Two dimensional nanomaterials, specifically graphene, can play a significant role in various photonic and electronic devices. This is especially true in handling the enormous heat in high density electronics and in no...Two dimensional nanomaterials, specifically graphene, can play a significant role in various photonic and electronic devices. This is especially true in handling the enormous heat in high density electronics and in nonlinear optics when using high power lasers. To model these systems it is important to know the thermal-optical properties of graphene. In this paper, we report on the thermal and optical linear and nonlinear properties of graphene materials using Z-scan system. In particular, we explore the thermo-optical properties of graphene, with and without gold nanorods （AuNRs）. The obtained results illustrate that the addition of gold nanorods causes a significant change in thermal nonlinear refractive index coefficients of graphene, due to the plasmonic enhancements.展开更多
Some theoretical methods have been reported to deal with nonlinear problems of composite materials but the accuracy is not so good. In the meantime, a lot of linear problems are difficult to be managed by the theoreti...Some theoretical methods have been reported to deal with nonlinear problems of composite materials but the accuracy is not so good. In the meantime, a lot of linear problems are difficult to be managed by the theoretical methods. The present study aims to use the developed method, the random microstructure finite element method, to deal with these nonlinear problems. In this paper, the random microstructure finite element method is used to deal with all three kinds of nonlinear property problems of composite materials. The analyzed results suggest the influences of the nonlinear phenomena on the effective properties of composite materials are significant and the random microstructure finite element method is an effective tool to investigate the nonlinear problems.展开更多
Functional materials with multiple properties are urgent to be explored to reach high requirements for applications nowadays.In this work,a new multifunctional one-dimensional(1D)chain compound[N(C_(3)H_(7))_(4)][Cu(o...Functional materials with multiple properties are urgent to be explored to reach high requirements for applications nowadays.In this work,a new multifunctional one-dimensional(1D)chain compound[N(C_(3)H_(7))_(4)][Cu(ohpma)]·H_(2)O 1(ohpma=deprotonated N-(2-hydoxyphenyl)oxamic acid)exhibiting both 1D antiferromagnetic and nonlinear optical properties,which are both originated from the same polar[Cu(C_(8)H_(4)NO_(4))]magnetic units,has been successfully synthesized by evaporation at room temperature.Bis-polydentate nature of the(ohpma)3−ligand with constrained tridentate and bidentate coordination sites conducts Cu^(2+)ions coordinating in different geometries and forms 1D chains along the c axis,which are further separated by the[N(C_(3)H_(7))_(4)]+cations.And the 1D magnetic chains further exhibit noncentrosymmetric polar arrangement.Nonlinear optical study shows polar compound 1 exhibits a discernible second-harmonic generation(SHG)efficiency and the calculation of the partial density of states indicates that the SHG efficiency of 1 is mainly originated from the polar[Cu(C_(8)H_(4)NO_(4))]magnetic units.Moreover,magnetic susceptibility shows a broad maximum around 70 K with strong intrachain interaction of J/k B=−113.0 K but no long-range order is observed down to 2 K,suggesting that 1 shows a good 1D magnetism.Both good 1D magnetism and SHG activity suggest that 1 could be as a potential multifunctional material,particularly.展开更多
Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an ef...Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.展开更多
Thin transparent oxide conducting films(TCOFs)of titanium and gallium substituted zinc oxide(TGZO)were fabricated via radio frequency(RF)magnetron sputtering technique.The effects of RF power on electrical,linear and ...Thin transparent oxide conducting films(TCOFs)of titanium and gallium substituted zinc oxide(TGZO)were fabricated via radio frequency(RF)magnetron sputtering technique.The effects of RF power on electrical,linear and nonlinear optical characteristics were investigated by Hall tester,Ultraviolet(UV)-visible spectrophotometer and optical characterization method.The results indicate that RF power significantly influences the electrical and optical properties of the deposited films.As RF power raises,the resistivity and Urbach energy fall initially and then rise,while the figure of merit,mean visible transmittance and optical bandgap show the reverse variation trend.At RF power of 190 W,the TGZO sample exhibits the highest electro-optical properties,with the maximum figure of merit(1.14×10^(4)Ω^(-1)∙cm^(-1)),mean visible transmittance(86.9%)and optical bandgap(3.50 eV),the minimum resistivity(6.26×10^(-4)Ω∙cm)and Urbach energy(174.23 meV).In addition,the optical constants of the deposited films were determined by the optical spectrum fitting method,and the RF power dependence of nonlinear optical properties was studied.It is observed that all the thin films exhibit normal dispersion characteristics in the visible region,and the nonlinear optical parameters are greatly affected by the RF power in the ultraviolet region.展开更多
The authors regret that one of the coauthors was inadvertently omitted in the previous paper. E. Varene was a member of the Institut fur Festk6rperphysik at the Technische Universitat Berlin and contributed to the res...The authors regret that one of the coauthors was inadvertently omitted in the previous paper. E. Varene was a member of the Institut fur Festk6rperphysik at the Technische Universitat Berlin and contributed to the results on cross-phase modulation.展开更多
This paper demonstrates an all-optical switching model system comprising a single pulsed pump beam at 355 nm and a CW He-Ne signal beam at 632.8 nm with 2-（2＇-hydroxyphenyl）benzothiazole （HBT） in ethanol solution...This paper demonstrates an all-optical switching model system comprising a single pulsed pump beam at 355 nm and a CW He-Ne signal beam at 632.8 nm with 2-（2＇-hydroxyphenyl）benzothiazole （HBT） in ethanol solution. The origins of the optical switching effect were discussed. By the study of nonlinear optical properties for HBT in ethanol solvent, this paper verified that the excited-state intramolecular proton transfer （ESIPT） effect of HBT and the thermal effect of solvent worked on quite different time scales and together induced the change of the refractive index of HBT solution, leading to the signal beam deflection. The results indicated that the HBT molecule could be an excellent candidate for high-speed and high-sensitive optical switching devices.展开更多
We investigated the influence of soaking time on the semi-conductivity and nonlinear electrical properties of TiO2- based varistor ceramic samples. We used a single sintering process and fabricated six disk samples of...We investigated the influence of soaking time on the semi-conductivity and nonlinear electrical properties of TiO2- based varistor ceramic samples. We used a single sintering process and fabricated six disk samples of （Sr, Bi, Si, Ta）-doped TiO2- based varistor ceramics sintered at 1 250℃ for 0.5 h, 1.0 h, 2.0 h, 3.0 h, 4.0 h, and 5.0 h, respectively. The samples were characterized by X-ray diffraction, breakdown voltage, and complex impedance. The results show that as the soaking time increases from 0.5 h to 5.0 h, the breakdown voltage drops before rising while the nonlinear coefficient increases and then decreases. We suggest that, considering both grain semi-conductivity and nonlinear electrical properties of the TiO2-based varistor ceramics, the optimal soaking time is between 2.0 h and 3.0 h.展开更多
The effects of TiO2 on sintering and nonlinear electrical properties of(98.5-x)ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2(x=0.3,0.5,0.7,0.9 mol%)ceramic varistors prepared by the ceramic technique are investigated in this...The effects of TiO2 on sintering and nonlinear electrical properties of(98.5-x)ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2(x=0.3,0.5,0.7,0.9 mol%)ceramic varistors prepared by the ceramic technique are investigated in this work.The optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption percentages.The optimum sintering temperature is found to be 1200℃,at which each of the samples shows a maximum firing shrinkage and minimum water absorption.Also minimum water absorption appears in a sample of x=0.9 mol%.Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase sintering.The crystal size of ZnO decreases with increasing TiO2 doping.The addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x=0.7 mol%of TiO2,further addition negatively affects it.A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 kHz.The temperature and composition dependences of the dielectric constant and AC conductivity are also studied.The increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.展开更多
On the basis of adding the bond functions (3s 3p 2d) to the basis sets 6-311G ( 2d 2p ) for increasing the efficiency of the basis sets , we have carried out the MP2 calculations of nonlinear optical properties includ...On the basis of adding the bond functions (3s 3p 2d) to the basis sets 6-311G ( 2d 2p ) for increasing the efficiency of the basis sets , we have carried out the MP2 calculations of nonlinear optical properties includintg dipole moment uo,polarizibili- ty ao and hyperpolarizability , for CH4-nFn (n = 1 , 2 , 3). The results are in good a- greement with those of experimentsl The roles of the bond functions in the calcula- tions are shown , i. e., the improved values of the properties are about 2%-7% at the SCF level and about 6%-30% at the correlated level (MP2). It is shown that the more important role of the bond functions in calculating is the im- provement of the effects of the corrections of electronic correlations and the increase of the effects is in the order of. In addition , it is also shown that the cal-, culated value of a property does not change with the bond-function location in our calculations except for the regions close to the nuclei in a molecule.展开更多
We quantitatively investigate the third-order optical nonlinear response of Co-doped ZnO thin films prepared by magnetron sputtering using the Z-scan method. The two-photon absorption and optical Kerr effect are revea...We quantitatively investigate the third-order optical nonlinear response of Co-doped ZnO thin films prepared by magnetron sputtering using the Z-scan method. The two-photon absorption and optical Kerr effect are revealed to contribute to the third-order nonlinear response of the Co-doped ZnO films. The nonlinear absorption coefficient β is determined to be approximately 8.8 × 10-5 cm/W and the third-order nonlinear susceptibility X（3） is 2.93 × 10-6 esu. The defect-associated energy levels within the band gap are suggested to be responsible for the enhanced nonlinear response observed in Co-doped ZnO films.展开更多
Static second-order nonlinear optical effects of amino acid zinc(II) porphyrins 1, 2, 3 and 4 were calculated by the TDHF/PM3 method based on the molecular structures optimized at the semiempirical PM3 quantum chemi...Static second-order nonlinear optical effects of amino acid zinc(II) porphyrins 1, 2, 3 and 4 were calculated by the TDHF/PM3 method based on the molecular structures optimized at the semiempirical PM3 quantum chemistry level, showing due to the cancellation of symmetric center, these amino acid zinc(II) porphyrins exhibit second order nonlinear optical response. The analysis of β components indicated that these amino acid zinc(II) porphyrins are of multipola- rizabilities, and they may be ascribed as the “mixture” of octupolar and dipoar molecules with ||βJ=3||/||βJ=1|| ≈ 5. It is found that there are no significant differences between the static β values of non-chiral and chiral amino acid zinc(II) porphyrins. However, the βxyz component, which is quite important to quadratic macroscopic χ (2) susceptibility of chiral material, is increased significantly with the increase of side chain group of amino acids.展开更多
UV-Vis spectrum and the third-order nonlinear optical properties of the chiral camphor-derived β-diketonate have been studied at the B3LYP/6-31G＊ level. The results showed that the introduction of electron-drawing g...UV-Vis spectrum and the third-order nonlinear optical properties of the chiral camphor-derived β-diketonate have been studied at the B3LYP/6-31G＊ level. The results showed that the introduction of electron-drawing group -CF3 and -C3F7 on β-diketonate made the strongest absorption peak red-shift and the lowest energy absorption blue-shied. Introduction of -OC2H5 on the benzene or pyridine ring made the lowest energy absorption blue-shift. When the -C2H3 was introduced on the benzene or pyridine ring, the lowest energy absorption was red-shifted. Introduction of electron-donating group on β-diketonate can enlarge their nonlinear optical properties. On the contrary, the introduction of electron-drawing group dropped it down.展开更多
Variation of nonlinear optical properties with surface roughness of ZnO thin films deposited on coming glass substrates at different annealing temperature （TA） was reported. The films were characterized by X-ray dif...Variation of nonlinear optical properties with surface roughness of ZnO thin films deposited on coming glass substrates at different annealing temperature （TA） was reported. The films were characterized by X-ray diffraction （XRD）, UV-Vis-NIR transmission and single beam z-scan technique using second harmonics of Nd：YAG laser. Surface morphology of the samples was investigated by atomic force microscopy （AFM）. Surface roughness was found minimum （8.4 nm） for ZnO sample annealed at 450℃. The nonlinear optical properties （NLO） were found to be dependent on surface roughness and the highest value of third order nonlinear susceptibility （X（3）=4.3x 10-7 esu） was obtained for ZnO at TA 450℃.展开更多
Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises ...Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb--Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices.展开更多
The fully oxidized state of polyaniline (PANI), pernigraniline (PN), was synthesized by oxidation of the emeraldine base form of PAM dissolved in NMP solvent with m-chloroperoxybenzoic acid. The resulted PN was charac...The fully oxidized state of polyaniline (PANI), pernigraniline (PN), was synthesized by oxidation of the emeraldine base form of PAM dissolved in NMP solvent with m-chloroperoxybenzoic acid. The resulted PN was characterized by FTIR and UV-Visible spectra. The third-order nonlinear optical properties of PN in concentrated sulfuric acid (PN/H2SO4) were measured by a degenerated four wave mixing (DFWM) method. The results obtained suggest that the soliton-pair intermediate state associated with the degenerated state does not play a major role in the third order nonlinear optical properties of PANI.展开更多
The structures of several recently reported organometallic NLO chromophores, (thio-phene) manganese tricarbonyl cations, were fully optimized at the DFT non-local (GGA) level. The calculated results show that the fra...The structures of several recently reported organometallic NLO chromophores, (thio-phene) manganese tricarbonyl cations, were fully optimized at the DFT non-local (GGA) level. The calculated results show that the fragments 2-SC4H3CH=CHC6H4-R in these organometallic chromophores are not planar with dihedral angles of 42.2~59.8 between two aromatic rings, which are different from those of uncoordinated counterparts. Based on the DFT geometry opti-mization, the second-order nonlinear optical polarizabilities were calculated by using RPA method. The calculated results indicate that incorporation of +3Mn(CO) unit with thiophene leads to a sub-stantial increase in the second-order polarizability (b).展开更多
Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form vip-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films contain...Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form vip-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a vip exhibit high second harmonic coefficients （d33） compared with other two-dimensional chromophores.展开更多
Suspension of micrometer-sized 1,4-bis（4-methylstyryl）benzene（p-MSB） was converted into colloidal nanocrystal solution by irradiation with an femtosecond laser（800 nm, 1 kHz）. The prepared nanocrystals were rect...Suspension of micrometer-sized 1,4-bis（4-methylstyryl）benzene（p-MSB） was converted into colloidal nanocrystal solution by irradiation with an femtosecond laser（800 nm, 1 kHz）. The prepared nanocrystals were rectangular with ca. 100 nm in size. The same crystal structure as that of bulk crystals was confirmed by X-ray diffraction measurement. UV-Vis spectra and emission spectra of the nanoparticle dispersions in dichloromethane（poor solvent） were examined. The nanocrystal exhibits large quantum yield（89%）. The nonlinear optical properties of the nanocrystals were further studied by Z-scan technique with femtosecond laser duration of 120 fs at a wavelength of 800 nm. The results show that the nanocrystals exhibit strong nonlinear absorption.展开更多
文摘Two dimensional nanomaterials, specifically graphene, can play a significant role in various photonic and electronic devices. This is especially true in handling the enormous heat in high density electronics and in nonlinear optics when using high power lasers. To model these systems it is important to know the thermal-optical properties of graphene. In this paper, we report on the thermal and optical linear and nonlinear properties of graphene materials using Z-scan system. In particular, we explore the thermo-optical properties of graphene, with and without gold nanorods （AuNRs）. The obtained results illustrate that the addition of gold nanorods causes a significant change in thermal nonlinear refractive index coefficients of graphene, due to the plasmonic enhancements.
基金This work is supported by the National Natural Science Foundation of China under the Grant 19772037 and 19902014
文摘Some theoretical methods have been reported to deal with nonlinear problems of composite materials but the accuracy is not so good. In the meantime, a lot of linear problems are difficult to be managed by the theoretical methods. The present study aims to use the developed method, the random microstructure finite element method, to deal with these nonlinear problems. In this paper, the random microstructure finite element method is used to deal with all three kinds of nonlinear property problems of composite materials. The analyzed results suggest the influences of the nonlinear phenomena on the effective properties of composite materials are significant and the random microstructure finite element method is an effective tool to investigate the nonlinear problems.
基金supported by the National Natural Science Foundation of China(NSFC,No.22101091)the Fundamental Research Funds for the Central Universities(No.2019kfyXKJC016)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(No.B210003),Knowledge Innovation Program of Wuhan-Basic Research.
文摘Functional materials with multiple properties are urgent to be explored to reach high requirements for applications nowadays.In this work,a new multifunctional one-dimensional(1D)chain compound[N(C_(3)H_(7))_(4)][Cu(ohpma)]·H_(2)O 1(ohpma=deprotonated N-(2-hydoxyphenyl)oxamic acid)exhibiting both 1D antiferromagnetic and nonlinear optical properties,which are both originated from the same polar[Cu(C_(8)H_(4)NO_(4))]magnetic units,has been successfully synthesized by evaporation at room temperature.Bis-polydentate nature of the(ohpma)3−ligand with constrained tridentate and bidentate coordination sites conducts Cu^(2+)ions coordinating in different geometries and forms 1D chains along the c axis,which are further separated by the[N(C_(3)H_(7))_(4)]+cations.And the 1D magnetic chains further exhibit noncentrosymmetric polar arrangement.Nonlinear optical study shows polar compound 1 exhibits a discernible second-harmonic generation(SHG)efficiency and the calculation of the partial density of states indicates that the SHG efficiency of 1 is mainly originated from the polar[Cu(C_(8)H_(4)NO_(4))]magnetic units.Moreover,magnetic susceptibility shows a broad maximum around 70 K with strong intrachain interaction of J/k B=−113.0 K but no long-range order is observed down to 2 K,suggesting that 1 shows a good 1D magnetism.Both good 1D magnetism and SHG activity suggest that 1 could be as a potential multifunctional material,particularly.
基金Project supported by the Natural Science Foundation of Anhui Province(Grant No.1908085MA12)the National Natural Science Foundation of China(Grant No.21703222)。
文摘Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.
文摘Thin transparent oxide conducting films(TCOFs)of titanium and gallium substituted zinc oxide(TGZO)were fabricated via radio frequency(RF)magnetron sputtering technique.The effects of RF power on electrical,linear and nonlinear optical characteristics were investigated by Hall tester,Ultraviolet(UV)-visible spectrophotometer and optical characterization method.The results indicate that RF power significantly influences the electrical and optical properties of the deposited films.As RF power raises,the resistivity and Urbach energy fall initially and then rise,while the figure of merit,mean visible transmittance and optical bandgap show the reverse variation trend.At RF power of 190 W,the TGZO sample exhibits the highest electro-optical properties,with the maximum figure of merit(1.14×10^(4)Ω^(-1)∙cm^(-1)),mean visible transmittance(86.9%)and optical bandgap(3.50 eV),the minimum resistivity(6.26×10^(-4)Ω∙cm)and Urbach energy(174.23 meV).In addition,the optical constants of the deposited films were determined by the optical spectrum fitting method,and the RF power dependence of nonlinear optical properties was studied.It is observed that all the thin films exhibit normal dispersion characteristics in the visible region,and the nonlinear optical parameters are greatly affected by the RF power in the ultraviolet region.
文摘The authors regret that one of the coauthors was inadvertently omitted in the previous paper. E. Varene was a member of the Institut fur Festk6rperphysik at the Technische Universitat Berlin and contributed to the results on cross-phase modulation.
基金Project supported by the National Natural Science Foundation of China （Grant No 60178025） and the Key Laboratory of 0ptoelectronics Information Technical Science of Ministry of Education, Institute of Modern 0ptics, Nankai University, China.
文摘This paper demonstrates an all-optical switching model system comprising a single pulsed pump beam at 355 nm and a CW He-Ne signal beam at 632.8 nm with 2-（2＇-hydroxyphenyl）benzothiazole （HBT） in ethanol solution. The origins of the optical switching effect were discussed. By the study of nonlinear optical properties for HBT in ethanol solvent, this paper verified that the excited-state intramolecular proton transfer （ESIPT） effect of HBT and the thermal effect of solvent worked on quite different time scales and together induced the change of the refractive index of HBT solution, leading to the signal beam deflection. The results indicated that the HBT molecule could be an excellent candidate for high-speed and high-sensitive optical switching devices.
基金Funded by the Natural Science Foundation of China (No. 50872001 and No. 50642038)the Scientific Research Foundation of Education Ministry of Anhui Province (No. 2005KJ224 and No. KJ2007B132)the Graduate Student Innovation Programs of Anhui University (No. 20072006)
文摘We investigated the influence of soaking time on the semi-conductivity and nonlinear electrical properties of TiO2- based varistor ceramic samples. We used a single sintering process and fabricated six disk samples of （Sr, Bi, Si, Ta）-doped TiO2- based varistor ceramics sintered at 1 250℃ for 0.5 h, 1.0 h, 2.0 h, 3.0 h, 4.0 h, and 5.0 h, respectively. The samples were characterized by X-ray diffraction, breakdown voltage, and complex impedance. The results show that as the soaking time increases from 0.5 h to 5.0 h, the breakdown voltage drops before rising while the nonlinear coefficient increases and then decreases. We suggest that, considering both grain semi-conductivity and nonlinear electrical properties of the TiO2-based varistor ceramics, the optimal soaking time is between 2.0 h and 3.0 h.
文摘The effects of TiO2 on sintering and nonlinear electrical properties of(98.5-x)ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2(x=0.3,0.5,0.7,0.9 mol%)ceramic varistors prepared by the ceramic technique are investigated in this work.The optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption percentages.The optimum sintering temperature is found to be 1200℃,at which each of the samples shows a maximum firing shrinkage and minimum water absorption.Also minimum water absorption appears in a sample of x=0.9 mol%.Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase sintering.The crystal size of ZnO decreases with increasing TiO2 doping.The addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x=0.7 mol%of TiO2,further addition negatively affects it.A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 kHz.The temperature and composition dependences of the dielectric constant and AC conductivity are also studied.The increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.
文摘On the basis of adding the bond functions (3s 3p 2d) to the basis sets 6-311G ( 2d 2p ) for increasing the efficiency of the basis sets , we have carried out the MP2 calculations of nonlinear optical properties includintg dipole moment uo,polarizibili- ty ao and hyperpolarizability , for CH4-nFn (n = 1 , 2 , 3). The results are in good a- greement with those of experimentsl The roles of the bond functions in the calcula- tions are shown , i. e., the improved values of the properties are about 2%-7% at the SCF level and about 6%-30% at the correlated level (MP2). It is shown that the more important role of the bond functions in calculating is the im- provement of the effects of the corrections of electronic correlations and the increase of the effects is in the order of. In addition , it is also shown that the cal-, culated value of a property does not change with the bond-function location in our calculations except for the regions close to the nuclei in a molecule.
基金Supported by National Basic Research Program of China under Grant Nos 2011CB922200 and 2013CB922303
文摘We quantitatively investigate the third-order optical nonlinear response of Co-doped ZnO thin films prepared by magnetron sputtering using the Z-scan method. The two-photon absorption and optical Kerr effect are revealed to contribute to the third-order nonlinear response of the Co-doped ZnO films. The nonlinear absorption coefficient β is determined to be approximately 8.8 × 10-5 cm/W and the third-order nonlinear susceptibility X（3） is 2.93 × 10-6 esu. The defect-associated energy levels within the band gap are suggested to be responsible for the enhanced nonlinear response observed in Co-doped ZnO films.
基金This work was supported by the NNSFC (20476034 NSFC/HKUST43)+1 种基金 NSF of Guangdong Province (000489) and SRF for ROCS State Education Ministry.
文摘Static second-order nonlinear optical effects of amino acid zinc(II) porphyrins 1, 2, 3 and 4 were calculated by the TDHF/PM3 method based on the molecular structures optimized at the semiempirical PM3 quantum chemistry level, showing due to the cancellation of symmetric center, these amino acid zinc(II) porphyrins exhibit second order nonlinear optical response. The analysis of β components indicated that these amino acid zinc(II) porphyrins are of multipola- rizabilities, and they may be ascribed as the “mixture” of octupolar and dipoar molecules with ||βJ=3||/||βJ=1|| ≈ 5. It is found that there are no significant differences between the static β values of non-chiral and chiral amino acid zinc(II) porphyrins. However, the βxyz component, which is quite important to quadratic macroscopic χ (2) susceptibility of chiral material, is increased significantly with the increase of side chain group of amino acids.
基金supported by the National Natural Science Foundation of China(21172161)
文摘UV-Vis spectrum and the third-order nonlinear optical properties of the chiral camphor-derived β-diketonate have been studied at the B3LYP/6-31G＊ level. The results showed that the introduction of electron-drawing group -CF3 and -C3F7 on β-diketonate made the strongest absorption peak red-shift and the lowest energy absorption blue-shied. Introduction of -OC2H5 on the benzene or pyridine ring made the lowest energy absorption blue-shift. When the -C2H3 was introduced on the benzene or pyridine ring, the lowest energy absorption was red-shifted. Introduction of electron-donating group on β-diketonate can enlarge their nonlinear optical properties. On the contrary, the introduction of electron-drawing group dropped it down.
基金the National Natural Science Foundation of China，the Natural Science Foundation of Anhui University，the Doctor Research Foundation of Anhui University
基金DRDO,UGC and DST for financial support under SAP and FIST program,respectively
文摘Variation of nonlinear optical properties with surface roughness of ZnO thin films deposited on coming glass substrates at different annealing temperature （TA） was reported. The films were characterized by X-ray diffraction （XRD）, UV-Vis-NIR transmission and single beam z-scan technique using second harmonics of Nd：YAG laser. Surface morphology of the samples was investigated by atomic force microscopy （AFM）. Surface roughness was found minimum （8.4 nm） for ZnO sample annealed at 450℃. The nonlinear optical properties （NLO） were found to be dependent on surface roughness and the highest value of third order nonlinear susceptibility （X（3）=4.3x 10-7 esu） was obtained for ZnO at TA 450℃.
基金Project supported by the National Key Basic Research Program of China(Grant No.2012CB722703)the National Natural Science Foundation of China(Grant No.61377061)+2 种基金the Young Leaders of Academic Climbing Project of the Education Department of Zhejiang Province,China(Grant No.pd2013092)the Program for Innovative Research Team of Ningbo City,China(Grant No.2009B217)the K.C.Wong Magna Fund in Ningbo University,China
文摘Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb--Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices.
基金This work was partly supported by NNSFC,Chinese Academy of Sciences and Director Foundation of the Institute of Chemistry,Academia Sinica
文摘The fully oxidized state of polyaniline (PANI), pernigraniline (PN), was synthesized by oxidation of the emeraldine base form of PAM dissolved in NMP solvent with m-chloroperoxybenzoic acid. The resulted PN was characterized by FTIR and UV-Visible spectra. The third-order nonlinear optical properties of PN in concentrated sulfuric acid (PN/H2SO4) were measured by a degenerated four wave mixing (DFWM) method. The results obtained suggest that the soliton-pair intermediate state associated with the degenerated state does not play a major role in the third order nonlinear optical properties of PANI.
文摘The structures of several recently reported organometallic NLO chromophores, (thio-phene) manganese tricarbonyl cations, were fully optimized at the DFT non-local (GGA) level. The calculated results show that the fragments 2-SC4H3CH=CHC6H4-R in these organometallic chromophores are not planar with dihedral angles of 42.2~59.8 between two aromatic rings, which are different from those of uncoordinated counterparts. Based on the DFT geometry opti-mization, the second-order nonlinear optical polarizabilities were calculated by using RPA method. The calculated results indicate that incorporation of +3Mn(CO) unit with thiophene leads to a sub-stantial increase in the second-order polarizability (b).
基金supported by a Start-up Grant from Southeast University to Dr Chao-Zhi Zhang and the Science Foundation of Jiangsu Province of China(No.BK2004085).
文摘Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form vip-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a vip exhibit high second harmonic coefficients （d33） compared with other two-dimensional chromophores.
基金Supported by the National High-Tech Research and Development Program of China(No.2009AA03Z401)the National Natural Science Foundation of China(Nos.61077002,60807030)
文摘Suspension of micrometer-sized 1,4-bis（4-methylstyryl）benzene（p-MSB） was converted into colloidal nanocrystal solution by irradiation with an femtosecond laser（800 nm, 1 kHz）. The prepared nanocrystals were rectangular with ca. 100 nm in size. The same crystal structure as that of bulk crystals was confirmed by X-ray diffraction measurement. UV-Vis spectra and emission spectra of the nanoparticle dispersions in dichloromethane（poor solvent） were examined. The nanocrystal exhibits large quantum yield（89%）. The nonlinear optical properties of the nanocrystals were further studied by Z-scan technique with femtosecond laser duration of 120 fs at a wavelength of 800 nm. The results show that the nanocrystals exhibit strong nonlinear absorption.
