Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4719

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Access Right: Open AccessAuthor: search.filters.author.Bortolotti, Mauro

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  • Article
    Citation - WoS: 19
    Citation - Scopus: 21
    Synthesis and Additive Manufacturing of Calcium Silicate Hydrate Scaffolds
    (Elsevier, 2021) Oğur, Ezgi; Botti, Renata; Bortolotti, Mauro; Colombo, Paolo; Ahmetoğlu, Çekdar Vakıf
    A Calcium silicate hydrate (CSH) powder containing above 60 wt% xonotlite (remaining being tobermorite, scawtite and calcite) were produced from lime and ordinary recycled soda-lime glass via simple hydrothermal synthesis route. The thermogravimetric analysis demonstrated only similar to 20%weight loss up to 800 degrees C (at about the transformation temperature of CSHs to wollastonite), reaching a plateau in the 800-1200 degrees C temperature range. The synthesized CSH powder was employed for the fabrication of both green and heat-treated scaffolds by additive manufacturing (AM), possessing a high porosity (>80 vol%) and limited strength (similar to 0.9 MPa). (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
  • Article
    Citation - WoS: 8
    Citation - Scopus: 12
    Synthesis of Potassium-Sodium Niobate (Knn) From Nbo2
    (Elsevier, 2021) Piskin, Cerem; Karacasulu, Levent; Bortolotti, Mauro; Vakifahmetoglu, Cekdar
    KxNa1-xNbO3 (0 < x < 1) were synthesized via hydrothermal method using niobium dioxide (NbO2) as the niobium source instead of the most common one, Nb2O5. Potassium-rich KxNa1-xNbO3 (x > 0.5) was obtained from 8 M total hydroxide concentration after 6 h of reaction at 200 degrees C. Rietveld refinement of the XRD data revealed that all samples exhibited the secondary NaNbO3 phase. However, the lowest amount (3.74 vol%) was obtained for 24 h of reaction under 10 M alkaline solution. After 3 h of reaction, dodecahedra shaped hexaniobate phase (KxNa8-xNb6O19.nH(2)O) was observed. Those structures were, subsequently, replaced by similar to 3 mu m cube shaped KNN crystals, obtained under 10 M reaction in 24 h time period.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 17
    Electrical Characteristics of Low Temperature Densified Barium Titanate
    (Elsevier, 2020) Karacasulu, Levent; Tokkan, Melike; Bortolotti, Mauro; Ischia, Gloria; Adem, Umut; Ahmetoğlu, Çekdar Vakıf
    A low temperature densification technique, i.e. reactive hydrothermal liquid-phase densification (rHLPD) was followed to obtain highly dense BaTiO3 components at temperatures <= 240 degrees C. The formed ceramics were characterized concerning not only the structural features but also the electrical properties. The increase of both reaction time and temperature resulted in enhanced densification of BaTiO3 components reaching about 90% of theoretical density. The presence of the tetragonal BaTiO3 was demonstrated by both XRD and TEM analysis. Despite the low reaction temperatures, the samples showed promising dielectric, ferroelectric and piezoelectric functionality without additional annealing. A broad dielectric peak was observed around 135 degrees C at the Curie temperature; saturated hysteresis loops and corresponding butterfly-shaped strain-electric field loops were obtained. BaTiO3 sample subjected to hydrothermal reaction at 240 degrees C for 72 h yielded a piezoelectric coefficient of 84 pC/N.