Zirconium Abundances Research Articles

Oscillator strengths for Zr I and Zr II and a new determination of the solar abundance of zirconium

view Abstract Citations (249) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Oscillator strengths for Zr I and Zr II and a new determination of the solar abundance of zirconium. Biemont, E. ; Grevesse, N. ; Hannaford, P. ; Lowe, R. M. Abstract A new determination of the solar abundance of zirconium has been made using equivalent-width data measured on the Jungfraujoch solar atlas together with new oscillator strengths derived from measurements of atomic lifetimes and branching ratios for 34 lines of Zr I and 24 lines of Zr II. Excellent agreement is found between the results derived from Zr I and Zr II lines and also with recent meteoritic results. The mean abundance of zirconium in the sun is found to be A/Zr/ equals 2.56 plus or minus 0.05. Publication: The Astrophysical Journal Pub Date: September 1981 DOI: 10.1086/159213 Bibcode: 1981ApJ...248..867B Keywords: Abundance; Solar Spectra; Spectral Line Width; Transition Probabilities; Zirconium; Chemical Composition; Solar Instruments; Solar Oscillations; Solar Physics full text sources ADS |

The isotopic contosition of zirconium

The isotopic composition of zirconium has been measured. Normalized to 94Zr/ 90Zr = 0.3381, the isotopic ratios are 91Zr/ 90Zr = 0.21799 ± 0.00005, 92Zr/ 90Zr = 0.33338 ± 0.00006, and 96Zr/ 90Zr = 0.05439 ± 0.00007, where the errors correspond to the reproducibility of 14 standard runs. The same isotopic composition has been found in one chondrite, one achondrite and one lunar sample, and one terrestrial standard (granite G2). The absolute mass discrimination has been tested by analysing artificial mixtures of 91Zr- and 96Zr-enriched isotopes. Our preferred isotopic abundances of zirconium are: • 90Zr = 0.51444 +0.085 −0.025 91Zr = 0.11214 +0.008 −0.004 • 92Zr = 0.17150 −0.017 +0.008 94Zr = 0.17393 −0.057 +0.016 • 96Zr = 0.02798 −0.019 +0.008 where the errors are strongly correlated. The corresponding atomic mass of zirconium is 91.224 +0.002 −0.005, in agreement with the accepted value of 91.22.

The abundances of titanium, zirconium and hafnium in stony meteorites

The concentrations of Ti, Zr and Hf have been determined, by a stable isotope dilution method, in 27 chondrites, seven achondrites and standard rock samples BCR-1 and W-1. Among all chondrites investigated, enstatite chondrite Abee is lowest in Ti atomic ratio compared with Si while all carbonaceous chondrites show higher values. The Zr contents are higher in CII and CIII chondrites, relative to the other groups of chondrites. There is a clustering of Ti and Zr within each group. The Zr Hf ratios in CII, CIII. E and H chondrites are essentially the same, while that in the CI chondrite is lower and in L, LL and unequilibrated chondrites are higher. The concentrations of Ti, Zr, Hf and Ti Zr , Zr Hf ratios in achondrites are variable, even among members of the same group. Based on these results, condensation models for these elements are discussed. The variable results for Ti, Zr and Hf in achondrites may be due to the reheating recrystallization and metamorphic processes. ‘Cosmic atomic abundances’ of Ti, Zr and Hf are calculated as 2470, 11.2 and 0.185. respectively for Si = 10 6 atoms.

Lifetimes of excited states in Y I, Y II, and Zr I by beam-foil and beam-sputtering excitation

view Abstract Citations (24) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Lifetimes of excited states in Y I, Y II, and Zr I by beam-foil and beam-sputtering excitation. Andersen, T. ; Ramanujam, P. S. ; Bahr, K. Abstract Radiative lifetimes have been determined by beam-foil and beam-sputtering excitation for some excited states in Y I, Y II, and Zr I to test the reliability of the transition probabilities used so far for solar abundance determinations of yttrium and zirconium. The yttrium abundance in the sun should be increased by a factor of about 2 to log A(Y) = 2.35 + or - 0.20 by using the new transition probabilities, whereas the zirconium abundance should remain unchanged. Publication: The Astrophysical Journal Pub Date: July 1978 DOI: 10.1086/156268 Bibcode: 1978ApJ...223..344A Keywords: Abundance; Atomic Excitations; Ion Beams; Photosphere; Radiative Lifetime; Sputtering; Transition Probabilities; Yttrium; Zirconium; Decay; Foils (Materials); Graphs (Charts); Line Spectra; Metal Ions; Solar Atmosphere; Wavelengths; Solar Physics; Transition Probabilities full text sources ADS |

The abundances of zirconium and hafnium in the solar system

The concentrations of zirconium and hafnium have been determined in Orgueil, Murchison, Allende, Bruderheim and Alais by RNAA. The mean Zr/Hf weight ratio in the first four of these meteorites is 31.3 ± 2.2 indicating no major fractionation of Zr from Hf. Alais contains anomalously high amounts of many refractory lithophile elements, including Zr and Hf. Orgueil contains 3.1 ppm Zr and 0.11 ppm Hf, corresponding to 9.0 and 0.16 atoms, respectively, relative to 10 6 Si atoms.

Zirconium and hafnium in meteorites

The abundances of zirconium and hafnium have been determined in nine stony meteorites by a new, precise neutron-activation technique. The Zr/Hf abundance ratios for the chondrites vary in a rather narrow range, consistent with previously published observations from our group. Replicate analyses of new, carefully selected clean interior samples of the C1 chondrite Orgueil yield mean zirconium and hafnium abundances of 5.2 and 0.10 ppm, respectively. These abundances are lower than we reported earlier for two C1 chondrite samples which we now suspect may have suffered contamination. The new C1 zirconium and hafnium abundances are in closer agreement with predictions based on theories of nucleosynthesis than the earlier data.

Zirconium Isotopic Abundances in R Cygni

view Abstract Citations (19) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Zirconium Isotopic Abundances in R Cygni Peery, Benjamin F., Jr. ; Beebe, Reta F. Abstract Relative isotopic abundances of zirconium have been found from the spectrum of the long-periodvariable S star, R Cygni, by matching computed and observed profiles of the i 0-0 band of Zr'6O. Fractional abundances are 96Zr, 0.50; 1Zr, 0.05; 0iZr, 0.10; 9iZr, 0.05; 94Zr, 0.30; 96Zr, 0.00, with uncertainties of the order of +0.05. These results are close to the abundances to be expected from production of Zr by the s-process after extensive neutron exposure. Improved molecular constants of 90Zr160 have been determined. Publication: The Astrophysical Journal Pub Date: May 1970 DOI: 10.1086/150457 Bibcode: 1970ApJ...160..619P full text sources ADS | data products SIMBAD (2)

Zirconium abundances in meteorites and implications to nucleosynthesis

The atomic abundance of Zr has been established at 16± 5 Zr atoms/10 6 Si atoms in seventeen ordinary chondrites, which agrees well with Aller's (1962) solar value of 14 Zr atoms/10 6 Si atoms. Apparently, fractionation of Zr has occurred within the chondritic family, since 22 ± 3 Zr atoms/10 6 Si atoms were observed in seven Type II and Type III carbonacceous chondrites. Zr has been enriched in four Ca-rich achondrites by a factor of five, which is consistent with other trace-element enrichments. Zr may be depleted in Ca-poor achondrites and pallasitic olivines. The low Zr abundance in chondrites, coupled with Rb, Sr, Y and Mo chondritic abundances, indicates ~50 per cent enhancement of the odd-A mass distribution at A = 89 due to the neutron-shell closure. Abundance values of Zr and other nearby elements indicate Fe 56 seed nuclei were exposed to different neutron fluxes. The atomic ratio Zr/Hf of 100 in meteorites compared with 106 in the terrestrial crust indicates no serious fractionation between these two very similar chemical elements.

Zirconium and Hafnium in Stone Meteorites

The abundances of zirconium and hafnium in stone meteorites, were determined by neutron activation analysis. Specific radiochemical separations were used to obtain individual zirconium and hafnium samples of high radiochemical purity. The average abundance of zirconium in chondrites for six analyses was 35 parts per million; of hafnium, 0.19 ppm. The hafnium abundances are in good general agreement with the predictions of current theories of nucleosynthesis.

The hafnium to zirconium abundance ratio and specific radioactivity of some ores

The hafnium to zirconium abundance ratio and the specific radioactivity of some ores from different continents were measured spectroscopically and by Geiger counter respectively. hevesys postulation of a relationship between the radioactivity and hafnium content of zircons and the possibility of the abundance ratio serving as a geological indicator are discussed.