二氧化钛(TiO_(2))的形貌与其功能化应用密切相关,其是一种电子束辐照敏感材料,但特定形貌的纳米晶在电子束辐照下结构演变动力学机制尚未明晰。本研究通过水热法合成了具有条棒状(边缘陡直)、八面体双锥状(锥尖锐利)及薄片状的锐钛矿相...二氧化钛(TiO_(2))的形貌与其功能化应用密切相关,其是一种电子束辐照敏感材料,但特定形貌的纳米晶在电子束辐照下结构演变动力学机制尚未明晰。本研究通过水热法合成了具有条棒状(边缘陡直)、八面体双锥状(锥尖锐利)及薄片状的锐钛矿相TiO_(2)纳米晶,利用透射电子显微镜(transmission electron microscopy,TEM)原位监测不同形貌样品在电子束辐照下的结构演变过程。结合反傅里叶变换(inverse fast Fourier transform,iFFT)、电子能量损失谱(electron energy loss spectroscopy,EELS)和原位电子束辐照质谱等分析发现:TiO_(2)经过电子束辐照解离出O_(2)离子从而转变为γ-TiO;条棒状与双锥状纳米晶沿[100]方向辐照过程中,锐钛矿向γ-TiO的结构转变优先发生于边缘薄区并逐渐向内部扩展;而片状纳米晶沿[001]方向辐照过程中,相变区域无显著空间分布特征,且薄区易伴随非晶化现象。本研究揭示了由位移损伤和电离损伤协同作用下,TiO_(2)的形貌依赖的电子束辐照损伤机制,为辐照环境下TiO_(2)基材料的稳定性优化及利用电子束进行TiO_(2)/TiO异质结构设计提供了依据。展开更多
采用分子动力学模拟的方法,研究了LiCl-KCl-CeCl_3熔盐中CeCl_3的结构性质和热力学,获得了LiClKCl-CeCl_3熔盐中密度与组成、密度与温度的关系数据;径向分布函数g_(Ce-Cl)(r)的第一个峰位置为0.259nm,Ce^(3+)对应的第一个配位数约为6.9...采用分子动力学模拟的方法,研究了LiCl-KCl-CeCl_3熔盐中CeCl_3的结构性质和热力学,获得了LiClKCl-CeCl_3熔盐中密度与组成、密度与温度的关系数据;径向分布函数g_(Ce-Cl)(r)的第一个峰位置为0.259nm,Ce^(3+)对应的第一个配位数约为6.9;混合熔盐中计算数据与纯熔盐中数据的差异可以解释为混合熔盐中Ce^(3+)和Cl^-的相互作用比纯的CeCl_3更强;LiCl-KCl熔盐中Ce^(3+)的自扩散活化能为22.5 k J?mol^(-1),从活化能的本质来说,Ce^(3+)自扩散所需要克服的能垒要略低于U^(3+)(25.8 k J?mol^(-1))。当Ce^(3+)的摩尔分数从0.005增加到0.05时,其指前因子从31.9×10^(-5)cm^2?s^(-1)减少到21.8×10^(-5)cm^2?s^(-1);随着Ce^(3+)摩尔分数从0.005增长到0.05,单位体积内(忽略总体积的变化)Ce^(3+)的增加意味着其扩散阻力增加,而自扩散的能力降低,导致了指前因子的减小。展开更多
The mechanism of decomposition of calcium inosilicate(CaSiO_3) synthesized through chemical deposition method using analytical reagent NaSiO_3·9H_2O and CaCl_2 during the alkali fusion process using NaOH was inve...The mechanism of decomposition of calcium inosilicate(CaSiO_3) synthesized through chemical deposition method using analytical reagent NaSiO_3·9H_2O and CaCl_2 during the alkali fusion process using NaOH was investigated by Raman spectroscopy in situ,X-ray diffraction and Fourier transform infrared spectrometer(FTIR).The results show that the tetrahedral silica chains within CaSiO_3 are gradually disrupted and transformed into nesosilicate with the isolated SiO_4 tetrahedra at the beginning of the alkali fusion process.The three intermediates including Ca_2SiO_4,Na_2CaSiO_4 and Na_2SiO_3 appear simultaneously in the decomposition of CaSiO_3,while the final products are Ca(OH)_2 and Na_4SiO_4.It can be concluded that there exist two reaction pathways in the alkali fusion process of CaSiO_3:one is ion exchange,the other is in the main form of the framework structure change of silicate.The reaction pathway is led by silicate structure transformation in the alkali fusion process.展开更多
The solid polyferric sulfate(PFS) was made by oxidation of pyrite cinders with NaClO 3. It was first time discovered by X-rays diffractometry that when the solid PFS was prepared at temperature below 120 ℃ the main p...The solid polyferric sulfate(PFS) was made by oxidation of pyrite cinders with NaClO 3. It was first time discovered by X-rays diffractometry that when the solid PFS was prepared at temperature below 120 ℃ the main phase of the solid PFS is Fe 4.67(SO 4) 6(OH) 2·20H 2O which disappeared when heating was carried out above 130 ℃ for 2 h and complex physical chemical reactions occurred . In thermal spectra two TG mass loss peaks and DTA exothermic peaks at 170～290 ℃ and 27～160 ℃, respectively, were recorded.展开更多
文摘二氧化钛(TiO_(2))的形貌与其功能化应用密切相关,其是一种电子束辐照敏感材料,但特定形貌的纳米晶在电子束辐照下结构演变动力学机制尚未明晰。本研究通过水热法合成了具有条棒状(边缘陡直)、八面体双锥状(锥尖锐利)及薄片状的锐钛矿相TiO_(2)纳米晶,利用透射电子显微镜(transmission electron microscopy,TEM)原位监测不同形貌样品在电子束辐照下的结构演变过程。结合反傅里叶变换(inverse fast Fourier transform,iFFT)、电子能量损失谱(electron energy loss spectroscopy,EELS)和原位电子束辐照质谱等分析发现:TiO_(2)经过电子束辐照解离出O_(2)离子从而转变为γ-TiO;条棒状与双锥状纳米晶沿[100]方向辐照过程中,锐钛矿向γ-TiO的结构转变优先发生于边缘薄区并逐渐向内部扩展;而片状纳米晶沿[001]方向辐照过程中,相变区域无显著空间分布特征,且薄区易伴随非晶化现象。本研究揭示了由位移损伤和电离损伤协同作用下,TiO_(2)的形貌依赖的电子束辐照损伤机制,为辐照环境下TiO_(2)基材料的稳定性优化及利用电子束进行TiO_(2)/TiO异质结构设计提供了依据。
文摘采用分子动力学模拟的方法,研究了LiCl-KCl-CeCl_3熔盐中CeCl_3的结构性质和热力学,获得了LiClKCl-CeCl_3熔盐中密度与组成、密度与温度的关系数据;径向分布函数g_(Ce-Cl)(r)的第一个峰位置为0.259nm,Ce^(3+)对应的第一个配位数约为6.9;混合熔盐中计算数据与纯熔盐中数据的差异可以解释为混合熔盐中Ce^(3+)和Cl^-的相互作用比纯的CeCl_3更强;LiCl-KCl熔盐中Ce^(3+)的自扩散活化能为22.5 k J?mol^(-1),从活化能的本质来说,Ce^(3+)自扩散所需要克服的能垒要略低于U^(3+)(25.8 k J?mol^(-1))。当Ce^(3+)的摩尔分数从0.005增加到0.05时,其指前因子从31.9×10^(-5)cm^2?s^(-1)减少到21.8×10^(-5)cm^2?s^(-1);随着Ce^(3+)摩尔分数从0.005增长到0.05,单位体积内(忽略总体积的变化)Ce^(3+)的增加意味着其扩散阻力增加,而自扩散的能力降低,导致了指前因子的减小。
基金Project(20112120120003)supported by the Science and Technology Projects of Ministry of Education of ChinaProject(L2014120)supported by the Educational Commission of Liaoning Province,China
文摘The mechanism of decomposition of calcium inosilicate(CaSiO_3) synthesized through chemical deposition method using analytical reagent NaSiO_3·9H_2O and CaCl_2 during the alkali fusion process using NaOH was investigated by Raman spectroscopy in situ,X-ray diffraction and Fourier transform infrared spectrometer(FTIR).The results show that the tetrahedral silica chains within CaSiO_3 are gradually disrupted and transformed into nesosilicate with the isolated SiO_4 tetrahedra at the beginning of the alkali fusion process.The three intermediates including Ca_2SiO_4,Na_2CaSiO_4 and Na_2SiO_3 appear simultaneously in the decomposition of CaSiO_3,while the final products are Ca(OH)_2 and Na_4SiO_4.It can be concluded that there exist two reaction pathways in the alkali fusion process of CaSiO_3:one is ion exchange,the other is in the main form of the framework structure change of silicate.The reaction pathway is led by silicate structure transformation in the alkali fusion process.
文摘The solid polyferric sulfate(PFS) was made by oxidation of pyrite cinders with NaClO 3. It was first time discovered by X-rays diffractometry that when the solid PFS was prepared at temperature below 120 ℃ the main phase of the solid PFS is Fe 4.67(SO 4) 6(OH) 2·20H 2O which disappeared when heating was carried out above 130 ℃ for 2 h and complex physical chemical reactions occurred . In thermal spectra two TG mass loss peaks and DTA exothermic peaks at 170～290 ℃ and 27～160 ℃, respectively, were recorded.
