4,887 research outputs found
Síntesis y caracterización de granates del tipo Sm3-xTRxFe5O12 (TR = Dy, Gd, Lu y La)
Full text linkLos granates de tierras raras (TR3Fe5O12) presentan propiedades magneto-eléctricas y ópticas que permiten su aplicación en transformadores, dispositivos de microondas y de almacenamiento de datos. Estas propiedades dependen de su estructura y morfología, que son altamente influenciadas por la sustitución parcial o total de los sitios catiónicos, así como por el método de síntesis. El presente trabajo se enfocó en la obtención de los nuevos granates de formula Sm3-xTRxFe5O12 (TR= Gd, Dy, Lu y La) con x=0.0, 0.1, 0.2, 0.4, 0.6, 0.8 y 1.0 sintetizados por los métodos citrato y cerámico, con el fin de evaluar la influencia del catión sustituyente y método sobre sus propiedades. La caracterización por DRX, Raman, MEB, EDX, VSM y medida de resistividad, demostró la adecuada sustitución del Sm por Lu, Dy y Gd favoreciendo la obtención de materiales de fase pura, de estructura cúbica y con grupo espacial Ia-3d (230). En contraste, el La llevó a la formación de fases de Sm1-xLaxFeO3 lo que se explica en función de su radio iónico. El método citrato favoreció la obtención de granates con partículas de menor tamaño ( 1 µm) y de carácter ferrimagnético, de mayor Hc y Ms menor en comparación con las muestras obtenidas por el método cerámico, con un tiempo y temperatura de calcinación menores en 18 h y 300 °C. Los resultados obtenidos permiten concluir que las muestras del sistema Sm3-xTRxFe5O12 (TR= Gd, Dy, Lu) presentan potenciales aplicaciones en transformadores y conmutadores de microondas, con una importante disminución en los costos de producción.Abstract. Rare earth garnets (TR3Fe5O12) have magneto-electric and optical properties that allow their application in transformers, microwave and data storage devices. These properties depend on their structure and morphology, which are influenced by the partial or total substitution of the cationic sites, as well as by the synthesis method. The present work focused in the obtaining of new garnets with formula Sm3-xTRxFe5O12 (TR = Gd, Dy, Lu and La) with x = 0.0, 0.1, 0.2, 0.4, 0.6, 0.8 and 1.0 synthesized by method citrate and ceramic method, in order to evaluate the influence of substituent cation and. Synthesis method on their properties. The characterization by XRD, Raman, MEB, EDX, VSM and resistivity measurement, demonstrated the adequate substitution of Sm by Lu, Dy and Gd favoring the obtaining of pure phase materials with cubic structure and space group Ia-3d (230). on the other hand, the substitution with La carried generated the formation of phases of Sm1-xLaxFeO3 which is explained according to its ionic radius. The citrate method favored the obtaining of garnets with particles of smaller size (1 μm), ferrimagnetic character, of higher HC and smaller MS compareted to the samples obtained by the ceramic method, with a calcination temperature and time even 300 °C and 18 h below. The results obtained allow to conclude that samples of the Sm3-xTRxFe5O12 system (TR = Gd, Dy, Lu) present potential applications in transformers and microwave switches, with a significant decrease in production costs.Maestrí
Epitaxial strain and interface effects on the magnetoelastic behaviour of Dy/Ho and Dy/Lu superlattices
No full textThe basal plane magnetoelastic stress, Bγ,2, of Dy 16/Ho22, Dy14/Lu30 and Dy 21/Lu11 (0001) superlattices is investigated. For Dy 16/Ho22 we obtain Bγ,2 (12 T, 0 K) = 0.4GPa, while for Dy21/Lu11 and Dy21/Lu 11 it amounts 0.33 and 0.9 GPa, respectively. In the first case, the value obtained is explained in terms of the known values of B γ,2 for bulk Dy and Ho, including small interface and strain contributions, whereas in the Dy/Lu samples, Bγ,2 have large non-bulk contributions. The differences in epitaxial compression and in electronic structure for both kind of superlattices can explain these results. © 2004 Elsevier B.V. All rights reserved
Surface magnetic phase transitions in Dy/Lu superlattices
No full textDy/Lu superlattices comprising ferromagnetic Dy blocks coupled antiferromagnetically across the Lu blocks may be modelled as a chain of XY spins with antiferromagnetic exchange and six-fold anisotropy. We have calculated the stable magnetic phases for the cases of large anisotropy and a field applied along an easy direction. For an infinite chain an intermediate phase <1, 5,...> is predicted, where the notation gives the angle between the moment and the applied field in units of pi/3. Furthermore, the effects of surface reconstruction an determined for finite chains. A [Dy(20)Lu(12)](20) superlattice has been studied using bulk magnetization and polarized neutron reflectivity. The (1, 5...) phase has been identified and the results provide direct evidence in support of the theoretical predictions. Dipolar forces are shown to account for the magnitude of the observed exchange coupling. (C) 1999 Elsevier Science B.V. All rights reserved
Magnetic properties of Dy‐Lu alloys
Full text linkAlthough many binary heavy rare‐earth alloy systems have been studied extensively, there has been little work reported on the Dy‐Lu system. The properties of single‐crystal DyxLu1−x films grown by molecular beam epitaxy are reported. SQUID magnetometer and neutron diffraction measurements on samples with x=0.4, 0.5, and 0.6 show that the samples order helimagnetically with Néel temperatures of TN=90, 105, and 120 K, respectively. The helical turn angle was mapped as a function of temperature for each of the three alloys. Magnetic x‐ray scattering, the first in an alloy, was observed at the (002)± positions at 15 and 60 K in the x=0.4 sample using resonant exchange scattering of synchrotron radiation at the Dy LIII edge.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69501/2/JAPIAU-75-10-6592-1.pd
Magnetic properties of quadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, Sm-Gd, Dy-Lu)
Full text linkQuadruple perovskites Ba4LnRu3O12 (Ln=La, Nd, Sm-Gd, Dy-Lu) were prepared and their magnetic properties were investigated. They adopt the 12L-perovskite-type structure consisting of Ru3O12 trimers and LnO6 octahedra. All of these compounds show an antiferromagnetic transition at 2.5-30 K. For Ba4NdRu3O12, ferrimagnetic ordering has been observed at 11.5 K. The observed magnetic transition is due to the magnetic behavior of the Ru^[4.33+]3O12 trimer with S=1/2. Magnetic properties of Ba4LnRu3O12 were compared with those of triple perovskites Ba3LnRu2O9 and double perovskites Ba2LnRuO6
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No full textRobust tunability of magnetoresistance in half-Heusler R PtBi (R = Gd, Dy, Tm, and Lu) compounds
Full text linkWe present the magnetic field dependencies of transport properties for RPtBi (R=Gd, Dy, Tm, and Lu) half-Heusler compounds. Temperature- and field-dependent resistivity measurements of high-quality RPtBi single crystals reveal an unusually large, nonsaturating magnetoresistance (MR) up to 300 K under a moderate magnetic field of H=140 kOe. At 300 K, the large MR effect decreases as the rare earth is traversed from Gd to Lu and the magnetic field dependence of MR shows a deviation from the conventional H2 behavior. The Hall coefficient (RH) for R=Gd indicates a sign change around 120 K, whereas RH curves for R=Dy, Tm, and Lu remain positive for all measured temperatures. At 300 K, the Hall resistivity reveals a deviation from the linear field dependence for all compounds. Thermoelectric power measurements on this family show strong temperature and magnetic field dependencies which are consistent with resistivity measurements. A highly enhanced thermoelectric power under applied magnetic field is observed as high as ∼100 μV/K at 140 kOe. Analysis of the transport data in this series reveals that the rare-earth-based half-Heusler compounds provide opportunities to tune MR effect through lanthanide contraction and to elucidate the mechanism of nontrivial MR.This article is published as Mun, Eundeok, Sergey L. Bud'ko, and Paul C. Canfield. "Robust tunability of magnetoresistance in half-Heusler R PtBi (R= Gd, Dy, Tm, and Lu) compounds." Physical Review B 93, no. 11 (2016): 115134. DOI: 10.1103/PhysRevB.93.115134. Posted with permission.</p
Кристалічна структура сполук R5Pd2In4 (R = Y, Tb, Dy, Ho, Er, Tm, Lu)
Full text linkСполуки рідкісноземельних металів з паладієм та індієм R5Pd2In4 отримано сплавлянням чистих металів у дуговій печі в атмосфері аргону. Кристалічну структуру сполуки Y5Pd2In4 визначено з монокристальних даних (пр.гр. Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z=2, RI=0.0434, wR2=0.0742, 461 значень F2) і належить до структурного типу Lu5Ni2In4. Ізоструктурні сполуки знайденo з R=Tb, Dy, Ho, Er, Tm, Lu. Їх кристалічну структуру визначено методом порошку.Соединения редкоземельных металлов с палладием и индием R5Pd2In4 получены плавкой чистых металлов в дуговой печи в атмосфере аргона. Кристаллическая структура соединения Y5Pd2In4 определена из монокристаллических данных (пр. гр. Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z=2, RI=0.0434, wR2=0.0742, 461 значений F2) и принадлежит к структурному типу Lu5Ni2In4. Изоструктурные соединения найдены с R=Tb, Dy, Ho, Er, Tm, Lu. Их структура определена методом порошка.The rare earth-palladium-indium compounds R5Pd2In4 were prepared by arc-melting of pure metals under an argon atmosphere. Crystal structure of Y5Pd2In4 was refined from X-ray single crystal diffractometer data (space group Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z =2, RI=0.0434, wR2=0.0742, 461 F2 value) and belong to Lu5Ni2In4 structure type. Isostructural compounds were found with R=Tb, Dy, Ho, Er, Tm, Lu and their crystal structure was determined from X-ray powder data
Кристалічна структура сполук R5Pd2In4 (R = Y, Tb, Dy, Ho, Er, Tm, Lu)
No full textСполуки рідкісноземельних металів з паладієм та індієм R5Pd2In4 отримано сплавлянням чистих металів у дуговій печі в атмосфері аргону. Кристалічну структуру сполуки Y5Pd2In4 визначено з монокристальних даних (пр.гр. Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z=2, RI=0.0434, wR2=0.0742, 461 значень F2) і належить до структурного типу Lu5Ni2In4. Ізоструктурні сполуки знайденo з R=Tb, Dy, Ho, Er, Tm, Lu. Їх кристалічну структуру визначено методом порошку.Соединения редкоземельных металлов с палладием и индием R5Pd2In4 получены плавкой чистых металлов в дуговой печи в атмосфере аргона. Кристаллическая структура соединения Y5Pd2In4 определена из монокристаллических данных (пр. гр. Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z=2, RI=0.0434, wR2=0.0742, 461 значений F2) и принадлежит к структурному типу Lu5Ni2In4. Изоструктурные соединения найдены с R=Tb, Dy, Ho, Er, Tm, Lu. Их структура определена методом порошка.The rare earth-palladium-indium compounds R5Pd2In4 were prepared by arc-melting of pure metals under an argon atmosphere. Crystal structure of Y5Pd2In4 was refined from X-ray single crystal diffractometer data (space group Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z =2, RI=0.0434, wR2=0.0742, 461 F2 value) and belong to Lu5Ni2In4 structure type. Isostructural compounds were found with R=Tb, Dy, Ho, Er, Tm, Lu and their crystal structure was determined from X-ray powder data
Кристалічна структура сполук R5Pd2In4 (R = Y, Tb, Dy, Ho, Er, Tm, Lu)
No full textСполуки рідкісноземельних металів з паладієм та індієм R5Pd2In4 отримано сплавлянням чистих металів у дуговій печі в атмосфері аргону. Кристалічну структуру сполуки Y5Pd2In4 визначено з монокристальних даних (пр.гр. Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z=2, RI=0.0434, wR2=0.0742, 461 значень F2) і належить до структурного типу Lu5Ni2In4. Ізоструктурні сполуки знайденo з R=Tb, Dy, Ho, Er, Tm, Lu. Їх кристалічну структуру визначено методом порошку.Соединения редкоземельных металлов с палладием и индием R5Pd2In4 получены плавкой чистых металлов в дуговой печи в атмосфере аргона. Кристаллическая структура соединения Y5Pd2In4 определена из монокристаллических данных (пр. гр. Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z=2, RI=0.0434, wR2=0.0742, 461 значений F2) и принадлежит к структурному типу Lu5Ni2In4. Изоструктурные соединения найдены с R=Tb, Dy, Ho, Er, Tm, Lu. Их структура определена методом порошка.The rare earth-palladium-indium compounds R5Pd2In4 were prepared by arc-melting of pure metals under an argon atmosphere. Crystal structure of Y5Pd2In4 was refined from X-ray single crystal diffractometer data (space group Pbam, a=17.990(5), b=7.974(2), c=3.6112(9) Å, Z =2, RI=0.0434, wR2=0.0742, 461 F2 value) and belong to Lu5Ni2In4 structure type. Isostructural compounds were found with R=Tb, Dy, Ho, Er, Tm, Lu and their crystal structure was determined from X-ray powder data
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