State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
J Am Chem Soc. 2011 Oct 5;133(39):15605-12. doi: 10.1021/ja2049258. Epub 2011 Sep 12.
Highly uniform single crystal ultrathin ZnS nanowires (NWs) with 2 nm diameter and up to 10 μm length were fabricated using a catalyst-free colloidal chemistry strategy. The nanowires crystallized in hexagonal phase structure with preferential growth along the direction of the (001) basal plane. The strong polarity of the (001) plane composed of Zn cations or S anions drives the oriented attachment of ZnS nanocrystals (NCs) along this direction via electrostatic (or dipole) interaction. The ultrathin ZnS nanowires show intrinsic ferromagnetism at room temperature and other unusual properties related to its unique nature, such as large anisotropic lattice expansion, large blue-shift of UV-vis absorption band of the excition, and photoluminescence spectrum of the exciton band edge. First-principles DFT computation results show that Zn vacancies can induce intrinsic ferromagnetism in these undoped ZnS NWs. The main source of the magnetic moment arises from the unpaired 3p electrons at S sites surrounding the Zn vacancies carrying the magnetic moment ranging from 0.26 to 0.66 μ(B). Calculated results indicate that the magnetic moment of the ultrathin ZnS NWs can be increased by increasing the Zn vacancy concentration without significant energy cost. The calculated magnetization value (1.96 or 0.40 emu/g for Zn vacancies on the surface of NWs or inside, respectively) by Zn(53)S(54) supercell model is larger than our experimental value (0.12 emu/g at 1.8 K and 0.05 emu/g at 300 K), but the ferromagnetic result is qualitatively in agreement.
采用无催化剂的胶体化学策略，成功制备了具有 2nm 直径和长达 10μm 的高度均匀的单晶体硫化锌（ZnS）纳米线（NWs）。纳米线结晶为六方相结构，沿（001）基面的方向优先生长。由 Zn 阳离子或 S 阴离子组成的（001）面的强极性通过静电（或偶极）相互作用，驱动 ZnS 纳米晶（NCs）沿着这个方向进行定向附着。这些超薄的 ZnS 纳米线在室温下表现出本征铁磁性，以及与其独特性质相关的其他异常性质，例如大各向异性晶格膨胀、激子的紫外-可见吸收带的大蓝移，以及激子带边缘的光致发光光谱。第一性原理 DFT 计算结果表明，Zn 空位可以在这些未掺杂的 ZnS NWs 中诱导本征铁磁性。磁矩的主要来源是 Zn 空位周围 S 位未配对的 3p 电子，这些电子带有磁矩，范围为 0.26 到 0.66μB。计算结果表明，通过增加 Zn 空位浓度可以增加超薄 ZnS NWs 的磁矩，而不会带来显著的能量成本。Zn(53)S(54)超胞模型计算的磁化值（表面或内部 Zn 空位的 1.96 或 0.40 emu/g）大于我们的实验值（1.8 K 时为 0.12 emu/g，300 K 时为 0.05 emu/g），但铁磁性结果在定性上是一致的。
