Er3+ doped potassium gadolinium molybdate (KGM) phosphor with sensitizer Yb3+ ion was synthesized by the Pechini method using citric acid and ethylene glycol. The crystallization processes of the phosphor precurso...Er3+ doped potassium gadolinium molybdate (KGM) phosphor with sensitizer Yb3+ ion was synthesized by the Pechini method using citric acid and ethylene glycol. The crystallization processes of the phosphor precursors were characterized by X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TG-DSC), which indicated that ultrafine uniform crystallites of KGM:Er,Yb were obtained by sintering the precursors at above 650 ℃ for 5 h. Upconversion luminescence (UL) spectra of the samples were studied by a 976 nm semiconductor laser diode (LD) excitation. The UL spectra exhibited the green and red emission bands that were attributed to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, respectively. The possible UL mechanisms of Er3+ were explained by means of an energy level diagram. The maximum luminescent intensity was achieved when the concentration of Er3+, Yb3+ arrived at 1 mol.% and 20 mol.%, respectively.展开更多
Homogeneous (ZrO_2)0.92(Sc_2O_3)0.08 solid solution in fluorite cubic structure was prepared from the gels with altered molar ratios of citric acid (CA) to metal ions (M) and ethylene glycol (EG) via a polymeriz...Homogeneous (ZrO_2)0.92(Sc_2O_3)0.08 solid solution in fluorite cubic structure was prepared from the gels with altered molar ratios of citric acid (CA) to metal ions (M) and ethylene glycol (EG) via a polymerization route (Pechini method). Due to the enhanced chemical homogeneity (high level of mixing of metal ions and ligands) in the polymeric gels, Sc-doped zirconia can be crystallized at temperatures as low as 400 ℃. During the evolution from amorphous gel to the crystallized (ZrO_2)0.92(Sc_2O_3)0.08 fine powder, the bonding nature between carboxylate groups and Zr/Sc cations changed: unidentate→bridging→ionic upon calcination. The molar ratios of CA/M (1~4) and CA/EG (0.2~4) were demonstrated to affect the thermal behavior of the gels and thus the particle properties of the derived nanoparticulate oxide powders (including particle size and surface area). The as-sintered sample compacted from the nanosized powders prepared by calcining the gel with the highest content of organics (CA/M=4 and CA/EG=0.2) exhibited the best sinterability and the highest oxide ion conductivity.展开更多
Pr0.6-x NdxCa0.4 FeO3-δ ( x = 0.0, 0.2, 0.3, 0.4, 0.5, 0.6) were synthesized using Pechini method. A number of studies were conducted concerning composition, specific area, crystalline structure and microstructure ...Pr0.6-x NdxCa0.4 FeO3-δ ( x = 0.0, 0.2, 0.3, 0.4, 0.5, 0.6) were synthesized using Pechini method. A number of studies were conducted concerning composition, specific area, crystalline structure and microstructure of the samples by means of FT-IR, BET, XRD TG-DTA and SEM. The results show that all the samples with different doping amounts of Pr^3+ and Nd^3+ on A-site are fine dispersed, and mean particle size less than 100 nm. The powders have good sinterability, and the relative density is 95% after sintered at 1200 ℃ for 2 h. It is found that all specimens are entirely single phase solid solutions with orthorhombic perovskite structure, the stable perovskitetype phase is formed completely after calcination at 900 ℃.展开更多
Lead-free piezoelectric thin films of 0.055BaZrO3–0.935(K0.45Na0.5Li0.05)NbO3–0.01(Bi0.5Na0.5)TiO3(BZ–KNLN–BNT)were fabricated on(100)-LaNiO3/SiO2/Si substrates.The Pechini(polymeric ...Lead-free piezoelectric thin films of 0.055BaZrO3–0.935(K0.45Na0.5Li0.05)NbO3–0.01(Bi0.5Na0.5)TiO3(BZ–KNLN–BNT)were fabricated on(100)-LaNiO3/SiO2/Si substrates.The Pechini(polymeric precursor)method was carried out to prepare the complicated multi-component precursor solution.This method was suited for controlling the complex components accurately.The films crystallized at 700℃ showed a(100)pc-oriented perovskite structure,whose grain size was about 200 nm and thickness was about 700 nm.The Curie temperature Tc of the films was 292℃ that was near to that of the bulk ceramics.The preparation method used in this work provided a possibility for the application of multi-component lead-free piezoelectric films.展开更多
基金Project supported by Shandong Province Natural Science Foundation (Y2008F10)the Award Fund for Prominent Youth Scientists of Shandong Province (2008BS09006)Shandong Province Higher Educational Science and Technology Program (J10LD1810-13)
摘要Er3+ doped potassium gadolinium molybdate (KGM) phosphor with sensitizer Yb3+ ion was synthesized by the Pechini method using citric acid and ethylene glycol. The crystallization processes of the phosphor precursors were characterized by X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TG-DSC), which indicated that ultrafine uniform crystallites of KGM:Er,Yb were obtained by sintering the precursors at above 650 ℃ for 5 h. Upconversion luminescence (UL) spectra of the samples were studied by a 976 nm semiconductor laser diode (LD) excitation. The UL spectra exhibited the green and red emission bands that were attributed to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, respectively. The possible UL mechanisms of Er3+ were explained by means of an energy level diagram. The maximum luminescent intensity was achieved when the concentration of Er3+, Yb3+ arrived at 1 mol.% and 20 mol.%, respectively.
摘要Homogeneous (ZrO_2)0.92(Sc_2O_3)0.08 solid solution in fluorite cubic structure was prepared from the gels with altered molar ratios of citric acid (CA) to metal ions (M) and ethylene glycol (EG) via a polymerization route (Pechini method). Due to the enhanced chemical homogeneity (high level of mixing of metal ions and ligands) in the polymeric gels, Sc-doped zirconia can be crystallized at temperatures as low as 400 ℃. During the evolution from amorphous gel to the crystallized (ZrO_2)0.92(Sc_2O_3)0.08 fine powder, the bonding nature between carboxylate groups and Zr/Sc cations changed: unidentate→bridging→ionic upon calcination. The molar ratios of CA/M (1~4) and CA/EG (0.2~4) were demonstrated to affect the thermal behavior of the gels and thus the particle properties of the derived nanoparticulate oxide powders (including particle size and surface area). The as-sintered sample compacted from the nanosized powders prepared by calcining the gel with the highest content of organics (CA/M=4 and CA/EG=0.2) exhibited the best sinterability and the highest oxide ion conductivity.
摘要Pr0.6-x NdxCa0.4 FeO3-δ ( x = 0.0, 0.2, 0.3, 0.4, 0.5, 0.6) were synthesized using Pechini method. A number of studies were conducted concerning composition, specific area, crystalline structure and microstructure of the samples by means of FT-IR, BET, XRD TG-DTA and SEM. The results show that all the samples with different doping amounts of Pr^3+ and Nd^3+ on A-site are fine dispersed, and mean particle size less than 100 nm. The powders have good sinterability, and the relative density is 95% after sintered at 1200 ℃ for 2 h. It is found that all specimens are entirely single phase solid solutions with orthorhombic perovskite structure, the stable perovskitetype phase is formed completely after calcination at 900 ℃.
基金This work was partially supported by a research grant fromAme Hisaharu Foundation,Toyama,Japan.
摘要Lead-free piezoelectric thin films of 0.055BaZrO3–0.935(K0.45Na0.5Li0.05)NbO3–0.01(Bi0.5Na0.5)TiO3(BZ–KNLN–BNT)were fabricated on(100)-LaNiO3/SiO2/Si substrates.The Pechini(polymeric precursor)method was carried out to prepare the complicated multi-component precursor solution.This method was suited for controlling the complex components accurately.The films crystallized at 700℃ showed a(100)pc-oriented perovskite structure,whose grain size was about 200 nm and thickness was about 700 nm.The Curie temperature Tc of the films was 292℃ that was near to that of the bulk ceramics.The preparation method used in this work provided a possibility for the application of multi-component lead-free piezoelectric films.
摘要为开发高性能车载NO_2气体传感器敏感电极材料,以La_2O_3和Sr、Fe、Ni的硝酸盐、柠檬酸和乙二醇为原料,在pH=8~9的碱性条件采用Pechini法合成了约80~90 nm的复合氧化物(La0.8Sr0.2)_2FeNiO6-δ(LSFN)双钙钛矿粉末材料,并对合成工艺中柠檬酸(CA)与金属阳离子(M)的配比进行了研究。采用丝网印刷将其制备成基于氧化钇稳定氧化锆(YSZ)的NO_2传感器的敏感电极。运用TG/DTA、XRD、FSEM和ESEM对粉末材料和敏感电极进行了表征,并研究了烧结温度对LSFN敏感电极的NO_2敏感性的影响。研究结果表明:适当的柠檬酸与金属阳离子(CA/M)配比可降低材料的成相温度。XRD测试结果表明,LSFN的结构对称性会被烧结温度改变。对不同温度下烧结的LSFN敏感电极在550℃下的NO_2敏感性测试结果表明,其敏感性受烧结温度的影响,不同烧结温度下敏感电极形态可调控其NO_2敏感性。1300℃烧结的LSFN敏感电极的传感器具有较好的三维网络结构和最薄的电极厚度,表现出最高的NO_2敏感性,其灵敏度高达130. 17 m V/decade。