title: Fabrication of Self-Ordered Alumina Films with Large Interpore Distance by Janus Anodization in Citric Acid.
abstract: Self-organized porous anodic alumina (PAA) formed by electrochemical anodization have become a fundamental tool to develop various functional nanomaterials. However, it is still a great challenge to break the interpore distance (Dint) limit (500 nm) by using current anodization technologies of mild anodization (MA) and hard anodization (HA). Here, we reported a new anodization mode named "Janus anodization" (JA) to controllably fabricate self-ordered PAA with large Dintat high voltage of 350-400 V. JA naturally occurs as anodizing Al foils in citric acid solution, which possessing both the characteristics of MA and HA. The process can be divided into two stages: I, slow pore nucleation stage similar to MA; II, unequilibrium self-organization process similar to HA. The as-prepared films had the highest modulus (7.0 GPa) and hardness (127.2 GPa) values compared with the alumina obtained by MA and HA. The optical studies showed that the black films have low reflectance (<10 %) in the wavelength range of 250-1500 nm and photoluminescence property. Dintcan be tuned between 645-884 nm by controlling citric acid concentration or anodization voltage. JA is a potential technology to efficiently and controllably fabricate microstructured or hybrid micro- and nanostructured materials with novel properties.
authors.affiliation: College of Physics and Information Technology, Shaanxi Normal University, 710119 Xi'an, P. R. China.|School of Science, Ningxia Medical University, 750004 Yinchuan, P. R. China.
authors.forename: Yingjun
authors.initials: Y
authors.lastname: Ma
authors.affiliation: College of Physics and Information Technology, Shaanxi Normal University, 710119 Xi'an, P. R. China.
authors.forename: Yihao
authors.initials: Y
authors.lastname: Wen
authors.affiliation: College of Physics and Information Technology, Shaanxi Normal University, 710119 Xi'an, P. R. China.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Physics and Information Technology, Shaanxi Normal University, 710119 Xi'an, P. R. China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Physics and Information Technology, Shaanxi Normal University, 710119 Xi'an, P. R. China.
authors.forename: Zhiying
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: College of Physics and Information Technology, Shaanxi Normal University, 710119 Xi'an, P. R. China.
authors.forename: Chenchen
authors.initials: C
authors.lastname: Feng
authors.affiliation: College of Physics and Information Technology, Shaanxi Normal University, 710119 Xi'an, P. R. China.
authors.forename: Runguang
authors.initials: R
authors.lastname: Sun