To obtain high-quality homogeneous photonic glass-based structural color films over large areas, ... more To obtain high-quality homogeneous photonic glass-based structural color films over large areas, it is essential to precisely control the degree of disorder of the spherical particles used and reduce the crack density within the films as much as possible. To tailor the disorder and quality of photonic glasses, a heteroaggregation-based process was developed by employing two oppositely charged equal-sized polystyrene (PS) particle types. The influence of the particle size ratio on the extent of heteroaggregation in the suspension mixes is investigated and correlated with both the morphology and the resultant optical properties of the films. The results show that the oppositely charged particle size ratio within the mix greatly influences the assembled structure in the films, affecting their roughness, crack density, and the coffeering formation. To better differentiate the morphology of the films, scanning electron microscopy images of the microstructures were classified by a supervised training of a deep convolutional neural network model to find distinctions that are inaccessible by conventional image analysis methods. Selected compositions were then infiltrated with TiO 2 via atomic layer deposition, and after removal of the PS spheres, surface-templated inverse photonic glasses were obtained. Different color impressions and optical properties were obtained depending on the heteroaggregation level and thus the quality of the resultant films. The best results regarding the stability of the films and suppression of coffee-ring formation are obtained with a 35 wt % positively charged over negatively charged particle mix, which yielded enhanced structural coloration associated with improved film quality, tailored by the heteroaggregation fabrication process.
Photonic glass provides angle-independent, spectrally selective scattering that can be used as st... more Photonic glass provides angle-independent, spectrally selective scattering that can be used as structural colors. We show how the core-shell geometry of the particles can be used to improve the saturation of blue color.
Dopants are regularly used in sol-gel and powder metallurgy routes, however, the controlled inser... more Dopants are regularly used in sol-gel and powder metallurgy routes, however, the controlled insertion of such is quite challenging, especially in the case of nanostructures. Here we investigate the use of atomic layer deposition (ALD) as a potential technique to precisely introduce aluminum oxide as dopant or second phase into zirconia 3D macroporous nanostructures. The results show that the introduction of high Al 2 O 3 contents into the zirconia nanostructures successfully inhibited sintering when in comparison to undoped zirconia. Moreover, for the multinanolaminated and full-mix structures, the tetragonal phase was stabilized up to 1200 • C. Furthermore, the structures presented a photonic band gap even after heat treatment at 1200 • C for 2 h, enabling its application as inverse opal photonic crystals in high-temperature environments. The enhancement of thermal stability and high-temperature tetragonal phase stabilization is enabled jointly by the nanostructuring and homogeneous distribution of aluminum oxide provided by ALD super-cycles.
Structural coloration, which is based on spectrally selective scattering from optical structures,... more Structural coloration, which is based on spectrally selective scattering from optical structures, has recently attracted wide attention as a replacement of pigment colors based on the selective light absorption in chemical structures. Structural colors can be produced from transparent non-toxic materials and provide high stability under solar radiation. To provide angle independent non-iridescent colors, the structure should combine spectral selectivity with an isotropic response. Photonic glass (PhG), a disordered arrangement of monodisperse spheres, is a versatile structure to achieve that, which provides isotropic spectral selectivity via short-range order and Mie resonances. However, conventional PhGs show low color purity that hinders their future application. The interplay of single-particle scattering, short-range order, broadband absorption, and Fresnel reflection is a route to improve the color. In this perspective, we review the field of PhG based structural colors and discuss the physical mechanism behind the color generation by several established theories. We point out the current challenges in the theory and possible directions to improve color purity.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
To substitute conventional pigments, which often are toxic or suffer from fading in ultraviolet l... more To substitute conventional pigments, which often are toxic or suffer from fading in ultraviolet light, non-iridescent structural colors should demonstrate high spectral selectivity, while being also mechanically stable. However, conventional photonic glass (PhG) shows low color saturation due to the gradual transition in the reflection spectrum and low mechanical stability due to weak interparticle attachment. Here, a PhG with sharp spectral transition in comparison with the conventional full sphere PhG is designed by a conformal coating via atomic layer deposition (ALD) onto an organic PhG template. The ALD deposition allows to control the film thickness precisely for the highly saturated color. This structure can be described by hollow particle motifs with the effective size larger than the interparticle distance. Such unusual PhG is motivated by the achievable features in the spatial Fourier transform of a disordered assembly of such motifs. The surface-templated inverse PhG show...
arising from pigments originates from selective light absorption by chemical compounds. For struc... more arising from pigments originates from selective light absorption by chemical compounds. For structural colors, the light which will be reflected depends basically only on the nanostructure and the refractive index of the material which forms the nanostructure. [3] Therefore, non-absorbing structural colors are stable against UV radiation and can be fabricated from environment-friendly materials. Commercial pigments, on the contrary, are often based on toxic compounds which are sensitive to photobleaching or fade during processing at high temperatures. [4] In general, there are two types of structural colors either being iridescent or non-iridescent. [5-7] Iridescent structural colors are usually generated by socalled photonic crystals which possess a highly ordered and periodic structure. Hence, photonic crystals show short-and long-range orders. Due to the characteristic photonic bandgap and the resulting Bragg reflection, structural colors out of photonic crystals are strongly dependent on the viewing angle and also the illumination angle. [8,9] This can be a problem in applications where wide viewing angles are necessary as for alternatives for pigments. Photonic glasses (PhGs), on the other hand, are disordered structures with short-range order only and therefore the interaction with light results in non-iridescent structural color, meaning the color impression is independent from the viewing angle. [10,11] Inspired by structural colors from isotropic structures found in nature, some research groups produced structural colors based on the assembly of monodisperse polymer or silica spheres by generating structures with shortrange order. [12-16] However, these full sphere PhGs show weak spectral selectivity resulting in a low saturation of the structural colors. This observation can be explained by the Fourier transform (FT) of the disordered structure. The zero position of the motif FT of the conventional full sphere PhGs is on the right side of the main peak of the structure factor in reciprocal space resulting in a smooth spectral transition from weak to strong reflection. [17,18] As a consequence the reflected light is a mixture of colors rather than the reflection of only one selective color caused by a steep transition. Hence, full sphere PhGs exhibit low saturated structural colors or even appear white. [19] To overcome this problem, black particles like carbon black, [13,19,20] iron oxide, [21] cuttlefish ink [22] or graphene Non-iridescent structural colors can be obtained by the disordered arrangement of monodisperse spheres, a so-called photonic glass (PhG), in which the structure is designed to reflect or transmit light at specific wavelengths depending on the desired color. PhGs are possible alternatives for conventional pigments due to their wide viewing angle, stability against photobleaching, and environment-friendly fabrication. However, structural colors generated by common full-sphere PhGs reported in the literature show only low saturation. The recently developed PhG structure based on yttria-stabilized zirconia (YSZ) hollow spheres displays highly saturated blue structural color for tailored parameters. In this case, structural color originates from a sharp transition in the reflection spectrum generated by the specific design of the YSZ hollow sphere PhG fabricated via co-deposition. Here, a systematic study of the parameters resulting in highly saturated structural color, namely YSZ shell thickness, pore size, and film thickness, is presented. This work shows that by tailoring these parameters, the sharpness, spectral position, and reflectance of the transition can be tuned individually. Based on the gained knowledge, YSZ hollow sphere PhG with tailored optical properties can be easily fabricated.
Self-assembled periodic structures out of monodisperse spherical particles, so-called opals, are ... more Self-assembled periodic structures out of monodisperse spherical particles, so-called opals, are a versatile approach to obtain 3D photonic crystals. We show that a thin conformal coating of only several nanometers can completely alter the reflection properties of such an opal. Specifically, a coating with a refractive index larger than that of the spherical particles can eliminate the first photonic band gap of opals. To explain this non-intuitive effect, where a nm-scaled coating results in a drastic change of optical properties at wavelengths a hundred times bigger, we split the permittivity distribution of the opal into a lattice function convoluted with that of core-shell particles as a motif. In reciprocal space, the Bragg peaks that define the first Brillouin zone can be eliminated if the motif function, which is multiplied, assumes zero at the Bragg peak positions. Therefore, we designed a non-monotonic refractive index distribution from the center of the particle through th...
This paper was selected as Featured ARTICLES YOU MAY BE INTERESTED IN NEXAFS at nitrogen K-edge a... more This paper was selected as Featured ARTICLES YOU MAY BE INTERESTED IN NEXAFS at nitrogen K-edge and titanium Ledge using a laser-plasma soft x-ray source based on a double-stream gas puff target APL Photonics 4, 030807 (2019);
Non-iridescent structural colors based on disordered arrangement of monodisperse spherical partic... more Non-iridescent structural colors based on disordered arrangement of monodisperse spherical particles, also called photonic glass, show low color saturation due to gradual transition in the reflectivity spectrum. No significant improvement is usually expected from particles optimization, as Mie resonances are broad for small dielectric particles with moderate refractive index. Moreover, the short range order of a photonic glass alone is also insufficient to cause sharp spectral features. We show here, that the combination of a well-chosen particle geometry with the short range order of a photonic glass has strong synergetic effects. Using a first-order approximation and an Ewald sphere construction the reflectivity of such structures can be related to the Fourier transform of the permittivity distribution. The Fourier transform required for a highly saturated color can be achieved by tailoring the substructure of the motif. We show that this can be obtained by choosing core-shell par...
ABSTRACT In this work, we demonstrated the use of a promising sensor based on alumina Photonic Cr... more ABSTRACT In this work, we demonstrated the use of a promising sensor based on alumina Photonic Crystals (PC) which can be applied in the field of gas detection owing to the well structured PC with an ultra-narrow Photonic Bandgap (PBG), of which the full width at half maximum is only 30 nm. This type of PC was prepared successfully by using a compensation voltage mode method, which can effectively compensate for the chemical corrosion and the slowing down of ion exchange, resulting in a uniform diameter of the pores in the anodic alumina oxidation (AAO) from beginning to end. The as-prepared sample was applied to detect the concentration of organic vapor, such as ethanol, in this experiment. A large PBG shift is achieved when the concentration of ethanol changes, and the mechanism was also discussed theoretically. This sensor had a good repeatability due to the chemical and physical stability of the matrix material (alumina). These results indicate the potential applications of the as-prepared AAO based PC in the sensing field.
Different SrS:0.03Eu 2+ , 0.03Dy 3+ nanostructures (including nanoflower, nano hollow sphere and ... more Different SrS:0.03Eu 2+ , 0.03Dy 3+ nanostructures (including nanoflower, nano hollow sphere and rod-like porous nanostructure) were successfully synthesized by a microemulsion method together with post-annealing process. The photoluminescence and afterglow properties of these nanostructures were investigated. The evolution of morphology and the relation between morphology and the afterglow property were discussed. The results indicated that the material instable in solution could also be synthesized in nanoscale by microemulsion method together with post annealing.
published as an ASAP article. Please note that technical editing may introduce minor changes to t... more published as an ASAP article. Please note that technical editing may introduce minor changes to the manuscript text and/or graphics which may affect the content, and all legal disclaimers that apply to the journal pertain. In no event shall TUP be held responsible for errors or consequences arising from the use of any information contained in these "Just Accepted" manuscripts. To cite this manuscript please use its Digital Object Identifier (DOI®), which is identical for all formats of publication. Influences of dielectrics with light absorption on photonic bandgaps of porous alumina photonic crystals
HfGdON thin films with different N concentrations have been deposited on Si (100) substrates usin... more HfGdON thin films with different N concentrations have been deposited on Si (100) substrates using a radio frequency magnetron sputtering by changing the flow rate of N 2 during deposition. Results have indicated that N doping could partly suppress the formation of the low-k SiO x interfacial layer in the interfacial region, which induces the evolution of the composition of interfacial layer changes from SiO x to the mixture of SiO x and silicate. Reduction in band gap and valence band offset and increment in conduction band offset have been detected with the increase of N doping content. Moreover, the best electrical properties including the highest dielectric constant ($21.69), no obvious DV fb as well as the lowest leakage current density have been obtained with HfGdON films deposited at a N 2 flow rate of 7 sccm. It can be concluded that N doping content should be carefully controlled to meet the best performance requirement for future complementary metal-oxide-semiconductor device.
One-dimensional alumina photonic crystals with defect modes were successfully fabricated through ... more One-dimensional alumina photonic crystals with defect modes were successfully fabricated through inserting a constant voltage waveform into the periodic voltage signals. The transmission spectra show that the thickness of defects plays a key role in determining the transmittance of defect modes. When the thickness was ∼180 nm, an obvious defect mode with the high transmittance of 55% and a narrow full width at half maximum of 18 nm was observed in the original photonic band gaps. The defect mode shifted linearly with the increasing of refractive index of the analytes infiltrated into pores, indicating its potential application in chemical sensing or bio-sensing.
A LiTaO3 layered micro-nanostructure is fabricated and found to have potential application in the... more A LiTaO3 layered micro-nanostructure is fabricated and found to have potential application in the infrared detection field.
Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared u... more Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared using voltage compensation method. The as-prepared sample showed an ultra-narrow photonic bandgap. Asymmetric line-shape profiles of the photonic bandgaps have been observed, which is attributed to Fano resonance between the photonic bandgap state of photonic crystal and continuum scattering state of porous structure. And the exhibited Fano resonance shows more clearly when the sample is saturated ethanol gas than air-filled. Further theoretical analysis by transfer matrix method verified these results. These findings provide a better understanding on the nature of photonic bandgaps of photonic crystals made up of porous materials, in which the porous structures not only exist as layers of effective-refractive-index material providing Bragg scattering, but also provide a continuum light scattering state to interact with Bragg scattering state to show an asymmetric line-shape profile.
High-quality photonic crystals (PCs) based on the ordered pore arrays anodic alumina are fabricat... more High-quality photonic crystals (PCs) based on the ordered pore arrays anodic alumina are fabricated by the anodic oxidation method using the newly-designed periodic oxidation voltage wave. The obtained PCs own uniform narrow photonic band gaps (PBGs), steep photonic band edges, zero transmittances inside of the PBGs and high transmittances outside of the PBGs. Importantly, the high-quality PBGs of the anodic alumina PCs are tunable and controllable in the range from 350 nm to 1330 nm by modifying the anodizing voltage waveform. The benefit of newly-designed periodic oxidation voltage wave is to improve the optical properties of anodic alumina PCs.
ABSTRACT In this paper, we adopted a voltage compensation mode and prepared a porous anodic alumi... more ABSTRACT In this paper, we adopted a voltage compensation mode and prepared a porous anodic alumina oxidation template with very uniform pore diameter even when the pore length reaches to 60 mu m. This compensation voltage mode can effectively compensate the uneveness of the pore size caused by ion concentration decrease at the bottom of the pores directly involved in the anodic oxidation in the continuously growing process of holes, and the chemical corrosion effect of the pre-formed hole by electrolyte. This very uniform pore diameter alumina oxidation template will be helpful for further studies on the properties related to diameter of nanowires.
To obtain high-quality homogeneous photonic glass-based structural color films over large areas, ... more To obtain high-quality homogeneous photonic glass-based structural color films over large areas, it is essential to precisely control the degree of disorder of the spherical particles used and reduce the crack density within the films as much as possible. To tailor the disorder and quality of photonic glasses, a heteroaggregation-based process was developed by employing two oppositely charged equal-sized polystyrene (PS) particle types. The influence of the particle size ratio on the extent of heteroaggregation in the suspension mixes is investigated and correlated with both the morphology and the resultant optical properties of the films. The results show that the oppositely charged particle size ratio within the mix greatly influences the assembled structure in the films, affecting their roughness, crack density, and the coffeering formation. To better differentiate the morphology of the films, scanning electron microscopy images of the microstructures were classified by a supervised training of a deep convolutional neural network model to find distinctions that are inaccessible by conventional image analysis methods. Selected compositions were then infiltrated with TiO 2 via atomic layer deposition, and after removal of the PS spheres, surface-templated inverse photonic glasses were obtained. Different color impressions and optical properties were obtained depending on the heteroaggregation level and thus the quality of the resultant films. The best results regarding the stability of the films and suppression of coffee-ring formation are obtained with a 35 wt % positively charged over negatively charged particle mix, which yielded enhanced structural coloration associated with improved film quality, tailored by the heteroaggregation fabrication process.
Photonic glass provides angle-independent, spectrally selective scattering that can be used as st... more Photonic glass provides angle-independent, spectrally selective scattering that can be used as structural colors. We show how the core-shell geometry of the particles can be used to improve the saturation of blue color.
Dopants are regularly used in sol-gel and powder metallurgy routes, however, the controlled inser... more Dopants are regularly used in sol-gel and powder metallurgy routes, however, the controlled insertion of such is quite challenging, especially in the case of nanostructures. Here we investigate the use of atomic layer deposition (ALD) as a potential technique to precisely introduce aluminum oxide as dopant or second phase into zirconia 3D macroporous nanostructures. The results show that the introduction of high Al 2 O 3 contents into the zirconia nanostructures successfully inhibited sintering when in comparison to undoped zirconia. Moreover, for the multinanolaminated and full-mix structures, the tetragonal phase was stabilized up to 1200 • C. Furthermore, the structures presented a photonic band gap even after heat treatment at 1200 • C for 2 h, enabling its application as inverse opal photonic crystals in high-temperature environments. The enhancement of thermal stability and high-temperature tetragonal phase stabilization is enabled jointly by the nanostructuring and homogeneous distribution of aluminum oxide provided by ALD super-cycles.
Structural coloration, which is based on spectrally selective scattering from optical structures,... more Structural coloration, which is based on spectrally selective scattering from optical structures, has recently attracted wide attention as a replacement of pigment colors based on the selective light absorption in chemical structures. Structural colors can be produced from transparent non-toxic materials and provide high stability under solar radiation. To provide angle independent non-iridescent colors, the structure should combine spectral selectivity with an isotropic response. Photonic glass (PhG), a disordered arrangement of monodisperse spheres, is a versatile structure to achieve that, which provides isotropic spectral selectivity via short-range order and Mie resonances. However, conventional PhGs show low color purity that hinders their future application. The interplay of single-particle scattering, short-range order, broadband absorption, and Fresnel reflection is a route to improve the color. In this perspective, we review the field of PhG based structural colors and discuss the physical mechanism behind the color generation by several established theories. We point out the current challenges in the theory and possible directions to improve color purity.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
To substitute conventional pigments, which often are toxic or suffer from fading in ultraviolet l... more To substitute conventional pigments, which often are toxic or suffer from fading in ultraviolet light, non-iridescent structural colors should demonstrate high spectral selectivity, while being also mechanically stable. However, conventional photonic glass (PhG) shows low color saturation due to the gradual transition in the reflection spectrum and low mechanical stability due to weak interparticle attachment. Here, a PhG with sharp spectral transition in comparison with the conventional full sphere PhG is designed by a conformal coating via atomic layer deposition (ALD) onto an organic PhG template. The ALD deposition allows to control the film thickness precisely for the highly saturated color. This structure can be described by hollow particle motifs with the effective size larger than the interparticle distance. Such unusual PhG is motivated by the achievable features in the spatial Fourier transform of a disordered assembly of such motifs. The surface-templated inverse PhG show...
arising from pigments originates from selective light absorption by chemical compounds. For struc... more arising from pigments originates from selective light absorption by chemical compounds. For structural colors, the light which will be reflected depends basically only on the nanostructure and the refractive index of the material which forms the nanostructure. [3] Therefore, non-absorbing structural colors are stable against UV radiation and can be fabricated from environment-friendly materials. Commercial pigments, on the contrary, are often based on toxic compounds which are sensitive to photobleaching or fade during processing at high temperatures. [4] In general, there are two types of structural colors either being iridescent or non-iridescent. [5-7] Iridescent structural colors are usually generated by socalled photonic crystals which possess a highly ordered and periodic structure. Hence, photonic crystals show short-and long-range orders. Due to the characteristic photonic bandgap and the resulting Bragg reflection, structural colors out of photonic crystals are strongly dependent on the viewing angle and also the illumination angle. [8,9] This can be a problem in applications where wide viewing angles are necessary as for alternatives for pigments. Photonic glasses (PhGs), on the other hand, are disordered structures with short-range order only and therefore the interaction with light results in non-iridescent structural color, meaning the color impression is independent from the viewing angle. [10,11] Inspired by structural colors from isotropic structures found in nature, some research groups produced structural colors based on the assembly of monodisperse polymer or silica spheres by generating structures with shortrange order. [12-16] However, these full sphere PhGs show weak spectral selectivity resulting in a low saturation of the structural colors. This observation can be explained by the Fourier transform (FT) of the disordered structure. The zero position of the motif FT of the conventional full sphere PhGs is on the right side of the main peak of the structure factor in reciprocal space resulting in a smooth spectral transition from weak to strong reflection. [17,18] As a consequence the reflected light is a mixture of colors rather than the reflection of only one selective color caused by a steep transition. Hence, full sphere PhGs exhibit low saturated structural colors or even appear white. [19] To overcome this problem, black particles like carbon black, [13,19,20] iron oxide, [21] cuttlefish ink [22] or graphene Non-iridescent structural colors can be obtained by the disordered arrangement of monodisperse spheres, a so-called photonic glass (PhG), in which the structure is designed to reflect or transmit light at specific wavelengths depending on the desired color. PhGs are possible alternatives for conventional pigments due to their wide viewing angle, stability against photobleaching, and environment-friendly fabrication. However, structural colors generated by common full-sphere PhGs reported in the literature show only low saturation. The recently developed PhG structure based on yttria-stabilized zirconia (YSZ) hollow spheres displays highly saturated blue structural color for tailored parameters. In this case, structural color originates from a sharp transition in the reflection spectrum generated by the specific design of the YSZ hollow sphere PhG fabricated via co-deposition. Here, a systematic study of the parameters resulting in highly saturated structural color, namely YSZ shell thickness, pore size, and film thickness, is presented. This work shows that by tailoring these parameters, the sharpness, spectral position, and reflectance of the transition can be tuned individually. Based on the gained knowledge, YSZ hollow sphere PhG with tailored optical properties can be easily fabricated.
Self-assembled periodic structures out of monodisperse spherical particles, so-called opals, are ... more Self-assembled periodic structures out of monodisperse spherical particles, so-called opals, are a versatile approach to obtain 3D photonic crystals. We show that a thin conformal coating of only several nanometers can completely alter the reflection properties of such an opal. Specifically, a coating with a refractive index larger than that of the spherical particles can eliminate the first photonic band gap of opals. To explain this non-intuitive effect, where a nm-scaled coating results in a drastic change of optical properties at wavelengths a hundred times bigger, we split the permittivity distribution of the opal into a lattice function convoluted with that of core-shell particles as a motif. In reciprocal space, the Bragg peaks that define the first Brillouin zone can be eliminated if the motif function, which is multiplied, assumes zero at the Bragg peak positions. Therefore, we designed a non-monotonic refractive index distribution from the center of the particle through th...
This paper was selected as Featured ARTICLES YOU MAY BE INTERESTED IN NEXAFS at nitrogen K-edge a... more This paper was selected as Featured ARTICLES YOU MAY BE INTERESTED IN NEXAFS at nitrogen K-edge and titanium Ledge using a laser-plasma soft x-ray source based on a double-stream gas puff target APL Photonics 4, 030807 (2019);
Non-iridescent structural colors based on disordered arrangement of monodisperse spherical partic... more Non-iridescent structural colors based on disordered arrangement of monodisperse spherical particles, also called photonic glass, show low color saturation due to gradual transition in the reflectivity spectrum. No significant improvement is usually expected from particles optimization, as Mie resonances are broad for small dielectric particles with moderate refractive index. Moreover, the short range order of a photonic glass alone is also insufficient to cause sharp spectral features. We show here, that the combination of a well-chosen particle geometry with the short range order of a photonic glass has strong synergetic effects. Using a first-order approximation and an Ewald sphere construction the reflectivity of such structures can be related to the Fourier transform of the permittivity distribution. The Fourier transform required for a highly saturated color can be achieved by tailoring the substructure of the motif. We show that this can be obtained by choosing core-shell par...
ABSTRACT In this work, we demonstrated the use of a promising sensor based on alumina Photonic Cr... more ABSTRACT In this work, we demonstrated the use of a promising sensor based on alumina Photonic Crystals (PC) which can be applied in the field of gas detection owing to the well structured PC with an ultra-narrow Photonic Bandgap (PBG), of which the full width at half maximum is only 30 nm. This type of PC was prepared successfully by using a compensation voltage mode method, which can effectively compensate for the chemical corrosion and the slowing down of ion exchange, resulting in a uniform diameter of the pores in the anodic alumina oxidation (AAO) from beginning to end. The as-prepared sample was applied to detect the concentration of organic vapor, such as ethanol, in this experiment. A large PBG shift is achieved when the concentration of ethanol changes, and the mechanism was also discussed theoretically. This sensor had a good repeatability due to the chemical and physical stability of the matrix material (alumina). These results indicate the potential applications of the as-prepared AAO based PC in the sensing field.
Different SrS:0.03Eu 2+ , 0.03Dy 3+ nanostructures (including nanoflower, nano hollow sphere and ... more Different SrS:0.03Eu 2+ , 0.03Dy 3+ nanostructures (including nanoflower, nano hollow sphere and rod-like porous nanostructure) were successfully synthesized by a microemulsion method together with post-annealing process. The photoluminescence and afterglow properties of these nanostructures were investigated. The evolution of morphology and the relation between morphology and the afterglow property were discussed. The results indicated that the material instable in solution could also be synthesized in nanoscale by microemulsion method together with post annealing.
published as an ASAP article. Please note that technical editing may introduce minor changes to t... more published as an ASAP article. Please note that technical editing may introduce minor changes to the manuscript text and/or graphics which may affect the content, and all legal disclaimers that apply to the journal pertain. In no event shall TUP be held responsible for errors or consequences arising from the use of any information contained in these "Just Accepted" manuscripts. To cite this manuscript please use its Digital Object Identifier (DOI®), which is identical for all formats of publication. Influences of dielectrics with light absorption on photonic bandgaps of porous alumina photonic crystals
HfGdON thin films with different N concentrations have been deposited on Si (100) substrates usin... more HfGdON thin films with different N concentrations have been deposited on Si (100) substrates using a radio frequency magnetron sputtering by changing the flow rate of N 2 during deposition. Results have indicated that N doping could partly suppress the formation of the low-k SiO x interfacial layer in the interfacial region, which induces the evolution of the composition of interfacial layer changes from SiO x to the mixture of SiO x and silicate. Reduction in band gap and valence band offset and increment in conduction band offset have been detected with the increase of N doping content. Moreover, the best electrical properties including the highest dielectric constant ($21.69), no obvious DV fb as well as the lowest leakage current density have been obtained with HfGdON films deposited at a N 2 flow rate of 7 sccm. It can be concluded that N doping content should be carefully controlled to meet the best performance requirement for future complementary metal-oxide-semiconductor device.
One-dimensional alumina photonic crystals with defect modes were successfully fabricated through ... more One-dimensional alumina photonic crystals with defect modes were successfully fabricated through inserting a constant voltage waveform into the periodic voltage signals. The transmission spectra show that the thickness of defects plays a key role in determining the transmittance of defect modes. When the thickness was ∼180 nm, an obvious defect mode with the high transmittance of 55% and a narrow full width at half maximum of 18 nm was observed in the original photonic band gaps. The defect mode shifted linearly with the increasing of refractive index of the analytes infiltrated into pores, indicating its potential application in chemical sensing or bio-sensing.
A LiTaO3 layered micro-nanostructure is fabricated and found to have potential application in the... more A LiTaO3 layered micro-nanostructure is fabricated and found to have potential application in the infrared detection field.
Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared u... more Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared using voltage compensation method. The as-prepared sample showed an ultra-narrow photonic bandgap. Asymmetric line-shape profiles of the photonic bandgaps have been observed, which is attributed to Fano resonance between the photonic bandgap state of photonic crystal and continuum scattering state of porous structure. And the exhibited Fano resonance shows more clearly when the sample is saturated ethanol gas than air-filled. Further theoretical analysis by transfer matrix method verified these results. These findings provide a better understanding on the nature of photonic bandgaps of photonic crystals made up of porous materials, in which the porous structures not only exist as layers of effective-refractive-index material providing Bragg scattering, but also provide a continuum light scattering state to interact with Bragg scattering state to show an asymmetric line-shape profile.
High-quality photonic crystals (PCs) based on the ordered pore arrays anodic alumina are fabricat... more High-quality photonic crystals (PCs) based on the ordered pore arrays anodic alumina are fabricated by the anodic oxidation method using the newly-designed periodic oxidation voltage wave. The obtained PCs own uniform narrow photonic band gaps (PBGs), steep photonic band edges, zero transmittances inside of the PBGs and high transmittances outside of the PBGs. Importantly, the high-quality PBGs of the anodic alumina PCs are tunable and controllable in the range from 350 nm to 1330 nm by modifying the anodizing voltage waveform. The benefit of newly-designed periodic oxidation voltage wave is to improve the optical properties of anodic alumina PCs.
ABSTRACT In this paper, we adopted a voltage compensation mode and prepared a porous anodic alumi... more ABSTRACT In this paper, we adopted a voltage compensation mode and prepared a porous anodic alumina oxidation template with very uniform pore diameter even when the pore length reaches to 60 mu m. This compensation voltage mode can effectively compensate the uneveness of the pore size caused by ion concentration decrease at the bottom of the pores directly involved in the anodic oxidation in the continuously growing process of holes, and the chemical corrosion effect of the pre-formed hole by electrolyte. This very uniform pore diameter alumina oxidation template will be helpful for further studies on the properties related to diameter of nanowires.
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