标题： 形成温度和弯曲化学应变对二硫化钼氧化物纳米薄片电物理性质的影响 显示英文标题

标题： The effect of formation temperature and flexo-chemical strains on the electrophysical properties of the molybdenum-disulfide-oxide nanoflakes

摘要： 我们通过在水热条件下，将(NH4)6Mo7O24与硫脲在130oC至180oC的温度下反应，合成了由自组装的10-20 nm薄纳米片组成的二硫化钼氧化物纳米花。XPS、EDX和拉曼光谱结果的详细分析揭示了二硫化钼纳米片中存在大量钼的氧化物、硫化物和硫酸盐，这使得可以考虑其化学组成的“有效”公式MoSxOy。MoSxOy纳米片表现出对材料科学有趣且有应用前景的异常电输运特性。纳米片的化学组成和微观结构由合成温度决定，这被证明是电导机制的原因。具体而言，对于在合成温度T_s<<150oC和T_s>>150oC下制备的样品，电流-电压特性（I-V曲线）随着施加电压单调增加，在较低电压下呈非欧姆和滞回特性，并在较高电压下接近欧姆特性。在T_s=150oC时，I-V曲线呈现出具有明显负微分电阻部分的N型形状。无论是否有N型形状，I-V曲线都表现出滞回行为，增加和减少电压扫描之间的差异，滞回环参数由合成温度决定。值得注意的是，研究的纳米片在电压切换“开”和“关”后表现出非常长寿命的深充电和放电。考虑到氧非计量比和弯曲可能在纳米片中产生强烈的柔性化学应变，我们提出了压紧MoSxOy纳米片的柔性化学模型，该模型描述了观察到的I-V曲线。 显示英文摘要

摘要： We synthesized the powder of molybdenum-disulfide-oxide nanoflowers consisting of self-assembled 10-20 nm thin nanoflakes by reaction of (NH4)6Mo7O24 with thiourea in aqueous solution at temperatures from 130oC to 180oC in hydrothermal conditions. The detailed analysis of the XPS, EDX and Raman spectroscopy results reveal the significant amount of the molybdenum oxides, sulfides and sulfates in the molybdenum disulfide nanoflakes, which allows to consider the "effective" formulae MoSxOy for their chemical composition. The MoSxOy nanoflakes reveal unusual electric transport features interesting for material science and promising for applications. The chemical composition and microstructure of the nanoflakes, which are determined by the temperature of synthesis, is shown to be responsible for the electro-conduction mechanism. Namely, the current-voltage characteristics (I-V curves) grow monotonically with the applied voltage for the samples, synthesized at the temperatures T_s<<150oC and T_s>>150oC, being non-ohmic and hysteretic at lower voltages and becoming close to the ohmic at higher voltages. The I-V curves acquire N-like shape with a strongly pronounced negative differential resistivity part at T_s=150oC. Both with and without N-shape, the I-V curves manifest hysteretic behavior with the difference between increasing and decreasing voltage sweeps, and the hysteresis loop parameters are determined by the temperature of synthesis. Important, that the studied nanoflakes manifest very long living deep charging and discharging after the voltage switching "on" and "off".Considering that the presence of oxygen non-stoichiometry and bending can create strong flexo-chemical strains in the nanoflakes, we proposed the flexo-chemical model of the polar and electro-transport properties of the pressed MoSxOy nanoflakes, which describes the observed I-V curves.