A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups,3,3'-dimethyl-4,4'-diaminophenyl-3",5"-di-tert-butyltoluene,was successfully synthesized by a simple coupling reac...A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups,3,3'-dimethyl-4,4'-diaminophenyl-3",5"-di-tert-butyltoluene,was successfully synthesized by a simple coupling reaction using 3,5-di-tert-butylbenzaldehyde and o-toluidine as starting materials.A series of novel polyimides(PI 3a-3c)with large pendant groups were prepared with the obtained diamine monomer and three different commercial aromatic dianhydrides(3,3',4,4'-biphenyltetracarboxylic dianhydride,4,4'-oxydiphthalic anhydride,and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride)by one-step high temperature polycondensation.The prepared polyimides exhibited high solubility and good membrane forming ability:they could be dissolved not only in some high boiling solvents such as DMF,NMP,DMAc,and m-Cresol at room temperature,but also in some low boiling solvents such as CHCl3,CH2Cl2,and THF.Their solubility in most solvents could exceed 10 wt%,and the flexible membranes could be obtained by casting their solutions.The prepared membranes exhibited good gas separation properties.The permeability coefficients of PI 3c for CO2 and O2 were up to 124.6 and 42.8 barrer,respectively,and the selectivity coefficients for CO2/CH4 and O2/N2 were 14.7 and 3.3,respectively.The membranes had light color and good optical transmission.Their optical transmittance at 450 nm wavelength was in the range of 67%-79%,and the cutoff wavelength was in the range of 310-348 nm.They also had good thermal properties with glass transition temperature(Tg)values in the range of 264-302℃.In addition,these membranes possessed good mechanical properties with tensile strength ranging between 77.8-87.4 MPa,initial modulus ranging between 1.69-1.82 GPa,and elongation at break ranging between 4.8%-6.1%.展开更多
Transparent conductive cadmium indium oxide films (CdIn2O4) were prepared by r.f. reactive sputtering from Cd-In alloy targets under an Ar-O2 atmosphere. Electrical conductivity of the order of 105Ω-1.m-1 and the opt...Transparent conductive cadmium indium oxide films (CdIn2O4) were prepared by r.f. reactive sputtering from Cd-In alloy targets under an Ar-O2 atmosphere. Electrical conductivity of the order of 105Ω-1.m-1 and the optical transmission as high as 94% are easily attained by postdeposition annealing treatment. The effects of oxygen concentration in the reactive gas mixture and post-deposition annealing treatment on the optical transmittance as well as optical parameters, such as refractive index (n), extinction coefficient (k), real part (ε’) and imaginary part (ε") of the dielectric constant, were studied in the visible and near-infrared region. The highfrequency dielectric constant ε∞ the plasma frequency ωP, and the conduction band effective mass mc of different samples were also展开更多
Transparent microwave absorbers that exhibit high optical transmittance and microwave absorption capability are ideal,although having a fixed absorption performance limits their applicability.Here,a simple,transparent...Transparent microwave absorbers that exhibit high optical transmittance and microwave absorption capability are ideal,although having a fixed absorption performance limits their applicability.Here,a simple,transparent,and thermally tunable microwave absorber is proposed,based on a patterned vanadium dioxide(VO_(2))film.Numerical calculations and experiments demonstrate that the proposed VO_(2)absorber has a high optical transmittance of 84.9%at 620 nm;its reflection loss at 15.06 GHz can be thermally tuned from–4.257 to–60.179 dB,and near-unity absorption is achieved at 523.750 K.Adjusting only the patterned VO_(2)film duty cycle can change the temperature of near-unity absorption.Our VO_(2)absorber has a simple composition,a high optical transmittance,a thermally tunable microwave absorption performance,a large modulation depth,and an adjustable temperature tuning range,making it promising for application in tunable sensors,thermal emitters,modulators,thermal imaging,bolometers,and photovoltaic devices.展开更多
Reconfigurable intelligent surfaces(RISs)have aroused extensive attentions from academic and wireless communication communities due to their abilities to customize the electromagnetic(EM)characteristics of the propaga...Reconfigurable intelligent surfaces(RISs)have aroused extensive attentions from academic and wireless communication communities due to their abilities to customize the electromagnetic(EM)characteristics of the propagation channels flexibly and rapidly.Recent advances in theoretical innovations and prototype systems have demonstrated the advantages of RISs in terms of low cost,low power consumption,and easy deployment.Meanwhile,the optically transparent RISs are demanded in some application scenarios.In this paper,we propose a 2-bit metalmesh-based RIS with high optical-transparency.By analyzing the surface current distributions on the element,we employ the metalmesh-grid patterns and metalmesh-stripe patterns on the top and ground layers respectively.The metalmesh patterns can help improve the optical transparency of RISs,while maintaining similar microwave characteristics.The RIS can reach the optical transparency of 79%,and the reflection amplitude is greater than3.2 dB within the operating band.Finally,to verify the capability of the proposed RIS in wavefront controls,the far-field scattering patterns of the RIS with different coding sequences are investigated and the simulation results are in good agreement with the theoretical results.展开更多
The performances of two microstrip patch antennas with low visual impact are presented in this paper and compared to an opaque solution. These consist in a copper film deposited on a Borofloat 33 glass substrate throu...The performances of two microstrip patch antennas with low visual impact are presented in this paper and compared to an opaque solution. These consist in a copper film deposited on a Borofloat 33 glass substrate through a thin titanium gripping layer. The mesh is obtained by wet chemical etching. Antennas differ by the dimensions in the ground plane mesh pattern. The opaque antenna only consists of a full copper deposit. The transparency work was mainly carried out on the ground plane as it is the largest area available. Specific attention is paid to optical transparency in the visible light spectrum, sheet resistance and electromagnetic performances in the [2.8;3 GHz] bandwidth. They are measured in each case, compared and discussed. Both simulations and measurement results show good performance, especially the antenna with the most transparent ground plane: a high level of optical transparency of almost 73%, coupled with a sheet resistance of less than 0.028 Ohms/sq and a gain of about 3.22 dBi at 2.8 GHz, slightly higher than the gain of the reference opaque antenna of about 2.66 dBi at 2.99 GHz. The opaque reference antenna has a bandwidth of 1.30 GHz while those of the transparent antennas are about 1.60 GHz and 2.10 GHz (S<sub>11</sub> < −10 dB). This solution presents a real interest for low cost integrated and discrete antenna solutions in ISM band.展开更多
A visible transparent metamaterial absorber was designed and fabricated with ultrabroadband microwave absorption and low infrared emissivity to meet the increasing demand for multispectral compatible camouflage. The a...A visible transparent metamaterial absorber was designed and fabricated with ultrabroadband microwave absorption and low infrared emissivity to meet the increasing demand for multispectral compatible camouflage. The absorber was fabricated with a low-infrared emissive layer at the top, a microwave-absorbing layer in the middle, and a reflective layer at the bottom, which were separated by polymethyl methacrylate plates. The absorber showed an average visible transmittance of 55%, infrared emissivity of ~0.37, and effective microwave absorption bandwidth of 32.1 GHz with a total thickness of 3.0 mm. Furthermore,microwave absorption exhibited wide-angle stability and polarization insensitivity characteristics. The mechanism of microwave attenuation was further explored through effective electromagnetic parameters as well as surface current, electric field, magnetic field, and energy loss density distributions. The experimental results were consistent with those of the simulations and calculations, indicating the potential of the designed metamaterial absorber for future applications in multispectral compatible camouflage.展开更多
A family of new triphenylmethane(TPM)-based polyimides(PIs)containing bulky tert-butyldimethylsiloxy(TBS)side-groups(PI-TPMOSis)has been prepared by a post-polymerization modification via a simple silyl ether reaction...A family of new triphenylmethane(TPM)-based polyimides(PIs)containing bulky tert-butyldimethylsiloxy(TBS)side-groups(PI-TPMOSis)has been prepared by a post-polymerization modification via a simple silyl ether reaction of TPM-based PIs containing hydroxyl(OH)groups(PI-TPMOHs).The attachment of TBS side-groups in PI-TPMOSis can be achieved up to 100%,as confirmed by the 1H-NMR and IR spectra.Due to the presence of the TPM structure,PI-TPMOSi films still display the excellent thermal stability with high glass transition temperature(Tg)of 314–351°C and high degradation temperature(Td5%)of 480–501°C.It is quite remarkable that the introduction of TBS side-groups into PI-TPMOSi chains results in more superior optical,dielectric and solubility properties in comparison with the precursor PI-TPMOH films,probably due to the reductions of the packing density and charge-transfer complexes(CTCs)formation.The optical transmittance at 400 nm(T400)of PI-TPMOSi films is significantly increased from 45.3%–68.8%to 75.4%–81.6%of the precursor PI-TPMOH films.The dielectric constant(Dk)and dissipation factor(Df)at 1 MHz of PI-TPMOSi films are reduced from 4.11–4.40 and 0.00159–0.00235 to 2.61–2.92 and 0.00125–0.00171 of the precursor PI-TPMOH films,respectively.Combining the molecular design and simple preparation method,this study provides an effective approach for enhancement of various properties of PI films for microelectronic and photoelectric engineering applications.展开更多
A novel hybrid material prepared from graphene and poly(3,4-ethyldioxythiophene)(PEDOT)shows excellent transparency,electrical conductivity,and good flexibility,together with high thermal stability and is easily proce...A novel hybrid material prepared from graphene and poly(3,4-ethyldioxythiophene)(PEDOT)shows excellent transparency,electrical conductivity,and good flexibility,together with high thermal stability and is easily processed in both water and organic solvents.Conductivities of the order of 0.2 S/cm and light transmittance of greater than 80%in the 4001800 nm wavelength range were observed for fi lms with thickness of tens of nm.Practical applications in a variety of optoelectronic devices are thus expected for this transparent and flexible conducting graphene-based hybrid material。展开更多
In this study,the optical properties of transparent bioplastics have been investigated.The long-term technological goal is to establish biopolymers in a new market segment for demanding optical applications and to con...In this study,the optical properties of transparent bioplastics have been investigated.The long-term technological goal is to establish biopolymers in a new market segment for demanding optical applications and to contribute to a more sustainable economy.A collection of transparent bioplastics has been tested with respect to the long-term stability and the possibility of an application in optical components for LED lighting.The focus of materials testing was on the influence of short wavelength visible radiation as well as thermal loads.The results show,that some materials may be candidates for subsequent feasibility studies.To the best of our knowledge,the application of such polymers in complex technical products and in particular in luminaires has not yet been realized.The use of bio-based plastics for optical components therefore represents a novelty and has a high development potential.展开更多
This paper discusses a 40-Gbit/s transparent optical network focusing on the optical transport performance. We show 1200-km transmission with two WSOXC' sspaced by 400 km. In addition, network control issues are b...This paper discusses a 40-Gbit/s transparent optical network focusing on the optical transport performance. We show 1200-km transmission with two WSOXC' sspaced by 400 km. In addition, network control issues are briefly addressed.展开更多
Fine grained 8 mol%yttria-stabilized zirconia(8YSZ)transparent ceramics with high optical and mechanical properties were fabricated by air pre-sintering and hot isostatic pressing(HIP)using commercial 8YSZ powders as ...Fine grained 8 mol%yttria-stabilized zirconia(8YSZ)transparent ceramics with high optical and mechanical properties were fabricated by air pre-sintering and hot isostatic pressing(HIP)using commercial 8YSZ powders as the raw material.The pre-sintered ceramics with fine grains and appropriate relative density play a key role to achieve high transparency and suppressed grain size after HIP post-treatment at relatively low temperatures.With the increase of HIP temperature from 1350 to 1550℃,the in-line transmittance of 8YSZ ceramics at 600 nm increases from 56.9%to 71.5%(2.5 mm in thickness),and the average grain size increases from 2.4 to 16.3μm.The corresponding bending strength of 8YSZ transparent ceramics decreases from 328±20 to 289±19 MPa,the hardness(H)decreases from 12.9±0.1 to 12.5±0.2 GPa,and the fracture toughness(KIC)decreases from 1.30±0.02 to 1.26±0.03 MPa·m^(1/2).Systematical investigations were carried out to study the combination of high optical transparency and excellent mechanical properties in 8YSZ ceramics.展开更多
基金This work was finanially supported by the Key Research Project of Jiangsu Province(No.BE2017645)Scientifc Research and Innovation Project for Graduate Students in Jiangsu Province(No.KYCX19-1757)。and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China。
文摘A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups,3,3'-dimethyl-4,4'-diaminophenyl-3",5"-di-tert-butyltoluene,was successfully synthesized by a simple coupling reaction using 3,5-di-tert-butylbenzaldehyde and o-toluidine as starting materials.A series of novel polyimides(PI 3a-3c)with large pendant groups were prepared with the obtained diamine monomer and three different commercial aromatic dianhydrides(3,3',4,4'-biphenyltetracarboxylic dianhydride,4,4'-oxydiphthalic anhydride,and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride)by one-step high temperature polycondensation.The prepared polyimides exhibited high solubility and good membrane forming ability:they could be dissolved not only in some high boiling solvents such as DMF,NMP,DMAc,and m-Cresol at room temperature,but also in some low boiling solvents such as CHCl3,CH2Cl2,and THF.Their solubility in most solvents could exceed 10 wt%,and the flexible membranes could be obtained by casting their solutions.The prepared membranes exhibited good gas separation properties.The permeability coefficients of PI 3c for CO2 and O2 were up to 124.6 and 42.8 barrer,respectively,and the selectivity coefficients for CO2/CH4 and O2/N2 were 14.7 and 3.3,respectively.The membranes had light color and good optical transmission.Their optical transmittance at 450 nm wavelength was in the range of 67%-79%,and the cutoff wavelength was in the range of 310-348 nm.They also had good thermal properties with glass transition temperature(Tg)values in the range of 264-302℃.In addition,these membranes possessed good mechanical properties with tensile strength ranging between 77.8-87.4 MPa,initial modulus ranging between 1.69-1.82 GPa,and elongation at break ranging between 4.8%-6.1%.
文摘Transparent conductive cadmium indium oxide films (CdIn2O4) were prepared by r.f. reactive sputtering from Cd-In alloy targets under an Ar-O2 atmosphere. Electrical conductivity of the order of 105Ω-1.m-1 and the optical transmission as high as 94% are easily attained by postdeposition annealing treatment. The effects of oxygen concentration in the reactive gas mixture and post-deposition annealing treatment on the optical transmittance as well as optical parameters, such as refractive index (n), extinction coefficient (k), real part (ε’) and imaginary part (ε") of the dielectric constant, were studied in the visible and near-infrared region. The highfrequency dielectric constant ε∞ the plasma frequency ωP, and the conduction band effective mass mc of different samples were also
基金support from the National Natural Science Foundation of China(61975046)。
文摘Transparent microwave absorbers that exhibit high optical transmittance and microwave absorption capability are ideal,although having a fixed absorption performance limits their applicability.Here,a simple,transparent,and thermally tunable microwave absorber is proposed,based on a patterned vanadium dioxide(VO_(2))film.Numerical calculations and experiments demonstrate that the proposed VO_(2)absorber has a high optical transmittance of 84.9%at 620 nm;its reflection loss at 15.06 GHz can be thermally tuned from–4.257 to–60.179 dB,and near-unity absorption is achieved at 523.750 K.Adjusting only the patterned VO_(2)film duty cycle can change the temperature of near-unity absorption.Our VO_(2)absorber has a simple composition,a high optical transmittance,a thermally tunable microwave absorption performance,a large modulation depth,and an adjustable temperature tuning range,making it promising for application in tunable sensors,thermal emitters,modulators,thermal imaging,bolometers,and photovoltaic devices.
基金supported by the Program of Song Shan Laboratory(included in the management of Major Science and Technology Program of Henan Province)(221100211300-02)the National Key Research and Development Program of China(2017YFA0700201,2017YFA0700202,2017YFA0700203,2018YFA0701904)+5 种基金the National Natural Science Foundation of China(62288101,61731010)the 111 Project(111-2-05)the Jiangsu Province Frontier Leading Technology Basic Research Project(BK20212002)the Fundamental Research Funds for the Central Universities(2242022k30004)the National Science Foundation for Distinguished Young Scholars of China(62225108)the Southeast University-China Mobile Research Institute Joint Innovation Center(R207010101125D9).
文摘Reconfigurable intelligent surfaces(RISs)have aroused extensive attentions from academic and wireless communication communities due to their abilities to customize the electromagnetic(EM)characteristics of the propagation channels flexibly and rapidly.Recent advances in theoretical innovations and prototype systems have demonstrated the advantages of RISs in terms of low cost,low power consumption,and easy deployment.Meanwhile,the optically transparent RISs are demanded in some application scenarios.In this paper,we propose a 2-bit metalmesh-based RIS with high optical-transparency.By analyzing the surface current distributions on the element,we employ the metalmesh-grid patterns and metalmesh-stripe patterns on the top and ground layers respectively.The metalmesh patterns can help improve the optical transparency of RISs,while maintaining similar microwave characteristics.The RIS can reach the optical transparency of 79%,and the reflection amplitude is greater than3.2 dB within the operating band.Finally,to verify the capability of the proposed RIS in wavefront controls,the far-field scattering patterns of the RIS with different coding sequences are investigated and the simulation results are in good agreement with the theoretical results.
文摘The performances of two microstrip patch antennas with low visual impact are presented in this paper and compared to an opaque solution. These consist in a copper film deposited on a Borofloat 33 glass substrate through a thin titanium gripping layer. The mesh is obtained by wet chemical etching. Antennas differ by the dimensions in the ground plane mesh pattern. The opaque antenna only consists of a full copper deposit. The transparency work was mainly carried out on the ground plane as it is the largest area available. Specific attention is paid to optical transparency in the visible light spectrum, sheet resistance and electromagnetic performances in the [2.8;3 GHz] bandwidth. They are measured in each case, compared and discussed. Both simulations and measurement results show good performance, especially the antenna with the most transparent ground plane: a high level of optical transparency of almost 73%, coupled with a sheet resistance of less than 0.028 Ohms/sq and a gain of about 3.22 dBi at 2.8 GHz, slightly higher than the gain of the reference opaque antenna of about 2.66 dBi at 2.99 GHz. The opaque reference antenna has a bandwidth of 1.30 GHz while those of the transparent antennas are about 1.60 GHz and 2.10 GHz (S<sub>11</sub> < −10 dB). This solution presents a real interest for low cost integrated and discrete antenna solutions in ISM band.
文摘A visible transparent metamaterial absorber was designed and fabricated with ultrabroadband microwave absorption and low infrared emissivity to meet the increasing demand for multispectral compatible camouflage. The absorber was fabricated with a low-infrared emissive layer at the top, a microwave-absorbing layer in the middle, and a reflective layer at the bottom, which were separated by polymethyl methacrylate plates. The absorber showed an average visible transmittance of 55%, infrared emissivity of ~0.37, and effective microwave absorption bandwidth of 32.1 GHz with a total thickness of 3.0 mm. Furthermore,microwave absorption exhibited wide-angle stability and polarization insensitivity characteristics. The mechanism of microwave attenuation was further explored through effective electromagnetic parameters as well as surface current, electric field, magnetic field, and energy loss density distributions. The experimental results were consistent with those of the simulations and calculations, indicating the potential of the designed metamaterial absorber for future applications in multispectral compatible camouflage.
基金supported by the National Natural Science Foundation of China(Nos.52203014,52103010 and 52003200)the Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110767,2022A1515010969,2020A1515110897 and 2023A1515010999)+2 种基金the Open Fund for Key Lab of Guangdong High Property and Functional Macromolecular Materials,China(No.20220601)Guangdong Provincial Department of Education Featured Innovation Project(No.2021KTSCX138)the Science Foundation for Young Research Groups of Wuyi University(Nos.2020AL016 and 2019AL019).
文摘A family of new triphenylmethane(TPM)-based polyimides(PIs)containing bulky tert-butyldimethylsiloxy(TBS)side-groups(PI-TPMOSis)has been prepared by a post-polymerization modification via a simple silyl ether reaction of TPM-based PIs containing hydroxyl(OH)groups(PI-TPMOHs).The attachment of TBS side-groups in PI-TPMOSis can be achieved up to 100%,as confirmed by the 1H-NMR and IR spectra.Due to the presence of the TPM structure,PI-TPMOSi films still display the excellent thermal stability with high glass transition temperature(Tg)of 314–351°C and high degradation temperature(Td5%)of 480–501°C.It is quite remarkable that the introduction of TBS side-groups into PI-TPMOSi chains results in more superior optical,dielectric and solubility properties in comparison with the precursor PI-TPMOH films,probably due to the reductions of the packing density and charge-transfer complexes(CTCs)formation.The optical transmittance at 400 nm(T400)of PI-TPMOSi films is significantly increased from 45.3%–68.8%to 75.4%–81.6%of the precursor PI-TPMOH films.The dielectric constant(Dk)and dissipation factor(Df)at 1 MHz of PI-TPMOSi films are reduced from 4.11–4.40 and 0.00159–0.00235 to 2.61–2.92 and 0.00125–0.00171 of the precursor PI-TPMOH films,respectively.Combining the molecular design and simple preparation method,this study provides an effective approach for enhancement of various properties of PI films for microelectronic and photoelectric engineering applications.
基金the financial support from the Natural Science Foundation of china(NSFC)(#20774047)the Ministry of Science and Techology of china(MoST)(#2006CB932702)natural Science Foundation(NSF)of Tianjin City(#07JCYBJC03000,#08JCZDJC25300).
文摘A novel hybrid material prepared from graphene and poly(3,4-ethyldioxythiophene)(PEDOT)shows excellent transparency,electrical conductivity,and good flexibility,together with high thermal stability and is easily processed in both water and organic solvents.Conductivities of the order of 0.2 S/cm and light transmittance of greater than 80%in the 4001800 nm wavelength range were observed for fi lms with thickness of tens of nm.Practical applications in a variety of optoelectronic devices are thus expected for this transparent and flexible conducting graphene-based hybrid material。
基金This research was part of the BMBF funded project NAROK(project grant 031B062)。
文摘In this study,the optical properties of transparent bioplastics have been investigated.The long-term technological goal is to establish biopolymers in a new market segment for demanding optical applications and to contribute to a more sustainable economy.A collection of transparent bioplastics has been tested with respect to the long-term stability and the possibility of an application in optical components for LED lighting.The focus of materials testing was on the influence of short wavelength visible radiation as well as thermal loads.The results show,that some materials may be candidates for subsequent feasibility studies.To the best of our knowledge,the application of such polymers in complex technical products and in particular in luminaires has not yet been realized.The use of bio-based plastics for optical components therefore represents a novelty and has a high development potential.
文摘This paper discusses a 40-Gbit/s transparent optical network focusing on the optical transport performance. We show 1200-km transmission with two WSOXC' sspaced by 400 km. In addition, network control issues are briefly addressed.
基金This work was supported by the National Key R&D Program of China(Grant No.2021YFE0104800)the Key Research Project of Frontier Science of Chinese Academy of Sciences(Grant No.QYZDB-SSW-JSC022).
文摘Fine grained 8 mol%yttria-stabilized zirconia(8YSZ)transparent ceramics with high optical and mechanical properties were fabricated by air pre-sintering and hot isostatic pressing(HIP)using commercial 8YSZ powders as the raw material.The pre-sintered ceramics with fine grains and appropriate relative density play a key role to achieve high transparency and suppressed grain size after HIP post-treatment at relatively low temperatures.With the increase of HIP temperature from 1350 to 1550℃,the in-line transmittance of 8YSZ ceramics at 600 nm increases from 56.9%to 71.5%(2.5 mm in thickness),and the average grain size increases from 2.4 to 16.3μm.The corresponding bending strength of 8YSZ transparent ceramics decreases from 328±20 to 289±19 MPa,the hardness(H)decreases from 12.9±0.1 to 12.5±0.2 GPa,and the fracture toughness(KIC)decreases from 1.30±0.02 to 1.26±0.03 MPa·m^(1/2).Systematical investigations were carried out to study the combination of high optical transparency and excellent mechanical properties in 8YSZ ceramics.
