Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/22—Compounds of iron
  • C09C1/24—Oxides of iron
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
  • B22F1/054—Nanosized particles
  • B22F1/0551—Flake form nanoparticles
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G49/00—Compounds of iron
  • C01G49/02—Oxides; Hydroxides
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/0081—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/06—Treatment with inorganic compounds
  • C09C3/063—Coating
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/0036—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/0036—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity
  • H01F1/0045—Zero dimensional, e.g. nanoparticles, soft nanoparticles for medical/biological use
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/012—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials adapted for magnetic entropy change by magnetocaloric effect, e.g. used as magnetic refrigerating material
  • H01F1/017—Compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
  • B22F1/054—Nanosized particles
  • B22F1/0547—Nanofibres or nanotubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y40/00—Manufacture or treatment of nanostructures
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/01—Particle morphology depicted by an image
  • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
  • C01P2004/16—Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
  • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
  • C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/70—Nanostructure
  • Y10S977/762—Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/70—Nanostructure
  • Y10S977/81—Of specified metal or metal alloy composition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/84—Manufacture, treatment, or detection of nanostructure
  • Y10S977/89—Deposition of materials, e.g. coating, cvd, or ald
  • Y10S977/892—Liquid phase deposition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/84—Manufacture, treatment, or detection of nanostructure
  • Y10S977/895—Manufacture, treatment, or detection of nanostructure having step or means utilizing chemical property
  • Y10S977/896—Chemical synthesis, e.g. chemical bonding or breaking
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S977/00—Nanotechnology
  • Y10S977/902—Specified use of nanostructure
  • Y10S977/932—Specified use of nanostructure for electronic or optoelectronic application
  • Y10S977/952—Display

Definitions

• the present invention relates to a method of forming magnetically tunable photonic crystals based on anisotropic nanostructures.
• colloidal assembly has been widely explored to produce artificial structure color by manipulating the light interaction with physical periodic structures. Easily found in nature such as opals, bird feathers and butterfly scales, structure color is brilliantly iridescent, metallic, and free from photobleaching unlike conventional pigments or dyes. Most colloidal assembly processes mimic the formation of opals and create close-packed structures from monodisperse colloidal spheres. However, living systems often involve non-close-packed ordered assemblies of anisotropic motifs such as plates and rods, thus display significantly more complex structural color responses including strong angular dependence and polarization effect.
• anisotropic particles have shape-dependent physical and chemical properties, which can add more degrees of freedom for manipulating the collective properties of the resultant superstructures. This can be of particular interest to the fabrication of field- responsive colloidal photonic structures, in which static or dynamic structural changes are usually accompanied by switching of photonic properties. Efforts along this direction, however, have been very limited, mostly due to the unavailability of high quality anisotropic building blocks and the lack of effective mechanism for assembly and tuning.
• a method is disclosed of forming magnetically tunable photonic crystals comprising: synthesizing one or more precursory nanoparticles with anisotropic shapes; coating the one or more anisotropic precursory nanoparticles with silica to form composite structures; converting the one or more anisotropic precursory nanoparticles into magnetic nanomaterials through chemical reactions; and assembling the anisotropic magnetic nanoparticles into photonic crystals in a solvent.
• the one or more anisotropic precursory nanoparticles are iron oxyhydroxide (FeOOH) nanorods.
• Figures 1 (a)-1 (c) show (a) TEM image of typical FeOOH nanorods; (b) TEM image of magnetic nanoellipsoids obtained by coating these FeOOH nanorods with silica and then reducing them in H 2 ; and (c) the corresponding magnetic hysteresis loops of the nanoellipsoids. Scale bars: 200 nm.
• Figures 2(a)-2(d) show (a) scheme for the spontaneous alignment of nanoellipsoids under magnetic fields; (b) reflection spectra of photonic structures under perpendicular and parallel magnetic fields with varying strengths; (c) reflection spectra of photonic structures under magnetic fields with varying directions with respect to the direction of light; and (d) digital photo showing the photonic response of nanoellipsoids encapsulated in a flat glass tube under a nonideal linear Halbach array. Scale bar: 5 mm.
• Figures 3(a)-3(c) show (a) reflection spectra of the colloidal dispersion of the nanoellipsoids under different volume fractions in the absence of magnetic fields; (b) digital image of the dispersion of the nanoellipsoids in a glass capillary tube with a volume fraction gradient; and (c) dependence of reflection wavelength of photonic structures on the volume fraction of the nanoellipsoids, in the presence or absence of magnetic fields.
• Figures 4(a)-4(e) show (a) TEM image of typical FeOOH nanorods; (b) TEM image of magnetic nanoellipsoids obtained by coating these FeOOH nanorods with silica and then reducing them in H 2 ; Scale bar: 200 nm; (c) reflection spectra of photonic structures under perpendicular and parallel magnetic fields with varying strengths; (d) reflection spectra of photonic structures under magnetic fields with varying directions with respect to the direction of light; and (e) Digital photo showing the photonic response of nanoellipsoids encapsulated in a flat glass tube under a nonideal linear Halbach array. (Scale bar: 5 mm).
• an assembly which benefits from a unique synthesis towards highly uniform anisotropic colloidal ellipsoids.
• uniform magnetic ellipsoids are not directly available, an indirect approach by first synthesizing uniform iron oxyhydroxide (FeOOH) nanorods ( Figure 1 (a)) was taken, then coating them with silica to form composite ellipsoids, and finally converting the FeOOH into magnetic metallic iron through reduction.
• FeOOH uniform iron oxyhydroxide
• the silica coating can play multiple important roles here.
• the silica coating increases the dimension of FeOOH nanorods to the size range suitable for creating photonic responses in the visible spectrum.
• the silica coating provides a protection mechanism that prevents the disintegration of the nanorods during reduction.
• the conversion from FeOOH to Fe involves dehydration and reduction reactions, both of which induce significant morphological changes.
• the nanorods mostly shrank and disintegrated into small pieces after reduction.
• the overall rod shape however was well retained thanks to the ellipsoidal space created within the silica shells.
• the silica layer acts as a spacer that separates the magnetic nanorods by certain distance and limits their magnetic attraction, therefore preventing their colloidal dispersion from aggregation despite the ferromagnetic nature of the nanorods.
• a unique feature of the anisotropic nanoellipsoids is that their assemblies show strong dependence of photonic response on the field direction.
• orientational order In addition to the positional order that is usually considered for describing assemblies from spherical building blocks, one should take orientational order into account when nanoellipsoids are assembled.
• the orientation of nanoellipsoids can be easily controlled by external magnetic fields.
• nanoellipsoids rotate and align their long axis parallel to the field direction, as schematically shown in Figure 2(a).
• Such rotation not only gives rise to changes in orientational orders, but also affects positional orders and subsequently photonic properties of the assemblies.
• the field strength is also believed to play an important role in the perfection of ordering since it determines to what degree the nanoellipsoids can align.
• FIG. 1 shows the photonic property of structures assembled from nanoellipsoids, under magnetic fields with varying strengths and directions.
• Aqueous dispersions of nanoellipsoids were concentrated to a desired volume fraction to allow their spontaneous ordering into colloidal crystals.
• Figure 2(b) shows the reflection spectra of photonic structures under magnetic fields parallel and perpendicular to the direction of incident light.
• a magnetic field perpendicular to the light aligns nanoellipsoids to the perpendicular orientation as well so that the interplanar spacing is mainly determined by the short axis of nanoellipsoids, resulting in a reflection peak at shorter wavelength.
• the interplanar spacing is determined by the long axis of nanoellipsoids, accounting for a reflection peak at longer wavelength.
• the field strength is found to influence the intensity of reflectance rather than the wavelength, for both samples.
• the increased reflectance intensity is believed to result from the better orientational order of the nanoellipsoids under stronger fields: because of the limited amount of magnetic species embedded inside them, the rotation of nanoellipsoids requires a sufficiently high magnetic field to allow the magnetic torque to overcome the rotational resistance.
• the field direction is fixed, varying the field strength does not alter the reflection wavelength.
• the contribution of the magnetic interactions between nanoellipsoids to the interplanar spacing of the assemblies seems to be negligible, mainly owing to the effective separation of the magnetic nanorods by relatively thick silica coating.
• tuning field direction results in simultaneous rotation of nanoellipsoids, which further leads to changes in the interplanar spacing of the assemblies as well as their photonic properties.
• the photonic property of structures assembled from nanoellipsoids were investigated under a rotating magnetic field. As shown in Figure 2(c), the wavelength of reflectance peak reaches a minimum value when the field direction is perpendicular to the incident light, and gradually red shifts as the field switches from perpendicular to parallel to the incident light.
• Such shift in reflection wavelengths responds to the change of field direction immediately (within less than a second) and is fully reversible.
• a notable feature of such magnetic tuning is that the maximum intensity is achieved at the two end points when the magnetic fields are either parallel or perpendicular to the incident light. When the field direction is switched away from these two end points, the relative intensity decreases and reaches a minimum at the middle point ( ⁇ 45° from the parallel and
• the orientational dependence of the nanoellipsoidal assemblies can find direct use in creating photonic patterns under magnetic fields with inuniform field directions.
• Figure 2(d) when subjected to complex magnetic field produced by a nonideal linear Halbach array, which has a spatially rotating pattern of magnetisation, a dispersion of nanoellipsoids encapsulated in a flat glass tube exhibits a colorful pattern containing blue and green stripes.
• the interplanar spacing of the photonic assemblies is also determined by the volume fractions of the nanoellipsoids. As the volume fraction decreases, the distance between nanoellipsoids increases, resulting in the expansion of crystal lattice as well as red-shift of reflection wavelength. In the absence of magnetic fields, the reflection spectra of photonic assemblies under different volume fractions were recorded and then exhibited in Figure 3(a). The reflection peak shifted from 425 nm to 660 nm, as the volume fractions decreased from 32% to 10%. Consistently, a rainbow-like color effect was observed in Figure 3(b) in the dispersion of nanoellipsoids with a volume fraction gradient, which was achieved by centrifugation at 3000 rpm for 5 min.
• the enhanced orientational order can be explained by the reduced excluded volume of each nanoellipsoid at a higher volume fraction.
• the nanoellipsoids decreased orientational entropy but increased translational entropy to reach an energetically favorable structure, in which most of nanoellipsoids align parallel.
• a new class of magnetically responsive photonic crystals are disclosed whose diffraction property can be widely tuned by controlling the field direction.
• the novel colloidal crystals assembled from highly uniform shape- and magnetically anisotropic nanoellipsoids diffract at a minimum wavelength when the field direction is perpendicular to the incident angle and a maximum wavelength when the field is switched to parallel.
• the diffraction intensity reaches maximum values when the field is either parallel or perpendicular to the incident light, and decreases when the field direction is switched off-angle, displaying a unique U-shaped profile in reflectance peaks.
• the shift in diffraction in response to the change in field direction is instantaneous and fully reversible.
• the current system not only allows more opportunities in studying the assembly behavior of shape- and magnetically anisotropic nanostructures but also provides a new platform for building novel active optical components for various color presentation and display applications.
• the starting materials are not limited to FeOOH nanorods, and can be extended to other metal hydroxides, for example, Co(OH) 2 , Ni(OH) 2 and Fe(OH) 3 .
• the morphology of nanoparticles is not limited to ellipsoid, and can be extended to rods, plates, oblate spheroid, et al.
• the solvent for assembling nanoparticles into photonic structures can be but not limited to water, ethanol, glycol, and other polar or nonpolar solvents. A typical route for making nanoellipsoids- based photonic structures is listed below:
• the process started with the synthesis of FeOOH nanorods.
• FeCI 3 -6H 2 O was dissolved in 40 mL of deionized water and the concentration of Fe 3+ was adjusted to 0.02 M.
• the undissolved precipitates were discarded after centrifugation at 1 1000 rpm for 3 minutes.
• the supernatant was added to a three- neck flask and heated at 81 °C under magnetic stirring for 12 hrs. The particles were then isolated by centrifugation, washed with water for several times, and dispersed in 7.2 mL of water.
• a 3 mL aqueous dispersion of PAA-modified FeOOH was added into 20 mL of isopropanol, followed by the addition of 1 mL of ammonium hydroxide (-28% wt).
• 1 mL of ammonium hydroxide 28% wt.
• 400 ⁇ _ of tetraethyl orthosilicate (TEOS) was added into the above mixture in every 30 minutes until the total amount of TEOS reached 2.4 mL.
• TEOS tetraethyl orthosilicate
• the FeOOH@Si0 2 nanoellipsoids was heated to 500 °C under N 2 protection, and then reduced at this temperature for 2 hours by pure H 2 to produce the Fe@Si0 2 nanoellipsoids.
• nanoellipsoids were redispersed in water by sonication for 30 minutes
• the dispersion was added to a three-neck flask and refluxed at 100 °C for 2 hours.
• the nanoellipsoids were isolated by centrifugation and washed by water for several times. Size selection was then applied and non-dispersible aggregates were discarded by centrifugation at 2000 rpm for 2 minutes.
• the dispersions of nanoellipsoids were first concentrated to the maximum volume fraction beyond which aggregations will form, and a certain amount of water was then added into the dispersions to produce the desired concentration.
• Nanoellipsoids with higher aspect ratio can also be synthesized.
• FeCI 3 -6H 2 O was dissolved in 40 mL of deionized water and the concentration of Fe 3+ was adjusted to 0.1 M. 1g of CTAB was added into the solution. The undissolved precipitates were discarded after centrifugation at 1000 rpm for 3 minutes. The supernatant was added to a three- neck flask and heated at 90 °C under magnetic stirring for 18 hours. The particles were then isolated by centrifugation, washed with water for several times, and dispersed in 36 mL of water.
• the as-synthesized FeOOH nanorods were modified with PAA by the similar procedure.
• 200 pL of TEOS was added into the above mixture in every 30 minutes until the total amount of TEOS reached 1 .2 mL.
• the FeOOH@SiO 2 nanoellipsoids were isolated by centrifugation, washed with ethanol and water for several times, and dispersed in ethanol.
• the nanoellipsoids were reduced by H 2 , redispersed in water, and assembled into photonic structures.
• the as-assembled photonic structures also show angular-dependence property, and exhibit rainbow-like patterns when they are placed on a nonideal linear Halbach array.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Organic Chemistry (AREA)
• Power Engineering (AREA)
• Nanotechnology (AREA)
• Manufacturing & Machinery (AREA)
• Health & Medical Sciences (AREA)
• Composite Materials (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biomedical Technology (AREA)
• General Health & Medical Sciences (AREA)
• Molecular Biology (AREA)
• Compounds Of Iron (AREA)
• Silicon Compounds (AREA)
• Hard Magnetic Materials (AREA)
• Pigments, Carbon Blacks, Or Wood Stains (AREA)
• Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=57199401

Family Applications (1)

Country Status (6)

Cited By (3)

Families Citing this family (5)

Citations (10)

Family Cites Families (7)

• 2016
  • 2016-04-27 WO PCT/US2016/029461 patent/WO2016176267A1/en not_active Ceased
  • 2016-04-27 US US15/569,912 patent/US10796849B2/en active Active
  • 2016-04-27 JP JP2017556563A patent/JP6776267B2/ja active Active
  • 2016-04-27 CN CN202010780714.4A patent/CN111899973B/zh active Active
  • 2016-04-27 KR KR1020177033757A patent/KR102566859B1/ko active Active
  • 2016-04-27 CN CN201680037841.7A patent/CN107710350B/zh active Active
  • 2016-04-27 EP EP16787025.2A patent/EP3289596A4/en active Pending

Patent Citations (10)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events