三(2,4-戊二酮)合铱(Ⅲ)的热分解行为

Thermal Decomposition Behavior of Tris(2,4-pentanedionato-O,O′) Iridium(III)

采用TG DTA及GC MS联用分析手段研究了CVD (ChemicalVaporDepo sition ,化学气相沉积 )铱的前驱体三 ( 2 ,4 戊二酮 )合铱 (Ⅲ )的热分解行为 .结果表明 ,在氧气气氛下 ,三 ( 2 ,4 戊二酮 )合铱 (Ⅲ )在 2 5 8℃时开始燃烧分解 ,并伴随着升华失重 ,燃烧释放的热量远大于升华所需的热量 ,气相中的主要分解产物为 2 ,4 戊二酮、二氧化碳和 2 ,5 二甲基 3 乙酰基呋喃等 .而在惰性的氩气气氛下 ,三 ( 2 ,4 戊二酮 )合铱 (Ⅲ )从 2 3 9℃开始大量吸热升华并明显失重 ,它不会燃烧 ,只能随着温度的升高加快升华 ,当温度高于 3 0 0℃后开始分解 ,气相中的主要分解产物为 2 ,4 戊二酮、3 丁烯 2 酮和 2 ,5 二甲基呋喃等 .三 ( 2 ,4 戊二酮 )合铱 (Ⅲ )在氧气气氛下由于能够比较充分地氧化 ,因而分解产物种类比在惰性气氛下由于自身分解而生成的产物种类少并且稳定 .对不同气氛下所制备铱涂层的SEM研究结果表明 ,以三 ( 2 ,4 戊二酮 )合铱 (Ⅲ )作为前驱体制备铱涂层时 ,以掺有适量氧气的惰性气体 (比如氩气流量为 5 0mL·min-1,氧气流量为 3mL·min-1)作为载气能得到致密光亮的铱涂层 .本文还对三 ( 2 ,4 戊二酮 )合铱 (Ⅲ )主要热分解产物的自由基生成机理进行了探讨 .

The thermal decomposition behavior of tris(2,4-pentanedionato-O,O′) iridium(III) (1) has been studied with TG-DTA and GC-MS. The results show that compound 1 combusts, decomposes, sublimates and loses weight simultaneously at 258 ℃ in oxygen, and the heat emitting from the combustion is far greater than that absorbed by sublimation. Compound 1 decomposes, producing Ir, 2,4-pentanedione, carbon dioxide and 3-acetyl-2,5-dimethyl furan etc. in oxygen. Compound 1 absorbs a great deal of heat to sublimate and loses weight sharply from 239 ℃ in inert argon. Compound 1 can not combust with the increase of temperature in argon but sublimation is accelerated. When heated above 300 ℃, compound 1 decomposes, forming Ir, 2,4-pentanedione, 3-butene-2-one and 2,5-dimethyl furan etc. in argon. When compound 1 decomposed in oxygen, fewer kind of thermolytic products can be obtained. However, CVD experiments indicate that better Ir coatings on Re base can be prepared by adopting an inert gas with the addition of oxygen in appropriate amount (e.g. Ar flow of 50 mL·min -1, O 2 flow of 1 mL·min -1) as carrier gas flow, for oxygen can prevent carbon from co-depositing with Ir on base. The forming mechanisms of thermolytic products were also proposed on the basis of the recombination of free radicals and oxidation of the organic ligands.