A series of pure and Y3＋-doped TiO2 nanoparticles with high photocatalytic activities were prepared by a sol-gel method using tetra-n-butyl titanate as precursor.The as-prepared catalysts were characterized by X-ray ...A series of pure and Y3＋-doped TiO2 nanoparticles with high photocatalytic activities were prepared by a sol-gel method using tetra-n-butyl titanate as precursor.The as-prepared catalysts were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and diffuse reflectance spectroscopy（DRS）.The results indicated that yttrium doping could effectively reduce the crystalline size,inhibit the anatase-to-rutile phase transformation and surppress the recombination of the photogenerated electron-hole pairs.The DRS results showed that the optical absorption edge shifted to red direction owing to yttrium ion doping.The photocatalytic activities of samples were evaluated by the photodegradation of methyl orange（MO） aqueous solution under 300 W high pressure mercury lamp irradiation.Photodegradation results revealed that Y3＋ doping could greatly improve the photocatalytic activity of TiO2.In this experiment,the optimal dosage was 1.5 mol.% when samples were calcined at 773 K for 2 h,which caused a MO photodegradation rate of 99.8% under UV irradiation for 70 min.展开更多
The structural and dielectric properties of Ba0.92Sr0.08Ti0.95Sn0.0503 （BSTS） ＋x（molar ratio, %） Y^3＋ceramics are investigated. Combining the lattice parameters and the distortion of crystal lattice, an alternat...The structural and dielectric properties of Ba0.92Sr0.08Ti0.95Sn0.0503 （BSTS） ＋x（molar ratio, %） Y^3＋ceramics are investigated. Combining the lattice parameters and the distortion of crystal lattice, an alternation of substitution preference of Y^3＋ ion for the host cations in perovskite lattice is found. Owing to Y^3- ion entering the A site, the maximum dielectric constant is 5 627 for 1.25% Y^3＋-doped samples; when Y^3- ion is more than 1.25%, it tends to occupy the B site in perovskite lattice, causing a drop in the dielectric constant. Owing to the appearance of oxygen vacancy, the optimized dielectric loss is 0.004 for 1.25% Y^3＋-doped samples. The thermal stability of BSTS ceramics is significantly improved and the Curie temperature shifts to lower value with the amount of Y2O3 increased, making it a superior candidate for capacitor applications.展开更多
基金National Natural Science Foundation of China(2009GZH0002,2009GZH0008)Jiangxi Provincial Key Program for Popularization of S&T Achievements(2009CCB00800)
基金supported by the National Natural Science Foundation of China(20871042)Natural Science Foundation of the Henan Province(0424270073)
文摘A series of pure and Y3＋-doped TiO2 nanoparticles with high photocatalytic activities were prepared by a sol-gel method using tetra-n-butyl titanate as precursor.The as-prepared catalysts were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and diffuse reflectance spectroscopy（DRS）.The results indicated that yttrium doping could effectively reduce the crystalline size,inhibit the anatase-to-rutile phase transformation and surppress the recombination of the photogenerated electron-hole pairs.The DRS results showed that the optical absorption edge shifted to red direction owing to yttrium ion doping.The photocatalytic activities of samples were evaluated by the photodegradation of methyl orange（MO） aqueous solution under 300 W high pressure mercury lamp irradiation.Photodegradation results revealed that Y3＋ doping could greatly improve the photocatalytic activity of TiO2.In this experiment,the optimal dosage was 1.5 mol.% when samples were calcined at 773 K for 2 h,which caused a MO photodegradation rate of 99.8% under UV irradiation for 70 min.
文摘采用高温固相反应法制备了Sr_(1-x)Ca_xSi_2O_2N_2∶Eu^(2+)系列荧光粉,研究Y^(3+)离子掺入对荧光粉发光性能的影响。对于Sr Si_2O_2N_2∶Eu^(2+),Y^(3+)离子掺入主要起到稳定Eu^(2+)价态的作用,避免Eu^(2+)氧化为Eu^(3+),从而提高Sr Si_2O_2N_2∶Eu^(2+)的发光性能。对于Ca Sr Si_2O_2N_2∶Eu^(2+),Y^(3+)离子掺入除了稳定Eu^(2+)价态作用外,还能有效减小Eu^(2+)取代Ca^(2+)后晶格膨胀引起的应力,提高Eu^(2+)在晶格中的溶解度。Sr_(1-x)Ca_xSi_2O_2N_2∶Eu^(2+)(x=0,0.15,0.3,0.6,0.75,0.95)系列荧光粉中随着Ca含量的增加,共掺Y^(3+)离子对样品发光强度的提高程度也随之增加(20%~80%)。
基金Supported by Chinese Doctor Foundation of Ministry of Education of China (No20040056055)
文摘The structural and dielectric properties of Ba0.92Sr0.08Ti0.95Sn0.0503 （BSTS） ＋x（molar ratio, %） Y^3＋ceramics are investigated. Combining the lattice parameters and the distortion of crystal lattice, an alternation of substitution preference of Y^3＋ ion for the host cations in perovskite lattice is found. Owing to Y^3- ion entering the A site, the maximum dielectric constant is 5 627 for 1.25% Y^3＋-doped samples; when Y^3- ion is more than 1.25%, it tends to occupy the B site in perovskite lattice, causing a drop in the dielectric constant. Owing to the appearance of oxygen vacancy, the optimized dielectric loss is 0.004 for 1.25% Y^3＋-doped samples. The thermal stability of BSTS ceramics is significantly improved and the Curie temperature shifts to lower value with the amount of Y2O3 increased, making it a superior candidate for capacitor applications.
