The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristi...The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristics investigated using scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS)showed that the MAO coatings displayed uneven crater-like holes and tiny cracks under lower voltage,while they exhibited relatively homogeneous crater-like holes without cracks under higher voltage.The thickness of MAO coatings increased with increasing voltage.The corrosion behavior of Mg-4Zn-1Mn alloy was improved by the MAO coatings.The MAO coatings prepared under 450 V and 500 V voltages possessed the best corrosion resistance with regard to the electrochemical corrosion tests and immersion corrosion tests,respectively.The MAO coatings fabricated under 450-500 V could provide a better corrosion protection effect for the substrate.展开更多
采用高温固相法合成Ca取代Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr的Sr3-x Ca x Al0.6Si0.4O4.4F0.6∶Ce3+荧光粉。由于Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr具有十配位Sr(1)和八配位Sr(2),所以激活剂离子Ce3+也具有两个不同的占位。结合Ce3+的光...采用高温固相法合成Ca取代Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr的Sr3-x Ca x Al0.6Si0.4O4.4F0.6∶Ce3+荧光粉。由于Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr具有十配位Sr(1)和八配位Sr(2),所以激活剂离子Ce3+也具有两个不同的占位。结合Ce3+的光谱结果和Van Uitert经验公式,分别研究了十配位Ce(1)3+和八配位Ce(2)3+的猝灭浓度和荧光寿命,指出是由于Ca的掺入减小了Ce(1)3+发光中心,增加了Ce(2)3+发光中心,从而出现随着Ca/Sr比增加,样品在400 nm激发下发光强度减小,而在460 nm激发下发光强度增大的现象。同时,Ca的掺入增强了粉体发光的热稳定性。调节Ca含量可以使粉体实现从绿黄色到黄色的发光,表明Sr3-x Ca x Al0.6Si0.4-O4.4F0.6∶Ce3+荧光粉是一款潜在的适合近紫外和蓝光激发的白光LED用荧光粉。展开更多
The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffra...The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffraction and electron probe scanning. In the materials, three phases were found, they are Sr 0.69 La 0.31 F 2.31 solid solution phase with a pure SrF 2 cubic structure whose lattice constant is 5.843 ?, SrS single phase with a NaCl cubic structure, and an unknown phase that is produced by the interaction of SrS and co precipitated powder. It was also found that SrS has no influence on the structure of Sr 0.69 La 0.31 F 2.31 solid solution.展开更多
采用高温固相法反应制备Ba0.11Sr2.89-2x Ce x Na x AlO4F(x=0.01,0.02,0.05,0.07,0.10,0.15)荧光粉。Ba0.11Sr2.89AlO4F体系中存在Sr(1)2+和Sr2+(2)两个格位。Sr2+(1)离子位于Wyck.4a格位,为十配位多面体构型。Sr2+(2)离子位于Wyck.8h...采用高温固相法反应制备Ba0.11Sr2.89-2x Ce x Na x AlO4F(x=0.01,0.02,0.05,0.07,0.10,0.15)荧光粉。Ba0.11Sr2.89AlO4F体系中存在Sr(1)2+和Sr2+(2)两个格位。Sr2+(1)离子位于Wyck.4a格位,为十配位多面体构型。Sr2+(2)离子位于Wyck.8h格位,为八配位的多面体构型。研究了Ba0.11Sr2.89-2x Ce x Na x AlO4F荧光粉的紫外-可见激发、发射光谱、荧光寿命及能量传递过程,讨论并指认了Ce3+在上述两个格位中的激发带位置及能级重心,发射光谱曲线分别由两个~463,~505和~550 nm宽带发射构成。随着Ce3+浓度增加,长波发射~550 nm逐渐增强,而色品坐标(x=0.199,y=0.351)蓝绿区逐渐变化到黄绿区域(x=0.389,y=0.489)。展开更多
文摘The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristics investigated using scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS)showed that the MAO coatings displayed uneven crater-like holes and tiny cracks under lower voltage,while they exhibited relatively homogeneous crater-like holes without cracks under higher voltage.The thickness of MAO coatings increased with increasing voltage.The corrosion behavior of Mg-4Zn-1Mn alloy was improved by the MAO coatings.The MAO coatings prepared under 450 V and 500 V voltages possessed the best corrosion resistance with regard to the electrochemical corrosion tests and immersion corrosion tests,respectively.The MAO coatings fabricated under 450-500 V could provide a better corrosion protection effect for the substrate.
文摘采用高温固相法合成Ca取代Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr的Sr3-x Ca x Al0.6Si0.4O4.4F0.6∶Ce3+荧光粉。由于Sr3Al0.6Si0.4O4.4F0.6∶Ce3+中Sr具有十配位Sr(1)和八配位Sr(2),所以激活剂离子Ce3+也具有两个不同的占位。结合Ce3+的光谱结果和Van Uitert经验公式,分别研究了十配位Ce(1)3+和八配位Ce(2)3+的猝灭浓度和荧光寿命,指出是由于Ca的掺入减小了Ce(1)3+发光中心,增加了Ce(2)3+发光中心,从而出现随着Ca/Sr比增加,样品在400 nm激发下发光强度减小,而在460 nm激发下发光强度增大的现象。同时,Ca的掺入增强了粉体发光的热稳定性。调节Ca含量可以使粉体实现从绿黄色到黄色的发光,表明Sr3-x Ca x Al0.6Si0.4-O4.4F0.6∶Ce3+荧光粉是一款潜在的适合近紫外和蓝光激发的白光LED用荧光粉。
文摘The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffraction and electron probe scanning. In the materials, three phases were found, they are Sr 0.69 La 0.31 F 2.31 solid solution phase with a pure SrF 2 cubic structure whose lattice constant is 5.843 ?, SrS single phase with a NaCl cubic structure, and an unknown phase that is produced by the interaction of SrS and co precipitated powder. It was also found that SrS has no influence on the structure of Sr 0.69 La 0.31 F 2.31 solid solution.
文摘采用高温固相法反应制备Ba0.11Sr2.89-2x Ce x Na x AlO4F(x=0.01,0.02,0.05,0.07,0.10,0.15)荧光粉。Ba0.11Sr2.89AlO4F体系中存在Sr(1)2+和Sr2+(2)两个格位。Sr2+(1)离子位于Wyck.4a格位,为十配位多面体构型。Sr2+(2)离子位于Wyck.8h格位,为八配位的多面体构型。研究了Ba0.11Sr2.89-2x Ce x Na x AlO4F荧光粉的紫外-可见激发、发射光谱、荧光寿命及能量传递过程,讨论并指认了Ce3+在上述两个格位中的激发带位置及能级重心,发射光谱曲线分别由两个~463,~505和~550 nm宽带发射构成。随着Ce3+浓度增加,长波发射~550 nm逐渐增强,而色品坐标(x=0.199,y=0.351)蓝绿区逐渐变化到黄绿区域(x=0.389,y=0.489)。
