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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6

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    PublicationOpen Access
    Enhanced sinterability, thermal conductivity and dielectric constant of glass-ceramics with PVA and BN additions
    (Multidisciplinary Digital Publishing Institute (MDPI), 2022) Akkasoğlu, Ufuk; Çiçek, Buğra; N/A; Department of Chemistry; Arıbuğa, Dilara; Balcı, Özge; Researcher; Department of Chemistry; Koç University AKKİM Boron-Based Materials _ High-technology Chemicals Research _ Application Center (KABAM) / Koç Üniversitesi AKKİM Bor Tabanlı Malzemeler ve İleri Teknoloji Kimyasallar Uygulama ve Araştırma Merkezi (KABAM); Graduate School of Sciences and Engineering; College of Sciences; N/A; 295531
    With the rapid development of the microelectronics industry, many efforts have been made to improve glass-ceramics' sinterability, thermal conductivity, and dielectric properties, which are essential components of electronic materials. In this study, low-alkali borosilicate glass-ceramics with PVA addition and glass-BN composites were prepared and successfully sintered at 770 degrees C. The phase composition, density, microstructure, thermal conductivity, and dielectric constant were investigated. It was shown that PVA addition contributes to the densification process of glass-ceramics (~88% relative density, with closed/open pores in the microstructure) and improves the thermal conductivity of glass material from 1.489 to 2.453 W/K.m. On the other hand, increasing BN addition improves microstructures by decreasing porosities and thus increasing relative densities. A glass-12 wt. % BN composite sample exhibited almost full densification after sintering and presented apparent and open pores of 2.6 and 0.08%, respectively. A high thermal conductivity value of 3.955 W/K.m and a low dielectric constant of 3.00 (at 5 MHz) were observed in this material. Overall, the resulting glass-ceramic samples showed dielectric constants in the range of 2.40-4.43, providing a potential candidate for various electronic applications.
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    PublicationOpen Access
    Development of highly luminescent and cytocompatible near-IR-emitting aqueous Ag2S quantum dots
    (Royal Society of Chemistry (RSC), 2012) Çizmeciyan, M. Natali; Erdem, Rengin; Özen, Can; Kurt, Adnan; N/A; Department of Physics; Department of Chemistry; Hocaoğlu, İbrahim; Sennaroğlu, Alphan; Acar, Havva Funda Yağcı; PhD Student; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 23851; 178902
    Colloidally stable and highly luminescent near-IR emitting Ag2S quantum dots (NIRQDs) were prepared by a very simple aqueous method using 2-mercaptopropionic acid (2MPA) as a coating. Emission of Ag2S-2MPA NIRQDs can be tuned between 780 and 950 nm. These NIRQDs have photoluminescence quantum yields (PLQY) around 7–39% and exhibit excellent cytocompatibility even at 600 mg mL 1 in NIH/3T3 cells. With such improved properties, Ag2S-2MPA NIRQDs have a great potential in practical bio-applications.
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    PublicationOpen Access
    Meso-2,3-dimercaptosuccinic acid: from heavy metal chelation to CdS quantum dots
    (Royal Society of Chemistry (RSC), 2012) Özen, Can; N/A; Department of Chemistry; Sevinç, Esra; Ertan, Fatoş Sibel; Ulusoy, Gülen; Acar, Havva Funda Yağcı; Faculty Member; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 178902
    DMSA (meso-2,3-dimercaptosuccinic acid) a prescription drug and a heavy-metal chelating agent, is shown to act both as a sulfur source and a capping agent in the aqueous synthesis of CdS quantum dots under mild conditions. Release of sulfur from DMSA depends on the solution pH and the reaction temperature. Combination of 70 C and pH 7.5 was determined as the best reaction conditions for a well-controlled reaction. Changing the SH/Cd ratio from 2.5 to 7 provides QDs emitting from blue to orange with 6–9% quantum yield with respect to Rhodamine 2B. Viability tests performed with HeLa and MCF-7 cell lines indicate a very low cytotoxicity. Mild reaction conditions and biocompatibility makes these particles valuable candidates for bio applications.