4%) nanoparticles have forged using a simple hydrothermal method. The effect of Al doping on the structural, morphological, and ...thermoelectric properties have investigated and it has found that Al occupies the Cu site and acts as an acceptor dopant. As compared to un-doped Cu2ZnSnS4, the electrical conductivity and Seebeck coefficient improved with the increase in Al doping concentration leads to a noticeable improvement in power factor. Meanwhile, increased grain size with the doping of higher radius atoms causes the improvement in the mobility of the charge carriers and hence electrical conductivity (27.31–36.1 S/cm). The Seebeck coefficient value has also improved by the energy filtering effect at the grain boundaries. As a result, the Al-doped sample (4%) has achieved maximum power factor value (1.82 × 10−7 Wm−1K−2), which is roughly 35% higher than pure CZTS.
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This study aims to determine the magnetic properties of Fe3O4 synthesized from rope bamboo and natural iron sand. In this study, natural magnetic bio-char of bamboo and iron sand was synthesized by ...the co-precipitation method at a calcination temperature of 500oC. Then it was characterized through several tests, namely XRD and VSM. The results of the XRD test showed that the synthesis of natural bamboo + iron sand produced HKL peaks that were identical to Fe3O4 where these peaks were the peaks of magnetite and hematite. Magnetic properties were tested using VSM through a hysteresis curve with samples classified as soft magnets.
