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Zirconia-toughened alumina (ZTA) ceramics have attracted much attention in the medical field as joint replacement materials due to their good mechanical properties and biocompatibility. However, the flexural strength of conventional ZTA is still slightly insufficient in traditional preparation techniques. In this study, by improving the slurry system, the effects of the solid content of the slurry, additives, and the pH of the slurry on the slurry system were investigated. ZTA powders with a uniform particle size distribution, high degree of sphericity and high flowability were prepared by spray granulation. The mechanical properties, microstructure and biocompatibility of the ZTA pressing were investigated after degreasing and sintering processes. The results showed that the hardness of the prepared ZTA ceramics was 1658.24 ± 28.04 H V, the fracture toughness was 4.016 ± 0.027 MPa m1/2, and the biaxial bending strength was 501.43 ± 21.44 MPa, and the three-point bending strength reached 635 MPa. The ZTA ceramics also possessed good biocompatibility and a low haemolysis rate, which aligns with the requirements of clinical biomedical implant materials. [ABSTRACT FROM AUTHOR]

In this paper, Bi2212 films were prepared on LaAlO 3 (100) and SrTiO 3 (100) substrates by the sol-gel method using Bi(NO 3) 3 ·5H 2 O, Sr(NO 3) 2 , Ca(NO 3) 2 ·4H 2 O and Cu(NO 3) 2 ·3H 2 O as raw materials. TritonX-100 (TX-100), fatty alcohol poly oxyethylene ether (AEO-9), poly (vinylpyrrolidone) (PVP) and poly (vinyl alcohol) (PVA) were used as surfactants, respectively, to improve the wettability between the sol and the substrate. When glycine and glycolic acid were used as complexing agents, these surfactants were stably miscible with the sols. The effects of different surfactant sol-gel systems on the wettability of substrates as well as the crystallinity, morphology, surface roughness and electrical transport properties of Bi2212 superconducting films were investigated. The results showed that flat and continuous c -axis epitaxial Bi2212 films were obtained using all these sol-gel systems. In particular, TX-100 and AEO-9 as surfactants showed stronger wettability of the sol-gel for both substrates. In addition, the films prepared using polymer surfactants PVP and PVA sol-gel systems showed less surface roughness. The same patterns were found in all the film samples prepared using precursor sols of different complexing agents, and all the films exhibited good electrical transport properties. This work lays a certain research foundation for the preparation of thin films by aqueous solvent sol-gel method. The method also shows great potential in terms of the stability of different sol-gel systems and the improvement of the wettability of different substrates. [ABSTRACT FROM AUTHOR]

The complexed sol-gel method has unique advantages in the preparation of multi-component functional thin films. In this paper, Bi2212 superconducting thin films were prepared by sol-gel method on SrTiO 3 (100) single crystal substrates. Glycine and glycolic acid were used as complexing agents. The thermal decomposition processes of the two sols were analyzed by contrasting thermal-thermogravimetric curves. The heat treatment processes of the different complexing agent systems were optimized to obtain films with flatter surface morphology. The phase composition of the intermediate products during the precursor heat treatment was changed by adjusting the conditions of the complexing agent and the acidity of the sol, which expanded the pure phase temperature interval of the final product. The pure phase temperature interval, morphology, surface roughness, and electrical transport properties of Bi2212 superconducting films prepared with different complexing agent sol-gel systems were investigated. When glycolic acid was used as the complexing agent, the Bi-2212 superconducting films showed the widest phase formation temperature zones of 25 K. They also had a smaller surface roughness of 10–15 nm. Other than that, all samples had good epitaxial properties, and electrical transport properties. This work provides a new idea for expanding the phase-forming temperature region of multicomponent functional ceramics. It also shows the promising potential of sol-gel method for preparing multicomponent functional films with high quality surfaces. [ABSTRACT FROM AUTHOR]

Lead-free ceramics have attracted considerable research attention owing to their environmentally friendly properties as well as their relatively good piezoelectric properties. Herein, we doped BiCoO 3 (BCO) onto (Bi 0.5 Na 0.5)TiO 3 –6BaTiO 3 (BNT-6BT) solid solution at various concentrations and investigated their dielectric and piezoelectric properties. After comparing the Rietveld refinement data with X-ray diffraction (XRD) results, it was found that all the BNT-6BT- x BCO ceramics (x = 0, 0.5%, 1%, and 1.5%) showed the morphotropic phase boundary conformation with coexisting tetragonal (P4bm) and cubic (Pm 3 (＿) m) phases. XRD refinement data also demonstrated that with increasing BCO concentration to 1.5%, the mole ratio between the tetragonal and cubic phases was close to 1:1, which enhanced the piezoelectric performance of the ceramic composites. At a BCO concentration of 1.5%, the strain and piezoelectric coefficient (d 33) of the sample reached 0.31% and 196 pC/N, respectively. The highest effective d 33 * of 489 pm/V was obtained at 110 °C with BNT-6BT-1.5BCO ceramics. The BNT-6BT-xBCO ceramics show great promise for use in high-temperature actuator applications. [ABSTRACT FROM AUTHOR]

Aqueous tape calendering offers the advantage of a simple fabrication process, inexpensive equipment, and environmental friendliness. Polyvinyl alcohol (PVA), as a polymer, is a conventional binder for aqueous tape calendering. In this innovative work, we aim to achieve a suitable process for tape calendering, by studying mechanical properties of the PVA polymer film with a series of plasticizers. The results show that the elongation at break of the PVA film reaches a maximum of 828.26%, using a triple plasticizer of glycerol, polyethylene glycol (PEG) 200, and PEG 400. With an optimized ratio of the binder to the plasticizer, a YSZ sheet with a relative density of 98% and a conductivity of 0.043 S cm−1 at 800 °C is obtained by sintering at 1400 °C, demonstrating comparable performance to those of the YSZ electrolytes by dry pressing. SEM reveals that the sintered YSZ body is dense, and has no visible open and closed pores. The mechanical properties characterization of the PVA polymer film adopted in this paper has instructive significant instruction for tape calendering and tape casting methods. • Mechanical properties measurement of the PVA film applied in an aqueous tape calendering. • The elongation at break of the PVA film reached 828%. • Combination of glycerol, PEG200 and PEG 400 plasticizer is a preferred choice for PVA binder. • The YSZ sheet sintered at 1400 °C has a density of more than 98% and a conductivity of 0.043 S cm−1 at 800 °C. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effects of ZrO 2 types including YSZ and nano-ZrO 2 as well as their contents on the phase compositions, macrostructures, microstructures, physical properties, mechanical properties and biocompatibility of Ti2448-ZrO 2 composites fabricated by spark plasma sintering (SPS). The mechanical properties such as hardness and compressive yield strength of the composites have been systematically investigated. The experimental results demonstrate that the hardness and compressive yield strength of the composites all dramatically increased with increasing the content of YSZ and nano-ZrO 2 . Meanwhile the nano-ZrO 2 could be beneficial to the uniformity of microstructure and improvement in mechanical strength of the composites. The biocompatibility of the composites containing nano-ZrO 2 was found to possess better corrosion resistance. In conclusion, Ti2448-ZrO 2 composites are potentially useful in biomedical applications with their mechanical and biological properties being evaluated in this work. [ABSTRACT FROM AUTHOR]

This paper reports a facile two-step synthesis route for the preparation of flower-like ZnO/α-Fe 2 O 3 nanorods (NRs). Flower-like ZnO NRs with the average diameter about 810 nm and length about 4.5 µm were firstly synthesized via a chemical solution method, and then ZnO NRs was coated with a continuous α-Fe 2 O 3 layer to form ZnO/α-Fe 2 O 3 core-shell structure through an ionic-layer adsorption and reaction method. The gas-sensing results show that the ZnO/α-Fe 2 O 3 NRs exhibit excellent sensitivity, selectivity, and response-recovery capacity to ethanol vapor at a low optimum temperature of 240 °C. In particular, compared with pure ZnO NRs and α-Fe 2 O 3 nanoparticles (NPs), the ZnO/α-Fe 2 O 3 NRs show an obvious improvement in gas sensing properties. The substantial improvement of sensing properties may be attributed to the unique microstructure and heterojunction formed between ZnO and α-Fe 2 O 3 . [ABSTRACT FROM AUTHOR]

A novel lead-free, high dielectric constant, ultra-wide temperature stable dielectric ceramic Ba 1−x Bi x Ti 1−x −y Zn 0.75x W 0.25x+y O 3+y (0.22≤x≤0.30, y=0.015) was synthesized by the traditional solid-state reaction method. The phase composition, electric and dielectric properties of the Ba 1−x Bi x Ti 1−x −y Zn 0.75x W 0.25x+y O 3 ceramics were investigated. The P-V-L dielectric theory was introduced. And, the chemical bond energy was calculated to track the changes in micro-structure. The relationships between chemical bond energy and the macroscopic dielectric properties(ε r , dielectric stability and dielectric loss ) in Ba 1−x Bi x Ti 1−x−y Zn 0.75x W 0.25x+y O 3+y ceramics were discussed systematically. Owing to the inhomogeneous micro-structure and the diffusion in phase transition, Ba 1−x Bi x Ti 1−x−y Zn 0.75x W 0.25x+y O 3+y ceramics showed a stable permittivity (~800±15%) over a ultra-wide temperature range (−30 to 375 °C). Moreover, dielectric loss was less than 0.02 and the insulation resistance was over 10 12 Ω cm. These features suggested that the Ba 1−x Bi x Ti 1−x−y Zn 0.75x W 0.25x+y O 3+y ceramic could be considered as a promising candidate material for energy storage applications in harsh environment. [ABSTRACT FROM AUTHOR]

Multi-component BaTiO 3 –Bi 0.5 Na 0.5 TiO 3 –Nb 2 O 5 (BBNN) system doped with divalent metal ions (Zn 2+ , Co 2+ , Ni 2+ ) was prepared by the conventional solid–state method.The X-ray diffraction patterns revealed all samples exhibited perovskite (P4mm) single phase. The dielectric properties and micro-mechanisms were discussed and validated. Novel theories, based on the characteristics of the different kinds of dielectric polarization, are proposed to explain the dielectric anomalies in the dielectric system. The relationships between microstructure and the dielectric properties were investigated systematically for the first time. The samples doped with 15 mol% Zn 2+ /Co 2+ presented good dielectric properties of an ultra-broad temperature stable range (from −50 and >300), high dielectric constant (ε~1925 for Zn 2+ / ε~1341 for Co 2+ ) and low dielectric loss (tan δ<0.02) were obtained. These features made the ceramics system have high practical values for miniaturization and harsh environments applications. [ABSTRACT FROM AUTHOR]

W–Re alloys find wide application in high-temperature measurements and as components of engines and aircraft. However, their low oxidation and thermal shock resistances have limited their application at high temperatures in oxidized atmospheres. In this work, an inner WSi 2 coating was first prepared on the surface of the W-26Re alloy by pack cementation. Subsequently, an outer ZrB 2 -HfO 2 -SiC (ZHS) coating was prepared by the sol-gel method and blade coating, using self-prepared nano-HfO 2 fibers introduced in different ratios (0%, 3%, 6%, and 9%). Following thermal shock tests at 1073–1773 K, the coatings toughened by nano-HfO 2 fibers with high melting point (above 3000 K) showed better thermal shock resistance, especially the 6% HfO 2 -doped coatings. The 6%Hf-ZHS coating underwent the highest number of thermal shock cycles (369), 385.5% and 210.1% higher than those experienced by W-26Re and ZHS. In addition, the thermal shock resistance of ZHS was 56.6% better than of the bare W-26Re alloy. Finally, the protection mechanism of the above coatings was explained by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

Antiferroelectric film capacitors have attracted increasing attention due to their excellent energy storage properties. In this work, PbZrO 3 (PZO) antiferroelectric films have been prepared on the flexible fluorphlogopite (Mica) and rigid Pt/Ti/SiO 2 /Si substrates with a seed layer of LaNiO 3 (LNO) layer by sol-gel process. The microstructure and energy storage properties of the films have been systematically studied. The results show that the Mica-Pt-LNO-PZO (M -LNO-PZO) thin film has an improved energy storage density (W rec) of 16.6 J/cm3 with a charge and discharge efficiency (η) of 50.4%. Furthermore, the flexible thin films exhibit good stability under a wide working temperature range of 25–140 °C and an electric fatigue endurance of 107 cycles. Besides, the capacitive films can endure a bending radius of 4 mm and 104 bending cycles (@ r = 4 mm) with almost unchanged in the energy storage properties. The excellent energy storage properties endow inorganic thin films with great potential in flexible electronic devices. [ABSTRACT FROM AUTHOR]

Pt-loaded curling-like Bi 2 WO 6 (BWO) microdiscs were fabricated via a simple one-step hydrothermal and impregnation route. Various characterization methods, such as XRD, EDS and TEM, were conducted to prove the successful Pt loading. Electron migration from the semiconductor BWO to the precious metal Pt was revealed by the blue shift of the Bi 4f and W 4f XPS peaks with the increase of the Pt loading amount and the ∼10-fold baseline resistance elevation of the BWO-based sensor by the Pt loading, proving the formation of Schottky junction. Among the pristine BWO and Pt-loaded BWO with different Pt loading amounts, 1 wt % Pt-loaded BWO exhibits the highest gas response of 209 in sensing 500 ppm triethylamine at 300 °C, a minimal selectivity coefficient of 130.6 against some typical interfering gases at the same concentration and a low detection threshold of 1 ppm. Additionally, the sensitization mechanism is discussed as the synergistic effect of noble metal catalytic effect and metal-semiconductor junctions. [Display omitted] [ABSTRACT FROM AUTHOR]

Hafnium oxide (HfO 2) fibers can be widely used in ultra-high temperature ceramics (UHTCs) as reinforced material in order to achieve better antioxidant performance and less cracks and flaking on surface of UHTCs in field of ultra-high temperature thermal protectors. Calcination temperature is one of essential parameters for forming HfO 2 fiber. In this work, one-dimensional (HfO 2) fibers were prepared through the electrospinning method and further post-calcination treatment. During the calcination treatment, the monoclinic-HfO2 (m-HfO 2) was formed from as-spun HfO 2 fibers at 432 °C, and only a small amount of m-HfO 2 was converted into the tetragonal HfO 2 at 1013 °C, which can increase the fiber density and decrease the grain size. However, the remaining m-HfO 2 was directly converted into the cubic HfO 2 at 1351 °C. The unique temperatures of forming monoclinic, tetragonal, cubic phase were much lower than the phase-transition temperature. The prepared HfO 2 fiber could still maintain fibrous morphology after 10 times cyclic thermal shock in air. Moreover, the fibers calcined at 900 °C and 1200 °C have better thermal shock resistance for their stable phase and fibrous morphology with uniform grain growth after the thermal shock test. [ABSTRACT FROM AUTHOR]

Bi ions-doped materials have attracted increasing attention because of their potential applications in LED light sources and imaging displays. However, the correlation between local glass network structure and visible emission of Bi ions is rarely discussed, which hinders the optimization of Bi ions-doped glass. In this work, we prepared the Bi ions-doped borosilicate glasses (Bi-Glass) with tunable visible emissions by changing the content of B 2 O 3. Their optical properties, structure, and temperature-dependent emission were investigated systematically. All the Bi ions-doped glasses show broadband luminescence from 350 nm to 700 nm, the emission bands show a blue shift from 454 nm to 435 nm when the concentration of B 2 O 3 increases from 0% to 10%. The emission intensity reaches the maximum value of 5% B 2 O 3 concentration, which attributes to the number and distribution of bismuth ions luminescent centers. Furthermore, thermoluminescence is observed in this glass system. In this study, the coordination structure around the active centers of bismuth can be changed by modifying the glass network structure, promoting the research of tunable luminescence of bismuth ions-doped glass. [ABSTRACT FROM AUTHOR]

BaSn 0.15 Ti 0.85 O 3 (BTS) thin films were deposited on Pt/Ti/SiO 2 /Si(1 0 0) substrate by pulsed laser deposition and the effects of substrate temperature on their structure, dielectric properties and leakage current density were investigated. The results indicate that the substrate temperature has a significant effect on the structural and dielectric properties of the BTS thin films which exhibit a polycrystalline perovskite structure if the substrate temperature ranges within 550–750 °C. The dielectric constant and loss tangent of the BTS thin films deposited at 650 °C are 341 and 0.009 at 1 MHz, respectively, the tunability is 72.1% at a dc bias field of 400 kV/cm, while the largest figure of merit (FOM) is 81.1. The effect of the substrate temperature on the leakage current of the BTS thin films is discussed. [ABSTRACT FROM AUTHOR]

During the preparation of Bi 2 Sr 2 CaCu 2 O 8+ δ (Bi2212) superconducting thin films by sol-gel method, the complexing agent and sintering conditions can significantly influence the quality and the performance of thin film. In this study, Bi2212 thin films were prepared on single crystal SrTiO 3 (001) substrate, and the phase purity, crystallinity, surface morphology and transport properties were studied particularly with different sintering temperature and time, complexing agent and its ratio to metal ions. Due to relatively low carbon content, tartaric acid (TA) as a complexing agent improved the film quality and transport properties compared with the traditional ethylenediamine tetraacetic acid (EDTA). When the complex ratios of TA to metal ions was 1:1, Bi2212 thin films exhibited good epitaxial properties, a high Bi2212 phase purity and a low surface roughness of 12.74 nm. Simultaneously, under these preparation condition, Bi2212 superconducting thin film showed a higher T c, onset of 93.28 K. [ABSTRACT FROM AUTHOR]

Al alloy was the optimal metal cover material for confined silicon carbide (SiC) against blunt tungsten-heavy-alloy projectiles based on a previous research. In this study, the influence of the aluminium (Al) alloy plate thickness on the ballistic performance of SiC was investigated to determine the optimal plate thickness. In addition, the ballistic responses of covered ceramic composite structures under various impact velocities were examined. The failure features of the cover plates and ceramic were elaborated based on tests and simulation analyses. The penetration weight calculated using the measured residual penetration was applied to characterise the ballistic performance of ceramic armour modules. The results showed that thin and thick cover plates could increase the loading rate of the ceramic pressure, thus attenuating their buffering effects on the ceramic. Therefore, the determination of the optimal cover plate thickness must simultaneously meet the requirements of stiffness and the reduced ceramic pressure loading rate. The optimal thickness for the Al alloy cover plate was 4 mm for lateral and back confined ceramic against blunt projectiles in this paper, which was obtained via a numerical simulation. Finally, the buffering effect of the cover plate on enhancing the structural ballistic performance varied with the impact velocities of the projectiles. This study provides insights for covered ceramic armour applications. [ABSTRACT FROM AUTHOR]

The effects of strain on the magnetic properties of Zr 2 N MXene have been investigated by the first-principles calculations. The ground state of strain-free Zr 2 N MXene is intrinsically antiferromagnetic. However, the magnetic state of Zr 2 N MXene tends to be ferromagnetic when the applied strain is higher than 4%. The transition of magnetic orderings from antiferromagnetism to ferromagnetism under tensile strains can be understood from the Stoner criterion. Besides, the critical temperature (T c) is about 470 K for the strain-free Zr 2 N MXene, indicating that the antiferromagnetic ordering can be robust and maintained at room temperature. The T c of antiferromagnetic states begins to decrease once the strain is exerted. As the FM ordering is favored, however, the T c then increases with the applied strain. Under 8% tensile strain, the T c comes to room temperature (300 K). In addition, both the orientation of easy-axis and the magnetic anisotropy energy (MAE) of Zr 2 N MXene fluctuate with the strain. At the strain of 2%, the MAE reaches the largest (203 μeV per Zr atom), mainly resulting from the spin-orbit interactions between occupied and unoccupied p x / p y states of Zr atoms. All these tunable and appealing properties make Zr 2 N MXene desirable for spintronic applications. [ABSTRACT FROM AUTHOR]

To determine the mechanism of microwave response in AZrNb 2 O 8 (A: Mn, Zn, Mg, Co, et al.) wolframites, CuZrNb 2 O 8 ceramic with low sintering temperature (920 °C) is successfully fabricated by solid-state reaction method. Meanwhile, its structural stability is synthetically evaluated, the vibration modes are also calibrated. Except for the extrinsic factor like sintering temperature, the condition of Jahn-Teller ion Cu2+ as intrinsic part is characterized for the first time in relation to the microwave dielectric properties of the system. In virtue of Raman and EPR spectra, it is predicted that the electronic structure of transition metal ions, as the less concerned factor, may be influential on the dielectric properties of ceramics at microwave range, especially in the structure with mixed ion occupancy. In addition, the CuZrNb 2 O 8 ceramic is well matched with the silver electrode, which makes it a prospective candidate for temperature compensation material of LTCC (low-temperature co-fired ceramic) passive integration technology. [ABSTRACT FROM AUTHOR]

Low-loss (Zn 1- x Ni x )ZrNbTaO 8 (0.02 ≤  x  ≤ 0.10) ceramics possessing single wolframite structure are initiatively synthesized by solid-state route. Based on the results of Rietveld refinement, complex chemical bond theory is used to establish the correlation between structural characteristics and microwave performance in this ceramic system. A small amount of Ni 2+ ( x  = 0.06) in A-site with the fixed substitution of Ta 5+ in B-site can effectually raise the Q  ×  f value of ZnZrNb 2 O 8 ceramic, embodying a dense microstructure and high lattice energy. The dielectric constant and τ f are mainly affected by bond ionicity and the average octahedral distortion. The (Zn 0.94 Ni 0.06 )ZrNbTaO 8 ceramic sample sintered at 1150 °C for 3 h exhibits an outstanding combination of microwave dielectric properties: ε r = 27.88, Q × f  = 128,951 GHz, τ f = –39.9 ppm/°C. Thus, it is considered to be a candidate material for the communication device applications at high frequency. [ABSTRACT FROM AUTHOR]

The interfacial structure of a SiC 3D /Al composite prepared by vacuum-pressure infiltration was investigated to determine whether interfacial reactions occur and specific orientation relationships exist between SiC and Al. The resulting SiC/Al interfaces were continuous and free of any precipitates and voids. There is no consensus for the orientation relationship between 6H-SiC and Al. In addition, the mismatch between the two phases at the interface was accommodated by mismatch dislocation. The stability of the SiC 3D /Al composite after annealing at 873 K for 10 h was determined. No Al 4 C 3 precipitated at the interface, although grain coarsening of Al occurred. Compared with the concentration gradients at the initial interfaces, those obtained at the interface after annealing were still steep, indicating that concurrent interdiffusion occurred between SiC and Al in a very narrow region near the interfaces. Theoretical calculations suggest similarly the chemical and structural stability of the SiC/Al interface during the annealing treatment. [ABSTRACT FROM AUTHOR]

Al 2 O 3 -SiC composite powders have been synthesized by carbothermal reduction reaction (CRR) method in molten salts medium under argon atmosphere, using coal ash and activated carbon as raw materials. The effect of NaCl-KCl molten salts quantity on the synthesis process was studied. The phase compositions and microstructures of Al 2 O 3 -SiC composite powders were characterized by XRD and SEM-EDS. Compared with conventional CRR method; it was found that the NaCl-KCl addition strongly promotes phase transformation and reduced synthesis temperature of nearly 100 °C. Experimental results showed that Al 2 O 3 -SiC composite powders can be synthesized with the mass ratio of coal ash to activated carbon( m CA : m C ) is 100:58 and an addition amount of 100% NaCl-KCl (mass fraction) at 1500 °C for 5 h. The reaction products have good performance with uniform particle distribution, aggregate-free and average particle size is about 0.5–1.5 µm. [ABSTRACT FROM AUTHOR]