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Designed single-phase ZrO2 nanocrystals obtained by solvothermal syntheses
CrystEngComm ( IF 2.6 ) Pub Date : 2020/01/31 , DOI: 10.1039/c9ce01992h
Mayara S. Santos 1, 2, 3, 4 , Jair C. C. Freitas 2, 3, 4, 5, 6 , Cleocir J. Dalmaschio 1, 2, 3, 4
Affiliation  

Design of metal oxide nanoparticles is a key study for obtaining high-functional materials with tunable properties. For that purpose, great progress on chemical methods for controlling the growth of nanoparticles during the synthesis has been made. However, an important challenge faced by this field of study is to completely understand the crystallization process and the chemical pathways during the syntheses that use growth-controlling agents. In this study, the synthesis of ZrO2 was conducted by a solvothermal methodology using three different organic solvents (oleic acid, benzyl alcohol and octyl alcohol) and adjusting the Zr precursor concentration, aiming to control the ZrO2 nanocrystal growth and obtain single-phase nanocrystalline particles. X-ray diffraction and Raman spectroscopy experiments indicated the formation of pure monoclinic, cubic and tetragonal ZrO2 nanocrystals for the syntheses using oleic acid, benzyl alcohol and octyl alcohol as solvents with precursor concentrations of 0.25, 0.50 and 0.50 mol L−1, respectively. Transmission electron microscopy was used to analyze the nanocrystal structure and to assess the crystal size distribution. Infrared and solid-state 13C nuclear magnetic resonance spectroscopy confirmed the presence of the organic ligands chemically bonded to the surface of the nanocrystals. Thermogravimetric analysis indicated an increasing ratio of ligand molecules/surface area as the acidity of the solvent increased. With the observations from this study, the solvent pKa value, the chemical structure and the type of coordination of the capping agents are ascribed as responsible for promoting different growth pathways, allowing pure crystalline phase zirconium oxide nanocrystals to be obtained.

中文翻译:

溶剂热合成设计单相ZrO2纳米晶

金属氧化物纳米颗粒的设计是获得具有可调性能的高功能材料的关键研究。为此,在合成过程中控制纳米颗粒生长的化学方法方面取得了很大的进步。然而,该研究领域面临的一个重要挑战是要完全了解使用生长控制剂的合成过程中的结晶过程和化学途径。在这项研究中,ZrO 2的合成是通过溶剂热方法,使用三种不同的有机溶剂(油酸,苄醇和辛醇)并调节Zr前体浓度来控制ZrO 2的。纳米晶体生长并获得单相纳米晶体颗粒。X射线衍射和拉曼光谱实验表明,以油酸,苯甲醇和辛醇为溶剂,前体浓度分别为0.25、0.50和0.50 mol L -1的情况下,形成了纯单斜晶,立方和四方的ZrO 2纳米晶体。。透射电子显微镜用于分析纳米晶体结构并评估晶体尺寸分布。红外和固态13C核磁共振波谱证实了化学键合到纳米晶体表面的有机配体的存在。热重分析表明,随着溶剂的酸度增加,配体分子/表面积的比率增加。根据这项研究的观察结果,溶剂p K a值,化学结构和封端剂的配位类型归因于促进了不同的生长途径,从而获得了纯晶相氧化锆纳米晶体。
更新日期:2020-03-09
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