Copper selenide nanoparticles are important materials with desirable properties for a broad scope of applications. Copper selenides are additionally known to adopt several different crystal structures and compositions. Here, we report the direct solution-phase synthesis of colloidal Cu_2–xSe nanoparticles that adopt a structure distinct from other known copper selenide phases. This Cu_2–xSe phase was determined to be structurally related to weissite Cu_2–xTe, which is a layered compound containing alternating Cu-rich and Cu-deficient layers sandwiching distorted hexagonal layers of chalcogen atoms. When the weissite-like Cu_2–xSe nanoparticles were annealed in solution, they converted to the more stable cubic berzelianite phase, indicating that they are metastable. Optical characterization of the weissite-like Cu_2–xSe nanoparticles showed a broad plasmon absorption band centered around 1550 nm, and the position of this absorption band shifted only slightly when subjected to reductive and oxidative conditions.

中文翻译：

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具有近红外等离子体共振的亚稳态硒化铜相的胶体纳米颗粒

硒化铜纳米颗粒是重要的材料，具有广泛应用中所需的性能。另外已知硒化铜采用几种不同的晶体结构和组成。在这里，我们报告了采用不同于其他已知硒化铜相结构的胶态Cu _{2– x} Se纳米粒子的直接溶液相合成。已确定此Cu _{2– x} Se相在结构上与weissite Cu _{2– x} Te有关，这是一种层状化合物，包含交替的富铜层和缺铜层，中间夹着变形的六方硫属元素原子。当类Weissite Cu _{2 – x}硒纳米颗粒在溶液中退火，它们转变为更稳定的立方铍青石相，表明它们是亚稳态的。呈Weissite状的Cu ₂ – _x Se纳米粒子的光学表征显示出一个宽的等离激元吸收带，中心在1550 nm附近，并且在经历还原和氧化条件时，该吸收带的位置仅发生了少许移动。