Effect of Er,Gd, and Nd Co-Dopants on the Properties of Sm-Doped Ceria Electrolyte for IT-SOFC

Doped ceria electrolytes of Ce_0.8Sm_0.20O_1.90 (SDC), Ce_0.8Er_0.08Sm_0.12O_1.90 (ESDC), Ce_0.8Gd_0.08Sm_0.12O_1.90 (GSDC), and Ce_0.8Nd_0.08Sm_0.12O_1.90 (NSDC) were prepared by a citric–nitrate combustion process. The thermal decomposition of the precursor was investigated by simultaneous thermogravimetric analysis and differential thermal analysis experiments. The phase structure of the calcined and sintered powders was characterized by X-ray diffraction analysis. All of the samples were fluorite-type ceria-based solid solutions. The calcined and sintered powders were also characterized by Fourier transform infrared spectroscopy. Scanning electron microscopy was used to characterize the samples after calcination and sintering. A relative density over 95 percent of the theoretical density was achieved after the sintering process. Electrical conductivities of the sintered samples were measured using the impedance spectra method. The highest ionic conductivity value was found to be 5.28 × 10^?2 S cm^?1 at 1023 K (750 °C) for GSDC sintered at 1673 K (1400 °C) for 6 hours.     

Preparation and characterization of Ce_(0.8)La_(0.2–x)Y_xO_(1.9) as electrolyte for solid oxide fuel cells

In this study, ultrafine Ce0.8La0.2–x Y x O1.9（for x=0, 0.05, 0.10, 0.15, 0.20） powders were successfully prepared by the sol-gel method.The samples were characterized by fourier transform infrared（FTIR）, thermogravimetric and differential scanning calorimetry（TG-DSC）, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, AC impedance and thermal expansion measurements.Experimental results indicated that highly phase-pure cubic fluorite electrolyte Ce0.8La0.2–x Y x O1.9 powders were obtained after calcining at 600 °C.The as-synthesized powders exhibited high sintering activity, the Ce0.8La0.2–x Y x O1.9 series electrolytes which have higher relative densities over 96% could be obtained after sintered at 1400 °C for 4 h.Ce0.8La0.15Y0.05O1.9 electrolyte sintered at 1400 °C for 4 h exhibited higher oxide ionic conductivity（σ800 oC=0.057 S/cm）, lower electrical activation energy（E a=0.87 e V） and moderate thermal expansion coefficient（TEC=15.5×10-6 K-1, temperature range 25–800 °C）.     

Helium ion irradiation effects on neodymium and cerium co-doped Gd2Zr2O7 pyrochlore ceramic

This paper studies the helium ions irradiation effects on Nd and Ce co-doped Gd_2 Zr_2 O_7 ceramics. where Nd replaces the Gd site and Ce replaces the Zr site respectively. A series of(Gd_(1-x)Nd_x)_2(Zr_(1-y)Ce_y)_2 O_7(0 ≤ x, y ≤ 1) ceramics were irradiated with a 500 keV He ions at room temperature at fluences ranging from 1 × 10~(15) to 1 × 10~(17) ions/cm~2. The irradiated samples were characterized using GIXRD, Raman and SEM measurements. From the GIXRD and Raman observations, the results indicate that all the samples display a deficient fluorite structure after irradiation. The irradiation toleration increases with the irradiation depth increasing under experimental conditions, and Nd_2 Ce_2 O_7 has the best irradiation stability in the(Gd_(1-x)Nd_x)_2(Zr_(1-y)Ce_y)_2 O_7(0≤ x. y≤1). Based on SEM results, the irradiated samples are still relatively dense and uniform, and no second phase exists.     

Synthesis and luminescent properties of BaGd2O4:Eu3+ phosphors with highly efficient red-emitting

The BaGd_(2-2 x)Eu_(2 x)O_4(BG, x = 0.01-0.09) phosphors were successfully synthesized via the sol-gel method,and BaY_(2-2 y)Eu_(2 y)O_4(BY, y = 0.005-0.07) phosphors were included for comparison. The pure phase BG phosphors with the ordered CaFe_2 O_4-type structure are obtained by annealing at 1300℃ for5 h. The phosphors with uniform particle size of 120 nm and good dispersion display typical Eu~(3+)emission with the strongest peak at 613 nm(~5 D_0→~7 F_2 transition of Eu3+) under optimal excitation band at 262 nm(CTB band). The presence of Gd~(3+) excitation bands on the PLE spectra monitoring the Eu3+emission directly proves an evidence of Gd~(3+)-Eu~(3+) energy transfer. Owing to the concentration quenching, the optimum content of Eu3+ addition is 5 at%(x = 0.05), and the quenching mechanism is determined to be the exchange reaction between Eu3+. All the BG samples have similar color coordinates and temperature of(0.64 ± 0.02, 0.36 ± 0.01) and 2000 ± 100 K,respectively. The lifetime value of BaGd_(1.9)Eu_(0.1)O_4 for 613 nm is fitted to be 2.19 ± 0.01 ms, and the Eu~(3+) concentration does not change the lifetime significantly. Owing to the Gd~(3+)-Eu~(3+) energy transfer, the luminescent intensity of the BaGd_(1.9)Eu_(0.1)O_4 phosphor is better than BY system. The BG system served as a new type of phosphor is expected to be widely used in lighting and display areas.     

Ce3+ sensitized Tb3+ and Dy3+ photoluminescence in β-LaB5O9 prepared by sol–gel method

Rare earth (RE) pentaborates, both α- and β-polymorphs, are good candidates for photoluminescent hosts suitable for various RE activators. Ce³⁺ acts not only as an activator itself, but also as a sensitizer to other rare earth activators, like in the case of commercial green phosphor CeMgAl₁₁O₁₉:Tb³⁺. In this work, two solid solutions of β-La_0.9–xCe_0.1Tb_xB₅O₉ (0 ≤ x ≤ 0.15) and β-La_0.9–yCe_0.1Dy_yB₅O₉ (0 ≤ y ≤ 0.07) were prepared by sol–gel method with high crystallinity, and the phase purity was confirmed with careful analyses on powder X-ray diffraction patterns. Energy transfers are expected due to the overlapping of Ce³⁺ emission with the Tb³⁺/Dy³⁺ excitation. Indeed, the steady photoluminescence spectra indicate the decrease of the Ce³⁺ emission and the increase of the Tb³⁺/Dy³⁺ emission, and the fluorescence decay curves exhibit the decrease of the average lifetime of Ce³⁺. The energy transfer efficiency is estimated to be 60% at x = 0.15 and 55% at y = 0.07, respectively. The mechanism is likely through the dipole–dipole electric interactions for both cases. With this rationale, the Tb³⁺ and Dy³⁺ emissions are greatly enhanced, in particular, the white emission of Dy³⁺ in β-La_0.85Ce_0.1Dy_0.05B₅O₉ is enhanced by 20 times.     

Solid-state reaction synthesis and chemical stability studies in Nd-doped zirconolite-rich ceramics

In this study, Nd-bearing zirconolite-rich ceramics were prepared by solid-state reaction process using CaF_2,ZrO_2, Ti,TiO_2, Fe_2 O_3 and Nd_2O_3 as the raw materials. Neodymium was used as trivalent actinide surrogate and designed to substitute the Ca and Zr sites of zirconolite with general stoichiometry of Ca_(1-x)Zr_(1-x)Nd_(2 x)Ti_2O_7(0≤x≤0.3). Density of Fe-Nd-O sample reaches a maximum value of 4.13 g/cm~2 after being sintered at 1325 ℃ for 42 h. Three major phases, namely zirconolite, perovskite and pseudobrookite, are observed in all these samples. The EDX result shows that Nd_2O_3 can be successfully incorporated into the lattice structure of the prepared zirconolite-rich minerals and replace the Ca sites of zirconolite and perovskite with Fe~(3+) as the charge-compensating ion. Furthermore, the thermal conductivities are all in the range of 1.51-1.67 W/(m·K). The normalized elemental leaching rates of Ca and Nd in the Fe-Nd-0.2 sample keep in low values of 6.20 × 10~(-2) and 4.86 x 10~(-4) g/(m~2·d) after 42 d.     

Phase relations,microstructure, and valence transition studies on CaZr_(1-x)Ce_xTi_2O_7(0.0≤x≤1.0) system

In this study, Ce-doped zirconolite was synthesized through high-temperature solid-state reaction at 1250 ℃ in air for 96 h. The crystal phase.microstructure and valence transition were studied by X-ray diffraction(XRD), scanning electron microscopy(SEM), and X-ray photoelectron spectroscopy(XPS).Phase relations of CaZr_(1-x)Ce_xTi_2O_7 systems were determined by XRD analyses and Rietveld refinements.Four different phases are identified, namely zirconolite, perovskite, pyrochlore, and cerianite. The phase transformation(2M-zirconolite → 4M-zirconolite → Ce-pyrochlore) is caused by cations rearrangement as cerium content increases. The solubility limit of cerium ions in CaZr_(1-x)Ce_xTi_2O_7 system is estimated to be approximately 0.80. Under sintering air atmosphere, partial reduction of Ce~(4+) in Ce~(3+) is detected in Ce 3d XPS spectra, and the ratio of Ce~(3+) and Ce~(4+) significantly decreases as cerium content increases.     

Synthesis and luminescence properties of novel Ce3+-doped Yb3Al5–xGaxO12 garnets with very fast decay time

A novel series of Ce~(3+)-doped Yb_3 Al_(5-x)Ga_xO_(12)(x = 0, 1,2, 3,4, 5) powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The ytterbium aluminum garnets were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, photoluminescence spectra and decay curves. Moreover, the substitution effect for the Al~(3+) sites with Ga~(3+) in 0.5 at%Ce:Yb_3 Al_(5-x)Ga_xO_(12)(x = 0,1, 2, 3, 4, 5) garnets were discussed. With the increase of Ga~(3+) ion concentration, the visible absorption peaks within 400-450 nm have blue shift phenomenon,while the absorption peaks in the range of 330-350 nm and the absorption band edge red shifts.Furthermore, the short decay times are very short with less than 10 ns due to the Yb~(3+) + Ce~(3+)→ Yb~(2+) + Ce~(4+) electron transfer reaction.     

Effect of erbium doping on phase composition,mechanical and thermal properties of ZrO2-based ceramics

Er_xTi_0.1Zr_0.9–xO_2–1.5x (x = 0.04, 0.05, 0.06, 0.07, 0.08) ceramics were synthesized by a solid-state reaction method. The influence of the Er³⁺ addition on the phase composition, Vickers hardness, fracture toughness, and thermal conductivity of this ceramic material was investigated. The X-ray diffraction results reveal that the c-ZrO₂ content increases from 1.85 vol% to 33.89 vol%, and the percentage of t-ZrO₂ decreases from 98.15 vol% to 66.11 vol% with the increase in Er³⁺ content from 4 mol% to 8 mol%. Moreover, the addition of Er³⁺ is beneficial to the volume expansion of the unit cell. At the same time, the incorporation of Er³⁺ weakens the coordination of oxygen ions around the metal cations, resulting in a corresponding decrease in the tetragonality of the t-ZrO₂. The Vickers hardness and fracture toughness of the Er_xTi_0.1Zr_0.9–xO_2–1.5x ceramics show increasing and decreasing trends, respectively. The thermal conductivity has a significant decline due to point defects caused by the Er³⁺ doping. The 8ETZ ceramic exhibits the highest Vickers hardness (12.7 GPa), the lowest fracture toughness (7.6 MPa?m^1/2), and the lowest average thermal conductivity (1.85 W/(m·K)) in the temperature range of 200–1000 °C. All of the above properties are higher than those of the Y₂O₃-stabilized ZrO₂ ceramic.     

Solid-State Phase Equilibria of the V-Si-Gd System at 973 K (700 °C)

The solid-state phase equilibria of the V-Si-Gd ternary system at 973 K (700 °C) were experimentally evaluated. The existence of nine binary compounds, namely, V₃Si, V₅Si₃, V₆Si₅, VSi₂, Gd₅Si₃, Gd₅Si₄, GdSi, GdSi_1.67, and GdSi_2?x , was confirmed, and no ternary compound was found at 973 K (700 °C). The homogeneity ranges of V₃Si and GdSi_2?x were investigated. It is worth mentioning that the Gd₃Si₄ compound was discovered through changing the experimental conditions, and its crystal structure was discussed.     

Synthesis and characterization of tungsten and barium co-doped La_2Mo_2O_9 by sol-gel process for solid oxide fuel cells

Herein, we demonstrate the synthesis of W and Ba co-doped La_2Mo_2O_9(LBMWO) nanocrystalline powder by a sol-gel process. In all the compositions have general formulae La_(1.9)Ba_(0.1)Mo_(2-x)W_xO_(8.95)(x = 0-0.40). The crystal structure, microstructure and conductivity of LBMWO were characterized by X-ray diffraction, scanning electron microscopy and electrical impedance spectroscopy. In addition, the thermal and decomposition properties of the LBMWO gel were analyzed by differential scanning calorimetry-thermogravimetric. The results reveal that all LBMWO powders calcined at 700 ℃ have a cubic structure;the average crystallite size is about 48 nm. The unit cell parameter of LBMWO powders increases with increase in W content. The as-synthesized nanocrystalline LBMWO samples exhibit excellent sinterability and a relatively lower sintering temperature of 900 ℃. A high relative density of -96% is achieved after sintering at 900 ℃ which is in good agreeme nt with the re sults of the SEM. Moreover, W and Ba codoping suppresses the phase transition and effectively stabilizes the β-phase at low temperature. At the same time,La_(1.9)Ba_(0.1)Mo_(1.85)W_(0.15)O_(8.95) exhibits high ionic conductivity, 3.07 x 10~(-2) S/cm at 800 ℃. It is therefore concluded that co-doping can improve the properties of La_2MO_2O_9 electrolytes.     

Synthesis and characterization of YAG: Ce3+ fluorescence powders by co-precipitation method

YAG:Ce³⁺(Yttrium aluminum garnet) fluorescence powders were successfully prepared by co-precipitation method using aluminum nitrate, yttrium nitrate, cerous nitrate as the starting materials and ammonium carbonate as precipitant. The products were characterized by X-ray powder diffraction, luminescence spectrometer, transmission electron microscope (TEM). The XRD results showed that the obtained YAG:Ce³⁺ fluorescence powders had the crystalline structures of YAG at calcinations temperature of 900 °C and the TEM results showed that the grain diameters were about 100 nm. The YAG:Ce³⁺ fluorescence powders, synthesized by co-precipitation method, had the best luminescence property when the Ce doping amount was x=0.06 in the molecular formula of Y_3-xCe_xAl₅O₁₂, the calcinations time was 2 h and the calcinations temperature was 1000 °C.     

Preparation of M/Ce1–xTixO2 (M=Pt,Rh, Ru) from sol-gel method and their catalytic oxidation activity for diesel soot

A series of Ce_1–xTi_xO₂ mixed oxide catalysts were synthesized by sol-gel method and then loading of noble metal (M = Pt, Rh, Ru) was used for soot oxidation. Ti-doped Ce_1–xTi_xO₂ catalysts (x is the molar ratio of Ti/(Ti + Ce) and ranges from 0.1 to 0.5) exhibit much better oxidation performance than CeO₂ catalyst, and the Ce_0.9Ti_0.1O₂ catalyst calcined at 500 °C has the best catalysis activity. Each noble metal (1 wt%) was supported on Ce_0.9Ti_0.1O₂ (M/C9T1) and the properties of the catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, Brunauer–Emmett–Teller (BET) method, and H₂-temperature programmed reduction (H₂-TPR) results. Results show that the introduction of Ti into CeO₂ forming Ti-O-Ce structure enhances the catalytic activity and increases the number of oxygen vacancies at the catalyst surface. The noble metal is highly dispersed over Ce_0.9Ti_0.1O₂, and M/C9T1 catalysts present enhanced activity in comparison to Ce_0.9Ti_0.1O₂. It is found that noble metals can greatly increase the activity of the catalyst and the corresponding oxidation rate of soot can enhance the electron transfer capacity and oxygen adsorption capacity of the catalyst. A small amount of Ti doping in CeO₂ can significantly improve the activity of the catalyst, while a large amount of Ti reduces the performance of the catalyst because a large amount of Ti is enriched on the surface of the catalyst, which hinders the contact and reaction between the catalyst and the soot.     

Evaluation of Dielectric Properties, Vibration Modes, and Crystal Structures in Ba[Zn(1?x)/3Ni x/3Nb2/3]O3 Ceramics

Microwave dielectric ceramics of Ba[Zn_(1?x)/3Ni _x/3Nb_2/3]O₃ (BZNN, x = 0.0, 0.5, 0.6, 0.7, 0.8) were sintered at 1773 K (1500 °C) for 3 hours by the conventional solid-state reaction method. To clarify the relationship between dielectric properties and crystal structures, vibration spectra (Raman spectroscopy and Fourier transform far-infrared reflection spectroscopy (FTIR)) and X-ray diffraction (XRD) were employed to study Ba[Zn_(1-x)/3Ni_x/3Nb_2/3]O₃ solid solutions. Crystal structures were determined as cubic perovskite structures, and no phase transition appears in substitution of Ni²⁺ to Zn²⁺ ions. Raman spectroscopy was used to discuss the correlation of dielectric properties with Raman shifts and full-width at half-maximum (FWHM) values, which indicate that dielectric properties are closely related to both FWHM values and A_1g(Nb) mode shifts. FTIR spectra and imaginary parts of dielectric constants were calculated to obtain the correlation between polar phonon modes and dielectric properties with Ni²⁺ concentration.     

Effects of Er3+ doping on structure and thermal properties of (Sm1–xErx)2Zr2O7 ceramics for thermal barrier coating

Rare earth Er³⁺ doped (Sm_1–xEr_x)₂Zr₂O₇ (x = 0.1, 0.2, and 0.3) ceramic samples were synthesized using a solid state reaction method. The microstructure and thermal properties of these ceramics were investigated to evaluate their potential as thermal barrier coating materials. The results show that ceramics are compact with regular-shaped grains of 1–5 μm size. (Sm_1–xEr_x)₂Zr₂O₇ has a pyrochlore structure mainly determined by ionic radius ratio, but the ordering degree decreases with increase of the Er₂O₃ content. There is no phase transformation from 1000 to 1200 °C, and the (Sm_1–xEr_x)₂Zr₂O₇ ceramics exhibit excellent phase stability during thermal treatment at 1200 °C for 100 h and 1400 °C for 50 h. The thermal conductivities of dense (Sm_1–xEr_x)₂Zr₂O₇ ceramics range from 1.52 to 1.59 W/(m·K), which is lower than that of Sm₂Zr₂O₇, and decrease as the Er₂O₃ content increases. Besides, the thermal expansion coefficient of (Sm_1–xEr_x)₂Zr₂O₇ is higher than that of Sm₂Zr₂O₇.     

Effect of coating modification of cordierite carrier on catalytic performance of supported NiMnO3 catalysts for VOCs combustion

NiMnO_3 perovskite catalysts supported on cordierite modified by Ce_xZr_(1-x)O_2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concentrations and GHSV of 15,000 h~(-1), which were characterized by BET, XRD, SEM, FT-IR, H_2-TPR and O_2-TPD. After coating modification, the specific surface area of catalysts is improved obviously.Among the catalysts, the Ce_(0.75)Zr_(0.25)O_2 coating modified NiMnO_3 catalyst exhibits the best catalytic activity for VOCs combustion with 95.6% conversion at 275 ℃ and has stable activity when catalyst is embalmed at 800 ℃. In addition, the catalyst also presents the excellent water-resistant and conversion stability over time-on-stream condition. The reason is that Ce_(0.75)Zr_(0.25)O_2 coating can promote more lattice distortion and defects and smaller crystal size, which improve oxygen transfer capability and dispersion of active component.     

Processing and Consolidation of Nanocrystalline Cu-Zn-Ti-Fe-Cr High-Entropy Alloys via Mechanical Alloying

In the current investigation, nanocrystalline multicomponent high-entropy alloys (HEAs) have been synthesized in the Cu _x Zn _y Ti₂₀Fe₂₀Cr₂₀ system (x/y = 1/0, 3/1, 1; and x + y = 40) by mechanical alloying and subsequently consolidated using spark plasma sintering (SPS) in argon atmosphere at a pressure of 50 MPa. A detailed X-ray diffraction and transmission electron microscopy study reveals the presence of both FCC copper solid-solution, (Cu)_ss and BCC chromium solid-solution, (Cr)_ss phases in both the mechanically alloyed powders as well as the sintered compacts. The phase formation and stability of the sintered multicomponent Cu _x Zn _y Ti₂₀Fe₂₀Cr₂₀ with x/y = 3/1 and x + y = 40 pellet have been studied at different sintering temperatures, i.e., 873 K, 973 K, 1073 K, and 1173 K (600 °C, 700 °C, 800 °C, and 900 °C). The important findings include that high Vickers bulk hardness of around 6 GPa and relative density of around 95 pct reported in the Cu _x Zn _y Ti₂₀Fe₂₀Cr₂₀ with x/y = 3/1 and x + y = 40 HEAs, SPSed at 1173 K (900 °C). The formation, consolidation, and microstructural details are analyzed critically and discussed.     

Chemical State, Site, Solid Solubility, and Magnetism of Fe in the Ferropericlase (Mg1–x Fe x )O Produced by Ball Milling of MgO and Fe

Ferropericlase (Mg_1–x Fe _x )O solid solution was prepared by ball milling of the mixture of MgO with a rock-salt structure and metal Fe powders in atmosphere and at room temperature. Differing from (Mg_1–x Fe _x )O prepared at high temperature by using MgO and FeO as starting materials, the solution of Fe in MgO is not continuous but limited in the ball milling process, and the solubility limit is less than 30 at. pct. About 92 pct of the Fe ions occupy the site of tetrahedral oxygen coordination in trivalent Fe (Fe³⁺) with high spin, whereas about 8 pct of the Fe ions occupy the site of octahedral oxygen coordination in bivalent Fe (Fe²⁺) with high spin. The Fe³⁺ and Fe²⁺ ions do not show a ferromagnetic but show a paramagnetic state. The as-milled (Mg_1–x Fe _x )O is metastable and decomposes to ferropericlase (Mg_1–y Fe _y )O (where y < x) and MgFe₂O₄ with spinel structure as annealed above 773 K (500  °C), and the content of Fe in the (Mg_1–y Fe _y )O increases with increasing annealing temperature. A bulk (Mg_1–x Fe _x )O was fabricated by annealing the as-milled (Mg_1–x Fe _x )O powders at 973 K (700  °C). It shows n-type conductivity, which is attributed to an electronic small polaron with an activation energy of 0.135 eV.     

Photoluminescence of BaGdB9O（16）：Eu^3＋ co-doped Al^3＋ or Sc^3＋ under UV-VUV excitation

Single phase of BaGd0.9-xMxEu0.1B9O16 (M=Al or Sc, 0≤x≤0.3) powder was prepared by the solid-state reaction and its photoluminescence (PL) properties were investigated under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation. Monitored with 613 nm emission, the excitation spectra of BaGd0.9-xMxEu0.1B9O16 consisted of three broad bands peaking at about 242, 208, and 142 nm, respectively. The one at about 242 nm originated from the charge transfer band (CTB) of O2-→Eu3+. The other two were assigned to the absorption of the host, which was overlapped with absorptions among borate groups, f→d transition of RE3+ (RE=Gd, Eu), and the charge transfer transition of O2-→Gd3+. The maximum emission peak was observed at about 613 nm in the emission spectra of BaGd0.9-xMxEu0.1B9O16 under both 254 and 147 nm excitation, which originated from the electric dipole 5D0→7F2 transition of Eu3+. When excited with 254 nm, the integral emission intensity of Eu3+ increased after Al3+ or Sc3+ substituting Gd3+ partly in BaGd0.9Eu0.1B9O16. Under 147 nm excitation, the integral emission intensity of Eu3+ decreased after some Gd3+ was replaced by Sc3+, but increased after adding appropriate Al3+ into BaGd0.9Eu0.1B9O16.     

Variation of optimum yttrium doping concentrations of perovskite type proton conductors BaZrl_xYxO3-~ （0~~~_0.3） with temperature

A solid state reaction method was used to prepare the perovskite-structured compounds BaZrl-xYxO3-a （x=0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3）. The X-ray diffraction （XRD） pattern indicated that the target perovsldte phases were obtained. With increasing Y con- centration the unit cell parameters of BaZrl-xYxO3-a samples were expanded, and Y doping became more difficult. However, high synthesis temperature is helpful to promote Y doping. The SEM results showed that the samples exhibited poor sinterability with in- creasing Y-doping content. Thermal gravimetric （TG） curves analysis showed the more mass decreasing of BaZrl-xYxO3-a （0≤x≤0.3） samples at high temperature with more Y doping and more proton introducing. The electrochemical impedance spectra （EIS） of specimens showed that conductivities of BaZrl_xYxO3（0≤x≤0.3） increased with increasing temperature from 300 to 900 ℃ in wet air. At 900 ℃, the conductivity of BaZrl-xYxO3-a （0≤x≤0.3） first increased with increasing doped amount of Y, and reached the high- est value of 1.07x 104 S/cm when x was 0.2, then decreased gradually with further increasing Y content. At 600 ℃, BaZr0.75Y0.2503-a displayed the highest conductivity, while the conductivity of BaZro.rYo.303-a was the highest at 300 ℃. The results indicated that there should be an optimum Y doping concentration yielding the highest conductivity at a constant temperature, and the optimum Y doping concentration should increase in the humidity atmosphere as the temperature decreases. So increasing the Y-doping concen- tration is helpful to improve the conductivities of BaZrl-xYxO3-a materials at low temperature.