Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
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Article Citation - Scopus: 4One-step hydrothermal synthesis of spinel manganese oxide ion-sieve from commercial Γ-Mno2 and its uptake performance for lithium(Elsevier Ltd, 2024) Toprak, Seyra; Demir, Mustafa MuammerThe selective extraction of lithium from aqueous systems necessitates efficient sorbent materials. Spinel-type lithium manganese oxide ion sieves (LMOs) have been bee recognized for their high performance in this application. However, the elevated market cost of the spinel form (λ-MnO2) raises economic concerns, posing challenges to the feasibility of the extraction process. In this study, the one-step hydrothermal synthesis of Li1.33Mn1.67O4 was carried out at 200 °C for 7 days using commercial γ-MnO2 powder and aqueous LiOH solution as reactants. The synthesized powder exhibited characteristic XRD reflections consistent with spinel Li1.33Mn1.67O4. Lithium ion-sieve (H1.33Mn1.67O4) was obtained by leaching the LMO product with dilute hydrochloric acid solution. The sorption capacity of γ-MnO2 is increased from 8.4 to 23.1 mg/g (C0=200 mg/L), this capacity is very close to the one of the commercial λ-MnO2. The synthesized spinel HMO sorbent achieved a maximum Langmuir adsorption capacity of 52.1 mg/g. The extraction efficiency reached 94% at the sorbent dose of 20 g/L. The distribution coefficients of metal ions were in the order Li+ > Ca2+ > K+ > Na+, emphasizing selective Li+ extraction from brines with high Na+ content. These findings highlight the successful development of a spinel-type lithium manganese oxide ion sieve from γ-MnO2 polymorph, which is nearly an order of magnitude cheaper than the selective λ-MnO2. The study addresses critical issue of economic feasibility in lithium extraction processes, providing a potential solution for the selective recovery of bulk lithium. © 2024 Elsevier LtdArticle Citation - WoS: 3Citation - Scopus: 2Electrocaloric Behaviour of Tape Cast and Grain Oriented Nbt-Kbt Ceramics(Elsevier Sci Ltd, 2024) Unal, Muhammet Ali; Karakaya, Merve; Irmak, Tugce; Yildirim-Ozarslan, Gokce; Avci, A. Murat; Fulanovic, Lovro; Adem, UmutWe have investigated the effects of grain orientation and tape casting process on the electrocaloric properties of 0.82Na(0.5)Bi(0.5)TiO(3)-0.18 K0.5Bi0.5TiO3 (0.82NBT-0.18KBT) ceramics at the Morphotropic Phase Boundary (MPB), using direct and indirect measurements. We observe a larger electrocaloric response for the template-free ceramics compared to 7 and 10 wt% template containing ones, suggesting that grain orientation along rhombohedral < 100 > does not improve the electrocaloric response. Indirect measurements yielded a large adiabatic temperature change of around 3 K under an electric field of 50 kV/cm, which is significantly higher than 0.9 K reached at a lower electric field of 40 kV/cm using the direct measurement.Article Citation - WoS: 18Citation - Scopus: 46Phosphor-Based White Led by Various Glassy Particles:control Over Luminous Efficiency(The Optical Society, 2019) Yüce, Hürriyet; Güner, Tuğrul; Balcı, Sinan; Demir, Mustafa MuammerGenerating white light through a mainstream remote phosphor design suffers from phosphor conversion efficiency loss due to a backscattering of light. Such a loss also reduces luminous efficiency of the resulting white light. To overcome this issue, various glassy scatterers with different morphologies such as glass bubbles, glass beads, and nanosized silica particles were employed as scatterers, together with a fixed amount of yellow phosphor (YAG:Ce3+) and a poly(dimethylsiloxane) (PDMS) matrix. In addition, the simulation of the system validates the rigorous multiple scattering of the incoming light most probably due to refractive index mismatch between the glass bubbles and surrounding PDMS matrix along with the internal reflections. (C) 2019 Optical Society of America