Search

To obtain BaZrO 3 -based electrolyte materials with both good sinterability and high proton conductivity, a Cu-doped B-site BaZr 0.5 Ce 0.3 Y 0.2- x Cu x O 3- δ (BZCYCu x ; x = 0, 0.05, 0.1) system is designed and synthesized. The effects of Cu doping on the crystal structure, sintering and electrical properties of BZCYCu x are systematically investigated. The BZCYCu 0.05 sample demonstrates the highest sintering density and total conductivity among the studied materials. BZCYCu 0.05 can be densified at 1250 °C, which is 300 °C lower than that for unmodified BZCY. The calculated results suggest that the increased conductivity in BZCYCu 0.05 benefits from a high apparent specific grain-boundary conductivity, which originates from a small space-charge potential and a large clean part of impurities in the electrolyte. A synthetic analysis based on impedance spectroscopy and distribution of relaxation time further confirms that BZCYCu 0.05 is more conductive. A single cell built using the BZCYCu 0.05 (∼46 μm) electrolyte shows an excellent power density of 258 mW cm−2 at 700 °C. These results indicate that BZCYCu 0.05 is a potential proton conductor for use in protonic ceramic fuel cells. [Display omitted] [ABSTRACT FROM AUTHOR]

To dispose the problem of ferronickel slag for its value-added application, it was used for preparing thermal insulation materials by sintering of the slag in the presence of another waste, fly ash cenosphere (FAC), as pore former. The thermodynamic and experimental analyses revealed that the original phase of the slag, olivine, could be transformed to thermal insulation phases, including enstatite and cordierite, by optimizing sintering temperature in the range 1100–1300 °C. Specifically, after initial decomposition of ferronickel slag, there existed a low-iron olivine phase and cordierite and enstatite became the dominant phases when the sintering temperature increased from 1100 °C to 1300 °C. Except for the phase transformation, the microstructural evolution with proper pore features (porosity and size) contributed to a resulting material with desirable thermal and mechanical properties. It was shown that the ferronickel slag sintered at 1200 °C for 2 h with the addition of 25 wt % FAC exhibited the optimal thermal and mechanical performance. Additionally, it possessed good acid and alkali resistances. The results confirmed the feasibility of co-utilization of ferronickel slag and FAC for producing superior thermal insulation materials at a proper temperature, making efficient utilization of both wastes. [ABSTRACT FROM AUTHOR]

Herein, highly transparent and conductive In 2 O 3 films were deposited by reactive high power impulse magnetron sputtering from a metal target without thermal assistance. Film deposition was performed at room temperature using oxygen flow rates selected based on target voltage hysteresis, and the obtained films were compared in terms of structure and electrical/optical properties. Notably, the use of high plasma density, peak power, and ionization efficiency resulted in the formation of highly crystalline films featuring a small grain size and a columnar structure with a preferred orientation. The minimal carrier concentration of 1.6 × 1021 cm−3 was observed for films deposited in metallic mode; the carrier mobility of these films increased from 23 to 51 cm2 V−1 s−1 as the oxygen flow rate increased from 7 to 10 sccm. Moreover, the oxygen flow rate significantly affected the conductivity of In 2 O 3 films, which ranged from semiconductor-like to insulator. The visible-light transmittance of In 2 O 3 films exceeded 85% when oxygen flow rate larger than 7sccm. The absorption edge of as-prepared films was located close to 350 nm and shifted to lower wavelengths with increasing oxygen flow rate, which was explained by the Burstein–Moss effect. The infrared transmittance of In 2 O 3 films was strongly dependent on the deposition mode. In agreement with Drude's theory, films deposited in transition mode at room temperature were highly transparent and conductive, which was ascribed to the use of controlled In:O ratios, whereas films deposited in other modes were shown to exhibit either excellent conductivity (metallic mode) or good optical transmittance (poisoning mode). Image 1 [ABSTRACT FROM AUTHOR]

Abstract MgAl 2 O 4 -graphene composites have been fabricated from combustion synthesized ceramic-graphene powder mixtures by spark plasma sintering. The synthesis and dispersion of graphene was accomplished readily by a combustion reaction between Mg powders and CO 2 gas. Compared with that of pure MgAl 2 O 4 , the relative density decreases from 100% to 95.1% and the average grain size decreases from 94 to 0.4 µm for composites containing 2.5 wt% graphene. The bending strength and fracture toughness of the as-prepared MgAl 2 O 4 -graphene composites increased by 34% (from 217 to 291 MPa) and 32% (from 1.91 to 2.52 MPa m1/2) at 0.5 wt% graphene content. The prepared MgAl 2 O 4 -graphene composites may provide an alternative refractory material to withstand harsh environments. [ABSTRACT FROM AUTHOR]

A novel approach for preparing thermal insulation materials by microwave sintering of ferronickel slag (FNS) in the presence of fly ash cenosphere (FAC) was proposed and evaluated. The study showed that during microwave radiation, the contact interface between FNS and FAC would preferentially form magnesium iron chromate spinel and magnesium iron aluminate spinel particles as hot spots by absorbing microwave vigorously, promoting decomposition and transformation of the raw materials into the thermal insulation phases, mainly cordierite and enstatite. After sintering at 900 °C by microwave for only 20 min with the addition of 25 wt% FAC, a thermal insulation material with thermal conductivity of 0.41 W/(m·K), bulk density of 1.46 g/cm3, compressive strength of 30.72 MPa, water absorption of 21.07%, and linear shrinkage of 7.06% was obtained. Compared with the conventional sintering method, the temperature was reduced by 300 °C, with the sintering time shortened by 6 times. This study represents a good example for clean and efficient value-added utilization of FNS, FAC and other relavent solid wastes. [ABSTRACT FROM AUTHOR]

Bismuth telluride-based materials are well known for their excellent thermoelectric (TE) properties within the near-room temperature range. However, the poor thermoelectric performance of their n-type counterparts has posed a major hindrance to the application of bismuth telluride-based thermoelectric generator (TEG). In this study, a dual optimization approach was implemented. Specifically, 2D ceramic nano-sized hexagonal boron nitride (h-BN) was introduced into n-type Bi 2 Te 2.7 Se 0.3 (BTS) to enhance its performance, aligning it with p-type materials. It is indicated that ceramic h-BN decoration leads to the emergence of a high density of dislocations, which boosts the phonon scattering and reduces lattice thermal conductivity significantly. Meanwhile, a high carrier mobility is maintained to ensure an improved power factor. With the addition of moderate ceramic h-BN, the composite material achieved a ZT value of 1.1 at 400 K. The geometric configuration of TEG was optimized using finite element methods to strike the optimal balance between output power (P o u t ) and efficiency (η). Based on the structure optimization results, the predicted P o u t and η increased by 48 % and 36 %, respectively. The fabricated TEG demonstrated to achieve an efficiency of 6.4 %. This work allows the evolution from bismuth telluride-based prototype to a functional TEG advanced in room-temperature heat recovery. [ABSTRACT FROM AUTHOR]

In this study, trace iron-doped 3D urchin-like titanium dioxide (Fe–TiO 2) were prepared via a straightforward water bath process. The successful incorporation of trace iron into the TiO 2 structure was confirmed through detailed EDX, EPR, and XPS analyses. Moreover, the Fe–TiO 2 photocatalyst exhibited remarkable efficacy in degrading the targeted compound, trimethoprim (TMP), achieving an impressive degradation rate of 95.6 % within a concise 60-min timeframe and a captivating mineralization rate of 32.1 % within 120 min. These performance metrics outshone those of pristine TiO 2 by substantial factors of 1.9 and 1.2, respectively. Photoelectric characterization results also confirmed that Fe doping significantly enhanced the efficiency of charge carrier separation of TiO 2. Furthermore, the catalytic performance of Fe–TiO 2 remains essentially unchanged after a tenfold expansion in equal proportion using the water bath doping system. This confirms the practicality of the batch preparation approach for Fe-doped TiO 2. The Fe–TiO 2 catalyst consistently demonstrated efficient degradation capabilities across various water sources, ranging from natural river water to treated secondary effluents from sewage plants and tap water, further emphasizing its significant potential for practical applications. This comprehensive study provides fresh insights into the batch preparation of doped catalysts and their utility in mitigating water pollution. [ABSTRACT FROM AUTHOR]

A triple-conducting Ba 0.95 La 0.05 Fe 0.8 Zn 0.2 O 3−δ (BLFZ) cobalt-free perovskite was evaluated as cathode for proton-conducting solid oxide fuel cells based on BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) electrolyte. BLFZ had a cubic perovskite structure and good chemical compatibility with BZCYYb electrolyte at temperatures below 1100 °C. The average thermal expansion coefficient of BLFZ is 20.4 × 10−6 K−1 at 30 °C-1000 °C. The polarization resistance (R p) of BLFZ decreased from 2.072 Ω cm2 in air to 1.334 Ω cm2 in wet air (3% H 2 O) at 600 °C due to the introduction of water. The single-cell power density with BLFZ–30 wt%BZCYYb composite cathode reached 329 mW cm2 at 750 °C, and the corresponding R p is 0.083 Ω cm2. Based on the impedance and distribution of relaxation time analyses, proton diffusion and incorporation to the electrolyte lattice (H a d + (N i) → H + (s u r f a c e , e l e c t r o l y t e) and H + (s u r f a c e , e l e c t r o l y t e) → H + (b u l k , e l e c t r o l y t e)) were the rate-limiting steps above 650 °C, whereas the oxygen incorporated into the lattice (O 2 − (B L F Z) → O 2 − (b u l k , e l e c t r o l y t e)) and proton bulk diffusion to the triple-phase boundary (H + (b u l k , e l e c t r o l y t e) → H + (T P B)) were the rate-limiting steps below 650 °C. The single cell with BLFZ–30 wt% BZCYYb composite cathode showed good stability at 700 °C during a 100-h test. [ABSTRACT FROM AUTHOR]

The effect of segregation behavior of non-metallic dopants (H/He/O) and metallic dopants (Be/Al/Mg/Y) on the performance of grain boundary (GB) in SiC has been systematically investigated by first-principles calculations. Firstly, the GB energy and excess volume of different GBs have been studied to evaluate the stability of GB and the capacity to accommodate dopant atoms. The solution energies of dopant atoms greatly reduce in the GB region compared with those in the bulk, which makes the dopant atoms inside the grain tend to segregate and aggregate near the GB. The driving force of GB on dopant segregation generally decreases with the increase of distance from GB plane, and the preferential site of dopant is closely correlated with the atomic size of dopant. In addition, H and Y atom possesses the lowest segregation energy at the interstitial and substitutional site near the GB, respectively. Next, the segregation of single dopant induced the changes in the strength and stability of GB have been explored. It is found that non-metallic dopants have the significant embrittlement effects on GB strength. However, the segregation of most metallic dopants could strengthen the GB and Mg atom has the most significant strengthening effect on the GB. The stability of GB can be greatly improved by segregation of Al and Y dopants. Besides, the aggregation of H atoms has the obvious embrittlement effect on the GB. Furthermore, the co-segregation behavior of different dopants has also been explored. Be and Mg dopants have the most significant inhibition effect on the segregation of detrimental impurities H/He/O due to the repulsive interaction between dopant atoms. The present results provide a new insight into the effect of dopant segregation on GB properties and are expected to be a useful guidance for screening the chemical composition and manipulating the performance of SiC-based ceramics. [ABSTRACT FROM AUTHOR]

Developing a new strategy to effectively prevent the restacking of MXene nanosheets will have significant impacts on designing flexible supercapacitor electrodes. Herein, a novel Ti 3 C 2 T x /polyvinyl alcohol (PVA) porous sponge with 3D interconnected structures is prepared by sol-gel and freeze-dried methods. This Ti 3 C 2 T x /PVA porous sponge is used as the template of in-situ polyaniline (PANI) polymerization, and the fabricated PANI@Ti 3 C 2 T x /PVA hydrogel composite is applied as flexible supercapacitors electrodes. 1D conductive polymer chains PVA could increase the interlayer spacing of Ti 3 C 2 T x nanosheets, which is beneficial to expose more electrochemical active sites. The supercapacitor based on PANI@Ti 3 C 2 T x /PVA hydrogel composite exhibits the coexistence of double-layer capacitance and pseudocapacitance behavior. This supercapacitor shows a maximum areal specific capacitance of 103.8 mF cm−2 at 2 A m−2, and it also exhibits a maximum energy density of 9.2 μWh·cm−2 and an optimum power density of 800 μW cm−2. The capacitance of this supercapacitor is almost not change under different bending angles. Moreover, 99% capacitance retention is achieved after 10 000 charge/discharge cycles of the supercapacitor. The synergistic effect between PANI and Ti 3 C 2 T x /PVA composite may improve the number of reactive sites and provide efficient channels for ion diffusion/electron transport. [ABSTRACT FROM AUTHOR]

The chromium-promoted preparation of forsterite refractory materials from ferronickel slag was investigated by microwave sintering of the slag with the additions of sintered magnesia and 0–10 wt% chromium oxide (Cr 2 O 3). The thermodynamic calculations revealed that the addition of Cr 2 O 3 can promote the formations of spinel and liquid phase and maintain high content of forsterite below 1500 °C. The experimental results showed that there existed a stronger promoting effect of Cr 2 O 3 additive on the properties of refractory materials in the microwave field than that in conventional sintering. It was attributed to the preferential formation and growth of spinel with stronger microwave absorption than other phases (e.g., enstatite), the existence of more forsterite, and the enhanced densification in association with the presence of more liquid phase at the same temperature. By microwave sintering of the mixture of ferronickel slag, 25 wt% sintered magnesia, and 4 wt% Cr 2 O 3 at 1350 °C for 20 min, a superior refractory material with refractoriness of 1801 °C, thermal shock resistance of 6 times, bulk density of 2.97 g/cm3, apparent porosity of 1.4%, and compressive strength of 197 MPa was obtained. Compared with that prepared by conventional sintering at 1350 °C for 2 h, the refractoriness and thermal shock resistance were increased by 175 °C and 100%, respectively. The present study provided a novel method for preparing high-quality refractory materials from ferronickel slag and relevant industrial wastes. [ABSTRACT FROM AUTHOR]

In order to improve antibacterial capability and cell biocompatibility of titanium (Ti), Ag nanoparticles (NPs) and a novel Zn source Na 2 Zn-EDTA (disodium zinc ethylenediaminetetraacetate tetrahydrate) were added in the electrolyte to fabricate Ag, Zn co-incorporated titania through micro-arc oxidation (MAO) method on metallic Ti substrate. Microstructural characterization reveals that the presence of both Ag NP clusters and micro-sized dicalcium phosphate dehydrate (DCPD) flakes on the surface of Ag, Zn co-incorporated TiO 2 coating. Ag species are mainly present as metallic Ag whereas Zn species tend to exist as Zn2+ within titania. Further, corrosion resistance, antibacterial property and cell biocompatibility of the resultant coatings were assessed. It is revealed that the Ag, Zn co-incorporated TiO 2 coating possesses favourable corrosion resistance, desirable in vitro antibacterial capability and cell biocompatibility without cytotoxicity, which is a promising candidate as a bio-ceramics for Ti-based implant. • Ag, Zn co-incorporated TiO 2 coating has been successfully produced using micro-arc oxidation method with Na 2 Zn-EDTA and Ag nanoparticles as Zn and Ag sources. • During the oxidation, dicalcium phosphate dehydrate flakes of micrometre scales were formed on the surface of Ag, Zn co-incorporated TiO 2 coating. • Ag, Zn co-incorporated TiO 2 coating exhibits excellent antibacterial capability and desirable bone formability. [ABSTRACT FROM AUTHOR]

The effects of the electrode-bulk interface on the dielectric properties of Ba 0.9988 Bi 0.0008 Zr 0.2 Ti 0.8 O 3 (BBZT) ceramics with a slight change in the thickness (≤15%) were investigated. In BBZT ceramics, the dielectric constant decreases with the increase of thickness, and the interface between electrode and bulk ceramics is considered the main reason. A formula is proposed to calculate the dielectric constant of bulk materials. According to the formula, the electrode-bulk interface has a slight influence on the frequency characteristics of the dielectric constant. However, the ferroelectric to paraelectric phase transition temperature changes from 10 °C to 15 °C for bulk ceramics when the electrode-bulk interface is taken into consideration. In a range of 0 °C–75 °C, obvious differences between ε B and ε T are observed due to the electric field induced by removable carriers. The dielectric tunability is degraded by the influence of electrode-bulk interface. BBZT ceramics have considerable tunability (>65% @100 kHz) and a low loss tangent (<0.006 @100 kHz) with an excellent FOM value (>270). This study demonstrates a method of calculating the dielectric constants of bulk ceramic layers and provides a theoretical basis for improving the performance of bulk materials using interfacial layers. [ABSTRACT FROM AUTHOR]

In the present work, the influence of Ag 2 O content on the microstructural feature, bio-corrosion behaviour and biological property of the resultant Ag-incorporated TiO 2 micro-arc oxidation (MAO) coating is investigated. It is revealed that, with the addition of an increased amount of Ag 2 O nanoparticles (NPs) in the MAO electrolyte, a less defective Ag-incorporated TiO 2 coating with pores of decreased dimensions could be produced, which also exhibits a higher anatase-to-rutile ratio along with a lower Ag 2 O-to-Ag ratio. Further, both antibacterial capability and bone formability of Ag-incorporated TiO 2 coatings were investigated. The results show that the addition of an increased amount of Ag 2 O NPs enhances antibacterial capability of the resultant coating, which also exhibits desirable biocompatibility. This work offers a promising fabrication method for dual functional Ag-incorporated TiO 2 coating with Ag 2 O NPs as Ag source. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) is a well-known material for biomedical applications and its performance depends greatly on its morphological features. Therefore, preparation of mesoporous HA with high surface area and adsorption capacity is highly deserved. In this research, a hydrothermal approach to synthesize mesoporous HA without post-processing calcination step is presented. The possibility using different polyphenols to generate mesoporous HA as well as using different phosphate sources to tailor the morphological features of HA is investigated. The as-prepared mesoporous HA particles are characterized by XRD, FTIR, SEM, TEM, BET, and zeta potential. Besides, the impacts of HA morphological features on model drug Dox are also studied. It is expected the strong interaction between –OH of polyphenols and Ca 2+ makes polyphenols molecules occupy the inner sites of growing HA particles. After the removal of polyphenols by hydrothermal treatment and ethanol extraction, the occupied sites are transformed into mesopores. The typical mesoporous HA generated in present work has a rod-like morphology with BET specific surface area of 106.6 m 2 /g and an average pore size of 14.4 nm. [ABSTRACT FROM AUTHOR]

Chinese mystery snail is a popular aquatic food in China, resulting in tonnes of shells as waste every year. In present work, these shells were recycled as calcium source to prepare HA. Initially, shells were found to decompose within 860 °C to porous CaO. The calcined shells were then hydrothermally utilized to synthesize HA with the help of different phosphate sources (PO 4 3− , P 2 O 7 4− , P 3 O 10 5− , and P 6 O 18 6− ). Under hydrothermal processing, condensed phosphate ions could be hydrolyzed into PO 4 3− to react with Ca 2+ . The prepared HA was subsequently characterized by XRD, FTIR, SEM, EDX and TEM. It was found condensed phosphates could result in significant changes to the morphology of HA in comparison to orthophosphate. In particular, P 6 O 18 6− related HA appeared to be mesoporous. The cytocompatibility of different phosphate source related HA was also investigated. [ABSTRACT FROM AUTHOR]

Lead-free barium tin titanate BaTi 0.85 Sn 0.15 O 3 (BTS) ferroelectric thin films have been deposited on Pt/Ti/SiO 2 /Si substrates by pulsed laser deposition. The structure and dielectric properties of thin films deposited at various oxygen pressures are investigated systematically. By optimizing the oxygen pressure during the deposition, the structure and dielectric properties are improved. The thin films grown at 15 Pa have the best crystal quality and the largest grain size, which result in the enhancement of the dielectric properties. The dielectric constant and loss tangent show the similar trend in the entire oxygen pressure range. The influence mechanisms of the oxygen pressure on the structure and dielectric properties are proposed. The BTS thin films deposited at 15 Pa with large figure of merit (FOM) of 81.1, high tunability of 72.1%, moderate dielectric constant of 341, low loss tangent of 0.009 are considered to be appropriate as a field tunable ferroelectric material for electrically tunable devices. [ABSTRACT FROM AUTHOR]

Biphasic calcium phosphate (BCP) compositions consisting of β-tricalcium phosphate (β-TCP) and calcium pyrophosphate (CPP) are potential biodegradable ceramics for bone regeneration. The present work demonstrates the formation of such dense ceramics by first preparing the precursors of nano-sized, amorphous, and equiaxed calcium pyrophosphate particles, and then sintering the precursors at 900 °C to transform them into desired BCP. However, if the complex of calcium tripolyphosphate was used, only CPP could be generated. It was also observed that the incorporation of Mg 2+ had several effects on the resulting products including: (1) promoting the generation of meso-porous precipitates; (2) favoring the formation of β-TCP instead of CPP; (3) reducing the grain size and increasing the density of the sintered ceramics, and (4) enhancing the negative electric charge of the BCP surface. Thus, the as-prepared BCP ceramics can serve as potential bone substitute materials in orthopedic applications. [ABSTRACT FROM AUTHOR]