LETTER
Vacuum-tight sample transfer stage for a scanning electron
microscopic study of stabilized lithium metal particles
Jane Y. Howe
•
Lynn A. Boatner
•
James A. Kolopus
•
Larry R. Walker
•
Chengdu Liang
•
Nancy J. Dudney
•
Charles R. Schaich
Received: 14 August 2011 / Accepted: 4 October 2011 / Published online: 19 October 2011
Ó Springer Science+Business Media, LLC (outside the U.S.) 2011
Abstract A vacuum-tight transfer stage is described, that
enables air or moisture sensitive specimens to be safely
transferred from a protective environment, like that in a dry
box, to a scanning electron microscope without exposing
the sample to ambient conditions. The transfer stage con-
cept described here is, in fact, applicable to the protected
transfer of hygroscopic or air-sensitive samples to any
vacuum-based analysis equipment where the transfer
device opens automatically under vacuum to reveal the
sample. This device concept is also applicable to the
transfer of samples under vacuum from one glove box to
another where the transfer chamber can be easily opened
manually to reveal the sample. An example of one appli-
cation of the device is provided by a controlled exposure
study of stabilized lithium metal particles (SLMP) at var-
ious stages of shelf life. We found that a reaction coating
formed on ‘‘fresh’’ SLMP after it was exposed to 100 Pa air
for as short as 15 m. Such a reaction to air exposure was
not observed on ‘‘aged’’ SLMP with a thickened carbonate
surface coating after 4 and 6 months of shelf life. The case
study of the surface coating on SLMP clearly demonstrated
the excellent vacuum performance of the novel transfer
stage.
Abbreviations
BSE Backscattered electron
EDS Energy dispersive X-ray spectroscopy
SE Secondary electron
SEM Scanning electron microscopy
SLMP
TM
Stabilized lithium metal particles
Introduction
One of the challenges of using scanning electron micros-
copy (SEM) and other vacuum-based analytical techniques
to characterize lithium battery materials is because of their
air and moisture sensitive nature. In a research laboratory
environment, lithium battery materials are processed in a
glove box filled with an over-pressure of dry argon. Left in
a normal air ambient for merely tens of seconds, these
materials can readily react with air and water vapor to
produce drastic morphological and chemical composition
changes. Thus, it is critical to protect the material during its
transfer from a glove box environment and its ultimate
loading into a scanning electron microscope. Koch and
Wild have designed an airtight cover for sample stubs for
the (SEM) [1] that uses a rubber O-ring sealed cover. Once
loaded into the SEM chamber, the cover can be removed
by pulling on a wire tied to the stage. This simple design is
low profile and inexpensive, yet the O-ring seal does not
provide adequate protection for extremely air and moisture
sensitive samples such as lithium metal. Subsequently, Hall
This study is declared a work of the U.S. government is not subject to
copyright protection in the United States.
J. Y. Howe (&) Á L. A. Boatner Á J. A. Kolopus Á
L. R. Walker Á N. J. Dudney
Division of Materials Science and Technology, Oak Ridge
National Laboratory, Oak Ridge, TN 37831, USA
e-mail: howej@ornl.gov
C. Liang
Center for Nanophase Materials Sciences, Oak Ridge National
Laboratory, Oak Ridge, TN 37831, USA
C. R. Schaich
Division of Measurement Science and System Engineering, Oak
Ridge National Laboratory, Oak Ridge, TN 37831, USA
123
J Mater Sci (2012) 47:1572–1577
DOI 10.1007/s10853-011-6029-z