A systematic review on competitive screening and independent variable unification focused on PAA structural parameter calculation formulas in mild anodization

Abstract

Porous anodized aluminium oxide (PAA) has wide and important applications in photonic crystals, energy science, nanotemplates, life science, medicine, aerospace and other scientific research and industrial manufacturing fields. The decisive factors determining its application value and specific performance are its own structural parameters. Therefore, the accurate calculation (but not destructive measurement) of each PAA structural parameter is of great significance for the design and application of PAA structures to satisfy different practical requirements. However, there is a significant problem because multiple distinct formulas proposed by different researchers are used for calculating single independent PAA structural parameters such as the pore diameter. Furthermore, these multiple distinct formulas for determining a single PAA structural parameter frequently yield different results. Compounding this issue, these single structural parameters serve as independent variables in formulas for calculating other PAA parameters. This propagation of uncertainty leads to multiple distinct results for other subsequent parameters. Consequently, in practice, for the calculation of a PAA structural parameter, it is difficult to discern which calculations are the most accurate. Regarding the aforementioned issues, this paper systematically reviews the key structural parameters of PAA and the most commonly used distinct calculation formulas of each key structural parameter. The independent variables of almost all mentioned calculation formulas are unified to the anodization voltage. Subsequently, extensive experimental data published by other researchers are substituted into all the formulas with the unified independent variable to perform an objective competitive screening for the optimal calculation formula of each PAA structural parameter. Finally, on the basis of the competitive screening and independent variable unification, an equation set of PAA structural parameter calculations is proposed for the accurate and convenient calculation of all key PAA structural parameters. The proposal of an equation set for the PAA structural parameter calculation provides a systematic, comprehensive theoretical model and mathematical tool for the design and calculation of PAA structures according to practical requirements in scientific research and engineering applications.