Sandia National Laboratories

About: Sandia National Laboratories is a facility organization based out in Livermore, California, United States. It is known for research contribution in the topics: Laser & Thin film. The organization has 21501 authors who have published 46724 publications receiving 1484388 citations. The organization is also known as: SNL & Sandia National Labs.

Crystal and defect chemistry of rare earth cations in BaTiO3

Abstract: This study revisits the issue of rare earth cation substitutions into barium titanate. Analysis based upon crystal chemistry, defect chemistry and metastable states is presented to aid interpretation of experimental data. Recent detailed and highly precise X-ray powder diffraction and Electron Paramagnetic Resonance experiments performed on samples produced with different A/B ratios and fired under different oxygen partial pressure conditions give rise to new insights into the material. Specifically, the site occupancy and the valence states for the rare-earth dopants in barium titanate are considered. Earlier work is also reviewed and compared to the studies performed here. Collectively a classification of the various types of behavior observed for the rare-earth series in barium titanate is presented.

Approximations for the exchange potential in electron scattering

Abstract: Four new exchange potentials (the semiclassical exchange approximation, the asymptotically adjusted free‐electron–gas exchange approximation, the second‐order free‐electron–gas exchange approximation, and the high‐energy exchange approximation) are derived. Calculations are performed for elastic electron scattering from helium and argon. The results are compared to one another and to calculations using Hara’s free‐electron–gas approximation and the exact nonlocal exchange potential. Three of the approximations to exchange are in good agreement with the exact exchange —except at very low energy— but are much easier to use. Thus they should be very useful in electron–atom and electron–molecule scattering calculations.

Reliable noninvasive measurement of blood gases

Abstract: This invention relates to methods and apparatus for, preferably, determining non-invasively and in vivo at least two of the five blood gas parameters (i.e., pH, [HCO3-], PCO2, PO2, and O2 sat.) in a human.

Minimum Lp-norm two-dimensional phase unwrapping

Abstract: We develop an algorithm for the minimum Lp-norm solution to the two-dimensional phase unwrapping problem. Rather than its being a mathematically intractable problem, we show that the governing equations are equivalent to those that describe weighted least-squares phase unwrapping. The only exception is that the weights are data dependent. In addition, we show that the minimum Lp-norm solution is obtained by embedding the transform-based methods for unweighted and weighted least squares within a simple iterative structure. The data-dependent weights are generated within the algorithm and need not be supplied explicitly by the user. Interesting and useful solutions to many phase unwrapping problems can be obtained when p< 2. Specifically, the minimum L0-norm solution requires the solution phase gradients to equal the input data phase gradients in as many places as possible. This concept provides an interesting link to branch-cut unwrapping methods, where none existed previously.

ac Conductivity of Glasses

Abstract: We investigate the ac conductivity of glasses due to atomic and electronic hopping between sites with random space and energy separations. Several examples are considered including the structural model of glasses recently introduced by Anderson, Halperin, and Varma, and by Philips. We find that glassy materials should quite generally exhibit a nearly linear conductivity-frequency relationship. The details of any particular conductivity mechanism should be contained in the deviation from linearity.