Effect of pH variation and annealing on covalently assembled nanodiamond films
Effect of pH variation and annealing on covalently assembled nanodiamond films
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DOI：
10.1016/j.apsusc.2021.150585
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发表时间：
2021-07-16
影响因子：
6.7
通讯作者：
Radadia, Adarsh D.
中科院分区：
文献类型：
--
作者：
Desai, Tithi;Patoary, Naim H.;Radadia, Adarsh D.
这项工作探讨了使用低离子强度的两性离子缓冲和沉积后的热退火对连续纳米金刚石薄膜的微观结构和热导率的影响，该薄膜是通过定向共价组装的爆轰纳米金刚石沉积的。两性离子缓冲液pH值的变化被发现调整的表面覆盖率，膜厚度，热导率，和膜的形态定量的表观孔隙率和孔径分布。这些膜的连续退火高达400摄氏度，显示了预期的酰胺键的断裂，将纳米金刚石保持在一起，随后纳米金刚石的机械聚集成分离的岛，失去膜的连续性并增加表观孔隙率。热传导率随退火的变化受缓冲液pH的影响，这表明与退火相关的形态变化可能与热传导率有复杂的关系。使用声子跳跃模型进一步分析热导率数据，以量化声子跨越边界的运动程度。总之，结果表明，一种方法来实现多孔，低成本的纳米晶金刚石薄膜与可调的薄膜形态和热导率。
This work examines the effect of using low-ionic strength zwitterionic buffer and post-deposition thermal annealing on the microstructure and thermal conductivity of continuous nanocrystalline diamond films that are deposited via the directed covalent assembly of detonation nanodiamonds. Variation of the zwitterionic buffer pH was found to tune the surface coverage, film thickness, thermal conductivity, and film morphology as quantified by apparent porosity and pore size distribution. The sequential annealing of these films up to 400 degrees C, showed the anticipated severance of amide bonds holding the nanodiamonds together, followed by the detri-mental aggregation of the nanodiamonds to segregated islands, losing film continuity and increasing apparent porosity. The change in thermal conductivity with annealing was subjective to buffer pH, suggesting that the morphology changes associated with annealing may have a complex relationship with thermal conductivity. The thermal conductivity data were further analyzed using a phonon hopping model to quantify the degree of phonon movement across boundaries. Overall, the results demonstrate a way to achieving porous, low-cost nano-crystalline diamond thin films with tunable film morphology and thermal conductivity.