| 查看: 609 | 回复: 3 | |||
| 当前主题已经存档。 | |||
| 【有奖交流】积极回复本帖子，参与交流，就有机会分得作者 jasonxmc 的 4 个金币 | |||
| 当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖 | |||
[交流]
纳米材料——晶体成核问题
|
|||
|
有两个问题: 1、为什么要快速成核？作者说 If nucleation is allowed to proceed over an extended period, reactants are unevenly depleted from solution leading to variations in growth rate for seed particles formed at different reaction times. 2、文中所说的临界浓度应该是金属原子的浓度吧。但是作者说 Fast nucleation is typically achieved by slowly building up the concentration of metal ions in solution through serial injections of the precursor materials until nucleation occurs. 文献：small 2008, 4, No. 3, 310 – 325 In homogeneous nucleation, seed formation proceeds according to the LaMer model (see Figure 4a), where reduction of metal ions occurs to generate a critical composition of atomic species in solution. Above this critical concentration, nucleation results in a rapid depletion of the reactants such that all subsequent growth occurs on the pre-existing nuclei. As long as the concentration of reactants is kept below the critical level, further nucleation is discouraged. This is particularly important for shape control: to obtain a highly shape-monodisperse yield of nanocrystals, nucleation must occur rapidly and instantaneously. This is exemplified by the synthesis of Ag nanocrystalline octahedra, whose reaction rate can be monitored by UV/vis spectroscopy (see Figure 4b). In other words, only a single nucleation event can occur. If nucleation is allowed to proceed over an extended period, reactants are unevenly depleted from solution leading to variations in growth rate for seed particles formed at different reaction times. Fast nucleation is typically achieved by slowly building up the concentration of metal ions in solution through serial injections of the precursor materials until nucleation occurs. However, preventing the fast reduction of metal ions – especially for colloidal syntheses carried out at reflux temperatures – is necessary to accumulate enough reactant species to reach the critical nucleation concentration. This accumulation may be aided by modifying the reactivity of the metal precursor. One possible method is through the formation of metal–surfactant or metal–polymer complexes in the reaction solution, which hinder the reduction reaction even under highly favorable conditions. |
回复此楼» 猜你喜欢
学院官方群-院士团队招生-学生自由度高-培养模式成熟已有10余名学生赴985海外深造
已经有0人回复
-
武汉纺织大学化工学院官方群-院士团队招生-学生自由度高-10余名学生赴985海外深造
已经有0人回复
-
金属材料论文润色/翻译怎么收费?
已经有164人回复
-
南昌航空大学蒋华麟教授课题组招收化学、环境、碳达峰碳中和及相关专业硕士信息
已经有0人回复
-
湖北师范大学复试调剂
已经有0人回复
-
武汉纺织大学_化工学院官方调剂群-院士团队招生-学生自由度高-每届发展好
已经有0人回复
-
河北大学材料与化工专业研究生（专硕）招收调剂生
已经有0人回复
-
河北大学无机化学专业招收调剂生
已经有0人回复
-
济南大学国家优青课题组 2026 调剂招生来啦
已经有0人回复
-
武汉纺织大学_化学院官方调剂群-院士团队招生-学生自由度高发展好-欢迎各位同学
已经有0人回复
» 本主题相关商家推荐: (我也要在这里推广)
元小雪
木虫 (职业作家)
- 应助: 0 (幼儿园)
- 贵宾: 0.947
- 金币: 2216.5
- 散金: 2484
- 红花: 2
- 帖子: 3767
- 在线: 124.5小时
- 虫号: 471521
- 注册: 2007-12-01
- 性别: MM
- 专业: 物理/
3楼2008-08-29 19:25:14
refnew
专家顾问 (知名作家)
-
专家经验: +181 - MN-EPI: 4
- 应助: 678 (博士)
- 贵宾: 0.577
- 金币: 9465.7
- 散金: 229
- 红花: 54
- 帖子: 6391
- 在线: 1613.5小时
- 虫号: 33447
- 注册: 2003-12-31
- 性别: GG
- 专业: 纳米生物学
- 管辖: 微米和纳米
2楼2008-08-29 18:51:51
4楼2008-08-29 19:28:42
