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"ABSTRAKSenyawa metal alloy (LaNi5) biasa digunakan untuk anode baterai Nickel-Metal Hydride (NiMH) karena mampu mengabsorpsi hidrogen dan dapatberoperasi pada kondisi tekanan dan temperatur ruang. Ketika oksida logam tanahjarang ditambahkan ke dalam anode sel baterai NiMH, tidak hanya chargeefficiency dan capacity-retention yang akan meningkat, tetapi juga menjadi rapidcharge dan high power cycling. Penelitian dilakukan untuk melihat karakteristikbahan anode LaNi5 setelah penambahan CeO2 dan proses anil. Metode yangdigunakan adalah mechanical alloying dengan mencampur serbuk LaNi5 denganserbuk CeO2 sebanyak 1%, 2%, dan 3% berat di dalam ball mill selama 120 menitpada putaran 240 rpm. Setelah itu, dilakukan proses anil pada temperatur 300°C,600°C, dan 900°C selama 6 jam di lingkungan gas argon. Kemudian, serbukdikarakterisasi dengan menggunakan XRD, SEM-EDX, dan BET. Pengujianelektrokimia dilakukan dengan menggunakan Electrochemical ImpedanceSpectroscopy (EIS) pada frekuensi 5 mHz ? 100 kHz. Penambahan konsentrasiCeO2 diatas 2%, akan memperkecil volume cell dan mengecilkan diameter pori.Konduktivitas tertinggi yang dicapai pada penelitian ini adalah sebesar 1.5332S/cm dengan diameter pori 0.0082 cc/g. Walaupun penambahan konsentrasi CeO2ke dalam material anode meningkatkan tahanan material, tetapi penambahan 1%CeO2 dapat meningkatkan ketahanan korosi material anode dengan Ecorr sebesar -0.6432 V. Peningkatan temperatur anil menyebabkan perubahan difraksi fasamenjadi fasa NiO dan La2O3 yang menyebabkan konduktivitas menurun dan nilaitahanan semakin besar.

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ABSTRACTA Lanthanum Nickel compound (LaNi5) is widely used for an anode ofNickel-Metal Hydride (NiMH) battery due to excellence on hydrogen absorptionand good capability to be operated at room temperature and pressure condition.Addition of rare earth oxide to the NiMH has increase charge-retention efficiencyand capacity also has both rapid charge and high power cycling. The experimenthas been conducted to observe the characteristic of the anode LaNi5 materialsafter addition of CeO2 and annealing. As method of this experiment, mechanicalalloying was done by mixed LaNi5 and CeO2 powder which had 1%, 2% and 3%weight mass in ball mill for 120 minutes at 240 rpm. After that, the annealing wascarried out at varied temperature, 300°C, 600°C and 900°C for 6 hours in argongas exposure. Then the powders were characterized with XRD, SEM-EDX, andBET. Electrochemical Impedance Spectroscopy (EIS) was used forelectrochemical testing on the frequency between 5 mHz - 100 kHz. The results ofthis experiment show that increasing CeO2 more than 2% concentration lead todecrease the volume of cells and the pore diameter. Furthermore, this is affect thevalue of ionic conductivity with the highest conductivity is 1.5332 S / cm and0.0082 cc / g in diameter pore. Although the addition of CeO2 concentration intothe anode material increases the resistance, the addition of 1% CeO2 can improvethe corrosion resistance of the anode material with Ecorr of -0.6432 V. Inconclusions, annealing temperature increasing will changes diffraction phase withthe dominant phase NiO and La2O3, thus the conductivity was decreasing and theresistance was increasing."

"Meningkatnya permintaan global akan logam tanah jarang (LTJ) dan masalah lingkungan yang terkait dengan penambangan tradisional telah mendorong eksplorasi sumber alternatif. Penelitian ini menyelidiki kelayakan pemulihan serium oksida (CeO2), sebuah LTJ berharga, dari limbah terak timah di Indonesia. Penelitian ini berfokus pada penilaian kelayakan teknis ekstraksi CeO2, evaluasi kelayakan ekonomi proses pemulihan, dan analisis dampak lingkungan, terutama terkait mitigasi radon. Proses ekstraksi skala laboratorium dilakukan, menunjukkan keberhasilan pemulihan CeO2 dengan tingkat ekstraksi maksimum 75,16% (Tarigan 2023) dalam kondisi optimal. Kelayakan ekonomi dinilai menggunakan kerangka analisis biaya-manfaat (CBA), menggabungkan analisis arus kas diskon (DCF). Hasil penelitian menunjukkan bahwa proyek ini layak secara finansial, dengan nilai kini bersih (NPV) positif sebesar Rp 100.536.458.975,00, tingkat pengembalian internal (IRR) sebesar 24%, dan periode pengembalian modal selama 6 tahun. Rasio manfaat-biaya (BCR) sebesar 1,49 semakin mendukung daya tarik ekonomi proyek ini. Penilaian dampak lingkungan mengungkapkan potensi risiko yang terkait dengan paparan radon dari terak timah, tetapi juga mengukur potensi penghematan biaya kesehatan akibat berkurangnya paparan radon. Temuan penelitian ini memiliki implikasi signifikan bagi industri pertambangan Indonesia dan pasar LTJ global, menyoroti potensi terak timah sebagai sumber sekunder LTJ dan menekankan pentingnya mengintegrasikan pertimbangan lingkungan dan kesehatan ke dalam proses industri.

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The increasing global demand for rare earth metals (REMs) and the environmental concerns associated with their traditional mining have led to the exploration of alternative sources. This study investigates the feasibility of recovering cerium oxide (CeO2), a valuable REM, from tin slag waste in Indonesia. The research focuses on assessing the technical feasibility of CeO2 extraction, evaluating the economic viability of the recovery process, and analyzing the environmental impact, particularly concerning radon mitigation. A laboratory-scale extraction process was conducted, demonstrating the successful recovery of CeO2 with a maximum extraction rate of 75.16% (Tarigan 2023) under optimized conditions. The economic viability was assessed using a cost-benefit analysis (CBA) framework, incorporating a discounted cash flow (DCF) analysis. The results indicate that the project is financially viable, with a positive net present value (NPV) of Rp100,536,458,975.00, an internal rate of return (IRR) of 24%, and a payback period of 6 years. The benefit-cost ratio (BCR) of 1.49 further supports the project's economic attractiveness. The environmental impact assessment revealed potential risks associated with radon exposure from tin slag, but also quantified the potential health cost savings resulting from reduced radon exposure. The findings of this study have significant implications for the Indonesian mining industry and the global REM market, highlighting the potential of tin slag as a secondary source of REMs and emphasizing the importance of integrating environmental and health considerations into industrial processes."

"ABSTRAKKaca konduktor memiliki fungsi strategis di berbagai aplikasi elektronik. Jenisyang menjanjikan adalah Fluorine-doped Tin Oxide (FTO). Dalam penelitian inidilakukan studi pengaruh waktu deposisi (5, 10, 20, 30, dan 40 menit) lapisan tipisFTO dengan metode spray pyrolysis menggunakan alat ultrasonic nebulizer yangtelah dimodifikasi terhadap nilai karakteristik lapisannya ditinjau dari sifat optis,kristalinitas, resistivitas, dan mikrostruktur. Variasi juga dilakukan denganmembandingkan prekursor Sn murni dan larutan yang telah didoping dengan Fsebanyak 2%wt untuk melihat pengaruh penambahan doping F pada larutanprekursor. Pengujian karakteristik lapisan dilakukan menggunakan XRD, SEM,UV-Vis spectroscopy, dan digital multimeter. Berdasarkan karakterisasi yangdilakukan diperoleh nilai terbaik untuk FTO yang dihasilkan adalah pada waktudeposisi 20 menit dengan nilai transmitansi 74%, energi band gap (Eg) 3,85 eV,dan sheet resistance (Rs) 7,99 Ω/sq.

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ABSTRACTConductive glass has strategic functions in various electronic applications. Oneof the lead is Fluorine-doped Tin Oxide (FTO). In this research, the effects ofdeposition time (5,10,20,30, and 40 minutes) for fabrication of FTO thin film uponspray pyrolysis process using modified ultrasonic nebulizer on its characteristicin terms of optical, crystalinity, resistivity and microstructure properties has beenstudied. Variation was also performed by comparing the pure Sn precursor andthe solution that has been doped with F 2%wt to see the doping effect toproperties of thin film. The thin film characterization were carried out using XRD,SEM, UV-Vis spectroscopy, and digital mutlimeter. Based on the results obtainedfor the best FTO was generated at the time of deposition is 20 minutes. Providing74% transmittance, band gap energy (Eg) 3.85 eV and sheet resistance (Rs) 7.99Ω/sq."

"Solid sorbents based on graphite electrode waste and cerium oxide (ceria, CeO2) have been studied with regard to CO2 capture. The acid-base properties of cerium oxide produce a sorbent for the capture of CO2. The aim of the study is to evaluate the performance of CO2 capture using graphite/CeO2 composites at different weights of Ce(NO3)3.6H2O (0.5, 1 and 2 g), namely G0.5, G1 and G2, respectively. Volumetric adsorption studies of CO2 on graphite/CeO2 composites and ceria were conducted at various pressures (P) of 3, 5, 8, 15 and 20 bar, and temperatures (T) of 303, 308, 318 K. Graphite waste before modification (GBM), activated graphite waste (GA), and CeO2 for capturing CO2 were also investigated. By varying the two parameters (P and T), we found that the maximum adsorption capacities of CO2 at 303 K and 20 bar were 0.0713, 0.0316, 0.1574, 0.0987, 0.1137, and 0.0964 kg/kg respectively, for GBM, GA, G0.5, G1, G2 and CeO2. The highest adsorption capacity of CO2 was found in the G0.5 composite. The adsorption performance of CO2 using ceria was almost similar to the G1 composite. We found that CO2 adsorption capacity decreases with an increasing temperature from 303 to 318 K. It was concluded that ceria and composite graphite waste/CeO2 are stable and selective CO2 sorbents. The work allows us to synthesize a new sorbent which can be effectively applied for CO2 capture. The adsorption capacity of CO2 depends significantly on the active site and chemical modifier of the sorbents."

"ABSTRAKPemberian doping Ce pada CaMnO3 akan membentuk sampel CexCa1-xMnO3. Sampel ini dibuat dengan metode zat padat dari bahan dasar CeO2, CaO dan MnO2 berdasarkan perhitungan stoikiometri untuk nilai x = 0,1 ; x = 0,5 dan x = 0,9. Preparasi sampel dimulai dengan mencampur semua bahan dasar dengan menggunakan ball mill selama 1 jam. Proses dilanjutkan dengan pemanasan menggunakan furnace dengan suhu 800 C selama 8 jam, kemudian proses ball mill kembali selama 1 jam, lalu sampel dipanaskan lagi pada suhu 1100 C selama 10 jam, kemudian sampel dikompaksi untuk uji XRD dan SEM. Hasil karakterisasi sampel dengan XRD direfinement menggunakan program GSAS. Berdasarkan analisis tersebut diperoleh informasi mengenai hal-hal sebagai berikut; untuk x = 0,1 ; x = 0,5 dan x = 0,9 pada sampel CexCa1-xMnO3 memiliki struktur kristal orthorombic; space group Pnma 62 , dan peningkatan komposisi Ce tidak menyebabkan perubahan space group dan struktur kristal. Meningkatnya komposisi Ce menyebabkan penurunan nilai parameter kisi dan volume unit sel.

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ABSTRACTce doping addition into CaMnO3 will form new material CexCa1 xMnO3. This material are made with solid method using raw materials such as CeO2, CaO and MnO2 based on stoichiometric analysis for x 0,1 x 0,5 and x 0,9. To get to this material we conduct some steps that consist of raw material mixing in a ball mill for 1 hour, 800 C heating for 8 hours, back to ball mill process for 1 hour, continued with 1100 C heating process for 10 hours, and pressed in a coin shape for XRD and SEM testing purpose. XRD test results will be refined using GSAS. Based on that analysis, we gained some information. The results showed that for any x, the CexCa1 xMnO3 crystal structure were orthorhombic with Pnma 62 space group. The increase of Ce did not influence the space group and crystal structure, but it caused the decrease of lattice parameter and unit cell volume."

"Sektor energi menjadi penyumbang 75% emisi gas rumah kaca yang dilaporkan oleh International Energy Agency tahun 2021. Oleh karena itu, transisi penggunaan energi fosil ke energi alternatif, salah satunya energi hidrogen (H2), harus diimplementasikan lebih luas lagi terutama terhadap kedua sektor tersebut untuk mengurangi emisi gas rumah kaca. Penelitian ini bertujuan untuk mengembangkan katalis berbasis tembaga (Cu) yang tinggi aktivitas katalitiknya pada reaksi methanol steam reforming (MSR) untuk memproduksi H2. Pemilihan support yang baik penting untuk performa katalis Cu. Dalam penelitian ini, Ce diperkenalkan sebagai dopan Zr pada sistem support CaZrO3. CeO2 dikenal sebagai support sekaligus promoter yang baik karena karakteristik oxygen storage capacity (OSC) yang tinggi sehingga dapat meningkatkan aktivitas katalitik Cu/CaCe(x)Zr(1-x)O3. Cu/CaCe(x)Zr(1-x)O3 disintesis dengan metode sol-gel dan dry impregnation dan diuji aktivitasnya pada reaksi MSR pada 250, 300, dan 350 °C. Komposisi Ce-Zr dan variabel temperatur dievaluasi pada penelitian ini. Cu/CaCe(x)Zr(1-x)O3 dikarakterisasi dengan XRF, XRD, Spektroskopi Raman, SAA, O2-TPO, dan TEM. Hasilnya, variasi rasio Ce-Zr telah sesuai dengan yang diharapkan, Cu telah berhasil diimpregnasi ke permukaan support, kelima katalis adalah material mesopori, dan Cu/CaCeO3 diketahui memiliki densitas oxygen vacancy (Ovac) tertinggi, yang menandakan OSC yang juga tinggi. Sesuai dengan perolehan densitas Ovac tertinggi, Cu/CaCeO3 unggul dalam uji reaksi MSR di ketiga temperatur uji, dengan konversi metanol, yield H2, dan produksi H2 pada temperatur tertinggi berturut-turut sebesar 98,37%, 86,59%, dan 0,0539 mol/min/gcat.

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The energy sector accounted for 75% of greenhouse gas emissions reported by the International Energy Agency in 2021. Therefore, the transition from fossil fuels to alternative energy sources, one of which is hydrogen (H₂) energy, must be widely implemented especially in those two sectors to reduce greenhouse gas emissions. This research aims to develop a copper (Cu)-based catalyst with high catalytic activity in the methanol steam reforming (MSR) reaction for H2 production. The selection of a suitable support is crucial for the performance of the Cu-based catalysts. In this study, Ce is introduced as a dopant in Zr within the CaZrO3 support system. CeO₂ is well-known to be an excellent support and promoter due to its high oxygen storage capacity (OSC) characteristic, which can enhance the catalytic activity of Cu/CaCe(x)Zr(1-x)O3. Cu/CaCe(x)Zr(1-x)O3 was synthesized using sol-gel and dry impregnation methods and tested for activity in the MSR reaction at temperatures of 250, 300, and 350 °C. The Ce-Zr composition and temperature variables are evaluated in this study. Cu/CaCe(x)Zr(1-x)O3 was characterized using XRF, XRD, Raman spectroscopy, SAA, O2-TPO, dan TEM. The results indicate that the desired and obtained ratios of the catalyst are in agreement with one another, Cu is successfully impregnated onto the surface of CaCe(x)Zr(1-x)O3, all five catalysts are mesoporous materials, and Cu/CaCeO3 exhibits the highest density of oxygen vacancies (Ovac), indicating a high OSC. Consistent with the highest Ovac density obtained, Cu/CaCeO3 excels in MSR reaction tests at all three test temperatures, with methanol conversion, H₂ yield, and H₂ production at the highest temperature being 98,37%, 86,59%, dan 0,0539 mol/min/gcat."

"Jenis kecenderungan ikatan lokal atomik lapisan tipis amorf silikon karbon terhidrogenasi (a-Sit-rCx: H) hasil deposisi sputtering dengan target grafit dan silikon telah ditentukan dengan menggunakan prosedur minimasi. Prosedur minimasi dilakukan terhadap fungsi dielektrik kompleks hasil eksperimen dengan fungsi dielektrik kompleks model tetrahedron yang dikembangkan oleh Mui-Smith. Lapisan tipis a-Si1-xC1:H yang dihasilkan dengan target grafit memiliki kecenderungan ikatan lokal atomik CD (chemically disordered) sedangkan hasil dart target silikon memiliki jenis kecenderungan ikatan lokal atomik CORD (chemical ordering with homogeneous dispersion). Kehadiran void pada lapisan tipis a-Si1-xCx: H untuk kedua jenis target juga dapat diketahui dari prosedur minimasi. Jumlah void yang cenderung konstan pada lapisan tipis yang dihasilkan dengan target grafit mendukung hasil para peneliti lain bahwa jumlah void bukan dipengaruhi oleh peningkatan konsentrasi karbon tetapi karena peningkatan hydrogen. Lapisan tipis yang dihasilkan dengan menggunakan target grafit memiliki jumlah void yang lebih tinggi dibandingkan lapisan tipis yang dihasilkan dart target silikon atau lapisan tipis yang dihasilkan dengan target silikon lebih kompak dibandingkan hasil target grafit.

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Determination of Local Atomic Bonding Preferences of Amorphous Silicon Carbon Deposited by 2 Sputtering Targets : Graphite and Silicon. The preferences of local atomic bonding of amorphous silicon carbon films deposited by graphite and silicon target has been determined by minimizing procedure. The experimental complex dielectric function has been minimized by complex dielectric function model developed by Mui-Smith. The preferences of local atomic bonding for films deposited by graphite target was chemically disordered (CD) whereas for films deposited by silicon target was chemical ordering with homogeneous dispersion (COHD). Minimization procedure shows the presence of voids in the films for both silicon and graphite targets. The monotonic behavior of voids with carbon concentration for films deposited by graphite target agree with other's researcher results that the amounts of void are not influenced by increasing carbon concentration but are influenced by hydrogen concentration. The films deposited by graphite target contain more voids than silicon target or films deposited by silicon target have a compact structure than graphite target."