Papers by Keyword: Sol-Gel Method

Abstract: Zinc oxide has taken over modern studies for its suitability for the electronics, sensors, and optical devices industries related to its structural, optical, and electrical properties. This study tries to improve the properties of zinc oxide by doping it with some materials with distinctive properties to add their properties to zinc oxide. So, potassium has been used for its electrical properties, manganese for its high stability, and cobalt for its optical properties. Experiments were done in the same conditions using the chemical weight sol-gel synthesis method. making Zn_0.96 X _0.04O (X = K, Mn, and Co) nanoparticles (NPs). Then, checked how their growth changed the structure of zinc oxide. Using XRD to fix structure and be sure that the doped X completely dissolved in ZnO without changing the structure of the wurtzite. The diffraction patterns demonstrated that all ZnO nanoparticles had hexagonal wurtzite structures and no impurity phase. The crystal sizes using the Scherrer formula are 19.48 nm for pure ZnO, 27.49 nm for Zn_0.96 K_0.04 O, 24.6 nm for Zn_0.96 Mn_0.04 O, and 44 nm for Zn_0.96 Co _0.04 O. The SEM image shows hexagonal wurtzite structure with particles 32 nm in size for pure ZnO and 28, 34, and 54 nm in size for Zn_0.96 X _0.04O, where X = K, Mn, and Co, respectively. The intensity of the Raman spectrum goes down for all X values of Zn_0.96 X _0.04O (X = K, Mn, and Co), and the E_2H peak is found between 430 and 450 cm^-1. The peak intensities get weaker with Mn and Co doping and stronger with K doping. However, the positions of the peaks move slightly when doping, which suggests that the K, Mn, and Co added to ZnO don't change the hexagonal wurtzite structure. This fits well with the XRD patterns that were seen. Rather, it can control the size of the crystal according to the purpose of its use, whether electrical, optical, or for manufacturing sensors.

Abstract: Continuous cockle shell dumping in open areas has become a global problem which generate major environmental issues. The conversion of the wastes into value-added products is highly desirable and economic. This work aimed to investigate the influence of sol-gel processing parameter on the properties of the synthesized calcium hydroxide (Ca(OH)₂). In this study, cockle shell waste was used as calcium carbonate (CaCO₃) precursor in the preparation of Ca(OH)₂ via sol-gel method and the processing parameter varied was hydrochloric acid (HCl) concentration (0.5, 1.0 and 2.0 M). The cockle shell based CaCO₃ and the prepared Ca(OH)₂ powders were characterized by X-ray diffraction (XRD), Fourier transform infra-Red (FTIR), field emission scanning electron microscopy with energy dispersive X-ray (FESEM-EDX), X-ray fluorescent (XRF) and particle size analyzer (PSA). The XRD analysis indicates that the calcium carbonate obtained from cockle shell was mainly in the form of aragonite polymorph. Upon sol-gel processing, the analysis of the sample shows the presence of portlandite and small traces of aragonite in all samples suggesting an incomplete reaction of the hydrolysis process. Ca(OH)₂ powder prepared using 1M HCl yields the smallest particle size.

Abstract: The paper discusses the influence of flame retardant compositions obtained in the system of silicic acid sol (SiO₂ sol) – flame retardants on the fire retardant properties of thin dense cotton fabrics and low density voluminous tapestry fabrics. The need to develop the optimal composition of a fire-retardant composition for a specific fabric, or to unify it for two main groups of fabric: thin and bulky low-density ones, is substantiated. Experimental coatings were obtained by applying SiO₂ sol, which was obtained by the reaction between liquid glass and acetic acid, followed by application of flame retardant solutions (diammonium hydrogen phosphate (DAHP) and urea) by spraying or by the bath method. As a result of the optimization, using the central composite uniform rotatable plan of the second order, it was established that the main effect of the flame retardant is exerted by diammonium hydrogen phosphate (DAHP). The content or concentration of urea depends on the concentration of DAHP used: if diluted DAHP solutions (9–10 %) are used, trace amounts of urea (0–0.5 %) must be added. In the case of using a concentrated DAHP solution (18–20 %), the concentration of the urea solution should also be increased to 8–10 %.

Abstract: By introducing, in addition to phosphorus, nitrogen and halogens into the structure of the organosilicon compound, a synergistic effect of the flame retardant effect of the fabric is achieved, but the issue of protecting the environment from the effects of thermal decomposition products of the flame retardant composition arises. In view of the numerous publications on the impact of thermal destruction products of flame retardants on the ecological state of the environment, the problem of finding safe types of flame retardants that do not release toxic decomposition products during thermal destruction has arisen. The aim of the work was to develop a phosphorus-and nitrogen-containing silicate fire-retardant composition based on safe components that do not produce toxic products during thermal destruction of the treated fabric. As a result of the conducted research, it was established the possibility of using modifying additives (orthophosphoric acid and ammonium dihydrogen phosphate) in the composition of protective sol based on liquid glass. It was established that the introduction of small additions of orthophosphoric acid into the SiO₂ золь сприяє утворенню суцільних тонких кремнеземних плівок на поверхні волокон ниток бавовняної тканини та значно збільшує час початку руйнування тканини під дією вогню. Позитивний результат досягався за умов одноразового просочування золем низької концентрації (8% SiO ₂ ). Встановлено, що додавання дигідрофосфату амонію також позитивно впливає на підвищення вогнезахисних властивостей тканини. Оптимальний діапазон концентрації розчину фосфоровмісної добавки становить 10-15%. Додаткове просочення вогнезахисним розчином підвищує вогнестійкі властивості текстильних матеріалів і перешкоджає остаточному прогоранню і тлінню.

Abstract: NaFePO₄, which is analogue to LiFePO_4, has been expected to show similar properties as LiFePO₄ that has a good cycle stability and excellent electrochemical performances. Here we report the synthesis of NaFePO₄ via sol-gel method and the structural study of NaFePO₄ as a cathode material for sodium-ion battery (SIB). The as-synthesized NaFePO₄ samples were calcined under air and argon atmosphere at the constant holding time of 10 hours with the variation of calcined temperature. In this report, we present the successfully synthesized NaFePO₄ based on XRD and SEM result. XRD results show the presence of NaFePO₄ as a major phase and some amount of secondary phase. SEM result indicates the plate-like particle which tends to agglomerate with the size range 2-5 .

Abstract: Differences in particle size can affect the magnetic properties of superconductors. At the nanoscale, superconductors have different magnetic properties than those at the micro or submicron size. The difference in particle size in superconducting materials can be obtained by giving the sintering temperature difference. In this work, we focus only on the magnetic properties in Eu_1.85Ce_0.15CuO_4+α-δ (ECCO) in the optimal-doped regime prepared by the sol-gel method with various sintering temperatures 700 °C, 800 °C and 900 ° C sizes with an annealing temperature 800 °C to obtain different particle. The lattice parameters and crystallite size were obtained using XRD. Based on the XRD results, the higher the sintering temperature variation, the larger the crystallite size produced with lattice distortion and expansion with a decrease in particle size. The magnetic properties of these materials have been investigated using a superconducting quantum interference device (SQUID) at temperatures between 2 K and 30 K with the applied field at 5 Oe. Based on the SQUID measurement, the magnetic properties of samples sintering at 700 °C and 800 °C were found to be ferromagnetic-like behaviour, while sintering at 900 °C was found to be paramagnetic with no trace of the superconductivity phase. The differences response of magnetic properties can be associated with the effect of the differences size of the crystallites in each material, that can relate to uncompensated spins produced by the surface effect.

Abstract: Barium Hexaferrite is a permanent magnet material known for its excellent quality and relatively inexpensive manufacture. Barium hexaferrite has good stability and can be applied in various technologies. In this research, the synthesis of barium hexaferrite has been successfully made from the primary materials Fe (NO₃)₃ and Ba (NO₃)₂ using the sol-gel method, as well as other materials such as NaOH, chitosan, molasses, acetic acid and distilled water as the primary solvents for several materials. In addition, variations in aging time 0 hours, 2 hours, 4 hours and 6 hours were added to see the effect on morphology, crystal structure and the magnetic properties of barium hexaferrite magnets. The characterization process is carried out with three testing processes, namely X-Ray Diffraction testing (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). From the XRD, it was found that the desired phase of Barium Hexaferrite (BaFe₁₂O₁₉) was formed, while in the SEM testing process, it was seen that the aging time of the barium hexaferrite sample decreased the particle size of the barium hexaferrite BaFe₁₂O₁₉ from an aging time of 0 hours seen 681.459 nm and at an aging time of 6 hours. Visible 538.859 nm particle size formed. The VSM characterization results showed that different aging times did not affect the barium hexaferrite nanomagnets' magnetic properties.

Abstract: M-type hexagonal ferrites have wide range of applications in magnetic recording media, microwave devices, micro electrochemical systems, high frequency devices, magneto-optical devices and many more. In present research, M-type strontium hexagonal ferrites doped with ‘magnesium’ having chemical composition (SrMg_xFe_12-xO₁₉) for x= 0.00, 0.05, 00.10, 0.15, 0.20, were synthesized to investigate the influence of rare earth metal doping on the structure and dielectric properties via sol-gel auto combustion technique. Molecular absorption/transmission, structural properties and dielectric response were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Dielectric measurements of ‘Mg’ doped strontium hexaferrites. X-ray diffraction analysis verified the magneto-plumbite structure. Crystal sizes were found in varying order for different concentrations of ‘Mg’ ranging from 12.357 to 15.375 nm. The FT-IR spectra exhibited higher frequency band (500–515.84 cm^-1) indicating tetrahedral site’s vibrations of metallic cations and lower frequency band (385.35–375.16 cm^-1) exhibiting octahedral sites due to metallic oxygen bond that confirmed the hexagonal structure. The resonance peaks were observed in dielectric constant, loss, tangent loss, AC conductivity, electric modulus and quality factor versus frequency graphs. The dielectric properties were found to be enhanced gradually by increasing concentration of magnesium. The best Q-factor was found for magnesium concentration (x=0.20). The dielectric parameters specify that these ferrite nanoparticles are good applicants for the higher frequency implementations.

Abstract: Herein, silica nanoparticles (SiO₂ NPs) were synthesized from a waste product of the zirconium carbide facility (WPZF). Firstly, the WPZF was characterized by using physical and chemical methods like X-ray powder diffraction (XRD), field emission scanning electron microscope (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), and energy dispersive X-ray analysis (EDXA) methods. Then WPZF proceeded via chemical reagents to synthesize SiO₂ NPs by using the sol-gel method. Obtained SiO₂ NPs were characterized by using XRD, SEM, EDXA, and transmission electron microscopy (TEM) methods. The yield of SiO₂ NPs reached up to 96.5% and particles were spherical with a diameter of 20 ± 3 nm. Most importantly observed SiO₂ NPs in this procedure has an amorphous structure.

Abstract: In this paper, studying synthesis and characterization of ferrospinel nickel ferrite. Nickel ferrite is prepared by using the sol-gel method, with a ratio of 2:1 of iron nitrate to nickel nitrate. First the starting material is dissolved in 100 ml of ethylene glycol solution to get the gel and then the gel was dried at 160°C then calcined at 600°C to obtain fine powder, second the nickel ferrite powder is pressed and sintered at 1200°C. To characterize nickel ferrite are used different techniques, such as: XRD is shown high purity, the purity of the nickel ferrite is known and the extent to which the material is affected by the temperatures of calcination and sintering. FT-IR that is shown absorption band between the elements of the components of nickel ferrite appears. The shape of the resulting powder is known through the SEM, the SEM images showed the spherical shape of the nickel ferrite powder, found the particular size of powder at 600°C ranges between405-264 nm and for sample after sintering at 1200°C ranges between589-353 nm, and our Physical characterization test down.