Research on Phosphorus Removal from Silicon by Induction Vacuum Refining and Its Thermodynamics-kinetics Mechanism

太阳能是一种巨大且对环境无污染的可再生能源，而直接将太阳能转化为电能的光伏技术将是未来人类利用太阳能最直接且最经济的方式。当前，能源与环境问题使得太阳能光伏成为世界各国的研究热点。 硅是制备太阳能电池的主要原材料之一，是全球半导体工业及光伏产业的基石。冶金法提纯太阳能级多晶硅，相对于化学法（如改良西门子法、硅烷法等）来说，具有低成本、低能耗、环境污染小、安全性高等优点，已得到世界各国广泛的认同与推崇。 磷作为硅的施主杂质，在太阳能电池基体中，其含量不得高于0.1ppmw。由于磷具有很高的分凝系数(0.35)，因此很难用定向凝固的方法去除。目前采用冶金法除磷的工艺主要包括酸洗工艺、合金定向凝...Solar energy is a huge clean sustainable energy resource. Photovoltaic technology can transfer solar energy to electricity directly, which will become the most direct and most economy way for human in using solar energy in the future. At present, PV technology has already been a research hot topic due to the energy crisis and environment issues. Silicon is one of the main materials for solar cell...学位：工学博士院系专业：材料学院材料科学与工程系_材料物理与化学学号：2072008015000

以氨燃料为介质的全生命周期储能效率估算

本文讨论了氨作为燃料使用会具备与传统化石燃料显著不同的环境效益,并进一步探讨了氨作为储能介质的特点,包括储能密度和规模大、受地理条件约束小、便于运输存储等。本文还针对目前的合成氨路线从理论分析和工业实际两个方面对合成效率进行了估算和评价。针对目前国内核能、风能、太阳能等清洁能源电力的低谷或弃电问题,建议采用以制氨的方式存储或外运,以便于在电力不足时将其用于发电。建议并评估了几条基于制氨并发电的路线,并基于现有氨燃料的发电效率计算了各路线在全生命周期内的总储能效率(25%~40%)和以电换电的效率[2.5~4.0(度/10度)]。福建省自然科学基金项目(2014J01209);;厦门大学能源学院-金隆昌氨能源及动力联合研发中心经费项目(0290K8110075);;福建省闽江学者经费项目(X170300101

多晶硅冶金法除磷的研究进展

磷是多晶硅中的一种主要杂质元素,目前国内外采用冶金法除磷的工艺主要包括酸洗除磷、合金定向凝固除磷和真空除磷工艺。其中,酸洗除磷工艺可以很有效地去除磷杂质,但仍未达到太阳能级多晶硅小于0.1×10-4%(质量分数)的要求。采用合金定向凝固工艺可以去除80%以上的磷杂质,但目前对凝固后硅中残留溶剂金属的去除方法还有待进一步的研究。通过真空感应熔炼实验已将磷含量从15×10-4%(质量分数)降低至0.8×10-5%(质量分数),并对除磷的热力学条件进行了初步探索

Elimination of phosphorus vaporizing from molten silicon at finite reduced pressure

对有限负压下熔体硅中磷的挥发去除进行研究。采用电子级硅配制SI-P合金,并采用gd-MS来检测实验前后硅中的磷含量。理论计算结果表明:在有限负压下,硅中的磷以P和P2的气体形式从熔体硅中挥发。实验结果显示:在温度1873k、真空度0.6-0.8PA、熔炼3600S的条件下,熔体硅中的磷从0.046%(460PPMW)下降到0.001%(10PPMW)。实验结果与理论结果一致表明:当熔体硅中磷的含量大且炉腔内气压相对较高时,磷的去除与气压高度相关;而当炉腔气压很低时,磷的去除基本与气压无关。原因是在相对高磷含量的熔体硅中,磷主要以P2气体的形式挥发;在磷含量较低时,磷主要以单原子气体P的形式挥发。Elimination of phosphorus vaporizing from silicon was investigated.Si-P alloy made from electronic grade silicon was used.All the samples were analyzed by GD-MS.Theory calculation determines that phosphorus evaporates from molten silicon as gas species P and P2 at a finite reduced pressure.The experimental results show that phosphorus mass fraction can be decreased from 0.046% (460ppmw) to around 0.001% (10ppmw) under the condition of temperature 1 873 K, chamber pressure 0.6-0.8 Pa, holding time 1 h.Both experimental data and calculation results agree that at high phosphorus concentration, phosphorus removal is quite dependent on high chamber pressure while it becomes independent on low chamber pressure.The reason is that phosphorus evaporates from molten silicon as gas species P2 at a relatively high phosphorus concentration, while gas species P will be dominated in its vapour at low phosphorus content.Project(2007J0012)supportedbytheNaturalScienceFoundationofFujianProvince;China;Project(2007HZ0005-2)supportedbytheKeyTechnologicalProgramofFujianProvince;China;Project(BASIC-10341702)supportedbyNorwegianResearchCounci

氨燃料缓解能源安全及替代天然气的可行性分析

文章主要针对我国面临的能源安全问题及现阶段出现的北方地区\"气荒\"现象,结合氨燃料储能密度高、燃烧清洁、热值较高、易储存运输、产业基础完善、用处广泛的特点以及厦门大学的锅炉及发电机掺氨燃烧运行成功的实验结果,定量分析氨燃料可缓解能源安全问题的程度及解决\"气荒\"问题的规模与容量。分析结果表明:引入氨能源体系可以有效优化中国的能源结构,改善过度依赖能源进口的现状,解决天然气短缺的问题。福建省闽江学者经费项目(X170300101);;\n厦门大学能源学院-金融昌氨能源及动力联合研发中心经费项目(0290K8110075

The Effect of Calcium Oxide Addition on the Removal of Metal Impurities from Metallurgical-Grade Silicon by Acid Leaching

The removal of metal impurities from metallurgical grade silicon (MG-Si) by acid leaching has been investigated with the addition of CaO. Prior to adding CaO, Fe is the main impurity in the MG-Si sample, and the 2nd-phase precipitates in silicon are Si-Fe-based alloys, such as Si-Fe, Si-Fe-Ti, Si-Fe-Al, Si-Fe-Mn, and Si-Fe-Ni. The phases of Si-Fe and Si-Fe-Ti are not appreciably soluble in HCl. After the introduction of CaO, Ca becomes the dominant impurity, and the 2nd-phase precipitates become Si-Fe-based alloys, such as Si-Ca, Si-Ca-(Fe, Ti, Ni, Al), and Si-Ca-Fe-Al. These are effectively leached with HCl. Therefore, the HCl leaching effect on the removal of metal impurities has been improved. The optimum content of Ca in the MG-Si samples after adding CaO is in the range of 1 pct to 4 pct, the contents of Fe, Al, Ti, and Ni have been decreased to a minimum of less than 5 ppmw (ppm by weight) each, and the acid leaching results do not show a dependence on Ca content at this range

The effect of calcium oxide addition on the removal of metal impurities from metallurgical-grade silicon by acid leaching

The removal of metal impurities from metallurgical grade silicon (MG-Si) by acid leaching has been investigated with the addition of CaO. Prior to adding CaO, Fe is the main impurity in the MG-Si sample, and the 2nd-phase precipitates in silicon are Si-Fe-based alloys, such as Si-Fe, Si-Fe-Ti, Si-Fe-Al, Si-Fe-Mn, and Si-Fe-Ni. The phases of Si-Fe and Si-Fe-Ti are not appreciably soluble in HCl. After the introduction of CaO, Ca becomes the dominant impurity, and the 2nd-phase precipitates become Si-Fe-based alloys, such as Si-Ca, Si-Ca-(Fe, Ti, Ni, Al), and Si-Ca-Fe-Al. These are effectively leached with HCl. Therefore, the HCl leaching effect on the removal of metal impurities has been improved. The optimum content of Ca in the MG-Si samples after adding CaO is in the range of 1 pct to 4 pct, the contents of Fe, Al, Ti, and Ni have been decreased to a minimum of less than 5 ppmw (ppm by weight) each, and the acid leaching results do not show a dependence on Ca content at this range. 漏 The Minerals, Metals & Materials Society and ASM International 2012