Speaker
Description
Porous anodizing has recently attracted great interest as a simple and inexpensive method to produce nanostructured materials. By varying the anodizing conditions, the structure of the formed porous anodic Al oxide can be tuned and subsequently functionalized, making it highly attractive for various industrial applications from nanoscale electronics and optoelectronics to template, catalysts and sensors surfaces.
During the growth of anodic Al oxide layers mostly performed in aqueous electrolytes, water incorporates in the film and therefore influences the intrinsic properties of the oxide formed. In this study [1], high-resolution neutron imaging was performed using the neutron microscope at POLDI beamline (SINQ, PSI) to visualize and quantify the water content in porous Al oxides as a function of anodizing conditions. While single crystal Al2O3 is almost neutron transparent, we confirm that, as expected, porous anodic Al oxides contain water incorporated directly in the oxide structure (structural) in addition to the one present in the pores (morphological). The differences in water content of porous anodic Al oxide layers are strongly related to the oxide growth parameters but interestingly cannot be directly correlated to a specific change in the amorphous oxide structure or in the pore morphology.
Investigations on reference Al oxides – C-sapphire, sintered Al oxide, plasma sprayed Al oxide, a commercial Al oxide membrane – and Al hydroxide further prove that neutron imaging is highly sensitive to crystalline structure and disorder, allowing differentiating crystalline Al oxides based on their phases and defect content. Lateral resolution permitting, high-resolution neutron imaging can become the ideal technique to study the changes occurring in porous ceramics, in particular with regards to the formation and thermal stability of hydroxides, which can be highly detrimental to surface protection and template applications.
[1] Ott N., Cancellieri C., Trtik P., Schmutz P., Materials Today Advances, 8 (2020) 100121
| Speaker Country | Switzerland |
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