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981.
Pb(Zr0.4Ti0.6)O3 [PZT(40/60)] thin films were deposited onto LaNiO3 (LNO) coated Si substrates by sol-gel technique. Three kinds of gases, air, O2 and N2, were used as the annealing ambient. The effect of the annealing ambient on their structure and ferroelectric properties was investigated. The results showed that both the films annealed in air and O2 were the complete perovskite phase with (1 0 0) preferential orientation, while those annealed in N2 were random orientation including some pyrochlore phases. As compared with the air ambient, either too much O2 or too much N2 was detrimental to the ferroelectric properties of PZT films. The difference in structure and ferroelectric properties was mainly associated with the intermediate phases and the concentration of domain pinning centers in the films. 相似文献
982.
A novel red long lasting phosphorescent materials β-Zn3(PO4)2:Mn2+,Sm3+ is firstly synthesized by high-temperature solid-state reaction. The influence of Sm3+ ions on luminescence and long lasting phosphorescence properties of Mn2+ in phosphor β-Zn3(PO4)2:Mn2+,Sm3+ are systematically investigated. It is found that the red phosphorescence (λ = 616 nm) performance of Mn2+ ion such as brightness and duration is largely improved when Sm3+ ion is co-doped into the matrix in which Mn2+ ion acts as luminescent center and Sm3+ ion plays an important role of electron trap. Thermoluminescence spectrums show that there exists one peak in β-Zn3(PO4)2:Mn2+,Sm3+, the depth of which is 0.33 eV, and that there are three peaks in β-Zn3(PO4)2:Mn2+, among which the depth of the lowest temperature peak in β-Zn3(PO4)2:Mn2+ is 0.37 eV. Such differences in the trap depth result in the improvement of red long lasting phosphorescence of Mn2+ in present matrix. 相似文献
983.
Yu Qiu 《Materials Research Bulletin》2005,40(5):794-799
Novel blue-emitting cyanuric acid-melamine complexes CAx·M1−x (x = 0.8-0.9) have been prepared by a simple two-step procedure from urea. Relatively strong and pure blue-light emission with a maximum at 470 nm was observed from these complexes. These complexes are very promising light-emitting materials due to their good thermal stability. 相似文献
984.
Ba2(Zn0.5Ti0.5X)O6 compounds from the general ABO3 perovskite family were synthesized by the classical solid-state route for X = Nb and Ta with various A/B ratios (1.005, 1 and 0.995). After the calcination step at 1100 °C, both compounds (X = Nb and Ta) contain mainly the cubic disordered ‘Ba2(Zn0.5Ti0.5X)O6’ phase but traces of BaTiO3 and secondary phases are often detectable. Nevertheless, after the sintering stage at higher temperature (from 1300 to 1500 °C) and for all A/B ratios investigated, Ti enters into the cubic perovskite structure, resulting in the formation of a unique ‘Ba2(Zn0.5Ti0.5X)O6’ phase. Attractive dielectric properties have been measured on the tantalum-based compound for A/B = 0.995 (Q ∼2000 at 7.4 GHz and ? = 39.6) as well as on the niobium-based phase for A/B = 1.005 (Q ∼2200 at 6.1 GHz and ? = 54.8). All these characteristics were confirmed at 1 MHz and a linear dependence of the permittivity versus temperature from −60 to 180 °C has also been evidenced for both formulations. Sinterability, dielectric properties and microstructure of such compounds are discussed with respect to the stoichiometry. 相似文献
985.
Sergio L. González-Cortés Tian-Cun Xiao Nick Rees Dora Méhn Malcolm L.H. Green 《Materials Research Bulletin》2005,40(7):1112-1119
The first examples of mesostructured materials containing Mo- and W-oxo-sulphur species incorporated into a poorly ordered MCM-41 framework have been prepared under hydrothermal condition and alkaline medium. The incorporation of oxygen-sulphur derivates of molybdenum and tungsten not only increases significantly the pore diameter, but also improves the thermal stability of the MCM-41-related mesoporous material. 相似文献
986.
In order to understand the relationship between crystal structure and thermoelectric properties, the neutron diffraction patterns of the thermoelectric materials with the nominal composition CexCo4Sb12 (x = 0.5, 1.0) were measured at room temperature, the data were fitted by the Rietveld profile refinement method using the Fullprof2k program. It is found that the sample Ce0.5Co4Sb12 is composed of two phases, its major phase is CoSb3 with skutterudite-structure and the Ce atom is not incorporated into the lattice, the impurity is monoclinic CoSb2. In the case of Ce1.0Co4Sb12, the major phase is filled skutterudite, about 10% of the 2a site is occupied by Ce atom, the second phase is monoclinic CoSb2. 相似文献
987.
Sayaka Yanagida Yoshikazu Kameshima Toshiya Watanabe 《Materials Research Bulletin》2005,40(8):1335-1344
TiO2 (anatase) coating was prepared on stainless mesh by electrophoretic (EPD) process utilizing an isopropyl alcohol (IPA)-based suspension with submicron TiO2 powder. When the deposition time was 30 s, a smooth thin coating was obtained. It remained crack-free even after sintering. Coating surface morphology was roughened by UV pre-illumination of the suspension. Photocatalytic decomposition of IPA to acetone and resultant electrochemical reaction at cathode during EPD provides heterogeneous deposition. 相似文献
988.
989.
Phase evolution, densification, and dielectric properties of MgTi2O5 dielectric ceramic, sintered with lithium borosilicate (LBS) glass, were studied. Reaction between LBS glass and MgTi2O5 was significant in forming secondary phases such as TiO2 and (Mg,Ti)2(BO3)O. The glass addition was not necessarily deleterious to the dielectric properties due to the formation of TiO2: permittivity increased and temperature coefficient of resonance frequency could be tuned to zero with the addition of LBS glass, although the inevitable glass-induced decrease of quality factor was not retarded by the formation of TiO2. The sintered specimen with 10 wt% LBS fired at 950 °C for 2 h showed permittivity of 19.3, quality factor of 6800 GHz, and τf of −16 ppm/°C. 相似文献
990.
Yi-Cheng Liou Chi-Ting Wu Ko-Hao Tseng Tzu-Chin Chung 《Materials Research Bulletin》2005,40(9):1483-1489
Synthesis of BaTi4O9 ceramics by a reaction-sintering process was investigated. The mixture of raw materials for stoichiometric BaTi4O9 were pressed and sintered into ceramics without any calcination stage involved. Pure BaTi4O9 phases were obtained at 1150-1280 °C. High-sintered density, 98.2-99.5% of theoretical value (4.533 g/cm3), can be obtained for pellets sintered at 1200-1280 °C for 2-6 h. Some rod-shaped grains 3-7 μm in the longitudinal axis appear in pellets sintered at 1230 °C. Both the size and the amount of these rod-shaped grains increase at higher sintering temperature. 相似文献