The master sintering curve (MSC) theory is one of the widely used theories to predict the densification behaviour of a given powder and green body irrespective of its thermal history. In this paper, MSC was constructed for a high Curie temperature piezoelectric, \mathrm{La_2}\mathrm{Ti_2}\mathrm{O_7} . Powder synthesis was carried out by the solid state reaction method, followed by uniaxial pressing to obtain green compacts. Dilatometric shrinkage study of green compacts was carried out up to 1450°C with heating rates of 5, 10 and 15°C/min. The apparent activation energy of sintering was found to be 1027 kJ/mol. The results of the present study can be used to predict the densification level obtained during pressureless sintering of the \mathrm{La_2}\mathrm{Ti_2}\mathrm{O_7} powders synthesised by the solid-state method.
This study investigates the effect of substituting \mathrm{Al_2}\mathrm{O_3} with \mathrm{B_2}\mathrm{O_3} (0-4mol%) in nepheline-based glasses intended for advanced dental applications. Differential scanning calorimetry, X-ray diffraction, Raman spectroscopy, dilatometry and scanning electron microscopy were used to examine the structural and thermal evolution of the modified compositions. Increasing B2O3 content decreased the glass transition and softening temperatures and suppressed nepheline crystallisation, leading to the enhanced amorphous stability. Raman analysis revealed progressive network depolymerisation due to the conversion of Al-O-Si linkages to BO3 structural units, while dilatometry demonstrated improved thermal expansion compatibility with zirconia and metal substructures. SEM confirmed that higher \mathrm{B_2}\mathrm{O_3} levels reduced crystal formation and yield smooth, homogeneous microstructures ideal for aesthetic dental applications. The results show that \mathrm{B_2}\mathrm{O_3} contents of 2-3mol% provide optimal thermal behaviour, translucency potential and structural uniformity, positioning these compositions as promising candidates for use in dental veneering porcelains, pressable glass-ceramics and CAD/CAM restorative materials.
This study presents a novel and sustainable precipitation method for synthesis of \mathrm{Fe_3}\mathrm{O_4} /ZnO composite powder directly from corrugated galvanised iron (CGI) waste, addressing gaps in waste-derived catalysts for advanced oxidation processes. XRD characterisation revealed that the \mathrm{Fe_3}\mathrm{O_4} /ZnO powder contains the dominant \mathrm{Fe_3}\mathrm{O_4} (magnetite) crystalline phase with minor amount of ZnO phase. FTIR spectroscopy verified Fe-O (571 cm−1) and Zn-O (450-500 cm^{-1} ) bonds, while XPS confirmed coexistence of Fe^{2+} / Fe^{3+} (710/724 eV) and Zn^{2+} (1022/1045 eV) cations essential for redox cycling. The composite powder showed irregular, agglomerated morphology (SEM/TEM, 20-150 nm particles), mesoporosity (BET 22.69 m^ {2} /g, Type IV isotherm) and superparamagnetic properties (Ms ≈ 51 emu/g). Preliminary Fenton-like tests achieved 85.47% methylene blue (MB) degradation in 60min (first-order reaction, k = 0.024 min^{-1} ) via •OH generation, with >93% efficiency over 4 reuse cycles and facile magnetic separation. This reinforces waste valorisation for sustainable wastewater treatment, demonstrating a synergistic effect at the \mathrm{Fe_3}\mathrm{O_4} /ZnO interface for scalable environmental remediation.
Boron carbide ( \mathrm{B_4}C ) ceramics, owing to their ultra-high hardness, low density and excellent neutron absorption capability, have significant potential in applications such as armour, nuclear industry and cutting tools. However, their inherently low fracture toughness at ambient temperature and difficulty in achieving full densification during sintering limit broader utilisation. In this study, TiB2 reinforcement phases were fabricated in situ within \mathrm{B_4}C via high-temperature and high-pressure sintering. The influence of sintering temperature on the phase composition, microstructure and mechanical properties of the \mathrm{B_4}C - \mathrm{TiB_2} composites was systematically investigated to optimise the sintering process and performance. The results indicate that, with increasing sintering temperature, Ti progressively reacts with \mathrm{B_4}C to form \mathrm{TiB_2} , achieving complete Ti consumption at 1300°C. At 1500°C, the composites exhibited optimal performance: relative density of 99.6%TD, Vickers hardness of 35.2GPa, flexural strength of 694.6MPa, and fracture toughness of 8.2MPa•m1/2. Further temperature increase to 1600°C led to abnormal grain coarsening and consequent properties degradation. High-temperature and high-pressure sintering combined with in situ reaction enables the fabrication of highly dense, high-performance \mathrm{B_4}C - \mathrm{TiB_2} composites, with temperature of 1500°C identified as the optimal sintering temperature. This work provides not only a viable pathway for manufacturing, but also a theoretical basis for designing high-performance B4C composites.
The present work developed a methodology for synthesising single-phase nanopowder based on an ordered phase with LaLuO3 perovskite type structure. The LaLu \mathrm{O_3} : Yb^{3+} nanopowder, doped with 2mol% Yb^{3+} , was synthesised by wet-chemical method from precursor nitrate solution and thermal treated to form pure perovskite phase. The synthesised nanopowder was comprehensively studied using IR spectroscopy, X-ray diffraction, scanning electron microscopy and adsorption-structural methods. The results of the X-ray diffraction analysis indicate that the synthesised powder is single-phase, with all the formed diffraction peaks corresponding to the ordered structure of the LaLu \mathrm{O_3} perovskite type. The unit cell parameters of the LaLu \mathrm{O_3} : Yb^{3+} (2mol%) phase are: a = 0.6023 nm, b = 0.8385 nm, c = 0.5822 nm and V = 0.294 nm3 whereas the average crystallite size is 51.2 nm. The nanopowder was consolidated using the spark plasma sintering (SPS) technique at 1380°C and 50MPa with dwell of 15min, resulting in a fully dense ceramic material of 8.16 g/ cm^{3} (i.e. 99.54% theoretical density).
This study reports the preparation of dendritic bismuth silicon oxide ( \mathrm{Bi_4}\mathrm{Si_3} \mathrm{O_{12}} ) microcrystals by using solid state reaction stages and heating of \mathrm{Bi_2}\mathrm{O_3} \mathrm{SoO_2} powder mixture at 800°C for different holding times and ambient conditions. X-ray diffractometer (XRD) and scanning electron microscopy (SEM) were used to analyse the prepared microcrystals. XRD analysis revealed that microcrystals showed the eulytite structure, with a gradual decrease in the proportion of \mathrm{Bi_{12}}\mathrm{SiO_{20}} phase and a considerable increase in \mathrm{Bi_4}\mathrm{Si_3} \mathrm{O_{12}} phase as the holding time increased during heating at 800°C. This phenomenon is attributed to the occurrence of a transformation in the system, change of crystal composition and generation of dendritic-structuredmicrocrystals by increasing the holding time. An ordered structure similar to typical preferential orientation growth was formed with the growing epitaxial structure of \mathrm{Bi_4}\mathrm{Si_3} \mathrm{O_{12}} grains on the favourable microcrystal surface. However, the domain structure gradually disappeared after a certain period.
A novel high-entropy perovskite, Ba( \mathrm{Ti_{0.2}}\mathrm{Zr_{0.2}}\mathrm{Hf_{0.2}}\mathrm{Sn_{0.2}}\mathrm{Ce_{0.2}} ) \mathrm{O_3} , was successfully synthesized through a conventional solid-state reaction route and finally sintered at 1350°C for 12 h. Powder X-ray diffraction and Rietveld refinement confirmed the formation of a single-phase cubic structure with space group Pm \overline{{3}}m . Scanning electron microscopy coupled with EDX mapping revealed an uniform microstructure and homogeneous elemental distribution. The electrical properties were investigated using impedance spectroscopy over a temperature range of 35 to 495°C and a frequency range of 100Hz to 1MHz. The real part of impedance decreased with increasing temperature, indicating negative temperature coefficient of resistance (NTCR) behaviour. The imaginary impedance and electrical modulus spectra exhibited temperature-dependent relaxation with peak shifting toward higher frequencies, confirming thermally activated charge transport. The Nyquist plot analysis revealed separate contributions from grains and grain boundaries, demonstrating mixed bulk and interfacial conduction mechanisms. These results establish Ba( \mathrm{Ti_{0.2}}\mathrm{Zr_{0.2}}\mathrm{Hf_{0.2}}\mathrm{Sn_{0.2}}\mathrm{Ce_{0.2}} ) \mathrm{O_3} as a promising candidate for high-temperature electronic and sensing applications.
In this study, hydroxyapatite (HAp) samples, co-doped with 0.44 at.% of zinc and different amount of quercetin (Zn/Que-HAp), were synthesised using a wet-chemical method and calcined at 900°C. XRD shows HAp as the primary phase with minor β-TCP. Compared to the Zn-doped sample without quercetin (Q1), quercetin co-doping induces clear structural changes (shifts of lattice parameters a from −0.0017 to +0.0006 nm and c from −0.0026 to −0.0005 nm), accompanied by changes in crystallinity (from −3.6% to +2.5%) and crystallite size (from −3.5 to +0.6 nm), evidencing a distinct co-doping effect. DTA/TGA reveal reduced total mass loss for the Que-containing compositions relative to the Zn-doped sample, indicating enhanced thermal stability of the co-doped lattice. SEM reveals granular morphologies with interconnected porosity, while EDX yields (Ca+Zn)/P ratios greater than 1.67, consistent with Ca-sufficient apatite and modified defect chemistry. DFT calculations resolve the site-specific effects of Zn substitution and predict a preference for perturbation at Ca2 sites. The electronic density of states retains a wide-gap, insulating character, with localised states sensitive to the dopant configuration. By correlating experiment and theory, we demonstrate that the organic-inorganic co-dopant pair offers an effective means to tune lattice metrics, phase balance, and thermal response without compromising the intrinsic insulating nature of HAp.
This study presents a novel and sustainable precipitation method for synthesis of Fe3O4/ZnO composite powder directly from corrugated galvanised iron (CGI) waste, addressing gaps in waste-derived catalysts for advanced oxidation processes. XRD characterisation revealed that the Fe3O4/ZnO powder contains the dominant Fe3O4 (magnetite) crystalline phase with minor amount of ZnO phase. FTIR spectroscopy verified Fe-O (571 cm(-1)) and Zn-O (450-500 cm(-1)) bonds, while XPS confirmed coexistence of Fe2+/Fe3+ (710/724 eV) and Zn2+ (1022/1045 eV) cations essential for redox cycling. The composite powder showed irregular, isotherm) and superparamagnetic properties (Ms approximate to 51 emu/g). Preliminary Fenton-like tests achieved 85.47% methylene blue (MB) degradation in 60 min (first-order reaction, k = 0.024 min(-1)) via center dot OH generation, with >93% efficiency over 4 reuse cycles and facile magnetic separation. This reinforces waste valorisation for sustainable wastewater treatment, demonstrating a synergistic effect at the Fe3O4 /ZnO interface for scalable environmental remediation.
A novel high-entropy perovskite, Ba(Ti0.2Zr0.2Hf0.2Sn0.2Ce0.2)O-3, was successfully synthesized through a conventional solid-state reaction route and finally sintered at 1350 degrees C for 12 h. Powder X-ray diffraction and Rietveld refinement confirmed the formation of a single-phase cubic structure with space group Pm-3m. Scanning electron microscopy coupled with EDX mapping revealed an uniform microstructure and homogeneous elemental distribution. The electrical properties were investigated using impedance spectroscopy over a temperature range of 35 to 495 degrees C and a frequency range of 100 Hz to 1 MHz. The real part of impedance decreased with increasing temperature, indicating negative temperature coefficient of resistance (NTCR) behaviour. The imaginary impedance and electrical modulus spectra exhibited temperature-dependent relaxation with peak shifting toward higher frequencies, confirming thermally activated charge transport. The Nyquist plot analysis revealed separate contributions from grains and grain boundaries, demonstrating mixed bulk and interfacial conduction mechanisms. These results establish Ba(Ti0.2Zr0.2Hf0.2Sn0.2Ce0.2)O-3 as a promising candidate for high-temperature electronic and sensing applications.
Biphasic calcium phosphate (BCP) ceramics are prevalent bone substitutes owing to their potential to accelerate bone development. However, improving the degradation ability and the osteoinductive properties of implantable bone filler BCP ceramics is technically challenging. The incorporation of strontium (Sr) into BCP can substantially improve the regeneration process, due to the distinct mode of action displayed by Sr, which concurrently enhances osteoblastogenesiswhile inhibiting osteoclastogenesis. The Sr-incorporated BCP samples were synthesised by aqueous precipitation process and the produced specimen was dip coated with curcumin to enhance the bactericidal impact of the composite. The specimens were characterised physically and biologically to evaluate their phase composition, wettability, biodegradation as well as responses towards biocompatibility, osteogenicity and antibacterial characteristics. According to the XRD data, the hydroxyapatite (HA)-crystals of Sr-doped BCP were partly converted to the β-tricalcium phosphate (β-TCP) phase after sintering at high temperatures. This came about as the Sr2+ partially substituted the Ca2+, and as a result, Ca-deficient HA was synthesised. Antibacterial assay of the synthesized composites demonstrated inhibitory action against S. Aureus bacteria, whereas cell culture using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) assay exhibited enhanced cell proliferation.
This study reports the preparation of dendritic bismuth silicon oxide (Bi4Si3O12 ) microcrystals by using solid state reaction stages and heating of Bi2O3-SiO2 powder mixture at 800 degrees C for different holding times and ambient conditions. X-ray diffractometer (XRD) and scanning electron microscopy (SEM) were used to analyse the prepared microcrystals. XRD analysis revealed that microcrystals showed the eulytite structure, with a gradual decrease in the proportion of Bi12SiO20 phase and a considerable increase in Bi4Si3O12 phase as the holding time increased during heating at 800 degrees C. This phenomenon is attributed to the occurrence of a transformation in the system, change of crystal composition and generation of dendritic-structured microcrystals by increasing the holding time. An ordered structure similar to typical preferential orientation growth was formed with the growing epitaxial structure of Bi4Si3O12 grains on the favourable microcrystal surface. However, the domain structure gradually disappeared after a certain period.
Determination of the contact area is a key issue for extracting the mechanical properties from the analysis of nanoindentation load-displacement (P-h) curves. In this paper, a new method for the direct determination of the contact area with the empirical equation A = C(h(c) + h(d))(2) was proposed. It is based on the consideration of round indenter tip correction, using the correction factor hd yielded by fitting the loading segment of the measured P-h curve and the contact depth hc determined from the unloading segment of the same curve. Thus, the mechanical properties can be extracted easily and directly without the need of the pre-calibration of area function. The applicability of this new method was examined by statistical analysis of a total of 497 nanoindentation tests performed on silica glass. It was shown that reliable results of Young's modulus and hardness can be obtained based on the proposed new method.
Phase stability and degradation of zirconia-based ceramics, which represents a very important industrial material, highly depend on the dispersity and structure of the raw powder materials. The aim of this research was to study the influence of the concentration of the precipitating agent (ammonia) on the agglomeration, morphology and crystallisation of zirconia particles during precipitation from zirconyl nitrate salt. By potentiometric titration, it was shown that precipitation with 1 M ammonia solution balances the processes of hydrolysis and precipitation. According to STA, XRD and PSD data crystallisation temperature decreases by 77°C when ammonia concentration is reduced from 0.5 to 0.2M resulting in the kinetic stabilisation of the tetragonal zirconia at 550°C. BET data showed that the highest specific surface area of the powders was obtained in the case of precipitation from 0.5 and 1M ammonium hydroxide solutions.
The present work developed a methodology for synthesising single-crystal nanopowder based on an ordered phase with LaLuO3 perovskite type structure. The LaLuO3:Yb3+ nanopowder, doped with 2 mol% Yb3+, was synthesised by wet-chemical method from precursor nitrate solution and thermal treated to form pure perovskite phase. The synthesized nanopowder was comprehensively studied using IR spectroscopy, X-ray diffraction, scanning electron microscopy and adsorption-structural methods. The results of the X-ray diffraction analysis indicate that the synthesized powder is single-phase, with all the formed diffraction peaks corresponding to the ordered structure of the LaLuO3 perovskite type. The unit cell parameters of the LaLuO3:Yb3+ (2 mol%) phase are: a = 0.6023 nm, b = 0.8385 nm, c = 0.5822 nm and V = 0.294 nm(3) whereas the average crystallite size is 51.2 nm. The nanopowder was consolidated using the spark plasma sintering (SPS) technique at 1380 degrees C and 50 MPa with dwell of 15 min, resulting in a fully dense ceramic material of 8.16 g/cm3 (i.e. 99.54% theoretical density).
This study investigates the effect of substituting Al2O3 with B2O3 (0-4 mol%) in nepheline-based glasses intended for advanced dental applications. Differential scanning calorimetry, X-ray diffraction, Raman spectroscopy, dilatometry and scanning electron microscopy were used to examine the structural and thermal evolution of the modified compositions. Increasing B2O3 content decreased the glass transition and softening temperatures and suppressed nepheline crystallisation, leading to the enhanced amorphous stability. Raman analysis revealed progressive network depolymerisation due to the conversion of Al-O-Si linkages to BO3 structural units, while dilatometry demonstrated improved thermal expansion compatibility with zirconia and metal substructures. SEM confirmed that higher B2O3 levels reduced crystal formation and yield smooth, homogeneous microstructures ideal for aesthetic dental applications. The results show that B2O3 contents of 2-3 mol% provide optimal thermal behaviour, translucency potential and structural uniformity, positioning these compositions as promising candidates for use in dental veneering porcelains, pressable glass-ceramics and CAD/CAM restorative materials.
Boron carbide (B4C ) ceramics, owing to their ultra-high hardness, low density and excellent neutron absorption capability, have significant potential in applications such as armour, nuclear industry and cutting tools. However, their inherently low fracture toughness at ambient temperature and difficulty in achieving full densification during sintering limit broader utilisation. In this study, TiB(2 )reinforcement phases were fabricated in situ within B4C via high-temperature and high-pressure sintering. The influence of sintering temperature on the phase composition, microstructure and mechanical properties of the B4C-TiB2 composites was systematically investigated to optimise the sintering process and performance. The results indicate that, with increasing sintering temperature, Ti progressively reacts with B4C to form TiB2, achieving complete Ti consumption at 1300 degrees C. At 1500 degrees C, the composites exhibited optimal performance: relative density of 99.6 %TD, Vickers hardness of 35.2 GPa, flexural strength of 694.6 MPa, and fracture toughness of 8.2 MPa & centerdot;m(1/2). Further temperature increase to 1600 degrees C led to abnormal grain coarsening and consequent properties degradation. High-temperature and high-pressure sintering combined with in situ reaction enables the fabrication of highly dense, high-performance B4C-TiB(2)composites, with temperature of 1500 degrees C identified as the optimal sintering temperature. This work provides not only a viable pathway for manufacturing, but also a theoretical basis for designing high-performance B4C composites.
This research examines how Vickers indentation-induced flaws affect the strength and failure probability of Mediterranean float glass (MFG), specifically under biaxial flexural testing in distilled water. In total, fifteen square samples (50 x 50 mm2 each) were subjected to a constant loading rate of 0.3 mm/min. Controlled defects were introduced using loads of 1 and 10 N at three distinct distances from the high-stress contact point (2, 10 and 18 mm) of the ring-on-ring bending device. The Weibull statistical distribution was utilized to capture the relationship between defect characteristics and the glass's mechanical behaviour. Key findings indicate that higher indentation loads (10 N) produce more severe flaws, which consistently lower both the mean time to failure (MTTF) and the Weibull scale parameter (i7), regardless offlaw position. Defects placed closer to the region of maximum stress, i.e. near the contact area, create stronger stress concentrations and thus a notable reduction in fracture resistance. The presence of water further aggravates these effects by accelerating crack growth, increasing stress concentrations and ultimately undermining the mechanical integrity of the glass. Analysis of the Weibull parameters revealed that the shape parameter (beta) decreases as flaws approach the high-stress region, suggesting greater heterogeneity and criticality of defects. The scale parameter (i7) also varies with both indentation load and defect location, underlining the inherent variability in glass strength depending on these factors. These results emphasize the need to account for both flaw geometry and environmental influences such as humidity when designing and applying float glass materials.
Dual-mode down-shifting and up-converting SrTiO3:Er3+/Yb3+ doped phosphor was synthesized via the solidstate ceramic route. Structural characterization via XRD confirms formation of the cubic SrTiO3 perovskite phase (space group Pm3m) with small amount of secondary Yb2Ti2O7 phase. SEM study confirms the irregular semispherical micrograins. UV-Vis data confirms the absorption of Yb3+ at 980 nm. Up-conversion study under the 980 nm laser irradiation exhibits the strong green colour bands at 526 and 548 nm as well as a red emission band at 660 nm, which arises due to the electronic transitions corresponding to 2H11/2-4I15/2, 4S3/2-4I15/2 and 4F9/2-4I15/2. The observed green and red colour bands were predominantly ascribed to the phenomenon of two-photon absorption. Also, down-shifting under 980 nm excitation exhibits a strong emission band at 1535 nm, which is the characteristic transition of the Er3+ ion arising from 4I13/2-4I15/2. Lifetime analysis was executed to study the decay dynamics of the green colour emission bands at 545 nm (4S3/2-4I15/2). Colour tuning was observed in the CIE coordinates at different laser input powers. Synthesized phosphor materials may be utilized as the green colour phosphor and in optical communications.
Double perovskite Nd2FeTiO6 (NFTO) compound was comprehensively studied to evaluate its promising characteristics for optoelectronic applications. Structure, electronic and optical properties were analysed by firstprinciples calculations. The crystal structure of NFTO was found to be monoclinic with space group P21/c, and its structural stability was confirmed through calculated formation energy and octahedral factor, and also by experimental results. The electronic band structure analysis indicates an indirect bandgap of 0.57 eV using PBE-GGA and 1.513 eV with mBJ potential, aligning closely with the experimental value of 1.77 eV obtained from UV-visible spectroscopy. Detailed optical property investigations demonstrate significant absorbance in the UV-visible range, indicating multiple electronic transitions. Additionally, the dielectric function analysis of the compounds highlights promising dielectric properties and efficient light absorption, making NFTO a suitable candidate for solar cells, photovoltaic and other optoelectronic devices.
