Mechanical properties and structural integrity of devices based on sol–gel mesoporous oxides thin films

• Published in: Journal of sol-gel science and technology Vol. 102; no. 1; pp. 185 - 196
• Main Authors: Ramallo, Juan Ignacio, Morrone, Josefina, Lionello, Diego Fernando, Angelomé, Paula C., Fuertes, María Cecilia
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.04.2022; Springer Nature B.V
• Subjects: Bilayers; Ceramics; Chemistry and Materials Science; Composites; Devices; Ductile-brittle transition; Failure modes; Flow stability; Glass; Indentation; Inorganic Chemistry; Interface stability; Materials Science; Mechanical properties; Monolayers; Multilayers; Nanotechnology; Natural Materials; Optical and Electronic Materials; Optical microscopy; Optical properties; Original Paper: Functional coatings; Self-assembly; Silicon dioxide; Sol-gel processes; Sol-Gel Research in Latin America; Stability analysis; Structural integrity; Synthesis; Thin films; thin films and membranes (including deposition techniques); Titanium dioxide; Yield strength; Mesoporous oxides; Mechanical properties; Chemical stability; Photonic crystals; Nanoindentation
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-021-05636-5

One of the current issues in the development of devices based on porous thin films synthesized by sol gel is the eventual failure of the structural integrity of these systems due to chemical or mechanical stresses. In order to design and build robust systems, it is necessary to evaluate the role that each material forming the device has over its mechanical performance and chemical stability, considering their individual properties, their spatial arrangement, and the interfaces between them. In this work, the structural and mechanical evaluation of multilayers based on silica and titania mesoporous films is presented, and the variables that affect the structural integrity of these multilayered devices are evaluated. In addition, the chemical and mechanical stability of these optical devices against flow stress is assessed, simulating operating conditions of the sensors in a liquid environment. Single layer, bilayers, and multilayered devices were synthesized using the sol–gel method in combination with surfactant self-assembly, and their mechanical and structural properties were evaluated with electron and optical microscopy, X-ray reflectometry, and instrumented indentation. After these studies, improvements to the materials forming the device are proposed to maximize the structural integrity of the system. In this work, the structural and mechanical evaluation of multilayers based on silica and titania mesoporous thin films is presented, and the variables that affect the structural integrity of these multilayered devices are evaluated. In addition, the chemical and mechanical stability of these optical devices against flow stress is assessed, simulating operating conditions of the sensors in a liquid environment. Highlights Silica mesoporous films present a ductile behavior while titania mesoporous films are more brittle. The spatial disposition of SiO 2 and TiO 2 layers in bilayer structures modifies the failure mode. The mesoporous SiO 2 –TiO 2 multilayer mechanical behavior is modulated by the SiO 2 layers. The optical and mechanical behavior of the photonic device changes after immersion in water at 40 °C.