The effect of carrier gas flow on structural and optical properties of TiO2 nanowires

Sani, S. Ramezani; Ali, A. Morteza; Jafari, Roya

doi:10.1016/j.physe.2011.06.016

Cited by 10 publications

(8 citation statements)

References 19 publications

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“…Indeed, carbon mainly was used for TiO 2 reduction. Also there are some papers that have used titanium and carbon as a source material [26,46]. Previously, TiO 2 and C as a source material were examined in our lab but NWs did not grow.…”

Section: Growth Mechanismmentioning

confidence: 99%

Effect of Argon CarriEffect of Argon Carrier Gas Flux on TiO2 Nanostructures

Dariani¹,

Qaleh²

2015

Nanoparticles Technology

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TiO 2 nanowires (NWs) have been fabricated by thermal evaporation method, using the vapor-liquid-solid (VLS) growth method and Au thin layer as a catalyst which were coated on titanium/quartz substrate. Optical and microstructure properties of TiO 2 NWs have been reviewed under different argon carrier gas flows. The gas flow was varied from 60 to 170 sccm. The X-ray diffraction patterns showed that TiO 2 NWs formed in rutile phase and their preferred orientation was in (110). The field emission scanning electron microscope figures indicated that with increasing gas flow, nanowires became thinner and longer. The absorbance curve of TiO 2 nanowires has been drawn by using spectrophotometer and their band gap was measured. Our results showed that the band gap has been enhanced in comparison with bulk one due to the quantum confinement. Also, the band gap enhanced from 3.35 to 3.45 eV by increasing the argon flow, since the wires became thinner and longer. The Williamson-Hall mechanism was applied as the vital tools for characterization of crystallite size and microstrain. Also, microstructure properties have been studied by X-ray diffraction analysis such as; dislocation density and texture coefficient. The crystallinity of TiO 2 NWs has been made better by enhancing Ar flow due to increasing of VLS growth method.

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Section: Growth Mechanismmentioning

confidence: 99%

Effect of Argon CarriEffect of Argon Carrier Gas Flux on TiO2 Nanostructures

Dariani¹,

Qaleh²

2015

Nanoparticles Technology

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“…1); in the first, (1) vapor phase method [11][12][13], besides Ti layer on substrate, another source such as Ti, TiO, and Ti:C tablet is used while in the second, (2) thermal oxidation method [14][15][16], only Ti layer on substrate is used.…”

Section: Introductionmentioning

confidence: 99%

“…The source could be obtained by a chemical reaction, say carbothermal reduction of titanium in the presence of carbon [11][12][13] or via Ti, or TiO powder evaporation [8][9][10][17][18][19][20][21]. In terms of existence or absence of catalyst, the growth mechanisms proposed for this method are in two groups: (1.1) vaporsolid (VS) (1.2) and vapor-liquid-solid (VLS).…”

Section: Introductionmentioning

confidence: 99%

“…We note that VS mechanism (1.1) is reported only at low pressure. In some other works of this method (1) [11][12][13], TiO 2 nanorod with 0.5-2.5 lm length and 40-150 nm diameter has been obtained by using vapor phase method and VLS mechanism. In VLS mechanism, Ti vapor is obtained by heating a Ti:C tablet (Ti source) at 1050°C at atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

“…In the case of 1.2.1 with Ti or TiO, the authors have reasoned that since Ti and TiO have low vapor pressure, the main source is not expected to be from vapor phase except at low pressure [17,26]. But in the case of 1.2.2 Ti:C source, they believed that due to chemical reactions between Ti and C, vapor phase Ti resulted from Ti:C tablet is the main source for growing TiO 2 nanowires [11][12][13]. Since this experiment (1.2.2), except for sources, is very similar to thermal oxidation experiment (2.1), there is some doubt about the role of vapor source.…”

Section: Introductionmentioning

confidence: 99%

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Growing TiO2 nanowires by solid–liquid–solid mechanism including two factors (Ti and O)

Pishekloo

Dariani

2016

Appl. Phys. A

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Identifying the growth factors of nanowires helps in controlling their structure and morphology and determining their optimal growth conditions. This study investigates the effect of titanium substrate in growing TiO 2 nanowires (NWs) with evaporation method. It reveals that the titanium in substrate is indeed the main source of growth. Using the substrate as the only source of growth with regulated amount of accessible oxygen in the furnace, NWs with lengths ranging from 1 to 70 lm were obtained. The results of the experiments show that the nanowires' growth is mainly controlled by diffusion of titanium atoms from the substrate through TiO 2 grain boundaries and surface diffusion toward NWs' tips rather than adsorption from vapor phase. The solid-liquid-solid mechanism including two factors (Ti and O) is proposed and discussed for growth of TiO 2 NWs.

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