Enhanced electrical properties of BNKT-BMN lead-free ceramics by CaSnO3 doping and their bioactive properties.

There is an increasing interest in using piezoelectric materials, including lead-free piezoceramics for medical applications. As a result, more attention has been placed on investigating the biological properties of these materials. In this research experiment, electrical, mechanical, and biological properties of lead-free 0.99Bi0.5(Na0.8K0.2)0.5TiO3-0.01Bi(Mg2/3Nb1/3)O3 or 0.99BNKT-0.01BMN doped with CaSnO3 (CSO) were investigated. The samples were synthesized by a modified solid-state reaction technique. X-ray diffraction (XRD) analysis showed that the samples presented a single perovskite phase. After adding CSO, electrical properties such as energy storage density (maximum W rec = 781 mJ cm-3) and electro-strain properties (maximum S max = 0.3%) were improved at room temperature. Mechanical properties were also enhanced for the modified samples with maximum values for Vickers hardness (H V) and elastic modulus (E m) of 6.11 GPa and 135 GPa, respectively. Biological assays for cytotoxicity, indicated that the samples had high cell viability, while the simulated body fluid (SBF) test revealed a moderate apatite forming ability. The samples were then coated with hydroxyapatite to improve their apatite-forming ability. The SBF testing for the coated samples showed that the coated samples had high apatite-forming ability. The obtained results pointed to the possibility of ceramics being used for multifunction electrical devices at room temperature and biomaterial applications.

Synergistic amalgamation of shellac with self-antibacterial hydroxyapatite and carboxymethyl cellulose: An interactive wound dressing for ensuring safety and efficacy in preliminary in vivo studies.

This study focuses on the synergistic formulation of environmentally friendly blended materials based on carboxymethyl cellulose (CMC) for advanced interactive wound dressing. New CMC hydrogels were prepared with two degrees of functionalization and chemically crosslinked with citric acid (CA) to fine-tune their properties. Additionally, CMC-based hybrids were created by blending with shellac (SHL) and incorporating self-antibacterial hydroxyapatite (HA) to inhibit bacterial growth and promote wound healing. The results demonstrate the successful production of superabsorbent hydrogels with typical swelling degrees ranging from 81% in water to 82% in phosphate-buffered saline (PBS). These hydrogels exhibit distinct morphological features and remarkable improvements in surface mechanical properties, specifically in their tensile properties, which show a significant increase from approximately 0.03 to 2.2 N/mm2 due to the formation of CMC-SHL-HA hybrid nanostructures. Furthermore, the cytocompatibility of these CMC-based hydrogels was investigated by assessing the in vitro cell viability responses of human skin fibroblasts. The results reveal the cell viability responses over 91%, indicating their biocompatibility with human cells. Moreover, the characteristics of surgical wounds were assessed before and after the application of the hydrogel on dogs, and no signs of infection were observed at any of the surgical sites post-surgery.

Improvements in piezoelectric and energy harvesting properties with a slight change in depolarization temperature in modified BNKT ceramics by a simple technique.

For many BNT-based ceramics, an attempt to increase the piezoelectric properties usually results in a decrease in depolarization temperature (T d). This trend limits the applications of the materials. Many previous experiments have used different methods to enhance the piezoelectric properties and improve the T d characteristic. In this study, we demonstrated a simple technique (thermal annealing) to enhance the piezoelectric properties with a very slight decrease in T d by ∼2 °C for a modified BNKT ceramic (BNKT doped with ZnO). Other phase transition characteristic temperatures of the studied ceramics were also slightly changed. The optimum dielectric (ε r = 651, tan δ = 0.0503, T F-R = 167.38 °C, T m = 305.41 °C, ε max = 5551, T B = 367.15 °C, T d = 155.98 °C, and γ = 1.43), ferroelectric (P max = 41.28 µC cm-2, P r = 35.85 µC cm-2, E c = 42.60 kV cm-1 and R sq = 1.42), piezoelectric (d 33 = 198 pC N-1, k p = 0.598, and g 33 = 34.35 × 10-3 Vm N-1), and energy harvesting (FoM = 6.80 pm2 N-1) were obtained for the 8 h annealed ceramic. Furthermore, higher energy harvesting properties (which were 32% higher than that of the unannealed ceramic) were obtained after employing this technique.

Tuning the Dielectric Constant and Surface Engineering of a BaTiO3/Porous PDMS Composite Film for Enhanced Triboelectric Nanogenerator Output Performance.

In this work, synergistic effects derived from surface engineering and dielectric property tuning were exploited to enhance the output performance of a triboelectric nanogenerator (TENG) based on an inorganic/porous PDMS composite in a contact-separation mode. BaTiO3 (BT)/porous PDMS films with different BT weight ratios were fabricated and evaluated for triboelectric nanogenerator (TENG) application. Maximum output signals of ca. 2500 V, 150 µA, and a power density of 1.2 W m-2 are achieved from the TENG containing 7 wt % BT, which is the best compromise in terms of surface roughness, dielectric constant, and surface contact area as evidenced by SEM and AFM studies. These electrical signals are 2 times higher than those observed for the TENG without BT. The 7BT/porous PDMS-based TENG also shows high stability without a significant loss of output voltage for at least 24 000 cycles. With this optimized TENG, more than 350 LEDs are lit up and a wireless transmitter is operated within 9 s. This work not only shows the promoting effects from porous surfaces and an optimized dielectric constant but also offers a rapid and template/waste-free fabrication process for porous PDMS composite films toward large-scale production.

Effectiveness of a Nanohydroxyapatite-Based Hydrogel on Alveolar Bone Regeneration in Post-Extraction Sockets of Dogs with Naturally Occurring Periodontitis.

Pathological mandibular fracture after dental extraction usually occurs in dogs with moderate to severe periodontitis. A nanohydroxyapatite-based hydrogel (HAP hydrogel) was developed to diminish the limitations of hydroxyapatite for post-extraction socket preservation (PSP). However, the effect of the HAP hydrogel in dogs has still not been widely investigated. Moreover, there are few studies on PSP in dogs suffering from clinical periodontitis. The purpose of this study was to evaluate the effectiveness of the HAP hydrogel for PSP in dogs with periodontitis. In five dogs with periodontitis, the first molar (309 and 409) of each hemimandible was extracted. Consequently, all the ten sockets were filled with HAP-hydrogel. Intraoral radiography was performed on the day of operation and 2, 4, 8 and 12 weeks post operation. The Kruskal-Wallis test and paired t-test were adopted for alveolar bone regeneration analysis. The results demonstrated that the radiographic grading, bone height measurement, and bone regeneration analysis were positively significant at all follow-up times compared to the day of operation. Moreover, the scanning electron microscopy with energy-dispersive X-ray spectroscopy imaging after immersion showed a homogeneous distribution of apatite formation on the hydrogel surface. Our investigation suggested that the HAP hydrogel effectively enhances socket regeneration in dogs with periodontitis and can be applied as a bone substitute for PSP in veterinary dentistry.

Influence of Al2O3 nanoparticle doping on depolarization temperature, and electrical and energy harvesting properties of lead-free 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 ceramics.

In this research article, the effects of Al2O3 nanoparticles (0-1.0 mol%) on the phase formation, microstructure, dielectric, ferroelectric, piezoelectric, electric field-induced strain and energy harvesting properties of the 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 (BNT-6BT) ceramic were investigated. All ceramics have been synthesized by a conventional mixed oxide method. The XRD and Raman spectra showed coexisting rhombohedral and tetragonal phases throughout the entire compositional range. An increase of the grain size, T F-R, T m, ε max and δ A values was noticeable when Al2O3 was added. Depolarization temperature (T d), which was determined by the thermally stimulated depolarization current (TSDC), tended to increase with Al2O3 content. The good ferroelectric properties (P r = 32.64 µC cm-2, E c = 30.59 kV cm-1) and large low-field d 33 (205 pC N-1) values were observed for the 0.1 mol% Al2O3 ceramic. The small Al2O3 additive improved the electric field-induced strain (S max and ). The 1.0 mol% Al2O3 ceramic had a large piezoelectric voltage coefficient (g 33 = 32.6 × 10-3 Vm N-1) and good dielectric properties (ε r,max = 6542, T d = 93 °C, T F-R = 108 °C, T m = 324 °C and δ A = 164 K). The highest off-resonance figure of merit (FoM) for energy harvesting of 6.36 pm2 N-1 was also observed for the 1.0 mol% Al2O3 ceramic, which is suggesting that this ceramic has potential to be one of the promising lead-free piezoelectric candidates for further use in energy harvesting applications.

Synthesis of Hydroxyapatite with Antibacterial Properties Using a Microwave-Assisted Combustion Method.

The prevention of implant-associated infections has been increasing clinically in orthopedic surgery. Hydroxyapatite with antibacterial properties was synthesized using a microwave-assisted combustion method. High crystallinity at low temperature can be achieved using this method. The synthesized hydroxyapatite exhibited a superior clear zone for both Gram-positive and Gram-negative bacteria. Electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) were used for the radical investigation. The application of intelligent ink testing and an antioxidant assay using DPPH reduction were also used to confirm the existence of radicals. These techniques provided data confirming that radicals are responsible for the antibacterial properties. The synthesized antibacterial hydroxyapatite would be a good candidate for the prevention any infection with medical implants and injection materials causing failure in bone repair.

Improvement of electric field-induced strain and energy storage density properties in lead-free BNKT-based ceramics modified by BFT doping.

In this research, the effects of Ba(Fe0.5Ta0.5)O3 (BFT) additive on the phase evolution, the dielectric, ferroelectric, piezoelectric, electric field-induced strain responses, and energy storage density of the Bi0.5(Na0.80K0.20)0.5TiO3-0.03(Ba0.70Sr0.03)TiO3 (BNKT-0.03BSrT) ceramics have been systematically investigated. The ceramics have been prepared by a solid-state reaction method accompanied by two calcination steps. X-ray diffraction indicates that all ceramics coexist between rhombohedral and tetragonal phases, where the tetragonal phase becomes dominant at higher BFT contents. The addition of BFT also promotes the diffuse phase transition in this system. A significant enhancement of electric field-induced strain response (S max = 0.42% and = 840 pm V-1) is noted for the x = 0.01 ceramic. Furthermore, the giant electrostrictive coefficient (Q 33 = 0.0404 m4 C-2) with a giant normalized electrostrictive coefficient (Q 33/E = 8.08 × 10-9 m5 C-2 V-1) are also observed for this composition (x = 0.01). In addition, the x = 0.03 ceramic shows good energy storage properties, i.e. it has a high energy storage density (W = 0.65 J cm-3 @ 120 °C) with very high normalized storage energy density (W/E = 0.13 µC mm-2), and good energy storage efficiency (η = 90.4% @ 120 °C). Overall, these results indicate that these ceramics are one of the promising candidate piezoelectric materials for further development for actuator and high electric power pulse energy storage applications.

Electrical and Magnetic Properties of Barium Hexaferrite Modified Barium Zirconium Titanate Lead-Free Ceramics.

The (BaZr0.07Ti0.93O3)/x(BaFe12O19); (BZT/xBF) (x = 0, 0.1, 0.5 and 1 mol%) ceramics have been prepared via a solid state reaction process. Effects of BF content on the physical, microstructural, magnetic and electrical properties have been systematically investigated. High density sintered specimens (5.65-5.74 g/cm³) are obtained for all compositions. SEM micrographs show a decrease of grain size value when BF is added. Examination of the dielectric spectra show that the two phase-transition temperatures as observed for pure BZT, merges into a single phase-transition temperature for the added-samples. The addition of BF also improves the magnetic behavior (M-H hysteresis loops) of BZT ceramic and resultes in slight changes in ferroelectric properties. The maximum of remanent magnetization (Mr) of 7.19 emu/g is obtained for the 1 mol% sample.

Non-Isothermal Crystallization Kinetics of Transparent Glass-Ceramic Phosphors Containing Calcium Magnesium Aluminosilicate Nanocrystals.

Glass-ceramic phosphors from CaO-MgO-SiO2-Al2O3-ZnO co-doped with 0.5Eu3+:0.1Sm3+ (mole%) were prepared by conventional melt-quenching method. Non-isothermal crystallization kinetics were performed by differential thermal analysis at various heating rates of 5, 10, 15 and 20 °C/min. The parent glasses were investigated by X-ray diffraction technique. From the heating rate dependence of crystallization temperature, the activation energy (Ea) of crystallization and Avrami parameter (n) were calculated by Kissinger equation and Ozawa equation, respectively. The results indicated that continuous nucleation and three-dimensional crystal growth were the dominating mechanisms in the crystallization process that was confirmed by scanning electronic microscopy and transmission electron microscopy. The luminescence properties were also determined by fluorescence spectroscopy in rang of 550-750 nm under 402 nm excitation. The results of XRD studies revealed the occurrence of diopside (Ca0.8Mg1.2Si2O6) phases and no other phase is observed. The emission spectra exhibited a strong red luminescence composed of 576, 599, 613 and 702 nm when excited at 402 nm.

Fabrication of g-C3N4 and a promising charcoal property towards enhanced chromium(VI) reduction and wastewater treatment under visible light.

The visible light driven photoactivity of g-C3N4 can be enhanced using charcoal as a supporter. Charcoal/g-C3N4 composite materials were prepared by the simultaneous thermal condensation of melamine and charcoal. The effect of different atmospheres (O2, air, and argon) on the reaction was investigated. The effect of different weight ratios of charcoal to melamine (1:1 and 1:4 wt%) was also investigated. The physical properties of the charcoal/g-C3N4 materials were analyzed using XRD, SEM, TEM, XPS, BET and FTIR techniques. It was found that an oxidation reaction of charcoal and g-C3N4 during preparation greatly affected the photoactivity. A composite of charcoal:melamine (1:4 wt%) prepared under an air atmosphere provided good photooxidation of methylene blue; whereas a composite of charcoal:melamine (1:4 wt%) prepared under an oxygen atmosphere exhibited good photoreduction of chromium (VI).

Effects of NiO nanoparticles on the magnetic properties and diffuse phase transition of BZT/NiO composites.

A new composite system, Ba(Zr0.07Ti0.93)O3 (BZT93) ceramic/NiO nanoparticles, was fabricated to investigate the effect of NiO nanoparticles on the properties of these composites. M-H hysteresis loops showed an improvement in the magnetic behavior for higher NiO content samples plus modified ferroelectric properties. However, the 1 vol.% samples showed the optimum ferroelectric and ferromagnetic properties. Examination of the dielectric spectra showed that the NiO additive promoted a diffuse phase transition, and the two phase transition temperatures, as observed for BZT93, merged into a single phase transition temperature for the composite samples.

Improvement in dielectric and mechanical performance of CaCu3.1Ti4O12.1 by addition of Al2O3 nanoparticles.

The properties of CaCu3.1Ti4O12.1 [CC3.1TO] ceramics with the addition of Al2O3 nanoparticles, prepared via a solid-state reaction technique, were investigated. The nanoparticle additive was found to inhibit grain growth with the average grain size decreasing from approximately 7.5 µm for CC3.1TO to approximately 2.0 µm for the unmodified samples, while the Knoop hardness value was found to improve with a maximum value of 9.8 GPa for the 1 vol.% Al2O3 sample. A very high dielectric constant > 60,000 with a low loss tangent (approximately 0.09) was observed for the 0.5 vol.% Al2O3 sample at 1 kHz and at room temperature. These data suggest that nanocomposites have a great potential for dielectric applications.