12035-79-9

Usage

Chemical Properties

Dark-olive, free-flowing powder.

Uses

Different sources of media describe the Uses of 12035-79-9 differently. You can refer to the following data:
1. Neptunium dioxide is a powder used to form metal targets that are to be radiated by plutonium.
2. Fabrication by powder metallurgy into target elements to be irradiated to produce Pu-238.

Hazard

Toxic. A radioactive poison.

Upstream product

• 21057-99-8 neptunium oxide 
• 33702-71-5 NpO₂⁽³⁺⁾ 
• 18973-22-3 neptunyl⁽²⁺⁾ 

Downstream Products

• 33702-71-5 NpO₂⁽³⁺⁾ 
• 21057-99-8 neptunium oxide 
• 18973-22-3 neptunyl⁽²⁺⁾ 
• 7732-18-5 water 

Related news

New Insights into the Thermal Expansion of neptunium dioxide (cas 12035-79-9) up to 2000 K08/03/2019

We report for the first time the thermal expansion of NpO2 up to 2000 K and compare it to the one of UO2 and PuO2. Lattice parameters were measured as a function of temperature by in situ X-ray diffraction with neutral, reducing and oxidizing atmospheres. Data for NpO2 under neutral and reducing...detailed

Relevant academic research and scientific papers

Behavior of Pu(VI) and Np(VI) in malonate solutions

Complexation of PuO22+ in solutions containing malonate anions C3H2O42- (L 2-) is studied by spectrophotometry. Mono- and bimalonate complexes are formed. The monomalonate complex was isolated as PuO2L· 3H2O. It is isostructural to UO2L·3H2O and forms rhombic crystals with the unit cell parameters a = 9.078(2), b = 7.526(2), and c = 6.2005(15) A, space group Pmn21. The electronic absorption spectrum of the monomalonate complex is characterized by a strong band at 843 nm. In malonate solutions, Pu(VI) is slowly reduced to the pentavalent state even in the cold. The reduction of Np(VI) is considerably faster and more sensitive to increasing temperature. Some kinetic features of the reduction are discussed. Pleiades Publishing, Inc., 2006.

Reduction of Pu(IV) and Np(VI) with carbohydrazide in nitric acid solution

The reduction of Pu(IV) and Np(VI) with carbohydrazide (NH 2NH)2CO in 1-6 M HNO3 solutions was studied. The Pu(IV) reduction is described by a first-order rate equation with respect to Pu(IV). At [HNO3] ≥ 3 M, the reaction becomes reversible. The rate constants of the forward and reverse reactions were determined, and their activation energies were estimated. Neptunium(VI) is reduced to Np(V) at a high rate, whereas the subsequent reduction of Np(V) to Np(IV) is considerably slower and is catalyzed by Fe and Tc ions. The possibility of using carbohydrazide for stabilizing desired combinations of Pu and Np valence states was examined. Pleiades Publishing, Inc., 2012.

Unusual Metal-Organic Framework Topology and Radiation Resistance through Neptunyl Coordination Chemistry

A Np(V) neptunyl metal-organic framework (MOF) with rod-shaped secondary building units was synthesized, characterized, and irradiated with γrays. Single-crystal X-ray diffraction data revealed an anionic framework containing infinite helical chains of actinyl-actinyl interaction (AAI)-connected neptunyl ions linked together through tetratopic tetrahedral organic ligands (NSM). NSM exhibits an unprecedented net, demonstrating that AAIs may be exploited to give new MOFs and new topologies. To probe its radiation stability, we undertook the first irradiation study of a transuranic MOF and its organic linker building block using high doses of γrays. Diffraction and spectroscopic data demonstrated that the radiation resistance of NSM is greater than that of its linker building block alone. Approximately 6 MGy of irradiation begins to induce notable changes in the long- and short-range order of the framework, whereas 3 MGy of irradiation induces total X-ray amorphization and changes in the local vibrational bands of the linker building block.

Kinetics of Reaction between Neptunium(VI) and 3,3'-Bis(diaziridinyl)

Reaction of Np(VI) with excess 3,3'-bis(diaziridinyl) yields the corresponding diazirine and is described by the equation 4NpO2(2+)+ H2N2HCCHN2H2 = 4NpO2(1+)+ N2HCCHN2 + 4H(1+). The rate of this reaction is described by the equation -d[Np(VI)]/dt = k[Np(VI)][H2N2HCCHN2H2]/[H(1+)], wherek=132.+-.10 min**-1 at 35.7°C and the ionic strength of the solution μ = 2. The activation energy of the reaction is E = 73.1.+-.4.6 kJmol**-1.

Kinetics of reactions of Np and Pu ions with hydroxylamine derivatives: VIII. Reduction of Np(VI) with N,N-dibutylhydroxylamine

The rate of Np(VI) reduction with (C4H9)2NHOH(1+) in HC1O4 and HNO3 solutions is described by the equation -d[Np(VI)]/dt = k*[Np(VI)]*[(C4H9)2NHOH(1+)]/[H(1+)], where k = 15.6 +/- 1.1 min**-1 at 25.5°C and ionic strength μ = 2 in an HC1O4 solution and k = 16.0 +/- 1.0 min**-1 at 26.0°C in an HNO3 solution. The activation energy is E = 45.8 +/- 0.8 and 71.9 +/- 0.2 kJ*mol**-1, respectively. The reaction mechanismis discussed in comparison with that of the other Np(VI) reactions with disubstituted hydroxylamines.

Kinetics of the reduction of neptunium(VI) by dicarboxylic acids

The reduction of tracer concentrations of Np(VI) by dicarboxylic acids has been shown to proceed via formation of the 1:1 metal-ligand complex and to form Np(V) but not Np(IV). The rate constants were in the sequence oxalate alkylmalonate ? succinate ? phthalate ≥ fumarate > glutarate. The results are consistent with a mechanism in which the rate-determining step involves loss of a methylene proton from the reductant.

Kinetic study of the oxidation of p-hydroquinone and p-toluhydroquinone by neptunium(VI) in aqueous perchlorate media

The oxidation of p-hydroquinone and p-toluhydroquinone by Np(VI) in aqueous perchlorate media can be described by the empirical rate law -d[Np(VI)]/dt = k[Np(VI)][H2Q] where H2Q is the appropriate hydroquinone. At 25° and I = 1.00 va

A kinetic study of the oxidation of formic acid by neptunium(VII) in aqueous perchloric acid solution

The empirical form of the rate law for the reaction 2NP(VII) + HCOOH = 2Np(VI) + 2H+ + CO2 at constant hydrogen ion concentration is -d[Np(VII)]/dt = k′[Np(VII)] [HCOOH]. At 25° and I = 1.0, k′ = a + b/[H+] where a = 0.4015 M-1 sec-1 and b = 5.38 × 10-2 sec-1. Apparent energies of activation for the respective parameters are 6.44 and 10.5 kcal/mol. There is no solvent deuterium effect on the a parameter but one of 4.2 for b. The respective values of a and b for the reaction with DCOOH (25°, I = 1.0) are 2.64 × 10-2 M-1 sec-1 and 5.10 × 10-3 sec-1 with apparent energies of activation 8.92 and 12.8 kcal/mol. The primary kinetic isotope effects form the basis for the suggestion that the mechanism is similar for the two reaction paths.

Kinetics of reduction of neptunium(VI) with oxalic acid in aqueous perchloric acid

The kinetics for the reduction of neptunium(VI) with oxalic acid has been studied in aqueous perchlorate media. The rate law for the reaction was found to be d[Np(V)]/dt = k [Np(VI)][total oxalate]/[H+] Specific velocity constants and activation energy have been determined. A possible mechanism has been suggested which explains the observed kinetics and the stoichiometry of the reaction.

The reduction of cobalt(III) by neptunium(V) and the neptunium(V)-chromium(III) complex

The rate law for the reaction Np(V) + Co(III) = Np(VI) + Co(II), from 5 to 25° in perchloric acid-lithium perchlorate solutions of constant ionic strength, is -d[Np(V)]/dt = k′[Np(V)] [Co(III)] where k′ = k0e-β[H+]. Under the same co