Sequential Cation Exchange in Nanocrystals: Preservation of Crystal Phase and Formation of Metastable Phases
Sequential Cation Exchange in Nanocrystals: Preservation of Crystal Phase and Formation of Metastable Phases
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DOI：
10.1021/nl202927a
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发表时间：
2011-11-01
期刊：
影响因子：
10.8
通讯作者：
Manna, Liberato
中科院分区：
文献类型：
--
作者：
Li, Hongbo;Zanella, Marco;Manna, Liberato
我们证明有可能将给定尺寸、形状（无论是球形还是棒状）和晶体结构（无论是六方细锌矿，即六方紧密堆积（hcp），还是立方闪锌矿，即面心立方（fcc））的CdSe纳米晶体转化为ZnSe纳米晶体，通过一系列的两个阳离子交换反应，即Cd2+ -> Cu+ -> Zn2+，保留了所有这些初始粒子的特征（即尺寸、形状和晶体结构）。从六方纤锌矿型CdSe纳米晶体开始，Cd2+与Cu+交换得到的Cu2Se纳米晶体处于亚稳的六方相，在电子显微镜下，我们可以看到单个纳米棒的Cu2Se纳米晶体向更稳定的fcc相转变。值得注意的是，这些亚稳的hcp Cu2Se纳米晶体可以在溶液中转化为ZnSe纳米晶体，从而产生纯hcp相的ZnSe纳米晶体。
We demonstrate that it is possible to convert CdSe nanocrystals of a given size, shape (either spherical or rod shaped), and crystal structure (either hexagonal wurtzite, i.e., hexagonal close packed (hcp), or cubic sphalerite, i.e., face-centered cubic (fcc)), into ZnSe nanocrystals that preserve all these characteristics of the starting particles (i.e., size, shape, and crystal structure), via a sequence of two cation exchange reactions, namely, Cd2+ -> Cu+ -> Zn2+. When starting from hexagonal wurtzite CdSe nanocrystals, the exchange of Cd2+ with Cu+ yields Cu2Se nanocrystals in a metastable hexagonal phase, of which we could follow the transformation to the more stable fcc phase for a single nanorod, under the electron microscope. Remarkably, these metastable hcp Cu2Se nanocrystals can be converted in solution into ZnSe nanocrystals, which yields ZnSe nanocrystals in a pure hcp phase.