Effect of Dopants on Zirconia Stabilization—An X-ray Absorption Study: I, Trivalent Dopants

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65562/1/j.1151-2916.1994.tb06964.x.pd

Correlation of Nearest Neighbour Distance and Bonding Parameters of Exafs of Some Mn and Co Systems

Analysing the EXAFS of several Mn and Co systems, the absorbing atom phase shift α and backscattering amplitude phase shift β are evaluated. It is shown that the parameters α and β vary linearly with the nearest neighbour distance, R, except in the systems CoCl$\text{}_{2}$·6H$\text{}_{2}$O, MnSO$\text{}_{4}$·H$\text{}_{2}$O and MnF$\text{}_{2}$. The nearest neighbour distance, R, in the complicated systems like smaltite and braunite minerals was also determined. The values are close to the crystallographic values

Chemical Shift of X-Ray K-Absorption Edge of Ni in Some of its Compounds and its Correlation with Partial Charge

X-ray absorption Ni K-edge spectra are recorded for the following systems: Ni metal, Ni(NO$\text{}_{3}$)$\text{}_{2}$ • 6H$\text{}_{2}$0, Ni$\text{}_{3}$(PO$\text{}_{4}$)$\text{}_{2}$ • 6H$\text{}_{2}$0, NiSO$\text{}_{4}$ • 6H$\text{}_{2}$0, NiCO$\text{}_{3}$, NiO and La$\text{}_{2}$NiO$\text{}_{4}$ using a Cauchois-type bent crystal spectrograph. The chemical shift of these systems is correlated with the partial charge determined using Sanderson's method. On the basis of regression analysis a relation ΔE = A$\text{}_{0}$ + A$\text{}_{1}$q + A$\text{}_{2}$q$\text{}^{2}$ -A$\text{}_{3}$q$\text{}^{3}$ + A$\text{}_{4}$q$\text{}^{4}$ between the chemical shift, ΔE, and the partial charge, q, has been suggested. The discrepancy in the shift of NiO and La$\text{}_{2}$NiO$\text{}_{4}$ has also been discussed

Determination of cation oxidation states in the spinel ZnMnFeO<SUB>4</SUB> by X-ray spectroscopy

The K absorption edges of zinc, manganese and iron have been recorded photographically in the spinel ZnMnFeO4, using a bent-crystal x-ray spectrograph. The positions of these edges have been compared with those in some bivalent and trivalent compounds. This comparison shows that the valence states of zinc, manganese and iron in this spinel are 2, 3 and 3 respectively

Design optimization of backup seal for sodium cooled fast breeder reactor

Design optimization of static, fluoroelastomer backup seals for the 500 MWe, Prototype Fast Breeder Reactor (PFBR) is depicted. 14 geometric variations of a solid trapezoidal cross-section were studied by finite element analysis (FEA) to arrive at a design with hollowness and double o-ring contours on the sealing face. The seal design with squeeze of 5 mm assures failsafe operation for at least 10 years under a differential pressure of 25 kPa and ageing influences of fluid (air), temperature (110 °C) and γ radiation (23 mGy/h) in reactor. Hybrid elements of 1 mm length, regular integration, Mooney–Rivlin material model and Poisson’s ratio of 0.493 were used in axisymmetric analysis scheme. Possible effects of reduced fluoroelastomer strength at 110 °C, ageing, friction, tolerances in reactor scale, testing conditions during FEA data generation and batch-to-batch/production variations in seal material were considered to ensure adequate safety margin at the end of design life. The safety margin and numerical prediction accuracy could be improved further by using properties of specimens extracted from seal. The approach is applicable to other low pressure, moderate temperature elastomeric sealing applications of PFBR, mostly operating under maximum strain of 50%