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Single-crystalline chromium silicide nanowires and their physical properties.

Hsu HF, Tsai PC, Lu KC - Nanoscale Res Lett (2015)

Bottom Line: It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere.The crystal structure and growth direction were identified, and the growth mechanism was proposed as well.This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Rd, Tainan, 701 Taiwan.

ABSTRACT
In this work, chromium disilicide nanowires were synthesized by chemical vapor deposition (CVD) processes on Si (100) substrates with hydrous chromium chloride (CrCl3 · 6H2O) as precursors. Processing parameters, including the temperature of Si (100) substrates and precursors, the gas flow rate, the heating time, and the different flow gas of reactions were varied and studied; additionally, the physical properties of the chromium disilicide nanowires were measured. It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere. The crystal structure and growth direction were identified, and the growth mechanism was proposed as well. This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

No MeSH data available.


TEM analysis of chromium silicide nanowires. (a) Low magnification, (b) high-resolution TEM images of CrSi2 nanowires grown at 700°C. The inset in (b) shows the corresponding fast Fourier transform (FFT) pattern with a zone axis of [1–10]. (c) Low magnification, (d) high-resolution TEM images of Cr5Si3 nanowires grown at 750°C. The inset in (d) shows the corresponding FFT pattern with a zone axis of [0–11].
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Fig2: TEM analysis of chromium silicide nanowires. (a) Low magnification, (b) high-resolution TEM images of CrSi2 nanowires grown at 700°C. The inset in (b) shows the corresponding fast Fourier transform (FFT) pattern with a zone axis of [1–10]. (c) Low magnification, (d) high-resolution TEM images of Cr5Si3 nanowires grown at 750°C. The inset in (d) shows the corresponding FFT pattern with a zone axis of [0–11].

Mentions: In this work, we controlled different parameters to realize how they influence the nanowires’ growth, morphology, and physical properties. With source and substrate at 700°C and the flow gas of 120 sccm, we obtained dense CrSi2 nanowires with a length of approximately 20 μm as shown in Figure 1a by chemical vapor deposition. Interestingly, in Figure 1b, the nanowires grew from the particle with almost coherent growth direction and the morphology was rare. XRD analysis in Figure 1c shows (111), (003), and (112) major plane peaks, indicating that the nanowires have a C40 hexagonal structure. The TEM image of Figure 2a shows that the nanowires are 10 to 50 nm in diameter. In Figure 2b, the high-resolution transmission electron microscopy (HRTEM) image and the corresponding fast Fourier transform (FFT) pattern in the inset identifies the materials to be single-crystal CrSi2 nanowires of a hexagonal structure with lattice constants, a = 0.4428 nm and c = 0.6369 nm (JCPDS card no. 35–0781); the growth direction is [001], and the interplanar spacing of plane (003) is 0.2098 nm. Additionally, we tried 750°C with hydrogen as reducing atmosphere and obtained Cr5Si3 nanowires of approximately 10 μm in length and of a different morphology as shown in Figure 1d. In Figure 1e, we found that the nanowires grew from nanoparticles again. XRD analysis in Figure 1f shows two phases, CrSi2 and Cr5Si3; for further investigation on the atomic structures of the nanowires, we conducted TEM analysis as shown in Figure 2. From the TEM image of Figure 2c, the nanowire was of approximately 80 nm in diameter. The HRTEM image and the corresponding FFT pattern in the inset of Figure 2d confirm that the single-crystal Cr5Si3 nanowire has a BCT D8m structure with lattice constants, a = 0.9165 nm and c = 0.4638 nm (JCPDS card no. 51–1357); also, the nanowire is with [100] growth direction, and the interplanar spacing of plane (200) is 0.4571 nm.Figure 1


Single-crystalline chromium silicide nanowires and their physical properties.

Hsu HF, Tsai PC, Lu KC - Nanoscale Res Lett (2015)

TEM analysis of chromium silicide nanowires. (a) Low magnification, (b) high-resolution TEM images of CrSi2 nanowires grown at 700°C. The inset in (b) shows the corresponding fast Fourier transform (FFT) pattern with a zone axis of [1–10]. (c) Low magnification, (d) high-resolution TEM images of Cr5Si3 nanowires grown at 750°C. The inset in (d) shows the corresponding FFT pattern with a zone axis of [0–11].
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Related In: Results  -  Collection

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Fig2: TEM analysis of chromium silicide nanowires. (a) Low magnification, (b) high-resolution TEM images of CrSi2 nanowires grown at 700°C. The inset in (b) shows the corresponding fast Fourier transform (FFT) pattern with a zone axis of [1–10]. (c) Low magnification, (d) high-resolution TEM images of Cr5Si3 nanowires grown at 750°C. The inset in (d) shows the corresponding FFT pattern with a zone axis of [0–11].
Mentions: In this work, we controlled different parameters to realize how they influence the nanowires’ growth, morphology, and physical properties. With source and substrate at 700°C and the flow gas of 120 sccm, we obtained dense CrSi2 nanowires with a length of approximately 20 μm as shown in Figure 1a by chemical vapor deposition. Interestingly, in Figure 1b, the nanowires grew from the particle with almost coherent growth direction and the morphology was rare. XRD analysis in Figure 1c shows (111), (003), and (112) major plane peaks, indicating that the nanowires have a C40 hexagonal structure. The TEM image of Figure 2a shows that the nanowires are 10 to 50 nm in diameter. In Figure 2b, the high-resolution transmission electron microscopy (HRTEM) image and the corresponding fast Fourier transform (FFT) pattern in the inset identifies the materials to be single-crystal CrSi2 nanowires of a hexagonal structure with lattice constants, a = 0.4428 nm and c = 0.6369 nm (JCPDS card no. 35–0781); the growth direction is [001], and the interplanar spacing of plane (003) is 0.2098 nm. Additionally, we tried 750°C with hydrogen as reducing atmosphere and obtained Cr5Si3 nanowires of approximately 10 μm in length and of a different morphology as shown in Figure 1d. In Figure 1e, we found that the nanowires grew from nanoparticles again. XRD analysis in Figure 1f shows two phases, CrSi2 and Cr5Si3; for further investigation on the atomic structures of the nanowires, we conducted TEM analysis as shown in Figure 2. From the TEM image of Figure 2c, the nanowire was of approximately 80 nm in diameter. The HRTEM image and the corresponding FFT pattern in the inset of Figure 2d confirm that the single-crystal Cr5Si3 nanowire has a BCT D8m structure with lattice constants, a = 0.9165 nm and c = 0.4638 nm (JCPDS card no. 51–1357); also, the nanowire is with [100] growth direction, and the interplanar spacing of plane (200) is 0.4571 nm.Figure 1

Bottom Line: It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere.The crystal structure and growth direction were identified, and the growth mechanism was proposed as well.This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Rd, Tainan, 701 Taiwan.

ABSTRACT
In this work, chromium disilicide nanowires were synthesized by chemical vapor deposition (CVD) processes on Si (100) substrates with hydrous chromium chloride (CrCl3 · 6H2O) as precursors. Processing parameters, including the temperature of Si (100) substrates and precursors, the gas flow rate, the heating time, and the different flow gas of reactions were varied and studied; additionally, the physical properties of the chromium disilicide nanowires were measured. It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere. The crystal structure and growth direction were identified, and the growth mechanism was proposed as well. This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

No MeSH data available.