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Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

By hydrothermal synthesis method for Gd3+doping, phosphors precursor was prepared with Eu3+ as activator and glutamate (Glu) as auxiliary complexing agent. And a series of CaSrMoO4 : Eu3+ : Gd3+ red phosphors were obtained under 800 °C calcination. The structure and morphology of the red phosphor were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), fluorescence spectrum (PL) was used to measure the luminous performance and life of phosphor powder, and color coordinate (CIE) analysis was performed on the results. The results showed that with the introduction of Gd3+, the energy exchanged between Eu3+ and the size of the prepared red phosphor was realized. Doping Gd3+ ions had little effect on the crystal structure, and the crystal was a tetragonal structure with uniform particle size distribution and small particle size, ranging from 1.0 to 1.3 µm. Ultraviolet light at 395 nm and visible light at 465 nm could be effectively excited, which was matched with ultraviolet LEI) and blue LEI) chips, and its fluorescence life was 460.67 ms. The color coordinate test result was more close to the standard red color coordinate than the commercial one, which conformed to the standard requirements of the Color TV Flash Powder Issued in China and was close to the standard value of the National Television Standard Committee of the United States. It has the potential to become a commercial red flash powder. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Piezoelectric acceleration sensors are used for monitoring the vibration state of high-temperature components of some important technical equipment, such as aero engines and heavy gas turbines. These sensors require a high Curie temperature piezoelectric ceramic as a sensitive element, and "lead-free"electronic components are an urgent requirement for environmental protection. Gd/Mn co-doped high-temperature lead-free piezoelectric ceramics((0.67BiFeO3-0.33Ba1-xGdxTiO3)+0.5%(mass fraction)MnO2, x=0-0.02, BF-BT) were prepared by a traditional solid-state reaction process. The effects of doping concentration x of Gd3+ on the phase composition, microstructure, piezoelectric property, dielectric relaxation behavior and AC impedance characteristic of BF-BTceramics were investigated. The results show that all samples have pure perovskite structure with coexistence of tripartite phase (R) and tetragonal phase (T), and the T phase content increases with the increasing Gd3+ doping concentration. Moderate amount(x < 0.02)of Gd3+ dopant diffusing into the perovskite lattice would also promote the grain growth of BF-BT ceramics. Gd3+ doped samples exhibit enhanced relaxation phase transition behavior. The phase transition temperature (Tm) decreases with the increase of x, while the dielectric relaxation degree (ΔTrelax) increases with the increase of x. The R-CPE equivalent circuit model has been utilized to match the complex impedance spectra(Cole-Cole diagrams) of the BF-BTceramics, indicating that the AC impedance of samples at high temperature is mainly contributed by the grain boundary. The activation energy of dielectric relaxation increases with the increasing Gd3+ doping concentration, demonstrating the substitution of Gd3+ for Ba2+ can reduce the donor doping effect.In general, when x=0.01, the sample exhibits the optimized electrical properties, including TC=425 ℃, d33=126 pC/N, kp=25.9%, and tanδ=0.059. The Gd3+ doped BF-BTceramics are expected to be used as a promising high-temperature piezoelectric material.

Gd2O3 doped CeO2(GDC) was widely used in solid oxide fuel cell (SOFC) because of its high ionic conductivity at 500-700 ℃. However, during the SOFC operation, Ce4+ was reduced to Ce3+ at the anode side of the battery, resulting in electronic leakage, which leaded to the degradation of SOFC battery performance. The Ce1-xGdxO2-δ(x=0.05,0.10,0.15,0.20,0.25, mole fraction) solid electrolyte was prepared by sol-gel method. The effects of different Gd3+ doping amount on the total conductivity and electronic conductivity of GDC electrolyte were studied, and the relationships between the total conductivity, electronic conductivity, and temperature, oxygen partial pressure were analyzed. The results show that, when the Gd2O3 doping content is 0.20, the total conductivity of GDC reaches the highest 8.59×10-2 S·cm-1 at 750 ℃. The electronic conductivity decreases with the increase of Gd3+doping amount, and reaches the highest 6.47×10-4 S·cm-1 at 750 ℃ when Gd3+doping amount is 0.10. The GDC with doping amount of 0.20 highlights the highestionic conductivity because of its highest total conductivity and smaller electronic conductivity.

Copyright of Journal of Synthetic Crystals is the property of Journal of Synthetic Crystals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Yb3+/EP(3+) -co-doped cubic NaYF4 and Yb3+/Er3+/Gd(3+) -tri-doped hexagonal NaYF4 nanocrystals were synthesized by a modified coprecipitation method with ethylenediamine tetraacetic acid (EDTA) as chelating agent. The samples' morphology, crystal phase and upconversion emission were measured with transmission electron microscope (TEM), X-ray diffraction patterns (XRD) and upconversion luminescence spectrum. TEM and XRD results showed that the phase transition from cubic to hexagonal was promoted through Gd3+ doping. It has been reported that the upconversion efficiency of hexagonal NaYF4 is higher than that of cubic NaYF4, however, the effect of crystal phase on upconversion luminescence has not been well understood. This work focuses analysis of measurement results to compare the effect of, crystal phase on the crystal field energy splitting and upconversion emission intensity as well as emission color, and a mechanism of luminescence enhancement and color tunability are revealed. Strong visible upconversion luminescence can be seen clearly by the naked eyes in both cubic phase and hexagonal phase samples upon excitation by a 980 nm laser diode with power of 10 mW, consisting of green emissions centered at around 525/550 nm originating from the transitions of 2H11/2/4 S3/2 --> 4 I15/2 and red emission at about 657 nm from 4F9/2 to 4 I15/2 of Er3+ ions respectively. In comparison to cubic sample, the hexagonal phase sample presented much stronger and sharper upconversion luminescence, whose emission efficiency was enhanced 10 times with an additional transition of 2 H9/2 --> 4I13/2 at 557 nm, furthermore, the intensity ratio of red to green emission increased from 2 :1 to 3 : 1. Doping NaYF4 nanocrystals with Gd3+ ions induced the hexagonal-to-cubic phase transition and thus decreased the crystal symmetry, consequently increased absorption cross-section and 4f-4f transition probabilities by relaxing forbidden selection rules, resulting in stronger emission. In the mean time, the decreasing unit-cell volume of the hexagonal phase increased the crystal field strength around the dopant ions and consequently led to that hexagonal phase samples present much sharper emission compared to cubic counterparts. It demonstrates that phase transition can tune crystal field energy splitting, luminescence intensity and emission color.

The authors prepared Na2SO4: Eu, Gd, and Na2Gd2 (SO4)4: Eu phosphors by heating, the mixed powder of GdF3, EuF3 and natural mirabilite with muffle furnace at 1 000 degrees C for 30 min and continually heating it with microwave at 750 degrees C for 10 min. With increasing the concentrations of Gd ion, the 610 nm emission intensity due to Eu3+ was strengthened. Gd3+ probably formed a bridge between substrate and the activator so that the energy is able to be transferred efficiently. The luminescence intensity, along with colorimetric purity, reaches the top with 21 mol% Gd3+ doping in the thenardite (Na2SO4: Eu) lattices, eventually coming up the quenching effects of concentration.