The effect of doping of La3+ ions on multiferoic Bi2-xLaxFe4O9 (x = 0; 0.2; 0.5; 1.0) as microwave absorber

The synthesis and characterization of Bi2-xLaxFe4O9 multiferoic material (x = 0; 0,2; 0,5; 1) have been used as microwave absorbers. Bi2-xLaxFe4O9 (x = 0; 0,2; 0.5; 1) material was made by solid state reaction with mechanical milling technique using high energy milling (HEM). X-ray diffraction (XRD) was used for characterization of formation phase and crystal structure, scanning electron microscopy-energy dispersive spectra (SEM-EDS) was used to characterize surface morphology and particle size, whereas vector network analysis (VNA) was used for characterization of absorption capability microwaves. The characterization results showed that all samples were in phase with orthorombic crystal structure, P bam space group. The average particle size was 578.5 nm with an almost homogeneous form. Meanwhile, the best sample in absorbing microwaves was obtained for x = 0.2 with reflection loss value (RL) around -21dB at 11.2 GHz frequenc

A Case Study: Technological Pedagogical and Content Knowledge (TPACK) of Pre-service Physics Teacher to Enhance the 4C’s Skills During Online Learning

Technological Pedagogical and Content Knowledge (TPACK) framework aims to provide an overview of teaching and learning that is integrated with technology to improve students' knowledge which supports 21st century skills. According to curriculum 2013 is expected to provide learning that develops students’ learning skills (critical thinking, creativity, collaboration, and communication) to face the world in the 21st century. The study is aimed to expose TPACK competence of pre-service teacher to enhance 10th grade students’ 21st century skills in physics learning. The method used descriptive qualitative, and data obtained from mentor’s feedback, teacher’s reflection in five meetings. As a result, TPACK component of pre-service teacher during five meetings of physics, was able to use technology to guide students well (TK1, TCK1, TPK1, and TPK2) and guide students to share ideas and knowledge (PK 3 and PCK3), discuss (PK4 and PCK4). The disadvantages of pre-service teachers which are still low is the content knowledge components and needs to be improved before becoming a professional teacher, so the teacher can integrate learning using technology properly. However, this study needs to be further developing the strategies to observed pre-service teache

Microwave Absorbing Properties of Ba0.6Sr0.4Fe12-zMnzO19 (z = 0 â 3) Materials in XBand Frequencies

Ba0.6Sr0.4Fe12-zMnzO19 (z = 0,1,2, and 3) were successfully synthesized by solid state reaction through a mechanical milling method. Stoichiometric quantities of analytical-grade MnCO3, BaCO3, Fe2O3, and SrCO3 precursors with purity greater than 99% were mixed. It was found that the best phase composition, having an absorber with high performance, was Ba0.6Sr0.4Fe11MnO19. Refinement of the X-ray diffraction patterns revealed that the Ba0.6Sr0.4Fe11MnO19 was single-phase and had a hexagonal structure (P63/mmc). Mechanical milling of Ba0.6Sr0.4Fe11MnO19 powders produced particles with a mean size of ~850 nm. SEM images revealed the morphology of the particles as being aggregates of fine grains. The magnetic properties of the Ba0.6Sr0.4Fe11MnO19 particles showed a low coercivity and a high remanent magnetization. The Ba0.6Sr0.4Fe11MnO19 has certain microwave absorber properties in the frequency range of 8-14 GHz, with an absorbing peak value of "‘8 dB and -10 dB at frequencies of 8.5 and 12.5 GHz, respectively. The study concludes that the Ba0.6Sr0.4Fe12-zMnzO19 that was successfully synthesized is a good candidate for use as an electromagnetic absorber material

Kompetensi Guru Kristen sebagai Fasilitator dalam Mengembangkan Kemampuan Berpikir Kritis Siswa di Era Digital [The Competence of Christian Teachers as Facilitators in Developing Students' Critical Thinking Skills in the Digital Age]

The background of this writing is based on the fact that critical thinking skills in Indonesia are categorized as low. Students' critical thinking skills are very important in the digital era. Technology plays an important role in education, especially for Christian teachers to have relevant competencies as facilitators. This writing aims to find out what competencies Christian teachers need to develop students' critical thinking skills in the digital era. The author uses a qualitative descriptive method in this research. The research results show that the competence of Christian teachers as facilitators is crucial for developing students' critical thinking skills in the digital era. In developing students' critical thinking skills in the digital era, Christian teachers as facilitators must operate within the framework of Christian education, which is based on Biblical truth. This approach aims to restore the image and likeness of God, which has been distorted in students. Humans, as images of God, possess unique qualities, making it essential for Christian teachers to develop students holistically. Holistic student development involves teachers fulfilling their role as facilitators in Christian education. The recommendation for further research is to examine the role of Christian teachers beyond that of facilitators in developing students' critical thinking skills in the digital era to evaluate the effectiveness of these roles. BAHASA INDONESIA ABSTRACT Latar belakang penulisan ini adalah fakta bahwa kemampuan berpikir kritis di Indonesia dikategorikan rendah. Kemampuan berpikir kritis siswa sangat penting di era digital. Teknologi memegang peranan penting dalam dunia pendidikan, khususnya bagi guru-guru Kristen untuk memiliki kompetensi yang relevan sebagai fasilitator. Penulisan ini bertujuan untuk mengetahui seperti apa kompetensi guru Kristen yang dibutuhkan untuk mengembangkan kemampuan berpikir kritis siswa di era digital. Penulis menggunakan metode deskriptif kualitatif dalam penelitian ini. Hasil penelitian menunjukkan bahwa kompetensi guru Kristen sebagai fasilitator sangat dibutuhkan untuk mengembangkan kemampuan berpikir kritis siswa di era digital. Dalam mengembangkan kemampuan berpikir kritis siswa di era digital, penerapan peran guru Kristen sebagai fasilitator perlu dilakukan dalam kerangka pendidikan Kristen yang mendasarkan pendidikannya pada kebenaran Alkitab untuk mengembalikan gambar dan rupa Allah yang telah terdistorsi dalam diri siswa di era digital. Manusia adalah gambar dan rupa Allah yang memiliki keunikan masing-masing. Oleh karena itu, hal ini membuat guru-guru Kristen harus mengembangkan siswa secara holistik. Pengembangan siswa secara holistik dilakukan dengan menjalankan perannya sebagai fasilitator dalam pendidikan Kristen. Rekomendasi untuk peneliti selanjutnya adalah meneliti efektivitas peran guru Kristen lainnya  dalam mengembangkan kemampuan berpikir kritis siswa di era digital

Synthesis and Characterization of Ba0.6Sr0.4Fe12O19/LaMnO3 Composites as Microwave Absorbers

The synthesis and characterization of Ba0.6Sr0.4Fe12O19/LaMnO3 composite material has been successfully carried out by mechanical alloying method using high energy milling. Crystal structure and surface morphology were characterized using x-ray diffraction and scanning electron microscopy. While the value of magnetization and the ability to absorb microwaves, vibrating sample magnetization and vector network analyzing were used, respectively. With variations in weight, does not change the crystal structure. The Ba0.6Sr0.4Fe12O19phase has a hexagonal structure and the LaMnO3 phase has an orthorhombic structure. Surface morphology has a heterogeneous size in the range of 200-450 nm with the form of platelets. The composite material Ba0.6Sr0.4Fe12O19/LaMnO3 is a hard-soft magnetic material with a magnetic saturation of Ms ~ 46.83 emu/g, Mr ~ 28.8 emu/g, and a coercive field of Hc ~ 3.88 kOe. The minimum reflection loss value is – 13.0 dB at 11.2 GHz frequency and 1.52 GHz bandwidth

THE STRUCTURAL, IMPEDANCE AND DIELECTRIC A FERRITE CORE OF IRON MANGANITE AND ITS COMPOSITE

THE STRUCTURAL, IMPEDANCE AND DIELECTRIC A FERRITE CORE OF IRON MANGANITE AND ITS COMPOSITE. Samples with single-phase MnFeO3 and multiphase MnFeO3/ZnFe2O4 (30/70), and MnFeO3/ZnFe2O4/LaMnO3 (30/40/30) have been successfully prepared as ferrite cores by the solid-state reaction method using high energy milling. Crystal structure, surface morphology, impedance, AC-conductivity and dielectric quantities, such as dielectric constant and dielectric loss have been studied. The crystalline structures for MnFeO3, ZnFe2O4, and LaMnO3 are hexagonal, cubic and monoclinic, The Rietveld program used for XRD analysis resulted in the composition fractions of single phase MnFeO3, multiphase MnFeO3/ZnFe2O4 (31/69), and MnFeO3/ZnFe2O4/LaMnO3 (31/40/29). The morphology of all samples has a heterogeneous shape and size with low porosity. The single-phase impedance of MnFeO3 is higher than the multiphase sample. The conductivity of the three samples has the same pattern, which is relatively constant at low frequencies and begins to increase at frequencies above 10 kHz. The dielectric constant and dielectric loss (tan ) have high values at low frequencies, decrease exponentially with increasing frequency and are relatively fixed at high frequencies

Microwave Absorbing Material of Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) with Broadband Characteristic at X-band Frequency

In this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition

Microwave Absorbing Material of Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) with Broadband Characteristic at X-band Frequency

In this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition

Metamaterial: Smart Magnetic Material for Microwave Absorbing Material

Metamaterial is an artificial, advanced material that has properties such as electromagnetic waves (EM), namely isotropic materials with permittivity and permeability in a single phase at a certain frequency. Smart magnetics is one of the metamaterials that is a modified magnetic material that has a single-phase permeability and permittivity as a function of frequency depending on the type of magnetic material used. Smart magnetics in this study include perovskite, ferrite, hexagonal ferrite, and composite systems. Research that has been carried out on perovskite, ferrite, hexagonal ferrite and composite smart magnetic system materials are La0.8Ba0.2FexMn½(1-x)Ti½(1-x)O3, NixFe3-xO4, and Ba(1-x)SrxFe2O4, Ba0.6Sr0.4Fe12-zMnzO19 and composite silicon rubber—iron oxide. The four smart magnetic material systems have an average microwave absorption in the X-band frequency range. Very varied reflection loss characteristics depend on the smart magnetic material system formed. It was concluded that smart magnetic material is a microwave absorbent that has reflection loss values in the X-band frequency range. Smart magnetic material is certainly not able to absorb microwaves on all band frequencies because each smart magnetic material has different resonance characteristics, so the maximum effort that can be done is to find the right composition of smart magnetic material which is expected to have the maximum wave absorption capability

Structural and Magnetic Properties of Barium-Strontium-Hexaferrite Material Ba0.6Sr0.4Fe10-xCoxMnTiO19 (x = 0.5; 1.0; and 1.5) as Microwave Absorbers

We discuss the structure properties of Ba0.6Sr0.4Fe10-xCoxMnTiO19(BSFCMTO) for x = 0.5, 1.0, and 1.5 that influence its magnetic properties as a microwave absorber. A solid-state reaction method using high-energy milling was used to synthesize hexaferrite. There were no structural changes when the Co2+ ion was substituted for the Fe3+ ion; the structures of all samples were hexagonal and the space group was P63/mmc. The surface morphology had heterogeneous particles with a size of 300 to 600 nm. The magnetic properties tended to decrease with an increasing number of Co2+ ion substitutions. The reflection loss (RL) had a minimum value of -14.89 dB. This value was reached at a frequency of 10.96 GHz and had a bandwidth at 1.24 GHz with a sample thickness of 1 mm in the Ba0.6Sr0.4Fe9.9Co0.1MnTiO19 sample