| 查看: 678 | 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
稀土发光分析｜核壳结构｜寿命拟合
已经有6人回复
-
稀土发光分析｜核壳结构｜寿命拟合
已经有0人回复
-
无机化学论文润色/翻译怎么收费?
已经有297人回复
-
稀土发光分析｜核壳结构｜寿命拟合
已经有0人回复
-
26 届青岛大学纺织化学与染整工程硕士（液体纳米分散染料方向）求申博建议
已经有4人回复
-
26 届青岛大学纺织化学与染整工程（液体纳米分散染料）求浙理工纺织 / 材料博导名额
已经有1人回复
-
敢问Acta Pharmaceutica Sinica B with Editor 三周了，能是什么情况？
已经有0人回复
-
求助 CeO2 Fe3O4 Cu2S CoFe2O4 标准卡 Jade 导出的数据
已经有0人回复
-
求助一篇MEMS散热器件文献
已经有0人回复
-
材化专业SCI论文（职称评定）
已经有0人回复
» 本主题相关商家推荐: (我也要在这里推广)
4楼2008-08-29 19:28:42
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
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
20