Dependence of pH Variation on the Structural, Morphological, and Magnetic Properties of Sol-Gel Synthesized Strontium Ferrite Nanoparticles

In this research work, an attempt of regulating the pH as a sol-gel modification parameter during preparation of SrFe12O19 nanoparticles sintered at a low sintering temperature of 900°C has been presented. The relationship of varying pH (pH 1–14) on structural microstructures and magnetic behaviors of SrFe12O19 nanoparticles was characterized by X-ray diffraction (XRD), field emission scanning microscope (FESEM), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR), and vibrating-sample magnetometer (VSM). The single-phase SrFe2O19 with optimum magnetic properties can be obtained at pH 1 with a sintering temperature of 900°C. As pH values increase, the presence of impurity Fe2O3 was observed. TGA data-varying pH shows that the total weight loss of most samples was at 30.44% which corresponds to the decomposition process. The IR spectra showed three main absorption bands in the range of 400–600 cm−1 corresponding to strontium hexaferrite. SEM micrographs exhibit a circular crystal type of strontium ferrite with an average crystal size in the range of 53–133 nm. A higher saturation magnetization Ms, remanent magnetization Mr, and hysteresis Hc were recorded to have a large loop of 55.094 emu/g, 33.995 emu/g, and 5357.6 Oe, respectively, at pH 11, which make the synthesized materials useful for high-density recording media and permanent magnets

Logical Approach: Consistency Rules between Activity Diagram and Class Diagram

Requirements engineering (RE) is a fundamental in software development process. Requirements engineering encompasses activities ranging from requirements elicitation and analysis to specification, verification and validation. Poor requirements have been proved to be a major cause of software problems such as cost overruns, delivery delays, failure to meet expectation and degradation. Requirements validation especially models validation has gained quite an interest from a lot of researchers. In recent times, several researchers have expressed a great deal of interest in requirements validation, specifically models validation. The field of research related to consistency checking has undergone a considerable boom from time to time. Numerous methods, approaches and techniques have been recommended to address the requirements inconsistency issues, particularly in models validation. In the software development industry, UML modelling has been extensively used. The different forms of the UML model that characterise the system from various perspectives somehow establish a relation among the models to keep them inseparable from one another. This is the reason why the inconsistency becomes unavoidable. The inconsistency in the models arises when there is an overlap of the elements of the various models representing the different parts of the system and an absence of cooperation. In this paper, the emphasis is given on the consistency rules that exist between the two models. The focus is also on the class diagrams and activity, and the conversion of the rules into logical predicates, where the logical predicates are assessed with a sample case study that constitutes of the two models

IMPLEMENTASI BUDAYA ORGANISASI DI SEKOLAH MENENGAH PERTAMA (Studi Kasus Di SMP Al Washliyah 42 Berastagi)

Penelitian  ini membahas mengenai bagaimana implementasi budaya organisasi dimana pada dasarnya budaya organisasi memiliki pengaruh agar  organisasi lebih efektif dan memiliki ciri khas yang menonjol, penerapan budaya organisasi di suatu lembaga atau sekolah tidak berbeda jauh dengan organisasi lainnya, adanya sebuah lembaga atau sekolah ialah sebagai organisasi pendidikan pastinya memiliki tujuan dan fungsi untuk mencerdaskan, mewariskan nilai budaya kepada anak didiknya, penelitian ini menggunakan metode penelitian kualitatif dimana Penelitian kualitatif mengkaji perspektif partisipan dengan strategi-strategi yang bersifat interaktif dan fleksibel. Penelitian kualitatif ditujukan untuk memahami fenomena-fenomena sosial dari sudut pandang partisipan menggunakan lingkungan alamiah sebagai sumber data. Dan dapat dilihat bahwa implementasi budaya organisasi di SMP Al Washliyah 42 Berastagi seperti organisasi pada umumnya yaitu dengan lama belajar 3 tahun. Materi pelajaran 70% ilmu umum dan 30% ilmu agama akan tetapi sekolah ini memiliki sistem yang tersentral pada pengurus pusat seperti adanya ispeksi setiap enam bulan sekali oleh petugas alwashliyah itu sendiri

Effect of pH variation on magnetic properties of strontium hexaferrite nanoparticles synthesized by sol gel process

A strontium ferrite (SrFe12O19) nanoparticle was prepared by sol gel auto combustion method at 800°C and 900°C and at various pH (pH 1, 3 and 5). The SrFe12O19 powder was characterized by using Thermogravimetric analyses (TGA), X-Ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM), and Field emission Scanning Microscope (FeSEM) to investigate thermal behavior, crystalline structure, magnetic properties and morphology. To review, the single crystal size of SrFe12O19 was found at 900°C has lower weight loss about 30.44%, crystalline size of 70.5 nm with Mr, Ms, and Hc were 64036 G, 44.188 emu/g and 27.593 emu/g. The average grain size was 80 ~ 100 nm. In brief, as pH increase, the Mr, Ms and Hc were increases

Elemental analysis and IR band characteristics of α-Fe2O3 and BaFe12O19 steel waste product based

This project focused on the elemental analysis and IR band characteristic of -Fe2O3 derived from recycled steel waste product. The steel waste flakes were ball milling for several hours to form a fine powder. The steel waste powder had been purified by using impurity separation technique and magnetic separation technique. The purified steel waste powder then oxidized at 500 oC to form hematite (Fe2O3). The hematite were used to synthesize BaFe12O19 by using salt-melt method. The samples were characterized using X-ray Fluorescence (XRF), Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX). The XRF and FTIR results show the formation of Fe2O3, the IR characteristic bands of Fe2O3 and single phase BaFe12O19 is obtained from recycled steel waste product

Annealing study of α-Fe2O3 nanoparticles steel-waste based: microstructure and magnetic behavior

The interest of this paper is to show the influence of annealing process on magnetic properties and microstructure of -Fe2O3 derived from steel waste product (mill scales). The mill scales flakes were wet ball milling for several hours to form a fine powder. The mill scales powder was purified by using magnetic separation to isolate the magnetic and non magnetic particles. The method was continue for Curie temperature separation technique. The purified powder was annealed at 400/450/500 and 550 °C at 6 oC/mins to form hematite, -Fe2O3. The annealed powders were milled for several hours by using mechanical alloying. Annealing at varied temperatures produced α-Fe2O3 nanopowders with average crystallite size 18.1 nm to 28.6 nm. Phase transformation occurred directly by annealing in air, conversion of FeO and Fe3O4 phase to form α-Fe2O3. The correlation between the magnetic properties and microstructure, of the sintered powders at 1200 oC enables to obtain microphase of α-Fe2O3 and Fe3O4 with different particle size and magnetic properties. The resultant α-Fe2O3 nanopowders are ferromagnetic with moderate coercivities

Synthesis and characterization of barium hexaferrites derived from steel waste by ammonium nitrate salt melt synthesis

In this paper, a series of barium hexaferrite BaFe12O19 with different powder to salt ratio (1:3, 1:4, 1:5) were prepared using ammonium salt melt technique. Iron oxide were process from steel waste product were mixed with barium carbonate, used as starting materials to produce barium hexaferrites. The ammonium nitrates in this experiment act as oxidizing agent in this synthesis. The BaFe12O19 powders were sintered at 1300°C for six hours and characterized using X-ray diffraction (XRD), Fourier transform Infrared (FTIR), Vibrating Sample Magnetometer (VSM) and Field emission Scanning Microscope (FeSEM) to investigate its crystallography, magnetic properties and morphology. The maximum coercivity and saturation magnetization obtained for sample ratio 1:3 of 1017 G and 90.9 emu/g, respectively. Increase the salt ratio decrease the coercivity and saturation magnetization values

Structural and magnetic properties of aluminum substituted yttrium iron garnet via sol-gel synthesis

Aluminum-substituted yttrium iron garnet (Al-YIG) powders was synthesize by using sol-gel citrate nitrate combustion technique with different doping concentration (x = 0.4, 0.6 and 1.0). The Y3-x Alx Fe5O12 samples were analyse of phase, structural and hysteresis by using X-ray diffraction (XRD), Fourier transform infra-red (FTIR) and Vibrating Sample Magnetometer (VSM).The powder resulted a single phase nanostructured garnet was formed. Room temperature saturation magnetization Ms and coercivity of Al-YIG powders decreased as a function of increasing Al content. The samples has a room temperature Ms of 9.2 emu/g and decreased to 1.5 emu/g. Coercivity Hc value decreases from 71.7 G to 51.4 G

Composition and magnetic properties of aluminium substituted yttrium iron garnet waste mill scales derived via mechanical alloying technique

This paper presents the effects of aluminium substitution on sample composition, density and magnetic properties of yttrium iron garnet, Y3Fe5O12 (YIG). Mill scales, in a form of flakes was obtained from the steel industry in Malaysia. The mill scales was purified to produce high purity hematite, Fe2O3. The mill scales derived Fe2O3 were used as raw material to prepare the aluminum substituted yttrium iron garnet Y3Fe(5-x) Al(x) O12 (Al-YIG) with variation compositional x = 0.0, 0.5, 1.0, 1.5 and 2.0 using mechanical alloying technique. X-ray fluorescence (XRF) was used to investigate the percentage compositions of the raw mill scales. The magnetic hysteresis of sample were investigate by using B-H tracer (MATS). Density of the Al-YIG bulk samples was found to decrease with increasing xAl2O3 content. The saturation magnetization Ms also shows a decrease with increase xAl2O3 content. The maximum saturation magnetization Ms and coercivity Hc was found at 310 G and 14.98 Oe, respectively. With increase xAl2O3 to 2.0%, the Ms and Hc were reduced to 29.35 G and 3.15 Oe, respectively