ABSTRACT Molecular dynamics (MD) simulations, based on a recently developed charge optimised many-body interatomic potential (COMB3) for titanium dioxide materials, have been employed to investigate the effects of size and shape on the thermal properties of rutile TiO2 nanoparticles (2–6 nm). The size and shape dependence of the melting temperature, cohesive energy, heat capacity and thermal expansion coefficients have been studied. Our MD simulation results show that the melting point of spherical nanoparticles increases with size increase. On the other hand, the heat capacity and thermal expansion coefficients decrease with increasing nanoparticle size. Also, to predict the thermal properties of rutile TiO2 nanoparticles, we merged two theoretical models (Qi-model and Zhu’s model) proposed for size and shape-dependent thermal properties of nanoparticles. The comparison between our MD simulation results with those predicted by theoretical models showed that the trends observed in our MD simulation results were in good agreement with those suggested by the theoretical models. However, the thermal properties obtained from MD simulations deviated from those calculated theoretically for small nanoparticles which could be due to the edge and corner effects disregarded in the theoretical model.

中文翻译：

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金红石型 TiO2 纳米粒子的尺寸和形状相关热性能：分子动力学模拟研究

摘要 基于最近为二氧化钛材料开发的电荷优化多体原子间势 (COMB3) 的分子动力学 (MD) 模拟已被用于研究尺寸和形状对金红石 TiO2 纳米粒子 (2- 6 纳米）。已经研究了熔化温度、内聚能、热容量和热膨胀系数的尺寸和形状依赖性。我们的 MD 模拟结果表明，球形纳米粒子的熔点随着尺寸的增加而增加。另一方面，热容量和热膨胀系数随着纳米颗粒尺寸的增加而降低。此外，为了预测金红石 TiO2 纳米颗粒的热性能，我们合并了两个理论模型（Qi 模型和朱的模型），用于纳米粒子的尺寸和形状相关的热特性。我们的 MD 模拟结果与理论模型预测的结果之间的比较表明，我们的 MD 模拟结果中观察到的趋势与理论模型所建议的趋势非常吻合。然而，从 MD 模拟获得的热性能与小纳米颗粒的理论计算值有所不同，这可能是由于理论模型中忽略了边角效应。