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Title: Influence of instrument conditions on the evaporation behavior of uranium dioxide with UV laser-assisted atom probe tomography

Atom probe tomography (APT) provides the ability to detect subnanometer chemical variations spatially, with high accuracy. However, it is known that compositional accuracy can be affected by experimental conditions. A study of the effect of laser energy, specimen base temperature, and detection rate is performed on the evaporation behavior of uranium dioxide (UO2). In laser-assisted mode, tip geometry and standing voltage also contribute to the evaporation behavior. In this investigation, it was determined that modifying the detection rate and temperature did not affect the evaporation behavior as significantly as laser energy. It was also determined that three laser evaporation regimes are present in UO2. Very low laser energy produces a behavior similar to DC-field evaporation, moderate laser energy produces the desired laser-assisted field evaporation characteristic and high laser energy induces thermal effects, negatively altering the evaporation behavior. The need for UO2 to be analyzed under moderate laser energies to produce accurate stoichiometry distinguishes it from other oxides. The following experimental conditions providing the best combination of mass resolving power, accurate stoichiometry, and uniform evaporation behavior: 50 K, 10 pJ laser energy, a detection rate of 0.003 atoms per pulse, and a 100 kHz repetition rate.
Authors:
 [1] ;  [1] ;  [2] ;  [1]
  1. Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering
  2. Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Publication Date:
OSTI Identifier:
1177617
Report Number(s):
INL/JOU--13-30695
Journal ID: ISSN 0022-3115; TRN: US1500054
DOE Contract Number:
AC07-05ID14517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Nuclear Materials; Journal Volume: 459
Publisher:
Elsevier
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 42 Engineering; URANIUM DIOXIDE; EVAPORATION; LASERS; TOMOGRAPHY; PROBES; Measuring Methods; Spatial Resolution; Optimization; KHz Range 100-1000; Temperature Range 0013-0065 K; MeV Range 01-10; MASS RESOLUTION; STOICHIOMETRY; VARIATIONS ATOM PROBE TOMOGRAPHY; LASER ASSISTED FIELD EVAPORATION; STOICHIOMETRY; URANIUM DIOXIDE