Ion irradiation induced phase transformation in gold nanocrystalline films

Abstract

Gold is a noble metal typically stable as a solid in a face-centered cubic (FCC) structure under ambient conditions; however, under particular circumstances aberrant allotropes have been synthesized. In this work, we document the phase transformation of 25 nm thick nanocrystalline (NC) free-standing gold thin-film via in situ ion irradiation studied using atomic-resolution transmission electron microscopy (TEM). Utilizing precession electron diffraction (PED) techniques, crystallographic orientation and the radiation-induced relative strains were measured and furthermore used to determine that a combination of surface and radiation-induced strains lead to an FCC to hexagonal close packed (HCP) crystallographic phase transformation upon a 10 dpa radiation dose of Au4+ ions. Contrary to previous studies, HCP phase in nanostructures of gold was stabilized and did not transform back to FCC due to a combination of size effects and defects imparted by damage cascades.

Phase stability of spherical Ferrum nanoparticles under radiation saturation with vacancies

“…Вплив опромінення зазвичай полягає у появі мігруючих вакансій та інших точкових дефектів, що показано в працях [3,4]. В експериментах аргументуються фазові та структурні зміни в наномасштабних структурах, наприклад, поліморфні перетворення, одержані в нанокристалічному золоті при опроміненні [5], фазовий перехід ОЦК-ГЦК у сплаві α-Fe-Ni, викликаний випромінюванням власних іонів при 673 К і флюенсі ~1,2 зна [6], зміни структурних властивостей Ni-наноструктур при іонному бомбардуванні [7], аморфізація після опромінення іонами гелію нанозерен TiN та зменшення нанотвердості, що залежить від розміру зерна [8].…”

Irradiation stability and induced ferromagnetism in a nanocrystalline CoCrCuFeNi highly-concentrated alloy

“…[26][27][28] The major challenge for application of nanocrystalline materials in extreme environments remains to prevent the manifestation of degradation mechanisms resulting in microstructural instabilities such as grain growth 24,26,[30][31][32][33][34][35][36] and phase transformations. [37][38][39][40][41][42] In order to do so, the nanocrystalline idea has been recently combined with the HCA concept. [4][5][6]43 Recent research indicated these emergent equiatomic metallic alloys can exhibit improved levels of radiation resistance when compared with conventional nuclear materials such as Zr-and Fe-based alloys.…”

Irradiation stability and induced ferromagnetism in a nanocrystalline CoCrCuFeNi highly-concentrated alloy

“…The major challenge for application of nanocrystalline materials in extreme environments remains to prevent the manifestation of degradation mechanisms resulting in microstructural instabilities such as grain growth [18,20,[24][25][26][27][28][29][30] and phase transformations [31][32][33][34][35][36]. In order to do so, the nanocrystalline idea has been recently combined with the HCA concept [3][4][5]37].…”