Papers by Keyword: Structural Property

Abstract: Ni_1-2xMg_xCu_xO and Ni_1-2xMg_xRu_xO nanoparticles (x = 0.005, 0.01, 0.02, 0.04, 0.08) were synthesized by the chemical co-precipitation method using salt chloride precursor and EDTA as a capping agent.The present work compares the impact of (Mg, Cu) and (Mg, Ru) co-dopants on the dielectric properties of NiO within a frequency range 0.1 -8 MHz and various dopant concentrations x = 0, 0.005, 0.01, 0.02, 0.04, 0.08. The dielectric properties and phase formation were investigated via an impedance analyser and XRD, respectively. X-ray diffraction patterns confirm the successful synthesis and crystallization of all Ni_1-2xMg_xCu_xO and Ni_1-2xMg_xRu_xO nanoparticles in the fcc structure except for Ni_0.92Mg_0.04Ru_0.04O and Ni_0.84Mg_0.08Ru_0.08O nanoparticles confirming a secondary RuO₂ pahse. Observed and calculated data from the impedance analyzer showed higher dielectric constants, ac conductivity, energy loss, and refractive index values for Ni_1-2xMg_xCu_xO than for Ni_1-2xMg_xRu_xO nanoparticles. However, the impedance values of (Mg, Ru) dual-doped NiO nanoparticles were higher compared with (Mg, Cu) dual-doped NiO nanoparticles. Both samples showed a decrease in dielectric constants, impedance, loss tangent, and refractive index as frequency increased (0.1-7.5MHz), with a vice versa behavior as dopant concentration rose, except for the impedance. Hence, Ni_1-2xMg_xCu_xO and Ni_1-2xMg_xRu_xO nanoparticles are good candidates for electrical and optical applications.

Abstract: The lithium aluminium titanium tantalum phosphates compounds Li₁₊xAl_xT_2-x-yTa_y(PO₄)₃ (LATTaP) with different compositions (x = 0.3; 0.02 ≤ y ≤ 0.05) were synthesized using a solid-state synthesis approach. The synthesized samples were characterized through various methods. TGA/DTG results indicate the thermal stability and complete breakdown of the stoichiometric compositions. This ensures LATTaP solid electrolytes remain stable under battery cycling, high-temperature environments, and battery applications. This was corroborated by the FTIR findings, which showed the total decomposition of volatile substances, including water molecules, CO₂, and HN₃; the wave bands associated with hydroxyl or carboxylic compounds were completely absent, with only the bands corresponding to the vibration of the PO₄ ionic group detected. This identifies chemical bonding, confirming the stability of the phosphate framework which determines structural integrity for long-term battery cycling without material degradation. The samples were successfully produced with an R-3c space group for structural characterization, assuming a hexagonal crystal structure, as referenced in the ICSD database 98-006-9677. XRD analysis demonstrated the presence of a single-phase NASICON-type crystal structure, which is essential for high ionic conductivity. The findings showed that the thermal properties of the materials are important to identify proper applicability of the material as a solid electrolyte.

Abstract: The morphological and structural transitions in CdSe hollow nanoparticles (hNPs) with zinc blende structure have studied by molecular dynamics (MD) simulation method under heating. The seven samples of CdSe-hNPs are constructed with different thicknesses from the solid NPs at 10nm and 15nm sizes. Morphological changes in CdSe-hNPs have presented by describing the first stage melting in hollow semiconductor NPs. The thermal effect on the atomic arrangement has also examined by the cubic zinc blende-to-wurtzite transformation occurred during the melting in hNPs. MD results show that the inner shells of those with thin walls have begun to melt at lower temperatures due to the thickness of the NPs. The first stage melting, which resulted in the filling of the void within the particle, takes place almost at the same temperature for hNPs with the thick wall thickness. Then, the melting of the particles is completed at higher temperatures. The cubic diamond structure disappears with the collapse of the inner cavity, and the hcp structure begins to appear at later temperatures.

Abstract: Spinel ferrite with the chemical formula of Mn_0.5Zn_0.5La_xFe_2-xO₄ (x = 0.02, 0.04, 0.06, 0.08, 0.10) were prepared by a sol-gel auto-combustion method. The effect of the rare-earth substitution on the microstructural properties of the synthesized powders were investigated through X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), while for the magnetic properties, vibrating sample magnetometer (VSM) measurements were made. XRD patterns revealed characteristic peaks corresponding to spinel Mn-Zn ferrite structures with accompanying secondary phases, such as Fe₂O₃ and LaFeO₃. The initial addition of La³⁺ into the spinel ferrite system resulted in an initial spike of the lattice parameter and crystallite size before proceeding to decrease as the rare-earth content continues to decrease. FESEM micrographs reveals agglomerated particles with considerable grain size distribution. The magnetic properties, especially the saturation magnetization, M_s, was found to decrease with each increase in La³⁺ substitution. The research findings revealed the critical influence of the La³⁺ substitution towards the overall structural and magnetic properties of the Mn-Zn ferrite samples.

Abstract: Organic devices are advantageous in term of high carrier mobility, lightweight and flexibility. The solution processed method offers economic and efficient device fabrication in small laboratory scale. The α-quaterthiophene (α-4T) is an oligomer and a p-type organic semiconductor. In this study, pure α-4T and polylactide acid (PLA)/α-4T films were spin-coated on glass and indium tin oxide (ITO) substrates at low spin frequency. The hydrated films were left to dry at room temperature and later in vacuum oven. The α-4T microstructures changed when blended with the polymer. The roughness of the 180 nm ITO film was found to be 1 - 30 nm and the organic layer formed uneven thickness (max ~ 300 nm) thicker toward the edge. The preparation of spin coated organic thin film is the first step towards realizing solution processed organic device in electronic packaging.

Abstract: The pretreatment of bamboo with dilute alkali and the effects on chemical components and enzymatic hydrolysis were studied, and the fiber structural properties of pretreated residues were studied with Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The results showed that dilute alkali was highly effective in delignification of the biomass, reducing the lignin content by 50-70%. Bamboo solid recovery was 74.40%, and cellulose, hemicellulose and lignin content were 60.02%, 25.93% and 9.08%, respectively, when pretreated with 1.0% sodium hydroxide, with a solid-liquid ratio of 1:10 at 100 °C for 40 min. Under the conditions, the pretreated residue was hydrolyzed for 72 h with cellulose and xylanase dosage 40 FPU/g cellulose, and the hydrolysis yield of cellulose was 81.38% and that of hemicelluloses was 84.78%, resulting in a total of 66.74 g fermentable sugars from 100 g dry bamboo. The SEM pictures indicated that the biomass structure was deformed and its fibers were exposed, and FTIR results verified the lignin removal by the pretreatment.

Abstract: Based on boundary surface elastoplastic theory, a boundary surface elastoplastic constitutive model is established which is considered both structural property and rheological behavior of soft clay with the method of taking Cam-Clay yield surface as boundary surface. The structural parameters are introduced to calculate structure-damage strain. Plastic volumetric strain is regarded as a function time t so that a rheological parameter is introduced. The constitutive model is validated by numerical analysis of triaxial rheological tests.

Abstract: Zinc oxide (ZnO) thin films were prepared by sol-gel spin coating technique, which were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), NKD thin film analysis system and fluorescence spectrophotometer. The results show that ZnO thin films with the each layer thickness of 80 nm present obvious c-axis orientation. With the increase of coating layers, the c-axis orientation characteristic weakens. The reason is considered that the growth mode of ZnO thin films transforms from layer growth to island growth. For the ZnO thin film with 4 layers, it has a compact surface and a uniform particle size of approximately 50 nm, and the photoluminescence (PL) spectrum primarily consists of two PL emission bands, one is a strong and narrow ultraviolet (UV) emission band, another is a weak and broad luminescence emission band from 400 nm to 650 nm. The average transmittance in the visible range is beyond 90%. A optical band gap of 3.26 eV, slightly less than the intrinsic band gap width of 3.37 eV, is obtained by Tauc plotting method. The defects, such as Zn or O vacancies, grain boundaries, are considered to be the main factors causing this situation.

Abstract: Nitrogen-doped TiO2 nanoparticles of commercial Degussa P25 have been prepared via a direct impregnation reaction using ammonium hydroxide solution as nitrogen source. The Samples were characterized by X-ray diffraction (XRD), BET surface area BJH pore charecterization and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDX). The results demonstrated that the nitrogen-doped TiO2 nanoparticles had a crystallite size 70.8 nm and a specific surface area of 6.4 m2/g with average pore diameter of 23.3 nm consisting mainly of titanium and oxygen. The photocatalyst activity was determined by degradation of phenol in an impinging stream reactor under visible light irradiation (λ> 400 nm). N-TiO2 catalyst exhibited higher photocatalytic activity in comparison with Degussa P25 under visible light irradiation.

Abstract: The comparison substitution with K, Ca and Zn respectively at the Cu site of YBa₂Cu_3-xM_xO_δ (x = 0.00 and 0.20) was performed based on superconducting and structural properties. All samples were prepared via a solid state technique. Resistivity and current density measurements (zero magnetic fields) were done using the four probe method and the structural and morphological properties were characterized using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) respectively. The critical current density (J_c) and critical temperature (T_{c zero}) of the substituted samples were found to be lower than that of the pure sample. T_{c zero} with K and Zn substitution was 78 K and 21 K respectively. This is due to the change in the hole concentration. J_c measured at 50 K showed values of 3.9790 A/cm², 4.4483 A/cm² and 2.9854 A/cm² for the pure sample, K and Ca substituted samples respectively. The decrease in J_c was due to the hole porosity and grain connection. All samples showed an orthorhombic crystal structure. The morphology of the fracture surface of samples as observed by FESEM displayed a loose structure of grain arrangement for sample Ca and Zn substituted samples.