The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin Films
In multicomponent thin films, properties and functionalities related to post-deposition annealing treatments, such as thermal stability, optical absorption and surface morphology are typically rationalized, neglecting the role of the substrate. Here, we show the role of the substrate in determining...
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| Format: | Article |
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MDPI AG
2021-08-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/11/9/2253 |
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| author | Vincenzo Balzano Emanuele Cavaliere Mattia Fanetti Sandra Gardonio Luca Gavioli |
| author_facet | Vincenzo Balzano Emanuele Cavaliere Mattia Fanetti Sandra Gardonio Luca Gavioli |
| author_sort | Vincenzo Balzano |
| collection | DOAJ |
| description | In multicomponent thin films, properties and functionalities related to post-deposition annealing treatments, such as thermal stability, optical absorption and surface morphology are typically rationalized, neglecting the role of the substrate. Here, we show the role of the substrate in determining the temperature dependent behaviour of a paradigmatic two-component nanogranular thin film (Ag/TiO<sub>2</sub>) deposited by gas phase supersonic cluster beam deposition (SCBD) on silica and sapphire. Up to 600 °C, no TiO<sub>2</sub> grain growth nor crystallization is observed, likely inhibited by the Zener pinning pressure exerted by the Ag nanoparticles on the TiO<sub>2</sub> grain boundaries. Above 600 °C, grain coalescence, formation of However, the two substrates steer the evolution of the film morphology and optical properties in two different directions. anatase and rutile phases and drastic modification of the optical absorption are observed. On silica, Ag is still present as NPs distributed into the TiO<sub>2</sub> matrix, while on sapphire, hundreds of nm wide Ag aggregates appear on the film surface. Moreover, the silica-deposited film shows a broad absorption band in the visible range while the sapphire-deposited film becomes almost transparent for wavelengths above 380 nm. We discuss this result in terms of substrate differences in thermal conductivity, thermal expansion coefficient and Ag diffusivity. The study of the substrate role during annealing is possible since SCBD allows the synthesis of the same film independently of the substrate, and suggests new perspectives on the thermodynamics and physical exchanges between thin films and their substrates during heat treatments. |
| first_indexed | 2024-03-10T07:21:57Z |
| format | Article |
| id | doaj.art-2895e5117660496181475d6700c85708 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-10T07:21:57Z |
| publishDate | 2021-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-2895e5117660496181475d6700c857082023-11-22T14:29:39ZengMDPI AGNanomaterials2079-49912021-08-01119225310.3390/nano11092253The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin FilmsVincenzo Balzano0Emanuele Cavaliere1Mattia Fanetti2Sandra Gardonio3Luca Gavioli4Interdisciplinary Laboratories for Advanced Materials Physics (i-LAMP), Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via Musei 41, 25121 Brescia, ItalyInterdisciplinary Laboratories for Advanced Materials Physics (i-LAMP), Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via Musei 41, 25121 Brescia, ItalyMaterials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270 Ajdovščina, SloveniaMaterials Research Laboratory, University of Nova Gorica, Vipavska 11c, 5270 Ajdovščina, SloveniaInterdisciplinary Laboratories for Advanced Materials Physics (i-LAMP), Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via Musei 41, 25121 Brescia, ItalyIn multicomponent thin films, properties and functionalities related to post-deposition annealing treatments, such as thermal stability, optical absorption and surface morphology are typically rationalized, neglecting the role of the substrate. Here, we show the role of the substrate in determining the temperature dependent behaviour of a paradigmatic two-component nanogranular thin film (Ag/TiO<sub>2</sub>) deposited by gas phase supersonic cluster beam deposition (SCBD) on silica and sapphire. Up to 600 °C, no TiO<sub>2</sub> grain growth nor crystallization is observed, likely inhibited by the Zener pinning pressure exerted by the Ag nanoparticles on the TiO<sub>2</sub> grain boundaries. Above 600 °C, grain coalescence, formation of However, the two substrates steer the evolution of the film morphology and optical properties in two different directions. anatase and rutile phases and drastic modification of the optical absorption are observed. On silica, Ag is still present as NPs distributed into the TiO<sub>2</sub> matrix, while on sapphire, hundreds of nm wide Ag aggregates appear on the film surface. Moreover, the silica-deposited film shows a broad absorption band in the visible range while the sapphire-deposited film becomes almost transparent for wavelengths above 380 nm. We discuss this result in terms of substrate differences in thermal conductivity, thermal expansion coefficient and Ag diffusivity. The study of the substrate role during annealing is possible since SCBD allows the synthesis of the same film independently of the substrate, and suggests new perspectives on the thermodynamics and physical exchanges between thin films and their substrates during heat treatments.https://www.mdpi.com/2079-4991/11/9/2253nanogranular composite thin filmsubstrate driven propertiesmorphologyoptical absorptionAg/TiO<sub>2</sub> |
| spellingShingle | Vincenzo Balzano Emanuele Cavaliere Mattia Fanetti Sandra Gardonio Luca Gavioli The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin Films Nanomaterials nanogranular composite thin film substrate driven properties morphology optical absorption Ag/TiO<sub>2</sub> |
| title | The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin Films |
| title_full | The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin Films |
| title_fullStr | The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin Films |
| title_full_unstemmed | The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin Films |
| title_short | The Role of Substrate on Thermal Evolution of Ag/TiO<sub>2</sub> Nanogranular Thin Films |
| title_sort | role of substrate on thermal evolution of ag tio sub 2 sub nanogranular thin films |
| topic | nanogranular composite thin film substrate driven properties morphology optical absorption Ag/TiO<sub>2</sub> |
| url | https://www.mdpi.com/2079-4991/11/9/2253 |
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