A new compound of KCdAsS_3(Mr = 322.60) was successfully synthesized using thiourea reactive flux method. The crystal structure was determined by single-crystal X-ray diffraction. The title compound crystallizes in a ...A new compound of KCdAsS_3(Mr = 322.60) was successfully synthesized using thiourea reactive flux method. The crystal structure was determined by single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic system of space group P21/n with a = 5.9537(7), b = 16.633(3), c = 6.093(1) ?, b = 90.781(3)°, V = 610.0(1) ?3, Z = 4, Dc = 3.513 g/cm3, m(Mo Kα) = 10.52 mm-1, F(000) = 592, R = 0.057 and w R = 0.136 for 899 observed reflections with I > 2σ(I). The crystal structure of KCdAsS_3 features [Cd As S3]-layers, which are separated by K+ ions. First-principles calculations show that KCdAsS_3 is an indirect band gap semiconductor with a band gap of 2.3 e V. The novel layered compound of tetrahedra CdS_4 and pyramids AsS_3 is potentially useful for photoluminescent, photocatalytic and photoelectric applications.展开更多
Investigation of the electric properties of semi-conducting materials in an applied ac electric fields gives information about the nature of charge transport and localized states in the forbidden gap. Layered crystals...Investigation of the electric properties of semi-conducting materials in an applied ac electric fields gives information about the nature of charge transport and localized states in the forbidden gap. Layered crystals usually contain structural defects, such as dislocations and vacancies that may form a high density of localized states near the Fermi level. So, the current study was carried out for insight into the dielectric Properties of Tl2S layered single crystals. These properties were studied using the ac measurements in the low temperatures ranging from 77 to 300 K. The real part of dielectric constant ε?, imaginary part of dielectric constant ε?, the dissipation factor tan δ and the alternating current conductivity σac were measured in an applied ac electric field of frequencies extending from 2.5 to 50 kHz. Based on the dependencies of these dielectric parameters on both the frequency and temperature, the dielectric properties of the crystals under investigation were elucidated and analyzed. The ac conductivity was found to obey the power law σac(ω) = Aωs with which the values of the exponent s were evaluated to be less than unity in the range 0.21 ≥ s ≥ 0.19. Furthermore, it was found that the temperature dependence of ac conductivity follows the Arrhenius relation via which the impact of temperature on the electrical processes in an applied ac electric field was illustrated and analyzed. The influences of temperature and frequency on both the exponent s and band gap were also discussed in this investigation.展开更多
Zeolite FSM 16 was synthesized by reconstruction of layered silicate in the presence of organic surfactant. With partial replacement of Ti 3+ with organic cations, TiO 2 nano structured particles were simultaneously b...Zeolite FSM 16 was synthesized by reconstruction of layered silicate in the presence of organic surfactant. With partial replacement of Ti 3+ with organic cations, TiO 2 nano structured particles were simultaneously built in the channel of the zeolite as the framework of the zeolite was formed. XRD, IR and Raman spectroscopic characterizations indicate that SiO 4 tetrahedron may be distorted and transferred from Q 3 to Q 2 form due to the pucker and reconstruction of the layered structure. The formation of TiO 2 nano structured particles had no influence on the formation of zeolite framework, however, the interaction obviously occurred between TiO 2 nano structured particles and zeolite framework.展开更多
基金Supported by the National Key Research and Development Program(No.2016YFB0901600)Science and Technology Commission of Shanghai(No.16JC1401700 and16ZR1440500)NNSFC(Nos.11404358 and 51402341)
文摘A new compound of KCdAsS_3(Mr = 322.60) was successfully synthesized using thiourea reactive flux method. The crystal structure was determined by single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic system of space group P21/n with a = 5.9537(7), b = 16.633(3), c = 6.093(1) ?, b = 90.781(3)°, V = 610.0(1) ?3, Z = 4, Dc = 3.513 g/cm3, m(Mo Kα) = 10.52 mm-1, F(000) = 592, R = 0.057 and w R = 0.136 for 899 observed reflections with I > 2σ(I). The crystal structure of KCdAsS_3 features [Cd As S3]-layers, which are separated by K+ ions. First-principles calculations show that KCdAsS_3 is an indirect band gap semiconductor with a band gap of 2.3 e V. The novel layered compound of tetrahedra CdS_4 and pyramids AsS_3 is potentially useful for photoluminescent, photocatalytic and photoelectric applications.
文摘Investigation of the electric properties of semi-conducting materials in an applied ac electric fields gives information about the nature of charge transport and localized states in the forbidden gap. Layered crystals usually contain structural defects, such as dislocations and vacancies that may form a high density of localized states near the Fermi level. So, the current study was carried out for insight into the dielectric Properties of Tl2S layered single crystals. These properties were studied using the ac measurements in the low temperatures ranging from 77 to 300 K. The real part of dielectric constant ε?, imaginary part of dielectric constant ε?, the dissipation factor tan δ and the alternating current conductivity σac were measured in an applied ac electric field of frequencies extending from 2.5 to 50 kHz. Based on the dependencies of these dielectric parameters on both the frequency and temperature, the dielectric properties of the crystals under investigation were elucidated and analyzed. The ac conductivity was found to obey the power law σac(ω) = Aωs with which the values of the exponent s were evaluated to be less than unity in the range 0.21 ≥ s ≥ 0.19. Furthermore, it was found that the temperature dependence of ac conductivity follows the Arrhenius relation via which the impact of temperature on the electrical processes in an applied ac electric field was illustrated and analyzed. The influences of temperature and frequency on both the exponent s and band gap were also discussed in this investigation.
文摘Zeolite FSM 16 was synthesized by reconstruction of layered silicate in the presence of organic surfactant. With partial replacement of Ti 3+ with organic cations, TiO 2 nano structured particles were simultaneously built in the channel of the zeolite as the framework of the zeolite was formed. XRD, IR and Raman spectroscopic characterizations indicate that SiO 4 tetrahedron may be distorted and transferred from Q 3 to Q 2 form due to the pucker and reconstruction of the layered structure. The formation of TiO 2 nano structured particles had no influence on the formation of zeolite framework, however, the interaction obviously occurred between TiO 2 nano structured particles and zeolite framework.
