本文選題：粒度　切入點(diǎn)：形貌　出處：《太原理工大學(xué)》2015年碩士論文

【摘要】：眾所周知，當(dāng)材料的尺寸達(dá)到納米級(jí)別時(shí)，由于表面效應(yīng)和小尺寸效應(yīng)，引起物質(zhì)在化學(xué)反應(yīng)平衡、反應(yīng)動(dòng)力學(xué)、相變、吸附、電化學(xué)和催化等方面產(chǎn)生了很大變化，而這些變化主要?dú)w因于其熱力學(xué)性質(zhì)的改變。因此，研究粒度和形貌對(duì)納米材料熱力學(xué)性質(zhì)的影響是非常重要和必要的。目前，關(guān)于粒度對(duì)納米顆粒熱力學(xué)性質(zhì)影響的研究報(bào)道較少，并且粒徑對(duì)其熱力學(xué)性質(zhì)的影響規(guī)律還不清楚，球形納米顆粒熱力學(xué)性質(zhì)的理論研究還不完善，，其它形貌納米顆粒熱力學(xué)性質(zhì)的理論研究還未見報(bào)道。 論文首先將界面變量引入到納米顆粒的吉布斯函數(shù)中，系統(tǒng)地推導(dǎo)出不同形貌（球形、立方形、棒狀和片狀）納米顆粒的表面熱力學(xué)性質(zhì)及其熱力學(xué)性質(zhì)分別與其粒度間的熱力學(xué)關(guān)系式，包括摩爾表面吉布斯能、摩爾吉布斯能、摩爾表面焓、摩爾焓、摩爾表面熵、摩爾熵、恒壓摩爾表面熱容和恒壓摩爾熱容；將Young-Laplace方程首次應(yīng)用于固體納米粒子，導(dǎo)出了固體納米顆粒的附加壓力，進(jìn)一步推導(dǎo)出固體納米顆粒的摩爾表面能、摩爾內(nèi)能、恒容摩爾表面熱容、恒容摩爾熱容。 其次，編寫出計(jì)算原子簇坐標(biāo)的VB源程序，根據(jù)鐵和銀的單晶胞參數(shù)，構(gòu)建出一系列不同粒度、不同形貌的納米鐵簇和納米銀簇模型；采用gaussian09軟件中量子化學(xué)的半經(jīng)驗(yàn)方法PM6分別對(duì)納米鐵簇和納米銀簇的熱力學(xué)性質(zhì)進(jìn)行了計(jì)算，得到了不同粒度、不同形貌納米團(tuán)簇的摩爾吉布斯能、摩爾焓、摩爾熵、摩爾內(nèi)能和恒容摩爾熱容，并討論了粒度和形貌對(duì)這些熱力學(xué)性質(zhì)的影響規(guī)律；還進(jìn)一步估算出納米鐵的Tolman長(zhǎng)度以及膨脹系數(shù)。 研究結(jié)果表明：納米顆粒的熱力學(xué)性質(zhì)主要與其粒度、表面張力、表面張力的溫度系數(shù)和膨脹系數(shù)有關(guān)；關(guān)于粒度對(duì)納米顆粒熱力學(xué)性質(zhì)的影響規(guī)律，量子化學(xué)的計(jì)算結(jié)果與納米顆粒的熱力學(xué)理論一致：納米顆粒的摩爾吉布斯能、摩爾焓、摩爾熵和摩爾內(nèi)能隨著納米顆粒粒度的減小而增大，恒容摩爾熱容則變化不大，隨著納米顆粒粒度的減小而略有減�。徊煌蚊驳募{米顆粒，如果原子數(shù)相同，則其各種熱力性質(zhì)差別不大。此外，還發(fā)現(xiàn)納米Fe簇的Tolman長(zhǎng)度大約為0.1，并且其膨脹系數(shù)為負(fù)值。 納米顆粒的熱力學(xué)理論及其粒度對(duì)熱力學(xué)性質(zhì)的影響規(guī)律對(duì)于納米顆粒在化學(xué)反應(yīng)、相變、吸附、電化學(xué)及其催化中的研究和應(yīng)用具有重要的指導(dǎo)作用。
[Abstract]:As we all know, when the size of the material reaches the nanometer level, because of the surface effect and the small size effect, the material changes greatly in the aspects of chemical reaction equilibrium, reaction kinetics, phase transition, adsorption, electrochemistry and catalysis, etc.These changes are mainly attributed to the changes in their thermodynamic properties.Therefore, it is very important and necessary to study the effect of particle size and morphology on the thermodynamic properties of nanomaterials.At present, there are few reports on the effect of particle size on the thermodynamic properties of nanoparticles, and the influence of particle size on the thermodynamic properties of nanoparticles is not clear, and the theoretical study of thermodynamic properties of spherical nanoparticles is not perfect.The thermodynamic properties of other morphology nanoparticles have not been reported.In this paper, the interface variables are introduced into the Gibbs function of nanoparticles, and the different morphologies (spherical, square, square) are deduced systematically.The surface thermodynamic properties of rod-shaped and flaky) nanoparticles and their thermodynamic relations with their particle size, including molar surface Gibbs energy, molar Gibbs energy, molar surface enthalpy, molar enthalpy, molar surface entropy, etc.Molar entropy, constant pressure molar surface heat capacity and constant pressure molar heat capacity. The Young-Laplace equation is applied to solid nanoparticles for the first time, the additional pressure of solid nanoparticles is derived, and the molar surface energy and intramolar energy of solid nanoparticles are further derived.Constant molar surface heat capacity, constant volume molar heat capacity.Secondly, a VB source program is written to calculate the coordinates of clusters. According to the unit cell parameters of iron and silver, a series of nano-iron clusters and nano-silver cluster models with different particle sizes and different morphologies are constructed.The thermodynamic properties of iron nanoclusters and silver nanoclusters were calculated by the semi-empirical method PM6 of quantum chemistry in gaussian09 software. The molar Gibbs energy, molar enthalpy and molar entropy of different particle sizes and morphologies of nanoclusters were obtained.The effects of particle size and morphology on these thermodynamic properties were discussed, and the Tolman length and expansion coefficient of nanocrystalline iron were also estimated.The results show that the thermodynamic properties of nanoparticles are mainly related to their particle size, surface tension, temperature coefficient of surface tension and coefficient of expansion.The calculated results of quantum chemistry are consistent with the thermodynamic theory of nanoparticles: the molar Gibbs energy, molar enthalpy, molar entropy and internal energy of nanoparticles increase with the decrease of particle size, but the constant volume molar heat capacity does not change much.With the decrease of the particle size, the thermal properties of the nanoparticles with different morphologies are not different if the number of atoms is the same.In addition, it is found that the Tolman length of Fe nanoclusters is about 0.1, and its expansion coefficient is negative.The thermodynamics theory of nanoparticles and the influence of particle size on thermodynamic properties have important guiding effects on the research and application of nanoparticles in chemical reaction, phase transition, adsorption, electrochemistry and their catalysis.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1

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