Textura de geles de fosfato de aluminio

Tesis - Universidad Complutense de Madrid, 1970.Fac. de Ciencias QuímicasTRUEProQuestpu

Textura de geles de fosfato de aluminio

S. E. Phan Văn Đại, Tổng Đốc en retraite. Né en 1880 à Đông Thái (Hà Tĩnh, Annam). Appartient à la famille de S. E. le Võ Hiển Hoàng Trọng Phu, vénérable conseiller de l'Empire d'Annam. Élevé de l’École de Hậu Bổ (1898-1899), de l’École Coloniale à Paris (1900-1904). Rédacteur du journal officiel "Đông văn Nhật Báo" en 1904. Nommé Tri-Huyện en 1906, Tuần Phủ en 1932 et Tổng Đốc en 1936, il prit sa retraite après 31 ans de services. Il s'occupe actuellement d’œuvres sociales. Il est membre de ..

Textura de geles de fosfato de aluminio

Tesis - Universidad Complutense de Madrid, 1970.Fac. de Ciencias QuímicasTRUEProQuestpu

Cómo diseñar al alumno una carrera científico-docente. La especialidad de ciencias

Más que seleccionar a un profesor para un puesto concreto habría que diseñar una carrera científico-docente atendiendo a las particularidades de las carreras de ciencias, en las que la investigación tiene un protagonismo decisivo

High-pressure synthesis, structural and complex magnetic properties of the ordered double perovskite Pb2NiReO6

The ordered double perovskite Pb2NiReO6 has been prepared at 6 GPa and temperatures ranging from 1273 to 1373 K. Its crystal structure determined by X-ray powder diffraction and selected area electron diffraction shows monoclinic symmetry with centrosymmetric space group I2/m (a = 5.6021(1) Å, b = 5.6235(1) Å, c = 7.9286(1) Å and β = 90.284°(1)). High angle annular dark field microscopy studies reveal the existence of compositional microdomains. The compound displays a re-entrant spin-glass transition from a ferrimagnetic ordering below TN 37 K between the Re+5 and Ni+3 (high spin configuration) magnetic sublattices to a spin-glass configuration. Magnetic field dependent magnetization measurements revealed wasp-waisted hysteresis loops at 5 K. These shaped features originate from the antiferromagnetic/ferromagnetic (AFM/FM) competing interactions

Influence of Structural (Cation and Anion) Order in the Superconducting Properties of Ozone-Oxidized Mo0.3Cu0.7Sr2RECu2Oy (RE = Yb, Tm, Gd, Nd, and Pr)

The influence of rare earth (RE) elements on superconducting properties of the transition element (TE)-substituted TExCu1−xSr2RECu2Oy cuprates has not been sufficiently emphasized so far. In the case of molibdocuprates with the general formula Mo0.3Cu0.3Sr2RECu2Oy, all the RE element containing compounds except La, Ce, and Lu can be prepared at room pressure. The influence of the crystal structure on the superconducting properties after ozone oxidation of the present system is reported selecting three groups of RE elements attending to their different atom sizes: small (Yb and Tm), medium (Gd), and big (Nd and Pr). Advanced transmission electron microscopy, various diffraction techniques, and spectroscopic analysis have been used to demonstrate that the increase of structural disorder complemented with a decrease in the hole content play a major role in the vanishing of superconductivity within the present system

Los impactos del cambio climático en Europa: evaluación basada en indicadores. Informe conjunto de la AEMA, CCI y la OMS

Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Una Estrategia en la Búsqueda de Materiales

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Core-level photoemission spectra of Mo0.3Cu0.7Sr2ErCu2Oy, a superconducting perovskite derivative. Unconventional structure–property relationships

Detailed studies of the electronic states for Mo0.3Cu0.7Sr2ErCu2Oy samples with different oxygen contents are presented here. The influence of oxygenation on the electronic states for the Mo0.3Cu0.7Sr2ErCu2Oy system from the semiconducting to the superconducting state has been investigated by means of X-ray photoelectron spectroscopy (XPS). The XPS studies show that Mo is in a mixed MoV and MoVI oxidation state and MoV is predominant over the MoVI in the as-prepared (AP) sample. Yet annealing under an oxygen atmosphere enhances the MoVI state. At the same time, a reduction in the copper species is observed. In the Cu 2p spectra, a larger energy separation between the satellite and main peaks (ES–EM) and a lower intensity ratio (IS/IM) are found to correlate with higher values of the superconducting transition temperature (TC). Analysis of these spectra within the Configuration Interaction (CI) model suggests that higher values of TC are related to lower values of the O 2p–Cu 3d charge transfer energy. The change in the Sr 3d and O 1s core level spectra correlates with the oxygen insertion in the (Mo/Cu)O1+δ chain site, after oxygenation. The hole concentration (Ph) in the copper plane has been obtained using the room temperature thermoelectric power (TEP) value; this shows an increasing tendency with increasing TC, after oxygenation. From these experimental results, one observes that TCincreases with decreasing charge transfer energy. This is, indeed, opposite to the accepted views and occurs in parallel with the shortening of the apical copper–oxygen distance (Cu2–O2) and the increasing of the CuO2 plane buckling angle