Quasi-thermodynamic model on hydride formation in palladium–hydrogen thin films: Impact of elastic and microstructural constraints
Quasi-thermodynamic model on hydride formation in palladium–hydrogen thin films: Impact of elastic and microstructural constraints
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DOI：
10.1016/j.ijhydene.2015.11.063
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发表时间：
2016-01
影响因子：
7.2
通讯作者：
S. Wagner;A. Pundt
中科院分区：
文献类型：
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作者：
S. Wagner;A. Pundt
采用不同微结构的（10-300）nm Pd-H薄膜研究了弹性和微结构约束对结构相变的影响。氢致应力主要来源于薄膜对衬底的粘附。应力改变氢的化学势μ H，从而改变氢化物相的稳定性。薄膜中的微结构约束通道应力释放。提出了一个热力学模型，推导出薄膜中H-H相互作用能EHH和氢化物形成的有效临界温度Tceff。它允许偶尔观察到低于T c e f f的μ H倾斜平台。EHH（15和30 kJ/mol H之间）和Tceff（340 K至490 K）降低高达50%相比，散装（EHH = 36.8 kJ/mol H，Tc = 563 K），对于所有的膜。衬底诱导应力（约（2-5）kJ/mol H）和微结构（约（5-8）kJ/mol H）的浓度依赖性贡献被分离。在300 K时，所有薄膜仍存在相分离.
The impact of elastic and microstructural constraints on structural phase transitions is investigated by using (10–300) nm Pd–H films of different microstructures. Hydrogen-induced stress mainly arises from the film's adhesion to a substrate. Stress changes the hydrogens' chemical potential μ H, modifying the hydride phase stability. Microstructural constraints channel stress release in films. A thermodynamic model is proposed to deduce the H–H interaction energy E HH and an effective critical temperature T c e f f of hydride formation in films. It allows for occasionally observed sloped plateaus of μ H below T c e f f. E HH (between 15 and 30 kJ/mol H) and T c e f f (340 K to 490 K) are reduced by up to 50% compared to bulk (E H H= 36.8 k J/m o l H, T c= 563 K), for all films. Concentration-dependent contributions of substrate-induced stress (of about (2–5) kJ/mol H) and microstructure (of about (5–8) kJ/mol H) are separated. For all films phase separation is still found at 300 K.