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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

Extinction coefficients of pure MFs and doped MFs. Extinction coefficients of pure MFs with different magnetic particle concentrations and MFs doped with 5CB as functions of magnetic induction.
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Figure 4: Extinction coefficients of pure MFs and doped MFs. Extinction coefficients of pure MFs with different magnetic particle concentrations and MFs doped with 5CB as functions of magnetic induction.

Mentions: For most practical applications to MF-based photonic devices, the values of birefringence and transmittance of the materials are two very critical parameters. Pure MFs and ferronematic materials with higher magnetic particle concentration have higher absorption, though they have a higher value of birefringence. The figure of merit of optical properties Q defined as Δn/α may be appropriate to evaluate their optical properties. The larger the value of Q is, the better the optical properties of the samples are. Though 5CB does not contribute to the birefringence, it will lessen the extinction coefficient of the sample, which will be beneficial to enhance the value of Q. To obtain the value of Q, the extinction coefficient α of the first two series of samples (Tables 1 and 2) as a function of magnetic induction are measured and shown in Figure 4. Figure 4 indicates that the extinction coefficient does not change with the field strength for a given sample. Moreover, the sample with higher volume fraction of magnetic particle has a larger extinction coefficient.


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)

Extinction coefficients of pure MFs and doped MFs. Extinction coefficients of pure MFs with different magnetic particle concentrations and MFs doped with 5CB as functions of magnetic induction.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Extinction coefficients of pure MFs and doped MFs. Extinction coefficients of pure MFs with different magnetic particle concentrations and MFs doped with 5CB as functions of magnetic induction.
Mentions: For most practical applications to MF-based photonic devices, the values of birefringence and transmittance of the materials are two very critical parameters. Pure MFs and ferronematic materials with higher magnetic particle concentration have higher absorption, though they have a higher value of birefringence. The figure of merit of optical properties Q defined as Δn/α may be appropriate to evaluate their optical properties. The larger the value of Q is, the better the optical properties of the samples are. Though 5CB does not contribute to the birefringence, it will lessen the extinction coefficient of the sample, which will be beneficial to enhance the value of Q. To obtain the value of Q, the extinction coefficient α of the first two series of samples (Tables 1 and 2) as a function of magnetic induction are measured and shown in Figure 4. Figure 4 indicates that the extinction coefficient does not change with the field strength for a given sample. Moreover, the sample with higher volume fraction of magnetic particle has a larger extinction coefficient.

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