Limits...
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 image of a collection of HfO2 nanosheets mounted on double sided carbon tape. The sides of each sheet can be distinguished by their apparent brightness. During growth, the darker side was attached to the interior wall of the quartz ampoule.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211360&req=5

Figure 1: SEM image of a collection of HfO2 nanosheets mounted on double sided carbon tape. The sides of each sheet can be distinguished by their apparent brightness. During growth, the darker side was attached to the interior wall of the quartz ampoule.

Mentions: In one set of samples, the heating cycle was performed twice without breaking vacuum. Of these samples, those containing Mn (nominal 25% doping) yielded a number of transparent sheets attached to the inner walls of the growth ampoule in addition to the usual HfTe2 powders. These sheets, larger examples of which can be seen in Figure 1, were barely detectable when the ampoules were first removed from the furnace. After some handling, but before the ampoules were cracked open, these sheets fell from the interior walls and landed on the HfTe2 powder contained within the ampoule. When this occurred, the mostly rectangular sheets rolled up so that the side exposed to the powder became the exterior. Their final curvature was much higher than would be expected from the 1.1 cm inner diameter of the silica ampoule.


Synthesis of freestanding HfO2 nanostructures.

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

SEM image of a collection of HfO2 nanosheets mounted on double sided carbon tape. The sides of each sheet can be distinguished by their apparent brightness. During growth, the darker side was attached to the interior wall of the quartz ampoule.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: SEM image of a collection of HfO2 nanosheets mounted on double sided carbon tape. The sides of each sheet can be distinguished by their apparent brightness. During growth, the darker side was attached to the interior wall of the quartz ampoule.
Mentions: In one set of samples, the heating cycle was performed twice without breaking vacuum. Of these samples, those containing Mn (nominal 25% doping) yielded a number of transparent sheets attached to the inner walls of the growth ampoule in addition to the usual HfTe2 powders. These sheets, larger examples of which can be seen in Figure 1, were barely detectable when the ampoules were first removed from the furnace. After some handling, but before the ampoules were cracked open, these sheets fell from the interior walls and landed on the HfTe2 powder contained within the ampoule. When this occurred, the mostly rectangular sheets rolled up so that the side exposed to the powder became the exterior. Their final curvature was much higher than would be expected from the 1.1 cm inner diameter of the silica 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