Structural and Valence State Modification of Cobalt in CoPt Nanocatalysts in Redox Conditions

ABSTRACTThe incorporation of Pu and Np in zirconolite (CaZrTi2O7) has been investigated over a range of redox conditions. Zirconolite formulations designed to favour either trivalent or tetravalent Pu and Np were prepared by limiting the amount of charge compensating additives available to maintain electroneutrality. From near-edge X-ray absorption spectroscopy the Pu valence state was found to vary with the processing atmosphere, from completely tetravalent when fired in air, and located on either the Ca or Zr sites, to trivalent, when substituted on the Ca site after annealing in 3.5% H2/N2. Np was predominantly tetravalent over the range of redox conditions examined and was readily incorporated on either of zirconolite's Ca or Zr sites. The charge compensation mechanisms at work in different zirconolites are also discussed.

Download Full-text

Valence state analysis of elements by EPMA and its application

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134752 ◽

1990 ◽

Vol 48 (2) ◽

pp. 230-231

Author(s):

Chen Liqing ◽

Liu Zuqin ◽

Zhang Wei

Keyword(s):

Valence State ◽

Line Intensities ◽

Valence States ◽

Valence Electrons ◽

Fe And Mn ◽

Intensity Ratios ◽

State Analysis

Valence state analyses of Fe and Mn in oxides by EPMA have been reported in literature. In this paper, the effects of valence state on intensity ratios ILα/IKα and ILα/ILβ of Cu, Ni, Co, Fe, Mn, Cr and their oxides, and on intensity ratios ILβ2/ILα1 and ILγ1/ILα1 of Mo, Nb, Zr and their oxides were studied. It was observed that intensity ratios change with valence states in accordance with some regularities, and these effects could be utilized for analyzing the valence states of catalysts.Valence state analysis of elements by EPMA is based on the fact that changes in the states of valence electrons in the outer shells of an atom cause corresponding changes in line intensities. The M electrons of Cu, Ni, Co, Fe, Mn, Cr and the N electrons of Mo, Nb, Zr are valence electrons. Line Kα1,2 and six lines of L are produced from the transitions of K-L2,3 and L-M or L-N respectively.

Download Full-text

Theory for the mixed-valence state

Le Journal de Physique Colloques ◽

10.1051/jphyscol:19795133 ◽

1979 ◽

Vol 40 (C5) ◽

pp. C5-374-C5-374 ◽

Cited By ~ 1

Author(s):

C. M. Varma

Keyword(s):

Valence State ◽

Mixed Valence ◽

Mixed Valence State

Download Full-text

MIXED VALENCE STATE OF Sm ON THE SURFACE OF AMORPHOUS La80-xSmxAu20 ALLOYS

Le Journal de Physique Colloques ◽

10.1051/jphyscol:19808198 ◽

1980 ◽

Vol 41 (C8) ◽

pp. C8-799-C8-802 ◽

Cited By ~ 4

Author(s):

G. Krill ◽

A. Amamou ◽

A. Berrada ◽

J. Durand ◽

N. Hassanain

Keyword(s):

Valence State ◽

Mixed Valence ◽

Mixed Valence State

Download Full-text

Tc-99m Labeled Complexes of Aldehydes and Glutamate as Cholescintigraphic Agents

Nuklearmedizin ◽

10.1055/s-0038-1624914 ◽

1975 ◽

Vol 14 (04) ◽

pp. 330-338

Author(s):

L. G. Colombetti ◽

J. S. Arnold ◽

W. E. Barnes

Keyword(s):

Nuclear Medicine ◽

Gall Bladder ◽

Rose Bengal ◽

Valence State ◽

Monosodium Glutamate ◽

Kinetic Studies ◽

Scintillation Camera ◽

Blood Clearance ◽

Lower Valence ◽

Wire Basket

SummaryTc-99m pyridoxylidene glutamate has proven to be an excellent biliary scanning agent, far superior in many respect to the commonly used 1-131 rose bengal. The preparation of the compound as previously reported by Baker et al is too time consuming and requires the use of an autoclave which is not available in most nuclear medicine departments. In our facility, we have been preparing similar compounds using several aldehydes and monosodium glutamate to make labeled complexes having the same pharmacological characteristics. The mixture of monosodium glutamate, aldehyde, and Tc-99m pertechnetate is made slightly alkaline, purged with helium, and placed in a sealed vial. The vial, which is protected by a wire basket, is then heated in a laboratory oven at 130° C for a period of 15 to 20 minutes. During this time, the technetium is reduced to a lower valence state and bound to the complex formed. Chromatographic data show that these compounds are chemically similar to that previously reported. The compounds prepared concentrate in the gall bladder of the rabbit in less than 10 minutes. Kinetic studies have been performed on dogs with a scintillation camera and small digital computer to measure rates of blood clearance, liver and gall bladder uptake, and excretion into the intestine. The aldehyde — glutamate complex promises to be a useful scanning agent for the diagnosis of biliary and hepatocellular diseases.

Download Full-text