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SAGALA, LIDIA PUSPITA SARI
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NANO STRUCTURE AND MAGNETIC PROPERTIES OF Zn FERRITE AND ZnCuNi FERRITE USING THE Co-PRECIPITATION METHOD SAGALA, LIDIA PUSPITA SARI
JRFES (Jurnal Riset Fisika Edukasi dan Sains) Vol 10, No 2 (2023): Jurnal Riset Fisika Edukasi dan Sains
Publisher : Universitas PGRI Sumatera Barat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22202/jrfes.2023.v10i2.7647

Abstract

AbstractZn Ferrite and ZnCuNi Ferrite with a composition of ZnFe2O4 and Zn0.9Cu0.05Ni0.05 Fe2O4 have been synthesis using the co-precipitation method. Zn Ferrite and ZnCuNi Ferrite have been synthesized at 100 oC. Structure, morphology and magnetic properties were obtained by the characterization of  X-ray Difraction (XRD), Field Emission-Scanning Electron Microscope (FE-SEM) and Vibrating Sample Magnetometer (VSM). The X-Ray Diffraction (XRD) characterization showed the cubic spinel structure of Zn Ferrite and ZnCuNi Ferrite. The microstructure and magnetic properties have been changed with the addition of Cu2+ and Ni2+ to ZnFe2O4. The grain size increased from 13.4098 nm to 13.7184 nm. The VSM test results also showed an increase in saturation mangetization from 14.76 emu/g to 26.67 emu/g. Meanwhile, the magnetic coercivity value experienced the opposite, which decreased from 87.85 Oe to 87.65 Oe. The addition of Cu2+ and Ni2+ increases the magnetization of the spinel ferrite and decreases its magnetic coercivity.  Keywords: FE-SEM; Magnetic Properties; Microstructure; VSM; XRDAbstrakZn ferit dan ZnCuNi ferit dengan komposisi ZnFe2O4 dan Zn0.9Cu0.05Ni0.05Fe2O4 masing-masing telah disintesis dengan menggunakan metode kopresipitasi. Zn ferit dan ZnCuNi ferit tersebut telah disintesis pada suhu 100 oC. Struktur, morfologi dan sifat kemagnetannya diperoleh dari karakterisasi X-ray Diffraction (XRD), Field Emission – Scanning Electron Microscope (FE-SEM) dan Vibrating Sample Magnetometer (VSM). Karakterisasi X-ray Diffraction (XRD) menunjukkan struktur spinel kubik pada Zn ferit dan ZnCuNi ferit.  Mikrostruktur dan sifat magnetik mengalami perubahan dengan adanya penambahan Cu2+ dan Ni2+ pada ZnFe2O4. Ukuran butir meningkat dari 13,409 nm menjadi 13,718 nm. Dari hasil uji VSM juga menunjukkan adanya peningkatan mangetisasi saturasi dari 14,76 emu/g menjadi 26,67 emu/g. Sementara nilai koersivitas magnet mengalami sebaliknya, yaitu menurun dari 87,85 Oe menjadi 87,65 Oe. Penambahan Cu2+ dan Ni2+ meningkatkan magnetisasi spinel ferit dan menurunkan nilai koersivitas magnetnya.  Kata kunci : FE-SEM; Sifat Magnetik; Mikrostruktur; VSM; XRD  
Student Thinking Structure Against Errors in Solving Mathematical Problems Based on Newman's Theory Supiarmo, M. Gunawan; Sagala, Lidia Puspita Sari; Ahmad Faqihi
EDUPEDIKA: Jurnal Studi Pendidikan dan Pembelajaran Vol. 2 No. 1 (2023): Februari 2023
Publisher : PELITA NUSA TENGGARA

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Abstract

Jenis penelitian yang digunakan adalah kualitatif-deskriptif. Penelitian ini dilakukan pada 3 sekolah dengan siswa yang berjumlah 112 orang. Pemilihan subjek dilakukan dengan teknik purposive sampling dengan kriteria, yaitu siswa yang memiliki kesalahan dalam menyelesaikan masalah matematika. Data penelitian terdiri atas jawaban, rekaman hasil wawancara semi terstruktur dan hasil think aloud siswa. Melalui tiga data tersebut, kategori kesalahan penyelesaikan masalah matematika akan dilihat berdasarkan teori Newman (1997) dan indikator tahapan berpikir siswa terhadap penyelesaian masalah matematika yang dikemukakan oleh Bloom (1956). Analisis data dilakukan melalui tahap mereduksi data, menyajikan data, dan menarik kesimpulan. Hasil penelitian menunjukkan bahwa struktur berpikir siswa yang mengalami kesalahan membaca, pada tahap mengingat mampu menguraikan informasi yang diketahui, namun siswa mengalami kesulitan dalam mengenali gambar. Sehingga struktur berpikir yang dimiliki belum mampu memenuhi tahap mengingat secara lengkap. Selanjutnya struktur berpikir siswa yang mengalami kesalahan memahami, hanya mampu memenuhi tahapan mengingat, namun pada tahap menafsirkan siswa belum dapat secara sempurna. This type of research is qualitative-descriptive. This research was conducted in three schools with 112 students. Subject selection was carried out using the purposive sampling technique with criteria, namely students who had errors in solving math problems. The research data consisted of answers, recordings of semi-structured interview results, and students' think-aloud results. Through these three pieces of data, categories of errors in solving math problems will be seen based on Newman's theory (1997) and indicators of students' thinking stages towards solving math problems proposed by Bloom (1956). Data analysis was carried out through the stages of reducing data, presenting data, and drawing conclusions. The findings revealed that students with reading errors had a thinking structure capable of deciphering known information during the remembering stage, but they had difficulty recognizing images. so that the structure of thinking that is owned has not been able to fulfill the complete recall stage. Furthermore, the thinking structure of students who have misunderstood is only able to fulfill the stages of remembering, but at the interpreting stage, students cannot do it perfectly.