Budhy Kurniawan - Profile on Academia.edu (original) (raw)

Papers by Budhy Kurniawan

Journal of Metals, Materials and Minerals

The result of adding carbon nanotubes (CNTs) to the lattice parameters, critical temperature and ... more The result of adding carbon nanotubes (CNTs) to the lattice parameters, critical temperature and electrical resistivity of the MgB2 superconductors is reported. Structurally, the addition of CNTs was found to decrease the a-lattice from 3.086 Ã… of CNTs free sample to 3.078 Ã… and 3.074 Ã… of 5% and 10% CNTs added samples due to a substitution of C at the B site which presence in the form of Mg(B1-xCx)2 main phase. The doping level x of CNTs added samples were 2.25 at% and 3.75 at% respectively. The unreacted CNTs presence as the second phase and further acting as the suppression agent for crystallite growth. The addition of CNTs is also to refine the grain size and improves the grain connectivity. Samples show a metallic behavior which observed only at temperatures above ~41 K, below which, a sharp transition of resistivity occurred toward zero resistivity, confirming the superconductivity behavior. This study concluded that the effect of CNTs addition affects the structural parame...

Research Square (Research Square), Apr 3, 2023

Magnetoresistance in perovskite materials has been extensively studied due to their great potenti... more Magnetoresistance in perovskite materials has been extensively studied due to their great potential in spintronics technology. Perovskite samples composite with metal oxides can modify electrical properties, which can subsequently improve LFMR under low magnetic fields. In this study, we investigate changes in electrical properties at different temperatures of polycrystalline (1-x)La0.7Sr0.2Ca0.1MnO3/xCuO (LC) composites, where x = 0, 0.05, 0.10, 0.15, and 0.20. Polycrystalline La0.7Sr0.2Ca0.1MnO3 (LSCMO) was synthesized using the sol-gel method and CuO powder as a filler was mixed with LSCMO using wet. The LC composite was then oven-dried to remove moisture, compacted at 10 MPa, and sintered at 1200°C for 12 hours. All samples in the LSCMO phase have a rhombohedral structure with space group R3c. The crystal structure parameters were studied using Rietveld refinement through GSAS II software. SEM results show that CuO is in the LSCMO grain boundary and confirmed by EDS. As the CuO composition increased, the magnetization decreased, as observed by VSM at room temperature. The electrical transport properties of pure LSCMO and LC composites were studied from 5 to 300 K characterized by a cryogenic magnetometer. LC resistivity is higher than LSCMO, and the more CuO content, the smaller the metal transition temperature. CuO present at the grain boundary can decrease the resistivity value as compared to LSCMO. Additionally, the CuO layer weakens spin polarized tunneling intergrain, ultimately impacting the magnetoresistance value. The highest magnetoresistance value is for the LC15 composite at a temperature of 5K with an external field of 2T at 28.5%.

Research Square (Research Square), Apr 5, 2023

Conducting optimization calculations for thermoelectric performance can be bene cial in guiding t... more Conducting optimization calculations for thermoelectric performance can be bene cial in guiding the direction of further experimental work. In our study, we utilize a combination of the rst principle and restructured single parabolic band model to investigate heavily doped semiconductors based on manganite. Ca0.5L0.5MnO3 (CLMO) and Ca0.5L0.25Bi0.25MnO3 (CLBMO) as samples shows optimization of 30% and 69% respectively at a temperature of 800 K from their respective optimal values. In addition, both samples show two to three orders of magnitude smaller lattice thermal conductivity than their electronic thermal conductivity. This excludes complex phononic transport mechanisms from the calculation of the gure of merit (ZT). The ZT calculations of CLMO and CLBMO are corrected by the ratio of the transport relaxation time of electrical conductivity to the transport relaxation time of electronic thermal conductivity, resulting in ZT values of 0.063 and 0.327 at a temperature of 800 K, respectively.

Sintesis dan studi sifat kelistrikan material La2-xSrxCuO4 (x= 0; 0,07; 0,11; 0,15; dan 0,18) dengan metode sol-gel = Synthesis and study of electrical properties of La2-xSrxCuO4 (x= 0; 0,07; 0,11; 0,15; dan 0,18) material with sol gel method

Pengaruh Substitusi Cu Terhadap Sifat Kemagnetan dan Sifat Kelistrikan Material La0,7(Ba0,97Ca0,03)0,3Mn1-xCuxO3 (x = 0; 0,03; 0,05; 0,07 dan 0,10) = Effect of Cu Substitution on the Magnetic and Electricity Properties of Material La0.7(Ba0.97Ca0.03)0.3Mn1-xCuxO3 (x = 0, 0.03, 0.05, 0.07 and 0.10)

Journal of Physics: Conference Series, 2019

The structure and morphology of Cu doped perovskite La0.7Ba0.2Sr0.1Mn1-xCuxO3 (x=0 and x=0.05) ob... more The structure and morphology of Cu doped perovskite La0.7Ba0.2Sr0.1Mn1-xCuxO3 (x=0 and x=0.05) obtained by doping Cu on Mn sites have been studied. The material has been synthesized by using a sol-gel method. Material La0.7Ba0.1Sr0.2Mn1-xCuxO3 (x = 0 and 0.05) was characterized by XRD and SEM. According to XRD result and Rietveld refinement, the crystal structure of both materials was hexagonal, and the cell volume was increased by the increment of the doping level. Characterization by SEM shows that the material has high homogeneity with larger crystallite average size when doped by Cu. By using point analysis of EDX characterization, it is confirmed that Cu ions have been successfully substituted. The composition of the material by using EDX does not make much difference from the calculation so that it can be inferred a good compositional purity.

Journal of Physics: Conference Series, 2019

La0.7Sr0.2Ba0.1Mn1-xNixO3 (x=0 and x=0.1) material has been successfully synthesized using sol-ge... more La0.7Sr0.2Ba0.1Mn1-xNixO3 (x=0 and x=0.1) material has been successfully synthesized using sol-gel method. The XRD pattern shows the sample has a single phase without impurities. The result of refinement showed that both samples formed a rhombohedral structure with R-3c (167) space group. The addition of nickel ions with a concentration of 10% does not change the crystal structure, but causes a decrease in lattice parameters, unit cell volume, Mn-O-Mn Bond angle, and increase Mn-O Bond length. The unit cell volume of La0.7Sr0.2Ba0.1MnO3 and La0.7Sr0.2Ba0.1Mn0.9Ni0.1O3 are 353.382 Å 3 and 352.036 Å 3. The Mn-O-Mn angle for both is 168.021 o and 163.829 o , while the Mn-O bond lengths are 1.9559 Å and 1.9624 Å respectively. Goldschmidt's tolerance factor was calculated to know the stability of the crystal structure. Tolerance factor calculation results confirm that the stable crystal structure is rhombohedral perovskite structure (0.97372 and 0.97154).

Aerosol and Air Quality Research

The development of Jakarta as a metropolitan city worsens the PM 2.5 concentration in the area, c... more The development of Jakarta as a metropolitan city worsens the PM 2.5 concentration in the area, causes health problems for the citizens, and becomes a major public concern. In this study, we use Pearson correlation and convergent cross mapping (CCM) to analyze any correlation between air quality and individual meteorological parameters, as well as the local PM2.5 nonlinear coupling pattern at two different locations in Jakarta. The influence of meteorological parameters and other pollutants in various seasons can be used to determine the variability of PM2.5. We found that the PM2.5 concentration is affected by PM10, SO2, and NO2 pollutant and is negatively correlated with precipitation, relative humidity, and the wind speed in all variations of the season. Causality analysis using CCM showed that PM2.5 coupling patterns differ for every season. The highest causality values (ρ) for air quality parameters are 0.74 (PM 10), 0.68 (SO2), 0.52 (wind speed), and 0.51 (temperature). In Central Jakarta and South Jakarta, the coupling pattern of PM2.5 concentration and air quality parameters increased during the DJF (December-February) season, while the coupling pattern of PM2.5 concentration and meteorological parameters increased during the DJF and MAM (March-May) seasons. During the JJA (June-August) season, most of the meteorological parameters did not have any impact, whereas the increased humidity during the SON (September-November) season also increased the PM2.5 concentration. In conclusion, the significant outcome of our research is to show that individual air quality and meteorological parameters had an influence on local PM2.5 concentrations in the Jakarta region. In addition, it has been proved that CCM can analyze mirage correlation better than other correlation methods.

IOP Conference Series: Materials Science and Engineering

In this work, synthesis and characterization of a polycrystalline Ni43Mn41Co5Sn11 (NMCS) alloy ar... more In this work, synthesis and characterization of a polycrystalline Ni43Mn41Co5Sn11 (NMCS) alloy are reported. Alloy preparation was conducted by melting the constituent components of the designated alloy under an inert Argon (Ar) atmosphere in a vacuum mini arc-melting furnace. Microstructure observation to the as-cast and annealed ingots showing dendritic structure in the as-cast sample. Series of annealing treatment to the sample at 1173 K have changed dendrites progressively in the homogeneous structure after 24 hours annealing time. The annealed sample consisted of a NiMnCoSn main phase with 99.3 % volume fraction. Hence, the 24 hours annealed ingot is a single phase alloy. The curie temperature of the annealed NMCS alloys was found in the range 348~351 K. Loop hysteresis evaluation of the annealed ingots showed that ingot which annealed for 12 hours showed the largest magnetization value of 57.96 emu/g.

Comparative trial of saccharin-added electrolyte for improving the structure of an electrodeposited magnetic FeCoNi thin film

Thin Solid Films

Correlation between microstructure and electrical transport properties of La 0.7 (Ba 1-x Ca x ) 0.3 MnO 3 ( x = 0 and 0.03) synthesized by sol-gel

Physica B: Condensed Matter

Spektra: Jurnal Fisika dan Aplikasinya, 2016

Penelitian terhdap sifat listrik material lanthanum manganat telah dilakukan. Perubahan sifat lis... more Penelitian terhdap sifat listrik material lanthanum manganat telah dilakukan. Perubahan sifat listrik senyawa mixed valence manganites dipengaruhi oleh pemberian doping pada site La dan Mn. Dalam penelitian kali ini, senyawa La0,67Sr0,33Mn1-xNixO3 dibuat dengan metode sintesa sol gel. Senyawa yang dibuat kemudian dikarakterisasi dengan menggunakan X-Ray Diffractometer (XRD) untuk mengetahui struktur sampel, selanjutnya diuji dengan menggunakan cryogenic magnetometer untuk mengukur resistivitas sampel sebagai fungsi temperatur. Hasil karakterisasi XRD menunjukkan bahwa senyawa yang dibentuk memiliki struktur Rhombohedral dengan space group R-3c dan ukuran kristalit kurang dari 100 nm. Pemberian doping Ni tidak merubah struktur kristal namun berpengaruh terhadap penurunan parameter kisi kristal dan ukuran kristalit. Hasil pengukuran resistivitas menunjukkan bahwa senyawa yang diuji berperilaku sebagai isolator dan doping Ni meningkatkan resistivitas sampel.

Temperature span of magnetocaloric effect in Nb-doped La0.7Ca0.3Mn1-xNbxO3 (x = 0, 0.002 and 0.01)

Physica B: Condensed Matter, 2017

Improving Hydrogen Physisorption Energy using SWCNTS through Structure Optimization and Metal Doping Substitution

International Journal of Technology, 2016

Research in finding suitable magnetocaloric material around room temperature made ferromagnetic (... more Research in finding suitable magnetocaloric material around room temperature made ferromagnetic (FM) (Ni-Mn)-based Heusler alloys receive considerable attention as a potential candidate for the magnetic refrigerator. This compound are associated with the shape-memory effect, magnetic superelasticity, and more others magneto-functional properties. The compounds were prepared by vacuum arc melter (VAM) under argon atmosphere which sintering and annealing process were running with quartz cube in vacuum condition. A small amount of coercivity value at σ = 0 in the hysteresis curve occurred whereas magnetization of the sample in various temperature does not reach saturation. The Currie temperature Tc of the sample was obtained at 358 K. Nevertheless, this is dubious value because at T = 300 K the curves had swooped down. Additional measurements necessary to taken as a comparison to verify this value.

Reflection Influence on Output Frequency Spectrum at Submillimeter Frequency Tunable Gyrotrons

MAKARA of Science Series, 2010

ABSTRACT Influence of output window reflections on oscillatory processes in gyrotrons has been st... more ABSTRACT Influence of output window reflections on oscillatory processes in gyrotrons has been studied. The processes in a gyrotron have been modeled numerically, and enhancement of the spectrum signal in the presence of reflections has been studied. Dependencies of output power versus time and frequency spectrum for different value of reflection coefficient are given. Possibilities of significant increasing of output spectrum are demonstrated experimentally. The results demonstrate significant influence of reflections on operation stability and composition of the output radiation of the gyrotron.Keywords: gyrotron, tunability, reflections, oscillation regime, radiation spectrum

Electrical transport and magnetoresistance properties of (1−x)La0.6Sr0.4MnO3/x(Sb2O3) composites

Journal of Alloys and Compounds, 2013

ABSTRACT Magneto-transport and magnetic studies on the (1 - x)(La0.6Sr0.4MnO3)/xSb(2)O(3) (x = 0.... more ABSTRACT Magneto-transport and magnetic studies on the (1 - x)(La0.6Sr0.4MnO3)/xSb(2)O(3) (x = 0.00, 0.03, 0.07, 0.12 and 0.18) composite system are reported. X-ray and microanalysis results reveal that there is no evidence of reaction between the La0.6Sr0.4MnO3 and Sb2O3 grains. The Curie temperature T-C of the composite system remains unchanged; however, magnetization decreases with Sb2O3 addition. Metal-insulator transition temperatures (T-rho) are found to lie in the range of 298-324 K for the derived samples at zero applied magnetic field. The increase of resistivity (rho) is related to the influence of the grain boundaries on the electrical conduction process. The percolation theory is introduced to understand and improve the properties of these mixed systems. An enhanced magnetoresistance (MR) at the whole temperature range and under a low magnetic field is observed in the composites with x = 0.03. We argue that the MR improvement is ascribed to the enhanced magnetic disorder at interfaces and grain boundaries as well as to the suppression of enhanced spin-dependent scattering of the conduction electrons by the applied magnetic field.

A systematic investigation of electrical transport and magnetoresistance properties of polycrysta... more A systematic investigation of electrical transport and magnetoresistance properties of polycrystalline La0.8Ca0.2-xAgxMnO3 (x = 0 and 0.05) is reported in this work. According to the resistivity data measured from 40 to 250 K, transition from metallic to insulator behavior upon heating were observed in both samples. Additionally, 5% silver substitution shifts the metalsemiconductor transition into a higher temperature. Furthermore, silver substitution also decreases the overall temperature compared to the original compound. In this work, this result can be well described using electron-electron, electron-phonon, and the interaction between electron, phonon, and magnon. Resistivity measurements under magnetic field influence shows that silver substitution improves the magnetoresistance properties compared to the original compound. The maximum ratio of magnetoresistance at 285 K was found to be 3.3% and 4.7% for x = 0 and 0.05, respectively.

28a-E-6 ACuCl_3(A=K, Tl, NH_4)の高圧磁化

日本物理学会講演概要集, Mar 15, 1999

Journal of Metals, Materials and Minerals

The result of adding carbon nanotubes (CNTs) to the lattice parameters, critical temperature and ... more The result of adding carbon nanotubes (CNTs) to the lattice parameters, critical temperature and electrical resistivity of the MgB2 superconductors is reported. Structurally, the addition of CNTs was found to decrease the a-lattice from 3.086 Ã… of CNTs free sample to 3.078 Ã… and 3.074 Ã… of 5% and 10% CNTs added samples due to a substitution of C at the B site which presence in the form of Mg(B1-xCx)2 main phase. The doping level x of CNTs added samples were 2.25 at% and 3.75 at% respectively. The unreacted CNTs presence as the second phase and further acting as the suppression agent for crystallite growth. The addition of CNTs is also to refine the grain size and improves the grain connectivity. Samples show a metallic behavior which observed only at temperatures above ~41 K, below which, a sharp transition of resistivity occurred toward zero resistivity, confirming the superconductivity behavior. This study concluded that the effect of CNTs addition affects the structural parame...

Research Square (Research Square), Apr 3, 2023

Magnetoresistance in perovskite materials has been extensively studied due to their great potenti... more Magnetoresistance in perovskite materials has been extensively studied due to their great potential in spintronics technology. Perovskite samples composite with metal oxides can modify electrical properties, which can subsequently improve LFMR under low magnetic fields. In this study, we investigate changes in electrical properties at different temperatures of polycrystalline (1-x)La0.7Sr0.2Ca0.1MnO3/xCuO (LC) composites, where x = 0, 0.05, 0.10, 0.15, and 0.20. Polycrystalline La0.7Sr0.2Ca0.1MnO3 (LSCMO) was synthesized using the sol-gel method and CuO powder as a filler was mixed with LSCMO using wet. The LC composite was then oven-dried to remove moisture, compacted at 10 MPa, and sintered at 1200°C for 12 hours. All samples in the LSCMO phase have a rhombohedral structure with space group R3c. The crystal structure parameters were studied using Rietveld refinement through GSAS II software. SEM results show that CuO is in the LSCMO grain boundary and confirmed by EDS. As the CuO composition increased, the magnetization decreased, as observed by VSM at room temperature. The electrical transport properties of pure LSCMO and LC composites were studied from 5 to 300 K characterized by a cryogenic magnetometer. LC resistivity is higher than LSCMO, and the more CuO content, the smaller the metal transition temperature. CuO present at the grain boundary can decrease the resistivity value as compared to LSCMO. Additionally, the CuO layer weakens spin polarized tunneling intergrain, ultimately impacting the magnetoresistance value. The highest magnetoresistance value is for the LC15 composite at a temperature of 5K with an external field of 2T at 28.5%.

Research Square (Research Square), Apr 5, 2023

Conducting optimization calculations for thermoelectric performance can be bene cial in guiding t... more Conducting optimization calculations for thermoelectric performance can be bene cial in guiding the direction of further experimental work. In our study, we utilize a combination of the rst principle and restructured single parabolic band model to investigate heavily doped semiconductors based on manganite. Ca0.5L0.5MnO3 (CLMO) and Ca0.5L0.25Bi0.25MnO3 (CLBMO) as samples shows optimization of 30% and 69% respectively at a temperature of 800 K from their respective optimal values. In addition, both samples show two to three orders of magnitude smaller lattice thermal conductivity than their electronic thermal conductivity. This excludes complex phononic transport mechanisms from the calculation of the gure of merit (ZT). The ZT calculations of CLMO and CLBMO are corrected by the ratio of the transport relaxation time of electrical conductivity to the transport relaxation time of electronic thermal conductivity, resulting in ZT values of 0.063 and 0.327 at a temperature of 800 K, respectively.

Sintesis dan studi sifat kelistrikan material La2-xSrxCuO4 (x= 0; 0,07; 0,11; 0,15; dan 0,18) dengan metode sol-gel = Synthesis and study of electrical properties of La2-xSrxCuO4 (x= 0; 0,07; 0,11; 0,15; dan 0,18) material with sol gel method

Pengaruh Substitusi Cu Terhadap Sifat Kemagnetan dan Sifat Kelistrikan Material La0,7(Ba0,97Ca0,03)0,3Mn1-xCuxO3 (x = 0; 0,03; 0,05; 0,07 dan 0,10) = Effect of Cu Substitution on the Magnetic and Electricity Properties of Material La0.7(Ba0.97Ca0.03)0.3Mn1-xCuxO3 (x = 0, 0.03, 0.05, 0.07 and 0.10)

Journal of Physics: Conference Series, 2019

The structure and morphology of Cu doped perovskite La0.7Ba0.2Sr0.1Mn1-xCuxO3 (x=0 and x=0.05) ob... more The structure and morphology of Cu doped perovskite La0.7Ba0.2Sr0.1Mn1-xCuxO3 (x=0 and x=0.05) obtained by doping Cu on Mn sites have been studied. The material has been synthesized by using a sol-gel method. Material La0.7Ba0.1Sr0.2Mn1-xCuxO3 (x = 0 and 0.05) was characterized by XRD and SEM. According to XRD result and Rietveld refinement, the crystal structure of both materials was hexagonal, and the cell volume was increased by the increment of the doping level. Characterization by SEM shows that the material has high homogeneity with larger crystallite average size when doped by Cu. By using point analysis of EDX characterization, it is confirmed that Cu ions have been successfully substituted. The composition of the material by using EDX does not make much difference from the calculation so that it can be inferred a good compositional purity.

Journal of Physics: Conference Series, 2019

La0.7Sr0.2Ba0.1Mn1-xNixO3 (x=0 and x=0.1) material has been successfully synthesized using sol-ge... more La0.7Sr0.2Ba0.1Mn1-xNixO3 (x=0 and x=0.1) material has been successfully synthesized using sol-gel method. The XRD pattern shows the sample has a single phase without impurities. The result of refinement showed that both samples formed a rhombohedral structure with R-3c (167) space group. The addition of nickel ions with a concentration of 10% does not change the crystal structure, but causes a decrease in lattice parameters, unit cell volume, Mn-O-Mn Bond angle, and increase Mn-O Bond length. The unit cell volume of La0.7Sr0.2Ba0.1MnO3 and La0.7Sr0.2Ba0.1Mn0.9Ni0.1O3 are 353.382 Å 3 and 352.036 Å 3. The Mn-O-Mn angle for both is 168.021 o and 163.829 o , while the Mn-O bond lengths are 1.9559 Å and 1.9624 Å respectively. Goldschmidt's tolerance factor was calculated to know the stability of the crystal structure. Tolerance factor calculation results confirm that the stable crystal structure is rhombohedral perovskite structure (0.97372 and 0.97154).

Aerosol and Air Quality Research

The development of Jakarta as a metropolitan city worsens the PM 2.5 concentration in the area, c... more The development of Jakarta as a metropolitan city worsens the PM 2.5 concentration in the area, causes health problems for the citizens, and becomes a major public concern. In this study, we use Pearson correlation and convergent cross mapping (CCM) to analyze any correlation between air quality and individual meteorological parameters, as well as the local PM2.5 nonlinear coupling pattern at two different locations in Jakarta. The influence of meteorological parameters and other pollutants in various seasons can be used to determine the variability of PM2.5. We found that the PM2.5 concentration is affected by PM10, SO2, and NO2 pollutant and is negatively correlated with precipitation, relative humidity, and the wind speed in all variations of the season. Causality analysis using CCM showed that PM2.5 coupling patterns differ for every season. The highest causality values (ρ) for air quality parameters are 0.74 (PM 10), 0.68 (SO2), 0.52 (wind speed), and 0.51 (temperature). In Central Jakarta and South Jakarta, the coupling pattern of PM2.5 concentration and air quality parameters increased during the DJF (December-February) season, while the coupling pattern of PM2.5 concentration and meteorological parameters increased during the DJF and MAM (March-May) seasons. During the JJA (June-August) season, most of the meteorological parameters did not have any impact, whereas the increased humidity during the SON (September-November) season also increased the PM2.5 concentration. In conclusion, the significant outcome of our research is to show that individual air quality and meteorological parameters had an influence on local PM2.5 concentrations in the Jakarta region. In addition, it has been proved that CCM can analyze mirage correlation better than other correlation methods.

IOP Conference Series: Materials Science and Engineering

In this work, synthesis and characterization of a polycrystalline Ni43Mn41Co5Sn11 (NMCS) alloy ar... more In this work, synthesis and characterization of a polycrystalline Ni43Mn41Co5Sn11 (NMCS) alloy are reported. Alloy preparation was conducted by melting the constituent components of the designated alloy under an inert Argon (Ar) atmosphere in a vacuum mini arc-melting furnace. Microstructure observation to the as-cast and annealed ingots showing dendritic structure in the as-cast sample. Series of annealing treatment to the sample at 1173 K have changed dendrites progressively in the homogeneous structure after 24 hours annealing time. The annealed sample consisted of a NiMnCoSn main phase with 99.3 % volume fraction. Hence, the 24 hours annealed ingot is a single phase alloy. The curie temperature of the annealed NMCS alloys was found in the range 348~351 K. Loop hysteresis evaluation of the annealed ingots showed that ingot which annealed for 12 hours showed the largest magnetization value of 57.96 emu/g.

Comparative trial of saccharin-added electrolyte for improving the structure of an electrodeposited magnetic FeCoNi thin film

Thin Solid Films

Correlation between microstructure and electrical transport properties of La 0.7 (Ba 1-x Ca x ) 0.3 MnO 3 ( x = 0 and 0.03) synthesized by sol-gel

Physica B: Condensed Matter

Spektra: Jurnal Fisika dan Aplikasinya, 2016

Penelitian terhdap sifat listrik material lanthanum manganat telah dilakukan. Perubahan sifat lis... more Penelitian terhdap sifat listrik material lanthanum manganat telah dilakukan. Perubahan sifat listrik senyawa mixed valence manganites dipengaruhi oleh pemberian doping pada site La dan Mn. Dalam penelitian kali ini, senyawa La0,67Sr0,33Mn1-xNixO3 dibuat dengan metode sintesa sol gel. Senyawa yang dibuat kemudian dikarakterisasi dengan menggunakan X-Ray Diffractometer (XRD) untuk mengetahui struktur sampel, selanjutnya diuji dengan menggunakan cryogenic magnetometer untuk mengukur resistivitas sampel sebagai fungsi temperatur. Hasil karakterisasi XRD menunjukkan bahwa senyawa yang dibentuk memiliki struktur Rhombohedral dengan space group R-3c dan ukuran kristalit kurang dari 100 nm. Pemberian doping Ni tidak merubah struktur kristal namun berpengaruh terhadap penurunan parameter kisi kristal dan ukuran kristalit. Hasil pengukuran resistivitas menunjukkan bahwa senyawa yang diuji berperilaku sebagai isolator dan doping Ni meningkatkan resistivitas sampel.

Temperature span of magnetocaloric effect in Nb-doped La0.7Ca0.3Mn1-xNbxO3 (x = 0, 0.002 and 0.01)

Physica B: Condensed Matter, 2017

Improving Hydrogen Physisorption Energy using SWCNTS through Structure Optimization and Metal Doping Substitution

International Journal of Technology, 2016

Research in finding suitable magnetocaloric material around room temperature made ferromagnetic (... more Research in finding suitable magnetocaloric material around room temperature made ferromagnetic (FM) (Ni-Mn)-based Heusler alloys receive considerable attention as a potential candidate for the magnetic refrigerator. This compound are associated with the shape-memory effect, magnetic superelasticity, and more others magneto-functional properties. The compounds were prepared by vacuum arc melter (VAM) under argon atmosphere which sintering and annealing process were running with quartz cube in vacuum condition. A small amount of coercivity value at σ = 0 in the hysteresis curve occurred whereas magnetization of the sample in various temperature does not reach saturation. The Currie temperature Tc of the sample was obtained at 358 K. Nevertheless, this is dubious value because at T = 300 K the curves had swooped down. Additional measurements necessary to taken as a comparison to verify this value.

Reflection Influence on Output Frequency Spectrum at Submillimeter Frequency Tunable Gyrotrons

MAKARA of Science Series, 2010

ABSTRACT Influence of output window reflections on oscillatory processes in gyrotrons has been st... more ABSTRACT Influence of output window reflections on oscillatory processes in gyrotrons has been studied. The processes in a gyrotron have been modeled numerically, and enhancement of the spectrum signal in the presence of reflections has been studied. Dependencies of output power versus time and frequency spectrum for different value of reflection coefficient are given. Possibilities of significant increasing of output spectrum are demonstrated experimentally. The results demonstrate significant influence of reflections on operation stability and composition of the output radiation of the gyrotron.Keywords: gyrotron, tunability, reflections, oscillation regime, radiation spectrum

Electrical transport and magnetoresistance properties of (1−x)La0.6Sr0.4MnO3/x(Sb2O3) composites

Journal of Alloys and Compounds, 2013

ABSTRACT Magneto-transport and magnetic studies on the (1 - x)(La0.6Sr0.4MnO3)/xSb(2)O(3) (x = 0.... more ABSTRACT Magneto-transport and magnetic studies on the (1 - x)(La0.6Sr0.4MnO3)/xSb(2)O(3) (x = 0.00, 0.03, 0.07, 0.12 and 0.18) composite system are reported. X-ray and microanalysis results reveal that there is no evidence of reaction between the La0.6Sr0.4MnO3 and Sb2O3 grains. The Curie temperature T-C of the composite system remains unchanged; however, magnetization decreases with Sb2O3 addition. Metal-insulator transition temperatures (T-rho) are found to lie in the range of 298-324 K for the derived samples at zero applied magnetic field. The increase of resistivity (rho) is related to the influence of the grain boundaries on the electrical conduction process. The percolation theory is introduced to understand and improve the properties of these mixed systems. An enhanced magnetoresistance (MR) at the whole temperature range and under a low magnetic field is observed in the composites with x = 0.03. We argue that the MR improvement is ascribed to the enhanced magnetic disorder at interfaces and grain boundaries as well as to the suppression of enhanced spin-dependent scattering of the conduction electrons by the applied magnetic field.

A systematic investigation of electrical transport and magnetoresistance properties of polycrysta... more A systematic investigation of electrical transport and magnetoresistance properties of polycrystalline La0.8Ca0.2-xAgxMnO3 (x = 0 and 0.05) is reported in this work. According to the resistivity data measured from 40 to 250 K, transition from metallic to insulator behavior upon heating were observed in both samples. Additionally, 5% silver substitution shifts the metalsemiconductor transition into a higher temperature. Furthermore, silver substitution also decreases the overall temperature compared to the original compound. In this work, this result can be well described using electron-electron, electron-phonon, and the interaction between electron, phonon, and magnon. Resistivity measurements under magnetic field influence shows that silver substitution improves the magnetoresistance properties compared to the original compound. The maximum ratio of magnetoresistance at 285 K was found to be 3.3% and 4.7% for x = 0 and 0.05, respectively.

28a-E-6 ACuCl_3(A=K, Tl, NH_4)の高圧磁化

日本物理学会講演概要集, Mar 15, 1999