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The probability that a nucleus will absorb a neutron--the neutron capture cross-section--is important to many areas of nuclear science, including stellar nucleosynthesis, reactor performance, nuclear medicine and defence applications. Although neutron capture cross-sections have been measured for most stable nuclei, fewer results exist for radioactive isotopes, and statistical-model predictions typically have large uncertainties.sup.1. There are almost no nuclear data for neutron-induced reactions of the radioactive nucleus .sup.88Zr, despite its importance as a diagnostic for nuclear security. Here, by exposing .sup.88Zr to the intense neutron flux of a nuclear reactor, we determine that .sup.88Zr has a thermal neutron capture cross-section of 861,000 [plus or minus] 69,000 barns (1[sigma] uncertainty), which is five orders of magnitude larger than the theoretically predicted value of 10 barns.sup.2. This is the second-largest thermal neutron capture cross-section ever measured and no other cross-section of comparable size has been discovered in the past 70 years. The only other nuclei known to have values greater than 10.sup.5 barns.sup.3-6 are .sup.135Xe (2.6 × 10.sup.6 barns), a fission product that was first discovered as a poison in early reactors.sup.7,8, and .sup.157Gd (2.5 × 10.sup.5 barns), which is used as a detector material.sup.9,10, a burnable reactor poison.sup.11 and a potential medical neutron capture therapy agent.sup.12. In the case of .sup.88Zr neutron capture, both the target and the product (.sup.89Zr) nuclei are radioactive and emit intense [gamma]-rays upon decay, allowing sensitive detection of miniscule quantities of these radionuclides. This result suggests that as additional measurements with radioactive isotopes become feasible with the operation of new nuclear-science facilities, further surprises may be uncovered, with far-reaching implications for our understanding of neutron capture reactions.The thermal neutron capture cross-section of .sup.88Zr is measured to be 861,000 [plus or minus] 69,000 barns, the second-largest neutron capture cross-section ever measured., Author(s): Jennifer A. Shusterman [sup.1] [sup.2] [sup.3] , Nicholas D. Scielzo [sup.1] , Keenan J. Thomas [sup.1] , Eric B. Norman [sup.4] , Suzanne E. Lapi [sup.5] , C. Shaun [...]

The species and ion charge state evolution of pulsed cathodic arc plasma was investigated at different pressures. A zirconium cathode was operated in a nitrogen environment, and the plasma composition was analyzed by time-of-flight charge-to-mass spectrometry.

The electronic structures of binary M21S8 (M = Nb, Zr) and isostructural ternary (M,M')(sub 21)S8 (M,M' = Hf, Ti; Nb, Ta) phases are analyzed by means of extended Huckel tight-binding band structure calculations. The distribution of hafnium and titanium atoms on the six crystallographically independent metal sites in the ternary phase Hf(sub 7.5)Ti(sub 13.5) are rationalized using metal-metal bond strength, electronegatavity/charge, and site volume arguments.

Several molecular dynamics studies are conducted to explain the tensile behavior that is exhibited by the different monoclinic Zr[O.sub.2] bicrystals. The tensile strength of these bicrystals is shown to be inversely related to the thickness of its grain boundary.

The reaction of the cation [Cp.sub.2]ZrMe([mu]-MeB[([C.sub.6][F.sub.5]).sub.3]) or Cp(t[Bu.sub.3]PN)TiMe([mu]-MeB[([C.sub.6][F.sub.5]).sub.5]) with [(R[C.sub.5][H.sub.4]).sub.2]Fe (R = H, Me) has produced stable, yet reactive cations. The early metal centers are stabilized by dative donation from Fe and an agostic interaction with a CH bond of a Fe-bound cyclopentadienyl ligand.

Pulsed dc magnetron sputtering from a Zr-Y (80/20 at. %) alloy target was utilized to synthesize thermally stable, stoichiometric, cubic yttria-stabilized zirconia (YSZ) thin-film electrolytes. Temperature-dependent impedance spectroscopy analysis of the YSZ films with Ag electrodes showed that the in-plane ionic conductivity was within one order of magnitude higher in films deposited with substrate bias corresponding to a decrease in grain size compared to films deposited at floating potential.

A study related to the additions of Zr to In2O3 (IO) and In2O3:SnO2 (ITO) sputtered thin films that allowed IO-based films to maintain optical transparency and high carrier concentration is presented. Analysis of films using Drude theory approximation indicated that the optical improvement is due to an increase in dielectric permittivity caused by Zr addition, and this strategy could also be applied to improve and develop other new transparent conducting oxides (TCOs).

Large-scale atomic/molecular massively parallel simulator (LAMMPS) is used for studying the liquid behaviors of [Cu.sub.61.8][Zr.sub.38.2], [Cu.sub.64.5][Zr.sub.35.5] and [Cu.sub.66][Zr.sub.34] amorphous alloys including their pair distribution functions, distributions of Voronoi clusters with different coordination numbers and mean square displacement of Cu and Zr atoms. The local cluster structure has shown that the majority of the glue atoms are Cu atoms in [Cu.sub.64.5][Zr.sub.35.5] amorphous alloy, leading to denser packing and better glass forming ability.

A study of the damage production in yttria-stabilized cubic zirconia single crystals irradiated with swift heavy ions is presented. The damage results from the formation of tracks due to the huge electronic excitations induced in the wake of incident ions might be usd to predict the damage evolution in other nonamorphizable ceramics irradiated with swift heavy ions.

Amorphous hafnia, zirconia, and hafnia-zirconia nanoparticles are prepared by combining aqueous solutions of hexamethylenetetramine (HMT) with hafnium dichloride oxide, zirconium dichloride oxide or a mixture of these two salts at room temperature. Nanoparticles of tetragonal and monoclinic structure are prepared by increasing the annealing temperature and/or using a less reducing environment.

Ab initio electronic structure theory calculations were used to predict the structure and stability of the Ge, Sn, and Zr analogues of silsesquioxanes (POSS) and the Si/Ge-mixed POSS. The results obtained can be applied to design new functional POSS.

The size-selective [Zr.sub.2]@[Si.sub.n] (n=16-24) caged clusters are investigated using density functional approach. Results suggest that encapsulation of the bimetallic zirconium atoms is favorable for increasing stabilities of silicon cages.

The theoretical and experimental studies on the very intense visible green photoluminescence (PL) observed in structurally ordered-disordered BaZr[O.sub.3] powders at room temperature are reported. The results showed that local defects in the cubic structure caused by [Zr[O.sub.5].[V.sup.z.sub.O] complex clusters play significant role in the formation of the hole-electron pairs, that gives rise to a charge gradient in the structure responsible for PL emission.

An unequivocal evidence for direct methyl group exchange within a class of cationic zirconium Ziegler-Natta initiators is described. The experiments provided the basis for a new strategy for the controlled production of well-defined stereoblock polyolefins.