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Intense ultraviolet emission from needle-like WO3 nanostructures synthesized by noncatalytic thermal evaporation.

Park S, Kim H, Jin C, Lee C - Nanoscale Res Lett (2011)

Bottom Line: Photoluminescence measurements showed that needle-like tungsten oxide nanostructures synthesized at 590°C to 750°C by the thermal evaporation of WO3 nanopowders without the use of a catalyst had an intense near-ultraviolet (NUV) emission band that was different from that of the tungsten oxide nanostructures obtained in other temperature ranges.The intense NUV emission might be due to the localized states associated with oxygen vacancies and surface states.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Inha University, 253 Yonghyeon-dong, Nam-gu, Incheon 402-751, Republic of Korea. cmlee@inha.ac.kr.

ABSTRACT
Photoluminescence measurements showed that needle-like tungsten oxide nanostructures synthesized at 590°C to 750°C by the thermal evaporation of WO3 nanopowders without the use of a catalyst had an intense near-ultraviolet (NUV) emission band that was different from that of the tungsten oxide nanostructures obtained in other temperature ranges. The intense NUV emission might be due to the localized states associated with oxygen vacancies and surface states.

No MeSH data available.


Thermal evaporation process. (a) Schematic diagram of the thermal evaporation system used to synthesize the tungsten oxide nanostructures. (b) Temperature versus substrate position showing five different substrate temperature zones.
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Figure 1: Thermal evaporation process. (a) Schematic diagram of the thermal evaporation system used to synthesize the tungsten oxide nanostructures. (b) Temperature versus substrate position showing five different substrate temperature zones.

Mentions: Tungsten oxide nanostructures were synthesized by a thermal evaporation technique without a catalyst. The thermal evaporation process was carried out in a conventional horizontal tube furnace, as shown in Figure 1. An alumina boat with a length of 4 cm and a diameter of 1.5 cm containing a mixture of WO3 and graphite powders (1:1) were placed at the center of the quartz tube, and five pieces of P-type Si(100) wafer used as substrates were placed in five different temperature zones approximately 12 cm away from the alumina boat in the downstream direction: zone 1 (450°C to 590°C), zone 2 (590°C to 750°C), zone 3 (750°C to 860°C), zone 4 (860°C to 920°C), and zone 5 (920°C to 930°C). After arranging the substrates, the tube was pumped down to 10-3 Torr using a rotary pump. High-purity nitrogen, and oxygen gases were introduced into the tube at flow rates of 200 and 5 sccm, respectively, throughout the entire synthesis process. The furnace temperature was increased to 1,050°C at a heating rate of 30°C/min. After being maintained at 1,050°C for 1 h, the furnace was cooled to room temperature, and the products were removed. During synthesis, the temperature in each of the five different zones was monitored using a thermocouple.


Intense ultraviolet emission from needle-like WO3 nanostructures synthesized by noncatalytic thermal evaporation.

Park S, Kim H, Jin C, Lee C - Nanoscale Res Lett (2011)

Thermal evaporation process. (a) Schematic diagram of the thermal evaporation system used to synthesize the tungsten oxide nanostructures. (b) Temperature versus substrate position showing five different substrate temperature zones.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211871&req=5

Figure 1: Thermal evaporation process. (a) Schematic diagram of the thermal evaporation system used to synthesize the tungsten oxide nanostructures. (b) Temperature versus substrate position showing five different substrate temperature zones.
Mentions: Tungsten oxide nanostructures were synthesized by a thermal evaporation technique without a catalyst. The thermal evaporation process was carried out in a conventional horizontal tube furnace, as shown in Figure 1. An alumina boat with a length of 4 cm and a diameter of 1.5 cm containing a mixture of WO3 and graphite powders (1:1) were placed at the center of the quartz tube, and five pieces of P-type Si(100) wafer used as substrates were placed in five different temperature zones approximately 12 cm away from the alumina boat in the downstream direction: zone 1 (450°C to 590°C), zone 2 (590°C to 750°C), zone 3 (750°C to 860°C), zone 4 (860°C to 920°C), and zone 5 (920°C to 930°C). After arranging the substrates, the tube was pumped down to 10-3 Torr using a rotary pump. High-purity nitrogen, and oxygen gases were introduced into the tube at flow rates of 200 and 5 sccm, respectively, throughout the entire synthesis process. The furnace temperature was increased to 1,050°C at a heating rate of 30°C/min. After being maintained at 1,050°C for 1 h, the furnace was cooled to room temperature, and the products were removed. During synthesis, the temperature in each of the five different zones was monitored using a thermocouple.

Bottom Line: Photoluminescence measurements showed that needle-like tungsten oxide nanostructures synthesized at 590°C to 750°C by the thermal evaporation of WO3 nanopowders without the use of a catalyst had an intense near-ultraviolet (NUV) emission band that was different from that of the tungsten oxide nanostructures obtained in other temperature ranges.The intense NUV emission might be due to the localized states associated with oxygen vacancies and surface states.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Inha University, 253 Yonghyeon-dong, Nam-gu, Incheon 402-751, Republic of Korea. cmlee@inha.ac.kr.

ABSTRACT
Photoluminescence measurements showed that needle-like tungsten oxide nanostructures synthesized at 590°C to 750°C by the thermal evaporation of WO3 nanopowders without the use of a catalyst had an intense near-ultraviolet (NUV) emission band that was different from that of the tungsten oxide nanostructures obtained in other temperature ranges. The intense NUV emission might be due to the localized states associated with oxygen vacancies and surface states.

No MeSH data available.