Papers by Author: T. de Lacerda-Arôso

Abstract: Ancient ceramic wall tiles, called “azulejo”, firstly used on Portuguese churches, monasteries and palaces (15-18th century) have progressively been used in particular houses till the last century. These tiles and its use in huge decorative panels can be considered as a precious but fragile cultural heritage from Brazil to India, in several countries influenced by Portuguese culture. Morphologically, these tiles are composed by a porous clay-based ceramic body, the terracotta, covered by a protective glassy phase, the glaze. As artistic paintings, these murals incorporated various kinds of pigments in the glaze layer to create a pictorial impact on the walls of rich palaces or churches, real and durable monumental works-of-art. In the 21st century, degradation marks are visible on these ceramic tiles because of their use under corrosive conditions (moisture, atmospheric cycles…) along centuries. In order to promote their conservation and enhance their restoration, the physical-chemical characterization of the azulejos is performed in the present work, using mainly non-destructive processes like micro-Raman spectroscopy or X-Ray diffraction. In particular, Raman spectroscopy allows the detection of some nano/microcrystals present in the amorphous glaze due to pigments or opacifying agents or related to the elaboration process of the azulejo. Based on the observation of various selected fragments, one states that very few pigments have been used as colouring agents in this ceramic art during 17-18th centuries. Thus, the relationship between the different colours, the introduced pigments and the structural aspects of the glass will be focused. Some features related with the ancient ceramic technology will also be discussed.

Abstract: Transparent conducting Al doped ZnO films have been deposited by dc magnetron sputtering on glass and polymer substrates at room temperature. Depositions have been carried out from an AZOY (contains a small amount of Y2O3 in addition to Al2O3 and ZnO) target under different conditions such as working pressure, substrate bias voltage and oxygen flow rate. The crystallinity of the Al doped ZnO films has been improved by using low-energy-ion bombardment. Likewise, the use of either the rotation or the static mode of the substrate during deposition influences the crystallinity and therefore the optical parameters and the electrical resistance of the films. Increasing the thickness of the films reduces the threshold strain at which the films can be deformed without provoking significant changes on their electrical properties.