The present work aimed to explore a kind of microwave dielectric materials with middle-permittivity, high Qf, near-zero τf, and lower sintering temperature. A series of Y2Ti2O7 microwave dielectric ceramics were synt...The present work aimed to explore a kind of microwave dielectric materials with middle-permittivity, high Qf, near-zero τf, and lower sintering temperature. A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. For improving the dielectric properties of Y2Ti2O7 system, Bi2O3, Nd2O3 and Nb2O5 were added and their effects on phase composition, micro-structure, and dielectric properties at microwave frequencies were investigated by means of X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The queuing score method for multi-target orthogonal design was used to obtain the optimum prescription. The results showed that the Y2Ti2O7 ceramics with 8 wt.% Bi2O3 and 1 mol.% Nd2O3-Nb2O5 were well sintered at 1350 ℃, exhibiting excellent dielectric characteristics, i.e. εr≈76, Qf≈18980 GHz, τf =＋25.5 ppm/℃.展开更多
Preconcentration/separation of Co（II）, Fe（III）, Pb（II）, Cr（IIl）, Cu（II） and Cd（II） ions using bis（5-bromo- 2-hydroxy-benzaldehyde）-2-methy1-1,5-pentane diimine （BBHBPDI） on SDS coated alumina has been ...Preconcentration/separation of Co（II）, Fe（III）, Pb（II）, Cr（IIl）, Cu（II） and Cd（II） ions using bis（5-bromo- 2-hydroxy-benzaldehyde）-2-methy1-1,5-pentane diimine （BBHBPDI） on SDS coated alumina has been reported. The influences of the analytical parameters including pH, ligand and SDS amount, type and concentration of eluent and sample volume on metal ions recoveries were investigated. At optimum values of all variables the relative standard deviation are between 2.5-2.7 and preconcentration factor was 375, while recoveries for all understudy metal ions are higher than 95%, determination limits are between 1.5-2.7. The method has been successfully applied to determination of Co（II）, Fe（III）, Pb（II）, Cr（III）, Cu（II） and Cd（II） ions content in some real samples.展开更多
基金supported by the Key University Science Research of Jiangsu Province (08KJA430002)the Priority Academic Program D velopment of Jiangsu Higher Education Institute
文摘The present work aimed to explore a kind of microwave dielectric materials with middle-permittivity, high Qf, near-zero τf, and lower sintering temperature. A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. For improving the dielectric properties of Y2Ti2O7 system, Bi2O3, Nd2O3 and Nb2O5 were added and their effects on phase composition, micro-structure, and dielectric properties at microwave frequencies were investigated by means of X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The queuing score method for multi-target orthogonal design was used to obtain the optimum prescription. The results showed that the Y2Ti2O7 ceramics with 8 wt.% Bi2O3 and 1 mol.% Nd2O3-Nb2O5 were well sintered at 1350 ℃, exhibiting excellent dielectric characteristics, i.e. εr≈76, Qf≈18980 GHz, τf =＋25.5 ppm/℃.
文摘Preconcentration/separation of Co（II）, Fe（III）, Pb（II）, Cr（IIl）, Cu（II） and Cd（II） ions using bis（5-bromo- 2-hydroxy-benzaldehyde）-2-methy1-1,5-pentane diimine （BBHBPDI） on SDS coated alumina has been reported. The influences of the analytical parameters including pH, ligand and SDS amount, type and concentration of eluent and sample volume on metal ions recoveries were investigated. At optimum values of all variables the relative standard deviation are between 2.5-2.7 and preconcentration factor was 375, while recoveries for all understudy metal ions are higher than 95%, determination limits are between 1.5-2.7. The method has been successfully applied to determination of Co（II）, Fe（III）, Pb（II）, Cr（III）, Cu（II） and Cd（II） ions content in some real samples.
