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HEritage Resilience Against CLimate Events on Site
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Critical role of a double-layer configuration in solution-based unipolar resistive switching memories
Publication . Carlos, Emanuel; Kiazadeh, Asal; Deuermeier, Jonas; Branquinho, Rita; Martins, Rodrigo; Fortunato, Elvira; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; IOP Publishing
Lately, resistive switching memories (ReRAM) have been attracting a lot of attention due to their possibilities of fast operation, lower power consumption and simple fabrication process and they can also be scaled to very small dimensions. However, most of these ReRAM are produced by physical methods and nowadays the industry demands more simplicity, typically associated with low cost manufacturing. As such, ReRAMs in this work are developed from a solution-based aluminum oxide (Al2O3) using a simple combustion synthesis process. The device performance is optimized by two-stage deposition of the Al2O3 film. The resistive switching properties of the bilayer devices are reproducible with a yield of 100%. The ReRAM devices show unipolar resistive switching behavior with good endurance and retention time up to 105 s at 85 °C. The devices can be programmed in a multi-level cell operation mode by application of different reset voltages. Temperature analysis of various resistance states reveals a filamentary nature based on the oxygen vacancies. The optimized film was stacked between ITO and indium zinc oxide, targeting a fully transparent device for applications on transparent system-on-panel technology.
Ionically Modified Cellulose Nanocrystal Self-Assembled Films with a Mesoporous Twisted Superstructure: Polarizability and Application in Ion-Gated Transistors
Publication . Grey, Paul; Fernandes, Susete N.; Gaspar, Diana; Deuermeier, Jonas; Martins, Rodrigo; Fortunato, Elvira; Godinho, Maria H.; Pereira, Luis; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); ACS - American Chemical Society
Mesoporous structures made of cellulose nanocrystals (CNCs) and their self-assembly into films are of great interest not only due to their abundancy and sustainability but also due to their ease of chemical modification and nanoscale biomimicry capabilities. However, their implementation in (opto)electronic devices requires further understanding on how these self-assembled twisted mesoporous superstructures respond to electrical stimulus. In this regard, this work focuses on the infiltration of solid CNC droplets with three distinct alkali ions (Li+, Na+, and K+) to yield films with improved electrochemical response when compared to pristine ones, while preserving their photonic character. Electrochemical characterization shows capacitances of up to 2.5 μF cm–2 allowing for their integration as solid-state gate electrolytes in amorphous indium–gallium–zinc–oxide transistors, resulting in low operating voltages (<2 V), on/off ratios of up to 6 orders of magnitude, and high saturation mobilities >10 cm2 V–1 s–1. Devices fabricated on Na+ and K+ infiltrated CNC films present the best characteristics, indicating pure capacitive charging of the semiconductor. The insights presented here contribute to applications in solid-state ionics in mesoporous structures or the combination of optically active electrolytes capable of providing unique functionalities in ion-gated transistors and circuitry.
Decay products of historical cements from the Palace of Knossos, Crete, Greece
Publication . Carvalho, Fernanda; R. A. Lima, Maria Margarida; Kavoulaki, Elissavet; Leal, Nuno; Simão, Joaquim; Galhano, Carlos; Águas, Hugo; Padeletti, Giuseppina; Veiga, João Pedro; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; DCT - Departamento de Ciências da Terra; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; VICARTE - Vidro e Cerâmica para as Artes; Elsevier
The Palace of Knossos, located on the island of Crete, Greece, is one of Europe's most important archaeological sites, serving as a testament to the Minoan civilization. Situated near the Mediterranean Sea, it is in close proximity to the seaport, airport, and industrial areas. Decay products commonly found in historical monuments within or near urban areas, such as black crusts and salt efflorescence, are also prevalent at the Palace of Knossos. To better understand the characteristics of the type of deterioration compounds found on cement in historical reconstruction zones, as well as their possible relationship with factors influencing the deterioration process, a multi-analytical approach was designed for the study of these materials. The results indicate that the black crusts primarily consist of gypsum and carbonaceous matter. However, the efflorescence salts are predominantly composed of thenardite instead of halite, despite the palace's proximity to the coastal area. These results may contribute to ongoing and future maintenance and preservation efforts for the monument.
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Entidade financiadora
European Commission
Programa de financiamento
H2020
Número da atribuição
700395