Browsing by Publisher "IOP Publishing Ltd"
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Item Recent progress in lanthanide-doped luminescent glasses for solid-state lighting applications - A review(IOP Publishing Ltd, 2021) Erol E.; Vahedigharehchopogh N.; Kibrisli O.; Ersundu M.C.; Ersundu A.E.Nowadays, solid-state white light-emitting diodes (wLEDs) have attracted remarkable attention for applications in general lighting, displays and numerous electronical devices due to their eminent efficiency, longer lifetime and higher mechanical durability compared to traditional incandescent and fluorescent lights. In current commercial wLEDs, a combination of Y3Al5O12:Ce3+ yellow phosphor with blue LED chip and epoxy resin is generally used to generate white light. However, there are some considerable frailties mostly originated from phosphor and resin such as, degradation upon heat, and moisture, inhomogeneous spectral distribution, and poor color rendering capability. Therefore, phosphor embedded glass-ceramics have been developed as a promising way to obtain durable solid-state lighting devices. However, in these methods, there is a greater risk of reactions between the phosphor material and the glass host. At this point, lanthanide-doped luminescent glasses have drawn great attention as a new generation phosphor and/or epoxy free white-light-emitting source owing to their favorable properties including high thermal and chemical stability, high transparency, and easy manufacturing process. This review article aims to comprehensively summarize the recent progress in singly (i.e., Dy3+, Eu2+), doubly (i.e., Dy3+/Eu3+, Dy3+/Tm3+, Dy3+/Ce3+, Ce3+/Sm3+, Ce3+/Tb3+) and triply (i.e., Ce3+/Tb3+/Mn2+, Eu3+/Tb3+/Tm3+, Ce3+/Tb3+/Eu3+, Tm3+/Tb3+/Sm3+, Ce3+/Dy3+/Eu3+, Ho3+/Tm3+/Yb3+, Er3+/Tm3+/Yb3+) lanthanide-doped glasses for solid-state lighting applications through down-shifting and up-conversion emissions. Theoretical background including energy transfer mechanisms, glass synthesis methods, radiative and colorimetric properties are given in details. Finally, various effective strategies are highlighted that minimize the critical challenges associated with lanthanides - such as providing energy transfer from quantum dots or nanoparticles to lanthanides, and doping lanthanides in low phonon energy glass - to improve the white light emission of luminescent glasses and broaden their application areas. © 2021 IOP Publishing Ltd.Item Energy Efficient Buildings with Algae(IOP Publishing Ltd, 2021) Yaman Y.; Tokuç A.; Sener I.; Altunacar N.; Köktürk G.; Deniz I.; Ezan M.A.The biggest part of the energy consumption of buildings is for thermal comfort. Awareness on climate change and concerns about the depletion of natural resources made the necessity to use renewable energy sources in buildings evident. In this context, microalgae have high surface efficiency and consume inorganic carbon, thus enabling carbon-neutral operation. They can be integrated into building façades with photobioreactors to reduce energy demands. This paper aims to clarify and discuss the role of microalgal technologies in energy-efficient architecture. The thermal performance and energy generation properties of microalgae façades are comprehensively reviewed. The results show that microalgae provide dynamic shading and thermal insulation, thus have the potential to significantly reduce the thermal load and energy demands of buildings and increase the building performance. Consequently, besides the thermal performance of microalgae façades, evaluation of daylight, lighting, environmental and cost performance, technical applicability and aesthetics are necessary. © Published under licence by IOP Publishing Ltd.Item Enhanced performance of ultra-thin polyaniline supercapacitor via aniline blue-WS SAMs with rich nucleation site(IOP Publishing Ltd, 2021) Kiymaz D.; Kiymaz A.; Dincalp H.; Zafer C.We report the ultrathin supercapacitor's superior performance via the vertically aligned one-dimensional polyaniline structure (1D PANI) growth on the fluorine-doped tin oxide (FTO) substrate. FTO electrodes were treated by the molecular-self assembly, and the effects of different self assembled monolayers (SAMs) on both the evolution of PANI and electrochemical performance were examined. We obtained 809.09 F g−1 specific capacitance from ∼120 nm thick PANI (at 20 mV s−1 scan rate of cyclic voltammetry) via aniline blue water soluble SAMs modification. The supercapacitor's internal dynamics were clarified by a new equivalent circuit model developed from the Graham model. Through the new model, accurate information about double-layer capacitance, percolation capacitance, and bulk capacitance, which composes the electrode's capacitive performance, could be obtained. This work provided novel knowledge to develop PANI deposition and hence to achieve greater capacitances. © 2021 IOP Publishing Ltd Printed in the UKItem Microstructural and mechanical characterization of powder-pack boronized Incoloy A286 superalloy(IOP Publishing Ltd, 2021) Türkmen İ.; Korkmaz A.In this study, Incoloy A286 superalloy were boronized successfully by powder-pack boronizing process at 850 °C, 900 °C and 950 °C for 4 h by using a boronizing powder mixture containing H3BO3 as boron source. The thickness and morphology of the boride layer was identified by microstructural examinations. The boride layer with complex, compact and smooth morphology was formed on the surface of the samples. As a result of XRD analyses, it was determined that the compact boride layer was formed many phases such as FeB, Fe2B, Fe3B, CrB and Ni4B3 etc. It was specified that the average hardness value of the boride layer was approximately between 2400 and 3000 HV by microhardness tests. Also the graphs of friction coefficient and values of the specific wear rate were obtained by performing ball on disk wear tests. It was identified that the specific wear rate of boronized samples was approximately 9.5 times lower than that of unboronized samples. © 2021 IOP Publishing LtdItem CdSe and CsPbBr3quantum dot Co-doped monolithic glasses as tunable wavelength convertors(IOP Publishing Ltd, 2022) Kibrisli O.; Erol E.; Ersundu A.E.; Celikbilek Ersundu M.CdSe and CsPbBr3 quantum dots (QDs) are well studied photoluminescent materials due to their extraordinary emission properties. However, their vulnerability against environmental conditions limits their integration into further applications. At this point, glass encapsulation offers promising durability features due to its robust and dense structure. In this study, CdSe and CsPbBr3 QDs are successfully synthesized in the same glass host through the melt-quenching technique followed by a single heat-treatment process. Excitation wavelength dependent photoluminescence properties are investigated and emission color tunability of monolithic glasses from yellow-green to red is demonstrated. Favorable quantum yield values are obtained as 21.78% and 16.63% under 345 and 365 nm excitation wavelengths, respectively. The prepared glasses demonstrate high potential to be used as tunable wavelength convertors for state-of-the-art photonic and opto-electronic applications. © 2021 IOP Publishing Ltd.