Bismuth layer-structured ferroelectric (BLSF) compound strontium bismuth titanate (SrBi4Ti4O15, SBT) with cerium modifications have been synthesized using conventional solid-state processing. X-ray ...powder diffraction (XRPD) analyses reveal that the cerium-modified SBT ceramics have a pure four-layer Aurivillius-type structure. The dielectric, ferroelectric, and piezoelectric properties of the cerium-modified SBT ceramics are investigated in detail. The results indicate that the cerium modifications into SBT increase the densities, decrease the sintering temperature, lower the dielectric loss tanδ, and reduce the coercive filed Ec. The piezoelectric measurements show that cerium is very effective in promoting the piezoelectric properties of SBT ceramics. The SBT ceramics modified with 4mol% CeO2 (SBT-4Ce) exhibit the optimized piezoelectric properties, with a piezoelectric constant d33 of 27pC/N, which is the highest value among the modified SBT-based piezoelectric ceramics ever reported. The temperature-dependent electrical impedance and electromechanical coupling coefficients (kp and kt) reveal that the electromechanical coupling characteristics have a significant deterioration at ~400°C because of the high conductivity at high temperature. But the temperature-dependent frequency constants (Np and Nt) and thermal annealing analyses indicate the cerium-modified SBT ceramics have good thermal stabilities of piezoelectric properties up to 450°C. These results demonstrate that the cerium-modified SBT ceramics are promising materials for high temperature piezoelectric sensors applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We investigated the ferroelectric, piezoelectric, and domain wall current properties affected by the distribution of a-oriented domains and c-oriented domains in flexible SrBi2Ta2O9 (SBT) thin films ...on flexible Pt/mica substrates. On the flexible Pt/mica substrates, the SBT thin films with a mixed crystallinity of a-oriented and c-oriented crystallinities exhibited the domain structures mixed with a-oriented domains and c-oriented domains. The SBT thin films with excellent a-oriented crystallinity showed improved ferroelectric and piezoelectric properties due to the polar axis perpendicular to the c-axis. In particular, 90o domain walls composed of a-domain and c-domain have larger domain wall currents than 180o domain walls composed of c-domains, which increases the leakage current of the SBT thin films.
•Flexible polycrystalline SrBi2Ta2O9 thin films on Pt/mica substrates.•Ferroelectric domain structures with rectangular a-domains and elongated c-domains.•Enhanced ferroelectric and piezoelectric properties with c-domain distribution.•Leakage current characteristics improved by increasing distribution of a-domains.•Domain wall currents of 90o domain walls and 180o domain walls.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Kontakti Srba i Habzburgovaca su otpočeli sredinom XV veka. U tom trenutku Habzburgovci su u liku Alberta Austrijskog prvi put seli na presto a Srbi su se borili za opstanak svoje srednjovekovne ...države. U kasnijem periodu karakter tih kontakata je bio drukčiji. Pojedinačni predstavnici Srba, feudalci prebegli na tlo Ugarske i nove vođe ratničkih družina povezivali su se sa Habzburgovcima nudeći im svoje vojničke usluge. Definitivan prelom nastaće u periodu posle Mohačke bitke kada se Habzburgovac Ferdinand I učvrstio na ugarskom prestolu. Time će otpočeti nov period veoma intenzivnih kontakata Srba sa Habzburgovcima koji će se najvećim delom odvijati na teritoriji razdrobljenog ugarskog kraljevstva koje se borilo za svoj opstanak.
Graphitic carbon nitride (g-C3N4) material with a similar structural phase to graphite opens new opportunities in energy conversion storage systems. The g-C3N4 sheets offered many defected sites that ...enhanced the adsorption and diffusion of electrolyte ions. High nitrogen concentration in g-C3N4 was ideal for increasing the binding energy between metals and carbon. The stability of pseudo-active metal oxides/chalcogenides supported by carbon results in improved capacitive performance. This study used a hydrothermal route to fabricate binary SrBi2O4/g-C3N4 composite onto g-C3N4 sheets. The SrBi2O4/g-C3N4 nanocomposite was characterized through various techniques including different analytical analyses. Among all evaluated electrodes for the electrochemical experiment binary composite SrBi2O4/g-C3N4 demonstrated the highest electrochemical activity and showed the capacitive of 777.2 F g−1 at 1 A g−1. Moreover, binary composite SrBi2O4/g-C3N4 was shown to have a lesser charge transfer resistance (Rct) of 0.87 Ω as compared to other bare fabricated materials. The exceptional electrochemical capability of SrBi2O4/g-C3N4 can be due to the combined effect of SrBi2O4 and g-C3N4 which included various redox state enhanced electrode wettability and superior structural and chemical stability. The composite material shows excellent power and high energy density of 319.95 W Kg−1 and 44.20 Wh Kg−1. Based on the findings our study suggested a practical approach to fabricated hybrid electrode materials that have optimum properties for use in energy storage devices in future supercapacitors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Predmet istraživanja u ovom radu su populacije koje su se u popisima stanovništva održanih u razdoblju 2001./2002. – 2021./2022. nacionalno izjasnili kao Hrvati u Srbiji i Srbi u Hrvatskoj. Svrha ...istraživanja je utvrditi sličnosti i razlike u odabranim dinamičkim i strukturnim demografskim pokazateljima između ove dvije manjinske zajednice, kao i u njihovom odnosu na ukupno i većinsko stanovništvo Srbije i Hrvatske, s ciljem procjene njihove demografske održivosti u budućnosti. U istraživanju je primijenjena deskriptivna i komparativna metoda, a brojčani rezultati su prikazani u agregiranim analitičkim tablicama. Navedena tema promatrana je u općem dinamičkom demografskom okviru koji je za obje zemlje i za obje manjinske populacije izrazito depopulacijski. Uz negativnu demografsku dinamiku obje populacije u promatranom razdoblju karakteriziraju i nepovoljni procesi u formiranju parcijalnih demografskih struktura, napose biološkoj (dob i spol), koja zahvaljujući ubrzanom starenju stanovništva, sve više postaje ograničavajućim čimbenikom njihove dugoročne demografske održivosti.
•The (2 0 0) facet of SrBi2Ta2O9 photocatalyst tends to accumulate electrons while (0 0 1) facet favors the accumulation of photogenerated holes.•High surface facet exposure of (2 0 0) plane in ...SrBi2Ta2O9 benifits photocatalytic NO removal.•Superoxide radicals play a vital role in photocatalytic NO removal by SrBi2Ta2O9.
Photocatalysts with exposure of different crystal facets often show great differences in their photocatalytic activities due to differences in surface atomic arrangement and coordination. Thus, the actual photoreaction mechanism of a specific crystal facet in photocatalysis deserves to be explored. In this paper, as a case study, SrBi2Ta2O9 photocatalyst with preferential facet exposure was explored for the photocatalytic removal of NO at a ppb level. The efficiency of NO removal was remarkably improved by tuning the crystal exposure facet with high (2 0 0) facet exposure ratio. Optimized exposure of (2 0 0) crystal facet in SrBi2Ta2O9 (SBT) by thermal calcination at 800 °C (SBT-800) leads to the highest NO removal activity of 51% under a 300 W Xe lamp for 20 min; under visible light, SBT 800 achieves a 5-fold enhancement in NO removal efficiency compared to its counterpart, SBT-900. Active species capture experiments prove that the superoxide radical ·O2− is the main active species for the photocatalytic removal of NO, and surface selective deposition experiments conclude that (2 0 0) is the main electron-rich crystal plane, based on which the results of density functional theory (DFT) computation reveal the BiO terminated nature of (0 0 1) crystal plane, where the models with both BiO and TaO terminated (0 0 1) planes were created and computated. Mechanistic study reveals that SrBi2Ta2O9 with a larger exposure of (2 0 0) facet provides more active reduction sites, thereby reducing more O2 to ·O2−, which further oxidizes the adsorbed NO to NO2−/NO3−. The present work underlines the role of facet tuning in the photoactivity modulation for NO removal photocatalytically.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This research article is related to the piezocatalytic activity of SrBi4Ti4O15 (SBT) ferroelectric ceramic by using Methylene blue (MB) as a model dye. The piezocatalytic activity was further ...enhanced by poling of the ceramic catalyst powder. The ferroelectric ceramic was synthesized via a solid-state reaction route and calcinated at 950 °C. The synthesized ceramic was characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The process the poling enhanced the piezocatalytic activity by around 30%. A parametric study was also performed to get an insight into the influence of factors affecting activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Formaldehyde (HCHO), as one of the main indoor toxic pollutions, presents a great threat to human health. Hence, it is imperative to efficiently remove HCHO and create a good indoor living ...environment for people. Herein, a layered perovskite material SrBi2Ta2O9 (SBT), was studied for the first time and exhibited superior photocatalytic efficiency and stability compared to commercial TiO2 (P25). Furthermore, a unique dark–light tandem catalytic mechanism was constructed. In the dark reaction stage, HCHO (Lewis base) site was adsorbed on the terminal (Bi2O2)2+ layer (Lewis acid) site of SBT in the form of Lewis acid-base complexation and was gradually oxidized to CO32− intermediate (HCHO → DOM (dioxymethylene) → HCOO− → CO32−). Then, in the light reaction stage, CO32− was completely converted into CO2 and H2O (CO32− → CO2). Our study contributes to a thorough comprehension of the photocatalytic oxidation of HCHO and points out its potential for day–night continuous work applications in a natural environment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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Layered bismuth-based photocatalytic materials have great potential for environmental purification. In this work, we developed two novel layered bismuth-based borate photocatalysts ...CaBi2B2O7 (CBBO) and SrBi2B2O7 (SBBO) via solid-phase reaction. The crystal structure, microstructure and optical properties were investigated. The photocatalytic activities were studied by decomposition of tetracycline hydrochloride (TH) and evolution of reactive oxygen species (ROS) under UV light irradiation. The results revealed that CBBO and SBBO exhibit benign TH degradation activity with certain mineralization abilities. Within 4 min illumination, almost 70% and 58% of tetracycline hydrochloride was degraded by CBBO and SBBO, respectively. The quantitative capture experiment of radicals showed that the production rate of OH and O2− was determined to be 1.27 × 10-7 and 10.98 × 10-7 mol·L-1 min-1 for CBBO and 1.01 × 10-7 and 11.75 × 10-7 mol·L-1 min-1 for SBBO, respectively. Density functional theory (DFT) calculation results demonstrated that CBBO has smaller effective masses of electrons and holes than SBBO, which results in higher charge separation efficiency and photocatalytic activity. This work provides two new layered bismuth-based borate photocatalysts for photocatalytic environmental applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bismuth layer-structured ferroelectric (BLSF) strontium bismuth titanate (SrBi4Ti4O15, SBT) ceramic oxides with B-site cobalt substitutions have been synthesized using conventional solid–state ...reaction. The dielectric, piezoelectric, and ferroelectric properties of cobalt-modified SBT are investigated in detail. The results indicate that cobalt is very effective in promoting the piezoelectric performance of SBT. The SBT modified with 3 mol% Co3+ (SBT-3Co) exhibits the optimized piezoelectric properties, with a piezoelectric constant d33 of 28 pC/N, which is the highest value among the modified SBT-based piezoelectric ceramics ever reported. The temperature-dependent electrical impedance, resonance frequencies, and electromechanical coupling factors (kp and kt) reveal that the cobalt-modified SBT ceramics have good thermal stabilities of electromechanical properties up to 300 °C. These results demonstrate that the cobalt-modified SBT ceramics are promising materials for high temperature piezoelectric sensors applications.
The manuscript deals with the thermal stabilities of piezoelectric properties of cobalt-modified SrBi4Ti4O15 (SBT) ceramics. The 3 mol% Co3+ modified SBT (SBT-3Co) ceramics exhibit a piezoelectric constant d33 of 28 pC/N and a Curie temperature Tc of 528 °C. The SBT-3Co ceramics have good thermal stabilities of electromechanical properties up to 300 °C. Display omitted
•A high level of piezoelectric performance (d33∼28 pC/N)is obtained.•High Curie temperature (Tc∼528 °C) is acquired for the optimal composition.•The SBT-3Co exhibits good thermal stabilities of electromechanical properties.•The Co-modified SrBi4Ti4O15 is promising as high temperature piezoelectric material.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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