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YPO4:Eu 3+ phosphors were synthesized by solution coprecipitation method assisted by urea in the precursor reaction solution. X-ray diffraction spectral analysis showed that the samples synthesized with urea had smaller particle size and lower crystallinity than those samples synthesized without urea.Moreover,the calculated strain result indicated that the Eu 3+ site in the former exhibited a lower crystal field symmetry than that in the latter.Hence,the influence of crystal field symmetry dominated luminescence efficiency rather than crystallinity because the luminescence intensity observed in Eu0.05Y0.95PO4 synthesized with 1.0 g urea was six-fold higher than that of the as-synthesized sample.With increased concentration of Eu 3+ ion,the luminescence intensity initially increased,and then subsequently decreased as the concentration of Eu 3+ ion exceeded 12 mol.%due to concentration quenching.The optimal condition for YPO4:Eu 3+ phosphor was Eu0.12Y0.88PO4 with 1.0 g urea added in the precursor.The luminescence intensity of the optimal condition was again enhanced 1.6-fold relative to that of Eu0.05Y0.95PO4 synthesized with 1.0 g-urea. 相似文献
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铜坑锡多金属矿床是桂西北大厂矿田中的一个超大型矿床,由上部锡多金属矿体和深部新勘查发现的锌铜矿体组成。通过流体包裹体显微测温实验及热力学参数估算,对比研究了不同矿体成矿流体特征及其演化,探讨了流体沉淀机制。研究表明,锡多金属矿和锌铜矿均发育有H2O-NaCl-CO2型、H2O-NaCl型及纯CO2型包裹体,锡多金属矿成矿流体均一温度126.6~403.5℃(集中于260~360℃),盐度w(NaCleq)集中于4%~6%,密度0.234~0.967 g/cm3,pH为5.69~6.87;Eh为-0.4526~0.1814 V,fs2介于10-13.56~10-7.78,fo2介于10-32.53~10-24.11;锌铜矿成矿流体均一温度为138~432℃(集中于280~400℃);盐度w(NaCleq)集中于4%~9%;密度0.244~1.098 g/cm3;pH为5.79~7.17;Eh为-0.5903~0.1255 V;fs2介于10-10.86~10-6.34,fo2介于10-40.72~10-30.25。空间上由深部锌铜矿→上部锡多金属矿,成矿流体呈现温度降低、盐度降低、酸碱度降低、氧化还原电位升高、硫逸度降低、氧逸度升高的变化规律。流体沸腾、混合作用可能是锡石沉淀重要原因,富CO2流体沸腾作用可能是锌铜矿质沉淀重要原因。 相似文献
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随着区块采出程度的提高,河南油田压裂改造的对象由大厚层转向中低渗透薄互层,薄互层主要分布在双河油田Ⅵ-Ⅸ、下二门下层系、B304井区部分井层、王集油田、井楼八区等,总计剩余储量超过1000×104t,压裂挖潜潜力较大。薄互层压裂面临着缝高失控压窜邻近水层、供油能力有限、改造程度较低导致压裂效果差等诸多难题,针对不同的薄互层特点,研究了薄互层压裂挖潜综合技术,形成了老油田压裂改造系列特色技术,保证了河南稀油老区的压裂效果,为河南油田薄互层的措施稳产提供了有力的技术支撑。 相似文献
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随着建筑设计市场逐步开放,应加强对国外建筑行业专业人员的注册管理,完善我国建筑行业专业人员的注册管理制度,并逐渐同国际接轨。本文系统介绍了欧美国家建筑师制度的法律依据、建筑师资格标准、建筑师注册管理等方面的做法和经验,与我国实际结合,提出借鉴意见。 相似文献
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