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    Facile production of CsPbBr3 perovskite single-crystals in a hydrobromic solution
    (2023) Özen, Murat; Cansu, Akyel; Özen, Songül Akbulut
    In this study, synthesis of CsPbBr3 perovskite single-crystals in a hydrobromic solution was investigated. Single-crystal growth experiments were conducted at the solution-nucleation border at a constant temperature or controlled cooling conditions. Working at the solution-nucleation border poses some practical difficulties such as fast precipitation. Often researchers opt to oversaturate the solution and use the supernatant after filtration. However, for conditions where the A to B ratio in the precursor solution for the formation of ABX3 is not 1, oversaturation is a waste of resources. In this work, precursor solutions were prepared for a particular working temperature and either held at a constant temperature or were gradually cooled to a predetermined temperature. The constant temperature method resulted in large and clear crystals as it reached saturation more slowly. Crystals prepared at high temperatures appeared to be more transparent with clear facets. Crystals prepared at low temperatures appeared to be opaque with multiple nuclei growth on a single-crystal. Seeding of the saturated solution resulted in larger single-crystals. The procedure adapted in this work made possible the production of clear CsPbBr3 perovskite single-crystals in a hydrobromic acid solution with sizes of up to 5 mm in only 10 days.
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    Vehicular and industrial sources of PGEs, Au and Ce in surface soil and roadside soils and dusts from two cities of Turkey
    (Sakarya University, 2021) Özen, Murat; Özen, Songül Akbulut; Çevik, Uğur
    In this study, rhodium, palladium, platinum, gold and cerium were determined by ICP-MS after trace-matrix separation in roadside dusts and soil samples along different motorways in Ankara and Bursa, and in soil samples taken from industrial locations in Nilüfer, Bursa. The clear presence of Pd and Rh was determined at different traffic locations. Platinum remained below the method’s quantification limit for most of the samples. Results showed that both cities showed relatively high concentrations of; Rh and Pt in tunnels and downtowns, Pd in tunnels, bus stations and crossroads, and Au in downtowns. Consistent with the daily road traffic, relatively high concentrations of Rh, Pd and Pt were determined for Ankara. Based on the limited data available for Pt, Pt:Pd ratios varied between 0.04 and 0.25, and Pt:Rh ratios varied between 0.59 and 2.1. Measurements at the industrial location showed an average Rh and Pd concentration of 11 and 359 µg/kg, respectively. On the other hand, Au concentrations remained below the method’s quantification limit except for one sampling location. The average Ce concentration was determined as 23 mg/kg. Platinum remained below the method’s quantification limit for all industrial sampling locations. Overall, high average Rh and Pt concentrations were determined at the traffic sites, while higher average Pd concentration was determined at the industrial locations. Cerium remained consistently below the earth’s crustal levels, which infers that no anthropogenic source can be attributed to Ce.