The transmittance (T) and the reflectance (R) were measured for (TMA)2ZnCl4 single crystals and hence the absorption coefficient (α), extinction coefficient (Kex.), refractive index (n), real and im-aginary dielectri...The transmittance (T) and the reflectance (R) were measured for (TMA)2ZnCl4 single crystals and hence the absorption coefficient (α), extinction coefficient (Kex.), refractive index (n), real and im-aginary dielectric constants (ε', ε") of (TMA)2ZnCl4 crystals were calculated as a function of photon energy. The analysis of the spectra behavior of the absorption coefficient in the absorption region revealed indirect transition. The dispersion of the refractive index is discussed in terms of the sin-gle oscillator Wemple-DiDomenico model. The single oscillator energy (E0), the dispersion energy (Ed), the lattice dielectric constant (εL) and the ratio of free charge carrier concentration to the ef-fective mass (N/m*) were estimated. The FTIR spectra were recorded to study the functional groups of the as grown and annealed samples.展开更多
Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon ...Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon modes are identified, which are fitted with the factorized form of the dielectric function. The dielectric property and optical conductivity of the MgAl2O4 crystal are analysed. From TO/LO splitting, the effective Szigeti charges and Born effective charges at different temperatures are calculated for studying the ionicity and the effect of polarization. Based on the relationship between the （LO-TO）1 splitting, which represents the transverse and longitudinal frequencies splitting of the highest energy phonon band in the reflectivity spectrum, and the ionic-covalent parameter, the four main phonon modes are assigned. MgA1204 can be considered as a pure ionic crystal and its optical characters do not change with decreasing temperature, so it may be used as a suitable substrate for high-Tc superconducting thin films.展开更多
The neodymium tungstate single crystals Nd-2(WO4)(3) were grown using the Czochralski method. The energy level scheme of Nd3+, was obtained through the spectral measurement. The upconversion luminescence of the crysta...The neodymium tungstate single crystals Nd-2(WO4)(3) were grown using the Czochralski method. The energy level scheme of Nd3+, was obtained through the spectral measurement. The upconversion luminescence of the crystals at 457 and 657 nm, corresponding to the (D5/2-->I11/2)-D-4-I-4 and (2)G(7/2)-->I-4(9/2) transitions, respectively, excited by 808 nm of a laser diode, was observed at room temperature. The fluorescence intensity and the excitation light power have a linear relationship at 457 nm and a quadratic relationship at 657 nm.展开更多
Superconducting La1.937Sr0.063CuO4 crystals grown by the travelling-solvent floating-zone technique were thermally treated under various temperatures and oxygen pressures for moderately adjusting the oxygen content. T...Superconducting La1.937Sr0.063CuO4 crystals grown by the travelling-solvent floating-zone technique were thermally treated under various temperatures and oxygen pressures for moderately adjusting the oxygen content. The response of intrinsic electronic property of the crystals to the change of hole density in La2-xSrxCuO4 in the vicinity of the magic doping of x= 1/16 （= 0.0625） is studied in detail by magnetic measurements under various fields up to 1 T. It is found that when the superconducting critical temperature （Tc） increases with the oxygen content, there appears also a new subtle electronic state that can be detected from the differential curves of diamagnetic susceptibility dx/dT of the crystal sample. In contrast with the intrinsic state, the new subtle electronic state is very fragile under the magnetic fields. Our results indicate that a moderate change in oxygen doping does not significantly modify the intrinsic electronic state originally existing at the magic doping level.展开更多
The 1-azido-2-chloro-4-nitrobenzene was prepared by nucleophilic substitution between 2-chloro-4-nitro-1-(trifluoromethylsulfinyl)benzene and sodium azide, and its structure was characterized by NMR spectrum and X-ray...The 1-azido-2-chloro-4-nitrobenzene was prepared by nucleophilic substitution between 2-chloro-4-nitro-1-(trifluoromethylsulfinyl)benzene and sodium azide, and its structure was characterized by NMR spectrum and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group P21/n, Z = 8 and Mr = 198.57. A cultivation process of the single crystal of unstable aryl azide was provided. The group of trifluoromethyl sulfinyl was found for the first time to be a new excellent leaving group of aromatic nucleophilic substitution reactions.展开更多
Thermoelectric power (S) measurements have been systematically investigated in high-quality La2-x-Srx-CuO4 single crystals with different Sr concentrations (x= 0.03, 0.05, 0.07, 0.1, 0.12). In this doping range studie...Thermoelectric power (S) measurements have been systematically investigated in high-quality La2-x-Srx-CuO4 single crystals with different Sr concentrations (x= 0.03, 0.05, 0.07, 0.1, 0.12). In this doping range studied, S remains positive, and with the increase of Sr concentration, room-temperature thermoelectric power S (290 K) decreases. An empirical formula which presents a relationship between hole concentration P and room-temperature thermoelectric power S (290 K) is reported in this note. Based on the theory of metallic diffusion model, the experimental results are discussed.展开更多
The new title compound, chiral 2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）- 2-oxoethyl acetate, has been synthesized via reduction, cyclization and acylation reaction. The structure of the product has been conf...The new title compound, chiral 2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）- 2-oxoethyl acetate, has been synthesized via reduction, cyclization and acylation reaction. The structure of the product has been confirmed by IR, 1H NMR, 13C NMR, LC-MS （ESI） and single-crystal X-ray diffraction. （R）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate crystallizes in monoclinic, space group P21/c with a = 11.867（2）, b = 8.4087（2）, c = 14.325（6） A^°, β = 117.59（2）°, Z = 4, V = 1266.9（6） A^°3, Dc = 1.307 g/cm^3, F（000） = 528, μ（MoKα） = 0.097 mm-1, R = 0.0453 and wR = 0.1237; （S）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate belongs to the triclinic system, space group P with a = 8.2647（17）, b = 8.7034（17）, c = 9.5479（19） A^°, α = 105.33（3）, β = 100.95（3）, γ = 105.14（3）°, Z = 2, V = 614.1（2） A^°3, Dc = 1.348 g/cm^3, F（000） = 264, μ（MoKα） = 0.10 mm-1, R = 0.0613 and wR = 0.1037. Both of the molecules prefer to form crystal packing through C–H…O hydrogen bonds.展开更多
文摘The transmittance (T) and the reflectance (R) were measured for (TMA)2ZnCl4 single crystals and hence the absorption coefficient (α), extinction coefficient (Kex.), refractive index (n), real and im-aginary dielectric constants (ε', ε") of (TMA)2ZnCl4 crystals were calculated as a function of photon energy. The analysis of the spectra behavior of the absorption coefficient in the absorption region revealed indirect transition. The dispersion of the refractive index is discussed in terms of the sin-gle oscillator Wemple-DiDomenico model. The single oscillator energy (E0), the dispersion energy (Ed), the lattice dielectric constant (εL) and the ratio of free charge carrier concentration to the ef-fective mass (N/m*) were estimated. The FTIR spectra were recorded to study the functional groups of the as grown and annealed samples.
基金Project supported by the National Natural Science Foundation of China （Grant No 10474128） and Chinese Academy of Sciences.
文摘Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon modes are identified, which are fitted with the factorized form of the dielectric function. The dielectric property and optical conductivity of the MgAl2O4 crystal are analysed. From TO/LO splitting, the effective Szigeti charges and Born effective charges at different temperatures are calculated for studying the ionicity and the effect of polarization. Based on the relationship between the （LO-TO）1 splitting, which represents the transverse and longitudinal frequencies splitting of the highest energy phonon band in the reflectivity spectrum, and the ionic-covalent parameter, the four main phonon modes are assigned. MgA1204 can be considered as a pure ionic crystal and its optical characters do not change with decreasing temperature, so it may be used as a suitable substrate for high-Tc superconducting thin films.
文摘The neodymium tungstate single crystals Nd-2(WO4)(3) were grown using the Czochralski method. The energy level scheme of Nd3+, was obtained through the spectral measurement. The upconversion luminescence of the crystals at 457 and 657 nm, corresponding to the (D5/2-->I11/2)-D-4-I-4 and (2)G(7/2)-->I-4(9/2) transitions, respectively, excited by 808 nm of a laser diode, was observed at room temperature. The fluorescence intensity and the excitation light power have a linear relationship at 457 nm and a quadratic relationship at 657 nm.
基金Project supported by the Ministry of Science and Technology of China (973 project Grant No 2006CB0L0302)the National Natural Science Foundation of China (Grant No 10574149)Chinese Academy of Sciences (Grant No KJCX2-SW-W18)
文摘Superconducting La1.937Sr0.063CuO4 crystals grown by the travelling-solvent floating-zone technique were thermally treated under various temperatures and oxygen pressures for moderately adjusting the oxygen content. The response of intrinsic electronic property of the crystals to the change of hole density in La2-xSrxCuO4 in the vicinity of the magic doping of x= 1/16 （= 0.0625） is studied in detail by magnetic measurements under various fields up to 1 T. It is found that when the superconducting critical temperature （Tc） increases with the oxygen content, there appears also a new subtle electronic state that can be detected from the differential curves of diamagnetic susceptibility dx/dT of the crystal sample. In contrast with the intrinsic state, the new subtle electronic state is very fragile under the magnetic fields. Our results indicate that a moderate change in oxygen doping does not significantly modify the intrinsic electronic state originally existing at the magic doping level.
文摘The 1-azido-2-chloro-4-nitrobenzene was prepared by nucleophilic substitution between 2-chloro-4-nitro-1-(trifluoromethylsulfinyl)benzene and sodium azide, and its structure was characterized by NMR spectrum and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group P21/n, Z = 8 and Mr = 198.57. A cultivation process of the single crystal of unstable aryl azide was provided. The group of trifluoromethyl sulfinyl was found for the first time to be a new excellent leaving group of aromatic nucleophilic substitution reactions.
基金The Elementary Innovation Team Foundation supported by NORINCO Group in China(2021CXTD52)The Taishan Scholars Foundation supported by Shandong Provence in China。
基金This work is partly supported by the National Natural Science Foundation of China (Grand No. 19904009)the Ministry of Science and Technology of China (NKBRSF-G1990646)the Natural Science Foundation of Zhejiang Province (Grand No. 199031).
文摘Thermoelectric power (S) measurements have been systematically investigated in high-quality La2-x-Srx-CuO4 single crystals with different Sr concentrations (x= 0.03, 0.05, 0.07, 0.1, 0.12). In this doping range studied, S remains positive, and with the increase of Sr concentration, room-temperature thermoelectric power S (290 K) decreases. An empirical formula which presents a relationship between hole concentration P and room-temperature thermoelectric power S (290 K) is reported in this note. Based on the theory of metallic diffusion model, the experimental results are discussed.
基金supported by the National Natural Science Foundation of China(No.31572042)Natural Science Foundation of Heilongjiang Province(B201303)the Research Science Foundation in Technology Innovation of Harbin(No.2015RAYXJ010)
文摘The new title compound, chiral 2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）- 2-oxoethyl acetate, has been synthesized via reduction, cyclization and acylation reaction. The structure of the product has been confirmed by IR, 1H NMR, 13C NMR, LC-MS （ESI） and single-crystal X-ray diffraction. （R）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate crystallizes in monoclinic, space group P21/c with a = 11.867（2）, b = 8.4087（2）, c = 14.325（6） A^°, β = 117.59（2）°, Z = 4, V = 1266.9（6） A^°3, Dc = 1.307 g/cm^3, F（000） = 528, μ（MoKα） = 0.097 mm-1, R = 0.0453 and wR = 0.1237; （S）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate belongs to the triclinic system, space group P with a = 8.2647（17）, b = 8.7034（17）, c = 9.5479（19） A^°, α = 105.33（3）, β = 100.95（3）, γ = 105.14（3）°, Z = 2, V = 614.1（2） A^°3, Dc = 1.348 g/cm^3, F（000） = 264, μ（MoKα） = 0.10 mm-1, R = 0.0613 and wR = 0.1037. Both of the molecules prefer to form crystal packing through C–H…O hydrogen bonds.
