陰離子對(duì)Mg(OH)2晶體生長(zhǎng)及形貌的影響機(jī)理

程沛，李雪,2,3，裴冰野，常睿璇，孫曉君，丁珂，范天博,2,3，劉云義,2,3

（1沈陽(yáng)化工大學(xué)化學(xué)工程學(xué)院，遼寧 沈陽(yáng) 110142；2遼寧省化工應(yīng)用重點(diǎn)實(shí)驗(yàn)室，遼寧 沈陽(yáng) 110142；3遼寧精細(xì)化工協(xié)同創(chuàng)新中心，遼寧 沈陽(yáng) 110142）

陰離子對(duì)Mg(OH)2晶體生長(zhǎng)及形貌的影響機(jī)理

程沛1，李雪1,2,3，裴冰野1，常睿璇1，孫曉君1，丁珂1，范天博1,2,3，劉云義1,2,3

（1沈陽(yáng)化工大學(xué)化學(xué)工程學(xué)院，遼寧 沈陽(yáng) 110142；2遼寧省化工應(yīng)用重點(diǎn)實(shí)驗(yàn)室，遼寧 沈陽(yáng) 110142；3遼寧精細(xì)化工協(xié)同創(chuàng)新中心，遼寧 沈陽(yáng) 110142）

以輕燒粉、氯化銨、硝酸銨、乙酸銨、硫酸銨為原料，氨氣為沉淀劑，采用氨循環(huán)法制備氫氧化鎂晶體，并通過(guò)掃描電鏡(SEM)、X射線衍射(XRD)對(duì)其進(jìn)行表征分析。采用 Materials Studio 分子模擬軟件中的CASTEP模塊，計(jì)算了 Cl?、、CH3COO?對(duì)氫氧化鎂晶體 (001)、(101) 晶面生長(zhǎng)的影響。結(jié)果表明，采用不同的鎂鹽得到不同形貌的氫氧化鎂晶體陰離子電負(fù)性越大，對(duì)晶體形貌影響越小；Mg(OH)2晶體的(001)、(101)晶面能量與布居數(shù)分析表明，Cl?、、CH3COO?使晶體的(001)、(101)面的表面能增大、Fermi能級(jí)減小，陰離子與(001)、(101) 晶面之間形成新的具有微弱共價(jià)性的離子鍵，影響晶體晶面的生長(zhǎng)。理論計(jì)算較好地解釋了不同形貌的氫氧化鎂晶體的形成原因。

輕燒粉；電負(fù)性；分子模擬；布居數(shù)；機(jī)理

Abstract:The magnesium hydroxide crystals were prepared by ammonia circulation method,using light burning powder,ammonium chloride,ammonium nitrate,ammonium acetate and ammonium sulfate as raw materials and ammonia gas as precipitant.X-ray diffraction(XRD) and scanning electron microscopy(SEM) have been employed to characterize these products.The effects of Cl?,and CH3COO?on the growth of (001) and (101)crystal planes of magnesium hydroxide crystals were calculated by the CASTEP module in the Materials Studio molecular simulation software.The results showed that magnesium hydroxide crystals with different morphologies were obtained by different magnesium salts.The larger the anionic electronegativity was,the smaller the effect on the crystal morphology.The (001) and (101) crystal face energy and population analysis of Mg(OH)2crystals showed that the surface energy increased and Fermi energy decreased of (001) and (101) planes of the crystals with Cl?,and CH3COO?.New ionic bond with weak covalency was formed between anion and the (001) and (101) planes which affected the growth of the crystal plane.The theoretical calculations explainedthe formation of magnesium hydroxide crystals with different morphologies.

Key words:light burning powder; electronegativity; molecular simulation; population; mechanism

引 言

近年來(lái)，隨著塑料、橡膠、涂料、合成纖維等高聚物材料的廣泛應(yīng)用，其易于燃燒的性質(zhì)同時(shí)也帶來(lái)了巨大的社會(huì)危害，因此含有阻燃劑的塑料越來(lái)越受到人們的關(guān)注[1-4]。無(wú)機(jī)阻燃劑由于具有低煙、無(wú)毒、熱穩(wěn)定性好、價(jià)格低廉等優(yōu)點(diǎn)，廣泛應(yīng)用于塑料中，在國(guó)內(nèi)外日益被廣泛采用。無(wú)機(jī)阻燃劑主要品種有氫氧化鋁、氫氧化鎂、無(wú)機(jī)磷化合物、硼酸鹽、氧化銻、鉬化合物等。……