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
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
Lead-free piezoelectric thin films of 0.055BaZrO_(3)–0.935(K_(0.45)Na_(0.5)Li_(0.05))NbO_(3)–0.01(Bi_(0.5)Na_(0.5))TiO_(3)(BZ–KNLN–BNT)were fabricated on(100)-LaNiO_(3)/SiO_(2)/Si substrates.The Pechini(polymeric ...Lead-free piezoelectric thin films of 0.055BaZrO_(3)–0.935(K_(0.45)Na_(0.5)Li_(0.05))NbO_(3)–0.01(Bi_(0.5)Na_(0.5))TiO_(3)(BZ–KNLN–BNT)were fabricated on(100)-LaNiO_(3)/SiO_(2)/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
The aim of the present work was to investigate the luminescent properties of europium-doped lanthanum aluminate (LaAlO3) powder prepared by Modified Pechini (MP) method. Samples were prepared at different Eu3+ concent...The aim of the present work was to investigate the luminescent properties of europium-doped lanthanum aluminate (LaAlO3) powder prepared by Modified Pechini (MP) method. Samples were prepared at different Eu3+ concentrations and calcined at 1600°C. Structural and morphology characterizations were obtained by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Luminescent properties were analyzed by photoluminescence (PL) and thermoluminescent phenomena. The XRD pattern shows pure lanthanum aluminate oxide LaAlO3 with a rhombohedral structure. Photoluminescence studies of the powders was related to 4f → 4f(5D0 → 7Fi) (i = 1, 2, 3, 4) transitions of Eu3+ ion, the most intense emission of Eu3+ in LaAlO3 was registered for the transition 5D0 → 7F1, for 5% of Eu3+. The recorded TL glow curves of excited samples showed a main TL peak, the main peak appeared its maximum as a function of excitation energy. The investigation demonstrates that polycrystalline LaAlO3:Eu3+ powders calcined at 1600°C have interesting luminescent characteristics.展开更多
Layered cathode material LiCo1/3Ni1/3Mn1/3O2 was synthesized by Pechini process, and investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic charge/discharge cycling. The sampl...Layered cathode material LiCo1/3Ni1/3Mn1/3O2 was synthesized by Pechini process, and investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic charge/discharge cycling. The sample is well-crystallized and has a phase-pure a-NaFeO2 structure. The particle sizes are uniform, and distributed in the range of 20-200 nm. The initial discharge capacity of the Li/LiCo1/3Ni1/3Mn1/3O2 cell was about 149 mAh·g-1 when it was cycled at a voltage range of 4.5-2.3 V with a specific current of 0.25 mA. The result is better in comparison with solid-state solution method. The synthetic procedure was discussed. Three major reactions: chelation, esterification, and polymerization successively occurred.展开更多
文摘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.
文摘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)
文摘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.
基金This work was partially supported by a research grant fromAme Hisaharu Foundation,Toyama,Japan.
文摘Lead-free piezoelectric thin films of 0.055BaZrO_(3)–0.935(K_(0.45)Na_(0.5)Li_(0.05))NbO_(3)–0.01(Bi_(0.5)Na_(0.5))TiO_(3)(BZ–KNLN–BNT)were fabricated on(100)-LaNiO_(3)/SiO_(2)/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.
文摘The aim of the present work was to investigate the luminescent properties of europium-doped lanthanum aluminate (LaAlO3) powder prepared by Modified Pechini (MP) method. Samples were prepared at different Eu3+ concentrations and calcined at 1600°C. Structural and morphology characterizations were obtained by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Luminescent properties were analyzed by photoluminescence (PL) and thermoluminescent phenomena. The XRD pattern shows pure lanthanum aluminate oxide LaAlO3 with a rhombohedral structure. Photoluminescence studies of the powders was related to 4f → 4f(5D0 → 7Fi) (i = 1, 2, 3, 4) transitions of Eu3+ ion, the most intense emission of Eu3+ in LaAlO3 was registered for the transition 5D0 → 7F1, for 5% of Eu3+. The recorded TL glow curves of excited samples showed a main TL peak, the main peak appeared its maximum as a function of excitation energy. The investigation demonstrates that polycrystalline LaAlO3:Eu3+ powders calcined at 1600°C have interesting luminescent characteristics.
文摘Layered cathode material LiCo1/3Ni1/3Mn1/3O2 was synthesized by Pechini process, and investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic charge/discharge cycling. The sample is well-crystallized and has a phase-pure a-NaFeO2 structure. The particle sizes are uniform, and distributed in the range of 20-200 nm. The initial discharge capacity of the Li/LiCo1/3Ni1/3Mn1/3O2 cell was about 149 mAh·g-1 when it was cycled at a voltage range of 4.5-2.3 V with a specific current of 0.25 mA. The result is better in comparison with solid-state solution method. The synthetic procedure was discussed. Three major reactions: chelation, esterification, and polymerization successively occurred.
