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Synthesis of freestanding HfO2 nanostructures.

Kidd T, O'Shea A, Boyle K, Wallace J, Strauss L - Nanoscale Res Lett (2011)

Bottom Line: This simple process resulted in the formation of nanometer scale crystallites of HfO2.The thinnest sheets appeared transparent when viewed in a scanning electron microscope.These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

View Article: PubMed Central - HTML - PubMed

Affiliation: Physics Department, University of Northern Iowa, Cedar Falls, IA 50614, USA. tim.kidd@uni.edu.

ABSTRACT
Two new methods for synthesizing nanostructured HfO2 have been developed. The first method entails exposing HfTe2 powders to air. This simple process resulted in the formation of nanometer scale crystallites of HfO2. The second method involved a two-step heating process by which macroscopic, freestanding nanosheets of HfO2 were formed as a byproduct during the synthesis of HfTe2. These highly two-dimensional sheets had side lengths measuring up to several millimeters and were stable enough to be manipulated with tweezers and other instruments. The thickness of the sheets ranged from a few to a few hundred nanometers. The thinnest sheets appeared transparent when viewed in a scanning electron microscope. It was found that the presence of Mn enhanced the formation of HfO2 by exposure to ambient conditions and was necessary for the formation of the large scale nanosheets. These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

No MeSH data available.


Related in: MedlinePlus

SEM images comparing the bright and dark sides of HfO2 nanosheets. (a) Wide view image of a curled sheet with a portion broken off. Bright and dark sides are both visible. (b) Close-up of the bright side. The surface has a lot of texture and contains micron scale clusters. Small dark circles can also be seen. (c) Close-up view of dark side. Surface is much smoother, although some particulate is attached. Small dark circles are again visible, measuring about 100 nm in diameter.
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Figure 2: SEM images comparing the bright and dark sides of HfO2 nanosheets. (a) Wide view image of a curled sheet with a portion broken off. Bright and dark sides are both visible. (b) Close-up of the bright side. The surface has a lot of texture and contains micron scale clusters. Small dark circles can also be seen. (c) Close-up view of dark side. Surface is much smoother, although some particulate is attached. Small dark circles are again visible, measuring about 100 nm in diameter.

Mentions: The differences between the two sides of these sheets can be more readily seen in Figure 2. The side that faced the interior of the growth ampoule has far more texture and contains a number of microscopic and sub-micron scale clusters. The large number of edges associated with these features makes this side appear brighter in the SEM. These clusters are well attached and likely formed during the growth process. The side that originally faced the ampoule walls appears darker in the SEM and is much smoother. There were far fewer particles attached to this side, and these particles sometimes seemed to shift position and their number increased as the samples were manipulated for various measurements. This indicates the particles on the smooth side appeared to be material that attached to the sheets after they were removed from the growth ampoule.


Synthesis of freestanding HfO2 nanostructures.

Kidd T, O'Shea A, Boyle K, Wallace J, Strauss L - Nanoscale Res Lett (2011)

SEM images comparing the bright and dark sides of HfO2 nanosheets. (a) Wide view image of a curled sheet with a portion broken off. Bright and dark sides are both visible. (b) Close-up of the bright side. The surface has a lot of texture and contains micron scale clusters. Small dark circles can also be seen. (c) Close-up view of dark side. Surface is much smoother, although some particulate is attached. Small dark circles are again visible, measuring about 100 nm in diameter.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211360&req=5

Figure 2: SEM images comparing the bright and dark sides of HfO2 nanosheets. (a) Wide view image of a curled sheet with a portion broken off. Bright and dark sides are both visible. (b) Close-up of the bright side. The surface has a lot of texture and contains micron scale clusters. Small dark circles can also be seen. (c) Close-up view of dark side. Surface is much smoother, although some particulate is attached. Small dark circles are again visible, measuring about 100 nm in diameter.
Mentions: The differences between the two sides of these sheets can be more readily seen in Figure 2. The side that faced the interior of the growth ampoule has far more texture and contains a number of microscopic and sub-micron scale clusters. The large number of edges associated with these features makes this side appear brighter in the SEM. These clusters are well attached and likely formed during the growth process. The side that originally faced the ampoule walls appears darker in the SEM and is much smoother. There were far fewer particles attached to this side, and these particles sometimes seemed to shift position and their number increased as the samples were manipulated for various measurements. This indicates the particles on the smooth side appeared to be material that attached to the sheets after they were removed from the growth ampoule.

Bottom Line: This simple process resulted in the formation of nanometer scale crystallites of HfO2.The thinnest sheets appeared transparent when viewed in a scanning electron microscope.These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

View Article: PubMed Central - HTML - PubMed

Affiliation: Physics Department, University of Northern Iowa, Cedar Falls, IA 50614, USA. tim.kidd@uni.edu.

ABSTRACT
Two new methods for synthesizing nanostructured HfO2 have been developed. The first method entails exposing HfTe2 powders to air. This simple process resulted in the formation of nanometer scale crystallites of HfO2. The second method involved a two-step heating process by which macroscopic, freestanding nanosheets of HfO2 were formed as a byproduct during the synthesis of HfTe2. These highly two-dimensional sheets had side lengths measuring up to several millimeters and were stable enough to be manipulated with tweezers and other instruments. The thickness of the sheets ranged from a few to a few hundred nanometers. The thinnest sheets appeared transparent when viewed in a scanning electron microscope. It was found that the presence of Mn enhanced the formation of HfO2 by exposure to ambient conditions and was necessary for the formation of the large scale nanosheets. These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

No MeSH data available.


Related in: MedlinePlus