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Title: Surface stability of oxygen deficient LiMn2O4 thin films.


Abstract not provided.

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Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the 224th meeting of the electrochemical society held October 27 - November 1, 2013 in San Francisco, CA.
Country of Publication:
United States

Citation Formats

Missert, Nancy A., Velmurugan, Jeyavel, and Garcia, Robert M. Surface stability of oxygen deficient LiMn2O4 thin films.. United States: N. p., 2013. Web.
Missert, Nancy A., Velmurugan, Jeyavel, & Garcia, Robert M. Surface stability of oxygen deficient LiMn2O4 thin films.. United States.
Missert, Nancy A., Velmurugan, Jeyavel, and Garcia, Robert M. Tue . "Surface stability of oxygen deficient LiMn2O4 thin films.". United States. doi:.
title = {Surface stability of oxygen deficient LiMn2O4 thin films.},
author = {Missert, Nancy A. and Velmurugan, Jeyavel and Garcia, Robert M},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Oct 01 00:00:00 EDT 2013},
month = {Tue Oct 01 00:00:00 EDT 2013}

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  • Abstract not provided.
  • We report on measurements of the in-plane resistivity [rho] and Hall coefficient R[sub H](B[parallel]c) of various oxygen-deficient epitaxial films of YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] in the normal state. The superconducting transition temperatures T[sub c] of the samples vary from 14 to 90 K. Both the resistivity and the Hall coefficient exhibit a strong dependence on the oxygen content and the temperature. As x increases, T[sub c] decreases continuously, while [rho] and R[sub H] gradually increase in magnitude. Furthermore, also the characteristic linear dependences of [rho] [proportional to] T and T[sup [minus]1] of the highly doped compounds changes to a nonlinearmore » behavior for the samples with T[sub c] lower than 60 K. The unusual doping and temperature dependence of R[sub H] will be compared to the predictions of our calculations, based on a two-dimensional tight-binding model using the relaxation-time approximation. The model considers also the next-nearest-neighbor hopping, which strongly influences the predicted Hall coefficient. Additionally, the contangent of the Hall angle cot[Theta][sub H] is discussed in the framework of the two-dimensional Luttinger liquid theory. 28 refs., 4 figs.« less
  • We report our studies of the nanolithographic surface modifications induced by an Atomic Force Microscope (AFM) in epitaxial thin films of oxygen deficient Lanthanum Barium Manganese Oxide (La{sub 0.67}Ba{sub 0.33}MnO{sub 3−δ}). The pattern characteristics depend on the tip voltage, tip polarity, voltage duration, tip force, and humidity. We have used Electron Energy Dispersive X-Ray Spectroscopy (EDS) to analyze the chemical changes associated with the surface modifications produced with a negatively biased AFM tip. A significant increase in the oxygen stoichiometry for the patterned regions relative to the pristine film surface is observed. The results also indicate changes in the cationmore » stoichiometry, specifically a decrease in the Lanthanum and Manganese concentrations and an increase in the Barium concentration in the patterned regions.« less
  • 3d-metal (Me) doped LiMn{sub 2}O{sub 4} thin films were deposited by rf magnetron sputtering of Li[Mn{sub 1.9}Me{sub 0.1}]O{sub 4} targets in Ar + N{sub 2} and Ar + O{sub 2} gas mixtures and annealed at 750{degrees}C in O{sub 2} for 1 h. From XRD measurements, the structure of the Me-doped thin film was dependent upon the element and the deposition conditions. The doping level of Me/Mn of cubic phase was less than 0.1 by EDX measurements. The Ti-LiMn{sub 2}O{sub 4} films exhibited a capacity close to theoretical for stoichiometric LiMn{sub 2}O{sub 4}. This improvement at 4 V comes at themore » expense of the capacity at 5 V. Cells with Ti-doped films exhibited the same low capacity fade as those with undoped LiMn{sub 2}O{sub 4} cathodes. Similar electrochemical changes were observed with the Cr- and Zn-LiMn{sub 2}O{sub 4} films. The discharge capacities above 4.5 V for the Ni-doped films were about equal to those below 4.5 V, and the thin-film cells could be cycled reversibility between 3.5 and 5.3 V.« less
  • The structure and electrochemical properties of LiMn{sub 2}O{sub 4} films depend upon the deposition and annealing conditions. Films which were deposited by rf magnetron sputtering of LiMn{sub 2}O{sub 4} in Ar + N{sub 2} gas mixtures and annealed in O{sub 2} at temperatures between 400 to 1000{degrees}C had the cubic spinel structure with an a-axis length that increased linearly from 8.13 to 8.25 {Angstrom} with increasing anneal temperature. Thin-film lithium cells with cathodes of different a-axis lengths exhibited marked differences in their voltage profiles. In particular, the ratio of the capacities at 4 V and 3 V increased with themore » a-axis length. A defect model of LiMn{sub 2}O{sub 4} which is consistent with the structural and electrochemical data is represented by [Li{sub 1-y+z}Mn{sup 2+}{sub y-z}]{sub 8a}[Mn{sup 2+}{sub z}]{sub 16c}[Li{sub x}Mn{sub 2-x}]{sub 16d}O{sub 4}. Based on this model and the results of in-situ XRD measurements, it is proposed that Mn ions migrate from 8(a) tetrahedral sites to 16(c) octahedral sites on charging the cells in the 5V plateau.« less