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"ABSTRAKSifat struktur, termal, dan listrik pada temperatur tinggi dari senyawa double perovskite Sr2(Fe,Ti)O6telah dipelajari pada penelitian ini.Sr2(Fe,Ti)O6 disintesis dengan metode solid state reaction. Hasil karakterisasi x-ray diffraction pada temperatur kamar menunjukkan bahwa semua sampel memiliki fase tunggal dan memiliki struktur kristal kubik double perovskite dengan space grup pm3m. Variasi jumlah atom Fe dan Ti mengakibatkan kenaikan parameter kisi dan grainsize. Grainsize yang diperoleh berkisar antara 30 nm sampai dengan 80 nm. Sifat listrik sebagai fungsi temperatur dan frekuensi dikarakterisasi menggunakan RLC-meter dengan metode spektroskopi impedansi. Hasil karakterisasi disajikan dalam Nyquist plot dan Bode plot yang digunakan untuk mengidentifikasi rangkaian ekuivalen dan parameternya. Rangkaian ekuivalen yang diperoleh menunjukkan pengaruh grain dan grain boundary terhadap sifat material. Konduktivitas dc Sr2(Fe,Ti)O6 sebagai fungsi temperatur dijelaskan dengan menggunakan persamaan Arrhenius. Energi aktivasi yang diperoleh dari hubungan konduktivitas dc sebagai fungsi temperatur menunjukkan pengaruh grain dan grain boundary pada sampel. Hal tersebut menunjukkan kemungkinan adanya oxygen vacancy pada material Sr2(Fe,Ti)O6. Kemungkinan ini diperkuat dengan hasil karakterisasi field emission scanning electron microscopy (FESEM) untuk menggambarkan morfologi sampel

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ABSTRACTStructure, thermal, and electrical properties of double perovskite material Sr2(Fe,Ti)O6 at high temperature have been studied. Sr2(Fe,Ti)O6 was synthesized by solid state reaction method. X-ray diffraction characterization at room temperature for all samples show single phase and having cubic double perovskite structure with pm3m space group. The variation of Fe and Ti atoms result an increasing of lattice parameter and grainsize which is found between 30 nm and 80 nm. The electrical properties as a function of temperature and frequency are characterized by using RLC-meter with impedance spectroscopy method. The impedance data are presented in Nyquist and Bode plot resulting in the equivalent circuit and its parameters. The equivalent circuit shows the effect of grain and grain boundary in the electrical properties of materials. DC conductivity of Sr2(Fe,Ti)O6 as a function of temperature was explained by using Arrhenius equation. The value of the activation energy which is evaluated from dc conductivity as a function of temperature shows the effect of grain and grain boundary. The activation energy exhibits of oxygen vacancy in Sr2(Fe,Ti)O6 which is also supported by morphology of Sr2(Fe,Ti)O6 characterized by field emission scanning electron microscopy (FESEM)."

"Telah dilakukan penelitian tentang studi sifat listrik dan optis bahan perovskite Ba(Fe,Ti)O3. Pada studi ini kami menguji sifat material multiferroik lewat difraksi sinar X dan spektroskopi impedansi. Hasil difraksi sinar X (XRD) menunjukkan bahan memiliki fasa tunggal dengan sistem kristal heksagonal dan space group P63/mmc. Struktur kristal Ba(Fe,Ti)O3 menjadi random perovskite ketika sampel dibuat dengan komposisi Fe dan Ti yang seimbang, sehingga mempengaruhi seluruh sifat bahan BaFe0,5Ti0,5O3. Pengukuran impedansi yang dinyatakan dalam bentuk Nyquist plot dan bode plot memperlihatkan bahwa penambahan Fe menyebabkan peningkatan konduktivitas ac dan melemahkan feroelektrisitas. Fitting rangkaian ekivalen dengan program Zsimpwin menunjukkan kemunculan induktansi (L) dan Constant Phase element (CPE) sebagai akibat penambahan ion magnetik Fe dan dispersi frekuensi pada sampel. Data hasil pengukuran reflektansi dengan menggunakan spektrofotometer UV VIS menunjukkan nilai celah energi berada dalam rentang 0,85 - 3,37 eV yang membuat bahan berpotensi menjadi semikonduktor.

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We have been investigating Study of electrical and Optical Properties Sample Perovskite Ba(Fe,Ti)O3. In this study, we have systematically measured the multiferroic material properties using XRD and impedance simulation. The result of X-ray diffraction (XRD) indicates that the material has a single phase with hexagonal crystal and space group P63/mmc. Random perovskite structure is shaped when the sample made with balanced composition between Fe and Ti and thus affecting the whole nature of the material BaFe0, 5Ti0,5O3. Impedance measurements which are signed in form of nyquist and bode plot show that the addition of Fe leds to an increase of ac conductivity and weakend ferroelectricity. Fitting the equivalent circuit with Zsimpwin program pilots the appearance of inductance (L) and constant phase element (CPE) as a result of adding magnetic Fe ions and frequency dispersion of the sample. Reflectance measurement data using a UV VIS spectrophotometer showed the value of the energy gap is in the range 0.85 to 3.37 eV which could potentially be a semiconductor."

"Summary: This book presents a complete overview of the powerful but often misused technique of Electrochemical Impedance Spectroscopy (EIS). The book presents a systematic and complete overview of EIS. The book carefully describes EIS and its application in studies of electrocatalytic reactions and other electrochemical processes of practical interest. This book is directed towards graduate students and researchers in Electrochemistry. Concepts are illustrated through detailed graphics and numerous examples. The book also includes practice problems. Additional materials and solutions are available online"

"Telah dilakukan suatu penelitian melalui spektroskopi impedansi untuk mengetahui sifat-sifat listrik bahan perovskite (Ba,Sr)TiO3 pada temperatur tinggi pada kisaran 25 hingga 425 oC. Sampel bahan perovskite (Ba,Sr)TiO3 berupa pellet terdiri dari enam buah. Tiga buah sampel disinter 1200°C masing-masing selama 1, 2, dan 3 jam. Tiga buah sampel yang lain disinter 1200°C selama 2 jam kemudian dianil 900°C masing-masing selama 1, 2 dan 4 jam. Data impedansi disajikan dalam bentuk Nyquist plot dan Bode plot yang digunakan untuk mengidetifikasi parameter rangkaian ekivalen. Parameter penting rangkaian ekivalen seperti resistansi dan kapasitansi dihitung sebagai fungsi dari temperatur. Sifat listrik bahan perovskite (Ba,Sr)TiO3 dapat dideskripsikan dengan rangkaian R, RC paralel maupun kombinasi dari keduanya yang menunjukkan adanya kontribusi dari grain, grain boundary, interface dan kontak. Hasil percobaan menunjukkan bahwa semakin lama waktu sintering dan annealing menyebabkan bergesernya temperetur transisi dari feroelektrik menjadi paraelektrik menuju temperatur yang lebih tinggi. Perbedaan lama waktu sintering dan annealing tidak menyebabkan perubahan nilai resistansi dan kapasitansi yang signifikan. Perbandingan nilai resistansi bahan perovskite (Ba,Sr)TiO3 baik yang disinter 1200 oC masing-masing selama 1, 2, dan 3 jam maupun dianil 900°C masing-masing selama 1, 2 dan 4 jam hasil pengukuran pada temperatur kamar dan 100°C dengan pengukuran pada temperatur 400°C sebesar dua orde. Energi aktivasi hasil percobaan pada rentang temperatur 325°C hingga 425°C adalah 0.52 eV.

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The electrical properties of (Ba,Sr)TiO3 perovskite materials are investigated by impedance spectroscopy in the temperature range 25 to 450°C. There are six pellets of (Ba,Sr)TiO3 perovskite materials. Three samples are sintered at 1200°C for 1, 2 and 3 hours. The rest were sintered at 1200°C for 2 hours then annealed at 900°C for 1, 2 and 4 hours. Impedance data are presented in the Nyquist plot which is used to identify an equivalent circuit. The fundamental circuit parameters such as resistance and capacitance are determined at different temperatures. The electrical properties of (Ba,Sr)TiO3 perovskite materials may also descripted by R, parallel RC, or both combinations that seems a grain, grain boundary, interface and contact contributions.

The results of the experiment shows that with longer sintering and annealing times consequently shifted the transition phase range from ferroelectric to paraelectric to the high temperatures. There are no significant value of both resistance and capacitance of the sintering or annealing times of the samples measurements, however resistance decreases two orders at increasing temperature measurements. The activation energy at temperature range 325°C to 425°C of the experiment is 0.52 eV."

"[Pada penelitian ini telah dilakukan studi spektroskopi dari zeolit ZSM-5 mesopori terimpregnasi oksida kobalt secara komprehensif. Co/ZSM-5 mesopori telah menarik perhatian para peneliti untuk digunakan sebagai katalis heterogen dalam reaksi oksidasi parsial metana. Dalam penelitian ini dilakukan sintesis zeolit NaZSM-5 mesopori dengan metode double template dengan TPAOH sebagai agen pengarah struktur dan PDDA sebagai template mesopori. Sebagian zeolit NaZSM-5 dimodifikasi menjadi HZSM-5 melalui proses tukar kation dengan NH4+ yang dilanjutkan dengan kalsinasi pada suhu 550°C. Selanjutnya, zeolit NaZSM-5 dan HZSM-5 diimpregnasi dengan ion kobalt dan dikalsinasi pada 550°C membentuk Co/NaZSM-5 dan Co/HZSM-5. Lalu, zeolit mesopori NaZSM-5, HZSM-5, Co/NaZSM-5, dan Co/HZSM-5 dikarakterisasi secara ekstensif dengan XRD, SEM, AAS, FTIR, 27Al Solid State NMR, Microbalance, dan Surface Area and Pore Size Analyzer untuk menjelaskan pengaruh perbedaan sifat permukaan zeolit katalis terhadap fenomena perbedaan hasil reaksi katalisis oksidasi parsial metana dengan oksidator oksigen dan katalis zeolit mesopori Co/NaZSM-5 dan Co/HZSM-5 pada penelitian sebelumnya, di mana persen konversi metana menjadi metanol meningkat seiring dengan waktu pada Co/HZSM-5 namun sebaliknya pada Co/NaZSM-5 justru menurun seiring dengan waktu. Hasil analisis menunjukkan bawa keasaman zeolit ZSM-5 sebagai support katalis berpengaruh terhadap loading Co dan aktivitas katalis.

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Spectroscopy study of mesoporous ZSM-5 zeolite impregnated with cobalt oxides has been done comprehensively. Mesoporous Co/ZSM-5 has gained the researchers’ attention for being used as heterogeneous catalyst for partial oxidation of methane. In this research, mesoporous NaZSM-5 zeolite was synthesized by using double template method with TPAOH as structure directing agent (SDA) and PDDA as mesoporous template. Some of NaZSM-5 were modified to HZSM-5 through NH4+-exchange process followed by calcination at 550°C. NaZSM-5 and HZSM-5 zeolite were impregnated with cobalt ions and calcined at 550°C to form Co/NaZSM-5 and Co/HZSM-5. Then, mesoporous NaZSM-5, HZSM-5, Co/NaZSM-5, and Co/HZSM-5 zeolite were extensively characterized using XRD, SEM, AAS, FTIR, 27Al Solid Sate NMR, Microbalance and Surface Area and Pore Size Analyzer to explain zeolite surface characteristics influence on difference results from methane partial oxidation with O2 as oxidant using mesoporous Co/NaZSM-5 and Co/HZSM-5 zeolite as catalyst in recent research. In which by using Co/HZSM-5 as catalyst %conversion of methane to methanol increase by the time, but %conversion decrease by using Co/NaZSM-5. By analysis, it can be concluded that ZSM-5 zeolite’s acidity affect the loading of Co and catalyst activity.;Spectroscopy study of mesoporous ZSM-5 zeolite impregnated with cobalt oxides has been done comprehensively. Mesoporous Co/ZSM-5 has gained the researchers’ attention for being used as heterogeneous catalyst for partial oxidation of methane. In this research, mesoporous NaZSM-5 zeolite was synthesized by using double template method with TPAOH as structure directing agent (SDA) and PDDA as mesoporous template. Some of NaZSM-5 were modified to HZSM-5 through NH4+-exchange process followed by calcination at 550°C. NaZSM-5 and HZSM-5 zeolite were impregnated with cobalt ions and calcined at 550°C to form Co/NaZSM-5 and Co/HZSM-5. Then, mesoporous NaZSM-5, HZSM-5, Co/NaZSM-5, and Co/HZSM-5 zeolite were extensively characterized using XRD, SEM, AAS, FTIR, 27Al Solid Sate NMR, Microbalance and Surface Area and Pore Size Analyzer to explain zeolite surface characteristics influence on difference results from methane partial oxidation with O2 as oxidant using mesoporous Co/NaZSM-5 and Co/HZSM-5 zeolite as catalyst in recent research. In which by using Co/HZSM-5 as catalyst %conversion of methane to methanol increase by the time, but %conversion decrease by using Co/NaZSM-5. By analysis, it can be concluded that ZSM-5 zeolite’s acidity affect the loading of Co and catalyst activity.;Spectroscopy study of mesoporous ZSM-5 zeolite impregnated with cobalt oxides has been done comprehensively. Mesoporous Co/ZSM-5 has gained the researchers’ attention for being used as heterogeneous catalyst for partial oxidation of methane. In this research, mesoporous NaZSM-5 zeolite was synthesized by using double template method with TPAOH as structure directing agent (SDA) and PDDA as mesoporous template. Some of NaZSM-5 were modified to HZSM-5 through NH4+-exchange process followed by calcination at 550°C. NaZSM-5 and HZSM-5 zeolite were impregnated with cobalt ions and calcined at 550°C to form Co/NaZSM-5 and Co/HZSM-5. Then, mesoporous NaZSM-5, HZSM-5, Co/NaZSM-5, and Co/HZSM-5 zeolite were extensively characterized using XRD, SEM, AAS, FTIR, 27Al Solid Sate NMR, Microbalance and Surface Area and Pore Size Analyzer to explain zeolite surface characteristics influence on difference results from methane partial oxidation with O2 as oxidant using mesoporous Co/NaZSM-5 and Co/HZSM-5 zeolite as catalyst in recent research. In which by using Co/HZSM-5 as catalyst %conversion of methane to methanol increase by the time, but %conversion decrease by using Co/NaZSM-5. By analysis, it can be concluded that ZSM-5 zeolite’s acidity affect the loading of Co and catalyst activity.;Spectroscopy study of mesoporous ZSM-5 zeolite impregnated with cobalt oxides has been done comprehensively. Mesoporous Co/ZSM-5 has gained the researchers’ attention for being used as heterogeneous catalyst for partial oxidation of methane. In this research, mesoporous NaZSM-5 zeolite was synthesized by using double template method with TPAOH as structure directing agent (SDA) and PDDA as mesoporous template. Some of NaZSM-5 were modified to HZSM-5 through NH4+-exchange process followed by calcination at 550°C. NaZSM-5 and HZSM-5 zeolite were impregnated with cobalt ions and calcined at 550°C to form Co/NaZSM-5 and Co/HZSM-5. Then, mesoporous NaZSM-5, HZSM-5, Co/NaZSM-5, and Co/HZSM-5 zeolite were extensively characterized using XRD, SEM, AAS, FTIR, 27Al Solid Sate NMR, Microbalance and Surface Area and Pore Size Analyzer to explain zeolite surface characteristics influence on difference results from methane partial oxidation with O2 as oxidant using mesoporous Co/NaZSM-5 and Co/HZSM-5 zeolite as catalyst in recent research. In which by using Co/HZSM-5 as catalyst %conversion of methane to methanol increase by the time, but %conversion decrease by using Co/NaZSM-5. By analysis, it can be concluded that ZSM-5 zeolite’s acidity affect the loading of Co and catalyst activity., Spectroscopy study of mesoporous ZSM-5 zeolite impregnated with cobalt oxides has been done comprehensively. Mesoporous Co/ZSM-5 has gained the researchers’ attention for being used as heterogeneous catalyst for partial oxidation of methane. In this research, mesoporous NaZSM-5 zeolite was synthesized by using double template method with TPAOH as structure directing agent (SDA) and PDDA as mesoporous template. Some of NaZSM-5 were modified to HZSM-5 through NH4+-exchange process followed by calcination at 550°C. NaZSM-5 and HZSM-5 zeolite were impregnated with cobalt ions and calcined at 550°C to form Co/NaZSM-5 and Co/HZSM-5. Then, mesoporous NaZSM-5, HZSM-5, Co/NaZSM-5, and Co/HZSM-5 zeolite were extensively characterized using XRD, SEM, AAS, FTIR, 27Al Solid Sate NMR, Microbalance and Surface Area and Pore Size Analyzer to explain zeolite surface characteristics influence on difference results from methane partial oxidation with O2 as oxidant using mesoporous Co/NaZSM-5 and Co/HZSM-5 zeolite as catalyst in recent research. In which by using Co/HZSM-5 as catalyst %conversion of methane to methanol increase by the time, but %conversion decrease by using Co/NaZSM-5. By analysis, it can be concluded that ZSM-5 zeolite’s acidity affect the loading of Co and catalyst activity.]"