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"Telah dilakukan sintesis bahan perovskite manganites La1-xAgx 0,8Ca0,2MnO3 yang disubtitusi dengan Ag pada site La dengan x = 0; 0,03; 0,07; 0,1; 0,2; 0,3; 04 dan 0,5. Pembuatan sampel dilakukan dengan metode sol-gel pada temperatur sintering 900 C. Prekursor yang digunakan adalah La2O3, AgNO3, Ca NO3 2.6H2O dan Mn NO3 2.4H2O. Hasil karakterisasi XRD untuk x < 0,1 menunjukkan fasa tunggal dengan struktur kristal orthorombik dan space group pnma. Pada x = 0,2; 0,3 dan 0,4 terdapat puncak Ag dan x = 0,5 terdapat puncak Ag, Ca dan nitrat. Pengujian nilai efek magnetoresistan di fokuskan pada x < 0,1. Ukuran rata-rata grain dari hasil karakterisasi SEM pada sampel yaitu dalam skala nanometer. Hasil kemurnian sampel telah dikonfirmasi menggunakan karektersasi EDX, dimana tidak terdapat pengotor atau impuritas. Hasil karakterisasi VSM menunjukkan bahwa nilai koersivitas semakin meningkat dengan meningkatnya doping Ag, nilai tertinggi HC = 234 Oe dengan sifat soft magnetik. Nilai optimum MR = 61,5 pada x = 0,07, temperatur 50 K di bawah pengaruh medan magnet luar sebesar 2T.

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The synthesis of perovskite manganites La1 xAgx 0.8Ca0,2MnO3 was substituted with Ag on La site with x 0 0.03 0.07 0.1 0.2 0.3 04 and 0.5. Sample preparation was done by sol gel method at sintering temperature 900 C. The precursors are La2O3, AgNO3, Ca NO3 2.6H2O and Mn NO3 2.4H2O. The XRD characterization results for x 0.1 showed a single phase with orthorombic crystal structure and pnma space group. There is Ag peak at x 0.2 0.3 and 0.4 and at x 0.5 there are Ag and Ca peaks. The magnetoresistance effect value test was focused on x 0.1. The average size of grain from SEM characterization results in the sample is in the nanometer scale.

The results of the purity of the sample have comfirmed using EDX characterization. VSM characterization results showed that coercivity value increases with increasing Ag doping, the highest value of Hc 234 Oe with soft magnetic properties. The optimum value of MR 61,5 at x 0.07, temperature 50 K under the influence of the external magnetic field of 2T."

"Pada zaman sekarang perkembangan teknologi berkembang pesat. Adanya modifikasi material perovskite berbasis manganit telah diteliti untuk diterapkan pada Colossal Magnetoresistance. Penelitian yang telah dilakukan mengenai struktur mikro dan sifat magnetik material perovskite manganites La0.67Sr0.33Mn1-xZnxO3 (x= 0; 0,15; 0,2; 0,4) yang disintesis dengan metode solid state bertujuan untuk melihat pengaruh yang ditimbulkan Zn pada material La0.67Sr0.33Mn1-xZnxO3 (x= 0; 0,15; 0,2; 0,4) berupa struktur morfologi dan sifat kemagnetannya. Karakterisasi XRD menunjukan bahwa struktur kristal material berbentuk rhombohedral pada space group R-3c dengan rata-rata ukuran kristal 106 nm, 103 nm, 101 nm dan 96 nm. Karakterisasi SEM dan EDS menunjukan perubahan ukuran grain dan memperlihatkan keberadaan unsur Zn sebagai pendoping. Ukuran grain mengecil seiring bertambahnya konsentrasi Zn dengan rata-rata ukuran grain 148 nm, 134 nm, 127 nm dan 117 nm. Karakterisasi VSM menunjukan kurva histeresis yang memperlihatkan material bersifat feromagnetik ketika 0 ≤ x < 0,2 dan berubah menjadi paramagnetik ketika x > 0,2 yang terlihat dengan menurunnya nilai magnetisasi dari 65,1 emu/gram, 14,4 emu/gram, 8,2 emu/gram dan 1,7 emu/gram.

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In this day and age, technological development is developing rapidly. The existence of modifications to manganese-based perovskite materials has been studied to be applied to Colossal Magnetoresistance. Research that has been conducted on the microstructure and magnetic properties of manganites perovskite material La0,67Sr0,33Mn1-xZnxO3 (x= 0; 0.15; 0.2; 0.4) synthesized by the solidstate method aims to see the influence that Zn has on the material La0,67Sr0,33Mn1-xZnxO3 (x= 0; 0.15; 0.2; 0.4) in the form of morphological structure and magnetisme properties. XRD characterization shows that the crystal structure of rhombohedral-shaped materials in the R-3c space group with an average crystal size of 106 nm, 103 nm, 101 nm and 96 nm. SEM and EDS characterizations show a change in grain size and show the presence of Zn elements as doping. Grain size decreases as Zn concentration increases with average grain sizes of 148 nm, 134 nm, 127 nm and 117 nm. VSM characterization shows a hysteresis curve that shows the material is ferromagnetic when 0 ≤ x < 0.2 and turns paramagnetic when x > 0.2 which is seen by decreasing the magnetization value of 65.1 emu/gram, 14.4 emu/gram, 8.2 emu/gram and 1.7 emu/gram."

"Manganite perovskite has a wide variety of potential applications as an advanced material, for example, in magnetic random access memory, spintronics, magnetoelectric, magnetic field sensors and cooling technology, based on magnetism and magnetic materials. In work on cooling technology, magnetic materials show a magnetocaloric effect. Manganite perovskite has some fundamental properties, such as Curie temperature, magnetic entropy change, temperature span and relative cooling power. Current works report detailed properties of manganite perovskite in La0.7Ca0.3MnO3 doped with Cu, which show magnetocaloric effects. The samples were synthesized by a conventional solid state reaction. A small amount of doping Cu 1%~3% at a Mn site maintains the First-Order Magnetic Transition (FOMT) without leading into the Second-Order Magnetic Transition (SOMT). Maximum magnetic entropy change increased as the Cu-doped decreased. Introducing a small percentage of Cu-doped on La0.7Ca0.3Mn1-xCuxO3 also implies decreasing the Curie temperature, TC. For all samples under external application in a field of 10 kOe, these resulted in a slightly wider temperature span and the Relative Cooling Power (RCP) of about 39 J/kg to 47 J/kg as the Cu-doped decreased. The small amount of Cu-doping on La0.7Ca0.3MnO3 keeps the rate of relative cooling power in a wider temperature range. It may be beneficial for cooling technology based on magnetism and magnetic materials."

"Material Ca0.9La0.05Bi0.05Mn1-xCuxO3(x = 0, 0.025, 0.05, 0.075, 0.1) disintesis menggunakan metode sol-gel. Karakterisasi menggunakan X-ray Diffractometer(XRD) menunjukkan bahwa material Ca0.05La0.05Bi0.05Mn1-XCuXO3memiliki struktur kristal perovskite orthorombik dan akibat dari subtitusi Cu ditemukan distorsi struktur pada material yang diindikasi dengan perubahan parameter kisi. Sedangkan hasil dari Scanning Electron Microscope(SEM) menunjukkan adanya perubahan ukuran grainyang meningkat dengan meningkatnya jumlah konsentrasi Cu pada material. Fenomena distorsi struktur memiliki pengaruh terhadap sifat kelistrikan dan kemagnetan dari material. Dari sifat kelistrikan, dengan menggunakan pengujian RLC meter pada rentang 1 – 100,000 Hz diperoleh bahwa pada temperatur ruang dengan meningkatnya subtitusi Cu, menghasilkan impedansi listrik material yang meningkat dari sekitar 266.4 (x = 0)menjadi sekitar 589465.3 (x = 0.1). Dengan meningkatnya impedansi bisa dianggap meningkatnya juga sifat resistansi. Sifat resistansi material menghasilkan resistansi yang meningkat dari sekitar 252 (x = 0) menjadi sekitar 589463 (x = 0.1). Hal ini disebabkan oleh meningkatnya konsentrasi subtitusi Cu mengakibatkan kurangnya hoppingelektron dikarenakan hilangnya ion Mn3+(Brajendra Singh, 2015) dan hasil Retvield Refinementyang menunjukkan bahwa transfer elektron yang lebih sulit yang disebabkan oleh berkurangnya sudut ikatan Mn-O-Mn dan bertambahnya panjang ikatan Mn-O (Rahman, 2019). Namun pada suhu 773 K, sifat resistansi material menurun dibandingkan dengan sifat resistansi pada temperatur ruang dari sekitar 143 (x = 0) hingga sekitar 100 (x = 0.1) pada masing-masing konsentrasi subtitusi Cu. Pada analisa magnetik, material Ca0.9La0.05Bi0.05Mn1-XCuXO3memiliki fasa paramagnetik. Dengan meningkatnya konsentrasi subtitusi Cu pada material, mengakibatkan nilai magnetisasi pada medan magnet sebesar 2 T yang cenderung menurun dari 1.1 emu/gr (x = 0) menjadi 0.9 emu/gr (x = 0.1). Hal ini dikarenakan oleh subtitusi Cu yang menghasilkan interaksi super-exchangeyang dimana meningkatnya ion Cu2+menyebabkan bertambahnya ion Mn4+dan berkurangnya ion Mn3+(K. Sakthipandi, 2019).

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Ca0.9La0.05Bi0.05Mn1-xCuxO3(x = 0, 0.025, 0.05, 0.075, 0.1) materials has been synthesized using sol-gel method. Characterization using the X-ray Diffractometer (XRD) showed that Ca0.9La0.05Bi0.05Mn1-xCuxO3has perovskite crystal structure of an orthorhombic and because of Cu substitution that been found a structure distortion on the materials which indicated with the changes of lattice parameters. Results form Scanning Electron Microscope (SEM) showed that there is an increasing of grain size with the increasing Cu substitution on the materials. Structure distortion phenomenon has some influence to the electrical and magnetic properties from the materials. From the electrical properties, using LRC meter testing with frequency range 1 – 100,000 Hz resulting that in the room temperature with the increasing Cu substitution, the electrical impedance of the materials become increased from around 266.4 (x = 0) become around 589465.3 (x = 0.1).With the increasing of the electrical impedance can be assumed that resistance of the materials is increasing as well. The resistance of the materials resulting in the increasing resistance from around 252 (x = 0) become around 589463 (x = 0.1). the increasing resistance caused by increasing Cu substitution which result in lack of hopping electron caused by absence of Mn3+(Brajendra Singh, 2015) and Retveild Refinement showed that decresing bond angle Mn-O-Mn and increasing bond length Mn-O wich made the electron transport become more difficult (Rahman, 2019) . But on the 773K, the materials resistance is decreasing compare with each Cu subtitution the resistance on room temperature from around 143 (x = 0) to around 100 (x = 0.1) in each Cu substitution sampels. On magnetic properties, Ca0.9La0.05Bi0.05Mn1-xCuxO3materials has paramagnetic phase. With the increasing Cu substitution on the materials, causing the decreased magnetization value on the 2T magnetic field from 1.1 emu/gr (x = 0) become 0.9 emu/gr (x = 0.1). This caused by Cu substitution which produced super-exhange interaction where the increasing Cu2+causing increased Mn4+and decreasing of Mn4+(K. Sakthipandi, 2019)."

"Telah dilakukan penelitian sifat listrik, sifat magnet, dan efek magnetoresistan bahan perovskite manganites La0,67Sr0,33Mn1-XNixO3. Sampel dibuat dengan metode sol gel. Hasil karakterisasi XRD menunjukkan bahwa sampel sudah memiliki fase tunggal dengan struktur rhombohedral dan space group R-3c. Pemberian doping Ni tidak mengubah struktur kristal namun menurunkan nilai parameter kisi kristal. Karakterisasi SEM-EDX menunjukkan bahwa unsur Ni sudah masuk ke dalam sampel dan adanya perubahan morfologi sampel ketika doping Ni divariasikan. Data resistivitas sebagai fungsi temperatur menunjukkan bahwa doping Ni meningkatkan besar resistivitas bahan dan menggeser temperatur transisi metal-isolator ke temperatur yang lebih rendah. Efek magnetoresistan yang diberikan menunjukkan adanya peningkatan persen magnetoresistan saat doping Ni dinaikkan. Sedangkan kurva histerisis yang dihasilkan menunjukkan bahwa pemberian doping Ni menurunkan sifat kemagnetan bahan yang ditunjukkan oleh penurunan magnetisasi bahan.

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The electrical properties, magnetic properties, and magnetoresistance effect of perovskite manganites La0,67Sr0,33Mn1-XNixO3 material have been studied. Samples were synthesized by using sol gel method. The result of XRD characterization showed that samples were single phase with Rhombohedral structure and R-3c space group. Ni doped did not change crystal structure but decreased lattice parameter. SEM-EDX characterization showed that Ni was included in the samples as a doping and the morphology of samples changed with various Ni doped.

Resistivity as temperature function showed that Ni doped increased the resistivity and decreased the metal-insulator transition temperature. Magnetoresistance effect of samples relatively enhanced with increased of Ni doping. While the hysteresis curve from VSM characterization showed that Ni doped decreased magnetic properties of samples."

"Material penyerap gelombang mikro saat ini banyak dikembangkan untuk aplikasi di bidang pertahanan militer, komunikasi, dan elektronik. Fungsi material penyerap gelombang mikro ini dapat menjadi material anti radar yaitu pelindung/penghalang dari sistem radar. Kriteria material yang dapat digunakan sebagai penyerap gelombang mikro diantaranya memiliki karakteristik permeabilitas dan permitivitas. Material yang potensial digunakan dan banyak dikembangkan saat ini adalah material perovskit oksida sistem ABO3. Pengembangan material perovskit oksida yang dilakukan pada penelitian ini bertujuan untuk mendapatkan nilai penyerapan yang tinggi dan memperluas daerah penyerapan. Polikristalin La0,7Ba0,3Mn(1-x)FexO3 (x=0; 0,1; 0,2; 0,25) telah berhasil disintesis dengan metode sol-gel, dengan bahan dasar La2O3, Ba(NO3)2, Mn(NO3)2.4H2O, dan Fe2O3. Setelah sintesis sol-gel, sampel dipanaskan dengan suhu 180oC selama 2,5 jam. Kalsinasi dilakukan pada suhu 800oC selama 2 jam. Kemudian sampel dikompaksi dengan tekanan 10 ton, lalu sampel disintering pada suhu 900oC selama 2 jam. Hasil refinement pola difraksi sinar-x menunjukkan bahwa material La0,7Ba0,3Mn(1-x)FexO3 (x=0; 0,1; 0,2; 0,25) memiliki struktur kristal rhombohedral, dengan ukuran kristalit 53,92nm; 37,73nm; 29,7nm; dan 26,3nm. Penambahan Fe di situs Mn pada material lantanum barium manganit oksida mampu memperbanyak daerah penyerapan gelombang mikro. Komposisi yang memiliki kinerja terbaik pada penyerapan gelombang mikro adalah La0,7Ba0,3Mn0,75Fe0,25O3. Hasil pengujian serapan gelombang mikro pada rentang 7-13 GHz terdapat dua frekuensi puncak serapan pada 10 GHz sebesar -6,26 dB dan 12 GHz sebesar -4,6 dB.

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Microwave absorber materials are currently being developed for applications in the fields of military defense, telecommunications, and electronics. The microwave absorber material can be an anti radar material for radar shielding. Permeability and permittivity characteristics are the criteria for microwave absorbing materials. Perovskite oxide of the system material ABO3 is currently being developed as the potential microwave absorber material. The goal of this research’s development in perovskite oxide materials is to increase the absorption area and expand absorption area. Polycrystalline La0.7Ba0.3Mn(1- x)FexO3 (x=0, 0.1, 0.2, 0.25) has been successfully synthesized using the sol-gel method, with the basic ingredients high purity La2O3, Ba(NO3)2, Mn(NO3)2.4H2O, and Fe2O3. After the sol-gel process has completeted, the sample was heated at 180oC for 2.5 hours. Calcination was carried out at 800oC for 2 hours. Then the sample was compressed with a pressure of 10 tons, then the sample was sintered at a temperature of 900oC for 2 hours. The results of the refinement of the x-ray diffraction pattern show that the La0.7Ba0.3Mn(1- x)FexO3 (x=0, 0.1, 0.2, 0.25) material has a rhombohedral crystal structure, with a crystallite size of 53.92nm; 37.73nm; 29.7nm; and 26.3nm. The addition of Fe at the Mn site in the lanthanum barium manganite oxide material can increase the microwave absorption area. La0.7Ba0.3Mn0.75Fe0.25O3 is the composition with the best microwave absorption performance. The microwave absorbing properties in the frequency range 7- 13 GHz revealed two peak absorption frequencies at 10 GHz of -6.26 dB and 12 GHz of -4.6 dB."

"Modern technology for refrigerators and coolers is based on the chemical gas Chlorofluorocarbon (CFC) compression method that is indicative of a high consumption of electricity. The CFC is also understood as a reason for global warming. One of the solutions to this issue is magnetic refrigeration technology, which is environmentally friendly because it does not use any hazardous chemicals or ozone depleting/greenhouse gases. Magnetic refrigeration technology is based on the magnetocaloric effect of magnetic refrigerant materials. Exploring the magnetocaloric effect of magnetic refrigerant materials is important because these contain many of the physical properties needed for magnetic refrigeration technology. Herein, the present work reports on the magnetocaloric effect of La0.7Ca0.3Mn1?xSnxO3 (x = 0.0, x = 0.02 and x = 0.04) compound samples produced with the solid state reaction technique. Curie temperature TC obtained for the La0.7Ca0.3Mn1?xSnxO3 (x = 0.0, x = 0.02 and x = 0.04) are 260 K, 176 K and 170 K with -?SM max of 4.32 J×kg-1×K-1, 1.61 J×kg-1×K-1 and 1.24 J×kg-1×K-1 and a refrigerant capacity of 48 J/kg, 41.43 J/kg and 28.53 J/kg for x = 0.0, x = 0.02 and x = 0.04, respectively. A small addition of Sn-doped resulted in a significant decrease of more than 80 K on the Curie temperature scale compared to that of La0.7Ca0.3MnO3. The large gap in the decreasing magnetic temperature phase transition might be useful as an option of metal/transition metal doped for tuning the Curie temperature of magnetic refrigerant materials."

"Kami melakukan perhitungan konduktivitas optis pada layered (perovskite) Pr0.5Ca1.5MnO4 untuk mengidentifikasi fenomena charge-ordering. Pemodelan melibatkan orbital Mn dan O yang berada pada bidang MnO2 dari layered Pr0.5Ca1.5MnO4. Interaksi yang diperhitungkan dalam pemodelan yaitu interaksi Coulomb inter-orbital dan intra-orbital, distorsi Jahn-Teller dan exchange interaction dengan menerapkan beberapa asumsi. Perhitungan dilakukan menggunakan Dynamical Mean Field Theory untuk mencapai self-consistency. Hasil perhitungan menunjukkan profile yang mendekati hasil eksperimen dengan puncak charge-ordering berada di bawah 1 eV dan puncak charge-transfer pada 3-3.7 eV. Di bawah temperatur TCO/OO (~325 K), puncak charge-ordering mengalami blue shift seiring dengan penurunan temperatur.

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We calculate the optical conductivity of layered (perovskite) Pr0.5Ca1.5MnO4 to capture charge-ordering phenomena. The calculations are based on a model which considers Mn and O orbitals within the MnO2 plane of layered Pr0.5Ca1.5MnO4. Interaction terms included in the model with some assumptions are the inter-orbital and intra-orbital Coulomb repulsions, the static Jahn-Teller distortion and the exchange interaction. We calculate within Dynamical Mean Field Theory to achieve self-consistency. The result shows a profile similar to recent experimental data, where the charge-ordering peak appears below 1 eV and charge-transfer peak at 3-3.7 eV. For temperature lower than TCO/OO (~325 K), the charge-ordering peak undergoes a blue shift as the temperature is decreased."