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Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals.

Wang X, Pu S, Ji H, Yu G - Nanoscale Res Lett (2012)

Bottom Line: The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties.In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT.The maximum relative enhanced value of QR exceeds 6.8% in our experiments.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Science, University of Shanghai for Science and Technology, Shanghai, 200093, China. shenglipu@gmail.com.

ABSTRACT
Ferronematic materials composed of 4-cyano-4'-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δn) and figure of merit of optical properties (Q = Δn/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of QR exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field.

No MeSH data available.


Related in: MedlinePlus

Figure of merit of optical properties and the relative enhancement of theQvalue. Figure of merit of optical properties of the pure MFs and MFs doped with 5CB and the relative enhancement of Q value of the corresponding ferronematic samples as functions of magnetic induction.
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Figure 5: Figure of merit of optical properties and the relative enhancement of theQvalue. Figure of merit of optical properties of the pure MFs and MFs doped with 5CB and the relative enhancement of Q value of the corresponding ferronematic samples as functions of magnetic induction.

Mentions: The calculated value of Q of the pure MFs and their corresponding ferronematic samples as a function of magnetic induction is plotted in Figure 5. From Figure 5, we can see that the value of Q for samples a to d increases gradually with the applied magnetic field and tends to saturate at high field, while the value of Q does not vary with the magnetic particle concentration under the same field strength. This means that the magnetic particle concentration has no influence on the figure of merit of optical properties of the samples. The magnetic-field-dependent values of Q for the corresponding ferronematic samples (samples a-5CB, b-5CB, c-5CB, and d-5CB) are very similar to those of the pure MF samples. However, the ferronematic samples have larger values of Q than their corresponding pure MF samples at high field region. When doped with 5CB, the magnetic particle concentration of the ferronematic samples will reduce compared with the corresponding pure MF samples. This will result in the decrease of birefringence and the increase of transparency of the sample. The experimental results in Figure 5 indicate that the latter effect outweighs the former one at high field region. This leads to the augment of the value of Q, i.e., enhanced optical properties for the ferronematic materials at high field region. Figure 5 also implies that 5CB is crucial to the figure of merit of optical properties of the samples and that magnetic particle concentration has no influence on the figure of merit of optical properties of the samples.


Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals.

Wang X, Pu S, Ji H, Yu G - Nanoscale Res Lett (2012)

Figure of merit of optical properties and the relative enhancement of theQvalue. Figure of merit of optical properties of the pure MFs and MFs doped with 5CB and the relative enhancement of Q value of the corresponding ferronematic samples as functions of magnetic induction.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475033&req=5

Figure 5: Figure of merit of optical properties and the relative enhancement of theQvalue. Figure of merit of optical properties of the pure MFs and MFs doped with 5CB and the relative enhancement of Q value of the corresponding ferronematic samples as functions of magnetic induction.
Mentions: The calculated value of Q of the pure MFs and their corresponding ferronematic samples as a function of magnetic induction is plotted in Figure 5. From Figure 5, we can see that the value of Q for samples a to d increases gradually with the applied magnetic field and tends to saturate at high field, while the value of Q does not vary with the magnetic particle concentration under the same field strength. This means that the magnetic particle concentration has no influence on the figure of merit of optical properties of the samples. The magnetic-field-dependent values of Q for the corresponding ferronematic samples (samples a-5CB, b-5CB, c-5CB, and d-5CB) are very similar to those of the pure MF samples. However, the ferronematic samples have larger values of Q than their corresponding pure MF samples at high field region. When doped with 5CB, the magnetic particle concentration of the ferronematic samples will reduce compared with the corresponding pure MF samples. This will result in the decrease of birefringence and the increase of transparency of the sample. The experimental results in Figure 5 indicate that the latter effect outweighs the former one at high field region. This leads to the augment of the value of Q, i.e., enhanced optical properties for the ferronematic materials at high field region. Figure 5 also implies that 5CB is crucial to the figure of merit of optical properties of the samples and that magnetic particle concentration has no influence on the figure of merit of optical properties of the samples.

Bottom Line: The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties.In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT.The maximum relative enhanced value of QR exceeds 6.8% in our experiments.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Science, University of Shanghai for Science and Technology, Shanghai, 200093, China. shenglipu@gmail.com.

ABSTRACT
Ferronematic materials composed of 4-cyano-4'-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δn) and figure of merit of optical properties (Q = Δn/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of QR exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field.

No MeSH data available.


Related in: MedlinePlus