Pure Phase Research Articles

Low-concentration H2S gas sensors based on MOF-derived Co3O4 nanomaterials

Metal-organic frameworks (MOF)-based gas sensors have garnered significant interest and are highly desirable for monitoring indoor air quality and mitigating various environmental reclamation challenges. Herein, we describe a unique approach for fabricating hydrogen sulfide (H2S) gas sensors based on MOF-derived cobalt oxide nanosheets (Co3O4 Ns) nanostructures. The surface morphology and porosity of the fabricated material were confirmed through comprehensive Brunauer-Emmett-Teller (BET) and electron microscopy analyses. Chemical composition and phase purity were identified using Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The sensor exhibited remarkable sensitivity towards hydrogen sulfide in the range of 0.5–100 ppm, reaching a maximum response of 1702.61 % at an operating temperature of 250 °C for 100 ppm H2S gas. Furthermore, the sensor demonstrated a detection limit of 500 ppb with a response rate of 78.22 %. A consistent stability over 30 days was observed, validating its suitability for real-world applications. The response and recovery times of the H2S gas sensors were assessed with τres/τrec = 63.56/103.34 s, offering valuable insights into their real-world applicability.

Aluminum doped non-stoichiometric titanium dioxide as a negative electrode material for lithium-ion battery: In-operando XRD analysis

Lithium-ion batteries (LIB) with titanium dioxide as anode material emerged as one of the most energy-storage systems. In this study, we investigate aluminum-doped non-stoichiometric titanium dioxide synthesized using sol-gel method and subsequent reduction treatment. Different analysis techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) tests are conducted for the analysis of material and performance of the battery. The XRD results affirmed that the sample consisted of pure titanium-dioxide phases with no other precipitated phases, such as aluminum oxide (α-Al2O3 or γ-Al2O3). XPS analysis evident that aluminum was successfully incorporated into the titanium-dioxide lattice and the presence of Ti3+ and oxygen vacancy signals confirmed its non-stoichiometric nature. TEM images implies that doping and its extent did not significantly affect the size and morphology of the nanoscale particles. The selected area electron diffraction shows that the sample consisted of a mixture of the anatase and rutile phases. The best-performing electrode was found to be the one composed of 1 % aluminum-doped non-stoichiometric titanium dioxide. After 200 charge-discharge cycles, the battery maintained a capacity of 195 mAh/g, retaining 97.5 % of its reversible capacity. Cyclic stability test under high current condition shows that the capacity remained at 157 mAh/g without any noticeable decay after 750 charge-discharge cycles at a 1 C rate. This material exhibited the lowest impedance and the highest lithium-ion diffusion rate. Additionally, in situ synchrotron-based XRD indicates coexistence of three phases such as a new reversible intermediate phase LiTiO2, a partially irreversible intermediate phase Li0.55TiO2, and the anatase phase. The analysis results indicated that the peak intensities and angular shifts were associated with the phase changes that occurred during charge and discharge of the electrochemical processes. The interaction mechanism study between lithium ions and the lattice of mixed phase (anatase, rutile) identified the occurrence of non-uniform stress resulting from lithium-ion insertion in the rutile phase, in addition to the irreversible reactions in both the rutile and anatase phases. Through the synergistic effect of heteroatom doping and oxygen vacancy treatment, the conductivity of titanium dioxide is enhanced, leading to improved performance in capacity, impedance, cycle life, and rate as an anode material in LIBs.

Tailoring the structural, magnetic and dielectric properties in holmium doped Ca-Ba hexaferrite nanoparticles by regulating the Ca-Ba (1:1) concentration for magnetic and electric applications

This work reports the synthesis and characterizations of holmium (Ho) doped Ba-Ca hexaferrites (Ba0.5Ca0.5Fe12-xHoxO19). Structural analysis confirms the pure hexagonal phase throughout, and morphology shows the uniformly distributed hexagonal-shaped particles. The incorporation of Ho3+ ions significantly enhanced magnetic properties, as evidenced by vibrating sample magnetometry (VSM), attributed to the reconfiguration of Fe3+ ions and the reinforcement of superexchange interactions. Across all samples, magnetic hysteresis (M−H) loops exhibited a consistent hard ferrimagnetic behavior, with saturation magnetization (Ms) values varying within the range of 28.64 to 36.33 emu/g, remanent magnetization (Mr) from 16.24 to 20.68 emu/g, and coercivity (Hc) from 1.771 to 2.059 kOe, respectively. The composition with x = 0.09 demonstrated the highest Ms, Mr, and Hc values. The dielectric properties underscore the potential applications of fabricated M−type hexaferrites in microwave technology due to their low dissipation factor and ε“, pivotal for minimizing signal attenuation in crucial components such as filters and resonators. Moreover, Ho doped Ba-Ca hexaferrites present promising alternatives to magnets in electric vehicle applications, suggesting avenues for further research and optimization in this domain.

Magnetic interaction in Sr0.7La0.3Fe11.75Co0.25O19–CoFe2O4 composite system: observation, evidence, and influence

(100-x) Sr0.7La0.3Fe11.75Co0.25O19–(x) CoFe2O4 composites were synthesized by the one pot sol–gel auto-combustion method. The individual phase purity, morphology, and magnetic hysteresis loop of the composite magnet were analyzed by x-ray powder diffraction, field emission scanning electron microscopy and vibrating sample magnetometer, respectively. The apparent observation of the room temperature hysteresis loop indicates the existence of interfacial exchange interactions. Nevertheless, saturation magnetization (Ms ) follows the trend of Vegard’s law. The nature of magnetic interaction and its dependency on the amount of each phase were analyzed by employing the Thamm–Hesse plot. The critical size of the soft phase particle did not corroborate with the results of ΔM vs H plot. However, this synthesis method is found to be successful in obtaining single-step magnetization reversal in hard–soft composite magnets. The deviation from ideal non-interacting Stoner–Wohlfarth particles puts the single hard phase into the limelight. The (BH)max in the range of 1.07–0.98 MGOe has been obtained for the synthesized composite magnet.

The synthesis and application of Ni2+-doped NIR-II Phosphors composed of MgAl2-xGaxO4 solid-solution

Near-infrared (NIR) light has been widely used in fields, such as biometrics recognition, security monitoring, lighting for indoor agriculture, food safety inspection and biomedical imaging. NIR phosphors are crucial components for NIR phosphor-conversion light-emitting diodes (NIR pc-LED). Compared with the traditional high-temperature solid phase method for spinel-type phosphors, the synthesis by the sol-gel combustion method is rapid, more efficient, and requires lower temperatures, with good homogeneity and uniformed nano-size particle. Here we report the synthesis of a panel of NIR phosphors that are composed of nano-sized Ni2+-doped MgAl2-xGaxO4 solid-solution of spinal crystals with high phase purity. By adjusting the ratios of Al/Ga, the Ni2+-doped phosphors with spinel (MgAl2O4) to hybrid-spinel (MgGa2O4) crystal structures were obtained. The phosphor with the Al/Ga ratio of 0.8–1.2 showed the maximal NIR emission intensity, which was 5.9 times higher than that of the MgAl2O4 spinel structure, with an internal photoluminescence quantum efficiency of 31.63 %. The phase transformation of the crystal form from spinel to hybrid-spinel resulted in a shift of the emission peak from 1223 nm to 1287 nm, realizing a ∼ 64 nm structure-dependent tunability of NIR luminescence. We assembled a NIR pc-LED device using the optimal phosphor and a commercially available near ultraviolet LED, and experimentally demonstrated its application for night-vision monitoring and bioimaging of veins in a human hand.

Preparation of high purity phase (Bi, Pb)-2223 superconducting films by sol–gel method

In this work, a (Bi, Pb)2Sr2Ca2Cu3O10+δ ((Bi, Pb)-2223) solution with good film-forming capability and chemical stability was synthesized through using metal acetates as raw materials, acrylic acid as an additive, and anhydrous methanol as a solvent to adjust the sol formula. Subsequently, (Bi, Pb)-2223 thin films were fabricated on LaAlO3 (LAO) single-crystal substrates via dip-coating technology at different heat treatment temperatures, and the structures and properties of (Bi, Pb)-2223 films were characterized. It was found that when the sol stoichiometric ratio of Bi: Pb: Sr: Ca: Cu was controlled at 1.9: 0.35: 2: 2: 3 and the gel film was heat-treated at 860 °C and dwelled for 120 min in an mixed atmosphere of N2: O2 = 96: 4, the prepared thin film with a pure (Bi, Pb)-2223 superconducting phase exhibited excellent biaxial texture, a dense surface structure, and had a T c of 106 K and a ΔT c of 6 K. The microstructure analysis revealed a layered epitaxial growth of the film along the LAO substrate with a regular arrangement of atoms and a consistent interlayer spacing.

Strength comparison for fully dense zirconium diboride ceramics tested by different methods

AbstractThe strength of zirconium diboride ceramics was tested by three different methods, 3‐point flexure, 4‐point flexure, and compression. Nearly full‐density ceramics were obtained by hot pressing commercial ZrB2 powder with the addition of .5 wt.% carbon as a sintering aid. The thermal properties and hardness were studied for ZrB2 milled with ZrB2 and WC media. Based on phase purity and higher thermal conductivity, ZrB2 ceramics prepared from powders milled with ZrB2 media were selected for mechanical property studies. The strength in 3‐point flexure was 546 ± 55 MPa. The flexure strength was 476 ± 41 MPa in 4‐point bending, which was ∼20% higher than the previously reported value of 398 MPa for ZrB2 with similar grain sizes due to higher relative density and lower impurity contents. Compression testing was performed at room temperature, and the strength was 1110 ± 358 MPa. Finally, the fracture toughness of pure ZrB2 ceramics was determined by the chevron‐notched beam method to be 3.6 ± .7 MPa m1/2. The strength and fracture toughness values are higher than those previously published for ZrB2 ceramics and can be attributed to higher density and lower grain size. The strength‐limiting flaw sizes were comparable to the grain size, suggesting that porosity and impurity phases did not play a significant role in the strength of these ceramics.

Unveiling the potential of Fe2O3/TiO2 system to produce clean water: An effective and low‒cost approach for arsenic removal from ground water

The aim of this project is to estimate and eliminate arsenic by using cost‒effective approach. For the purpose, anatase TiO2 has been synthesized and sensitized with Fe2O3 using hydrothermal approach. As‒synthesized adsorbents namely Fe2O3/TiO2 were employed to remove the arsenic (III and V) contents in the form of arsenomolybdate complex (AMC). The structural morphologies and optical characteristics have been examined and assessed by various advance approaches like XRD, FTIR, Raman, SEM and AFM techniques. The BET, EDX and XPS techniques have confirmed the porosity, phase purity and chemical compositions. The stability of adsorbents was evaluated using thermo–gravimetric analysis. To extend the utility of adsorbents for successful implementation, various ground drinking water samples have been collected from Tehsil Jahania‒PK. For the quick removal and spectroscopic quantifications, arsenic contents were first converted to the arsenomolybdate complex (AMC) and then extracted via adsorption. Langmuir and Freundlich isotherm models were employed to evaluate and confirm the adsorption efficiencies, whereas Temkin model was employed to assure the electrostatic attraction between Fe2O3/TiO2 and AMC. Results indicate that the maximum adsorption capacity of Fe2O3/TiO2 is 130.1 mg/g. On the basis of survey reports and results, it has been concluded that this approach hold potential to replace the traditional adsorbents used for arsenic removal technologies.

Phase transition behavior of benzene under dynamic compression: A stable precocious phase

The phase transitions of benzene under static and dynamic compression were measured by Raman spectroscopy. Under a static compression of up to 23.90 GPa, benzene underwent two phase transitions at approximately 0.71 GPa and 2.73 GPa, and one chemical transformation above 21.95 GPa. Under dynamic compression, liquid benzene was solidified by rapid compression from approximately 0.36 GPa to 3.81 GPa, 6.68 GPa, 9.96 GPa and 16.68 GPa, step by step within 5 ms. It was discovered that liquid benzene changed from the liquid phase into the coexistence phase of I&II at 3.81 GPa and 6.68 GPa, but then changed into two precocious phases at 9.96 GPa and 16.68 GPa. According to the alteration and evolution of the ν1 ring breathing mode (992 cm−1), rapid compression might hasten the mixed-phase’s structural transformation and make it easier to generate benzene pure phase. Decompression measurements on benzene suggest the precocious pure phase II produced by rapid compression can maintain its stable structure rather than undergo a phase change as the pressure decreases to 2.76 GPa. These phase behaviors may be attributed to the dynamic lattice instability brought on by the faster compression rate as well as the deviation from equilibrium state brought on by the dynamic pressure-induced temperature rise.

Microstructures and properties of Pr,Ce:Gd2O2S ceramics fabricated from powders synthesized at different initial water bath temperatures

Crystallized precursor with stacked layered was synthesized in hot water bath using oxide powders and concentrated sulfuric acid as raw materials. Gd2O2S powders with high phase purity were obtained by reducing the precursor under flowing hydrogen atmosphere. The influence of initial bath temperature of Gd2O3 and H2SO4 on the microstructure of Gd2O2S powders was investigated. The Gd2O2S:Pr,Ce powders showed a stacked layered structure and as the initial water bath temperature increases, the particle size of the flaky powders also increases. Using the synthesized powders, Gd2O2S:Pr,Ce scintillation ceramics were fabricated through pre-sintering in vacuum followed by HIP post-treatment in argon atmosphere. The Gd2O2S:Pr,Ce ceramics fabricated from the powders synthesized at lower initial water bath temperature show a rapid densification rate during pre-sintering. The Gd2O2S:Pr,Ce ceramic sample fabricated from powders synthesized at 7°C showed the highest optical transmittance, XEL intensity, and light yield value of 25,800 ph/MeV @ 662 keV γ rays. The PL decay time of Pr3+3P0→3H4 transition was measured to be ∼2.87 μs for all ceramic samples. The effect of the initial water bath temperature on optical transmittance and light yield of Gd2O2S:Pr,Ce ceramics was also discussed.

Synthesis and Characterization of Iron–Sillenite for Application as an XRD/MRI Dual-Contrast Agent

In the present work, iron–sillenite (Bi25FeO40) was synthesized using a simple solid-state reaction method and characterized. The effects of the synthesis conditions on the phase purity of Bi2O3/Fe3O4, morphological features, and possible application as an XRD/MRI dual-contrast agent were investigated. For the synthesis, the stoichiometric amounts of Bi2O3 and Fe3O4 were mixed and subsequently milled in a planetary ball mill for 10 min with a speed of 300 rpm. The milled mixture was calcined at various temperatures (550 °C, 700 °C, 750 °C, 800 °C, and 850 °C) for 1 h in air at a heating rate of 5 °C/min. For phase identification, powder X-ray diffraction (XRD) analysis was performed and infrared (FTIR) spectra were recorded. The surface morphology of synthesized samples was studied by field-emission scanning electron microscopy (FE-SEM). For the radiopacity measurements, iron–sillenite specimens were synthesized at different temperatures and mixed with different amounts of BaSO4 and Laponite solution. It was demonstrated that iron–sillenite Bi25FeO40 possessed sufficient radiopacity and could be a potential candidate to meet the requirements of its application as an XRD/MRI dual-contrast agent.

IR reflective performance of ZnO: Dy pigment on glass surface

In this paper, we have discussed the heat reflective properties of ZnO: Dy3+ pigment synthesized by the combustion method and co-precipitation method. The phase purity and crystalline nature of the prepared pigment have been studied using XRD and SEM. The IR-reflective properties of the pigment DRS have been measured. A paint formulation of the ZnO: Dy3+ pigment was prepared in alkyd resin. The performance of the heat-reflective paint has been investigated by coating the glass surface. From the present investigation, it is seen that the prepared ZnO: Dy3+ pigment is well suited to increase the IR reflectance to cool the surface.

Raman Spectroscopy as an Effective Tool for Assessment of Structural Quality and Polymorphism of Gallium Oxide (Ga2O3) Thin Films.

Raman spectroscopy, a versatile and nondestructive technique, was employed to develop a methodology for gallium oxide (Ga2O3) phase detection and identification. This methodology combines experimental results with a comprehensive literature survey. The established Raman approach offers a powerful tool for nondestructively assessing phase purity and detecting secondary phases in Ga2O3 thin films. X-ray diffraction was used for comparison, highlighting the complementary information that these techniques may provide for Ga2O3 characterization. Few case studies are included to demonstrate the usefulness of the proposed spectroscopic approach, namely the impact of deposition conditions such as metal-organic vapor-phase epitaxy and pulsed electron deposition (PED), and extrinsic elements provided during growth (Sn in the case of PED) on Ga2O3 polymorphism. In conclusion, it is shown that Raman spectroscopy offers a quick, reliable, and nondestructive high-resolution approach for Ga2O3 thin film characterization, especially concerning phase detection and crystalline quality.

A novel single near-infrared luminescence of negative thermal quenching materials for optical temperature measurement

In recent years, upconversion (UC) luminescence has gained attention due to its unique optical properties, and the thermal response spectral characteristics of these materials have been widely utilized in various fields including temperature sensing and biomedical research. However, the photoluminescence (PL) intensity of most rare earth ions doped phosphors decreases with increasing temperature, and the visible fluorescence emission penetration is still limited. In the work, the pure phase of Yb3+ and Er3+ ions co-doped Sc2Mo3O12 was successfully prepared. The Sc2Mo3O12: Yb3+, Er3+ sample showed a single emission of UC near-infrared (NIR) light. The optimum doping concentrations of 0.2 for Yb3+ ions and 0.01 for Er3+ ions were achieved. The possible upconversion luminescence (UCL) mechanism was investigated by analysing the UCL spectra, the down-shift (DS) excitation and emission spectra of Sc2Mo3O12: Yb3+, Er3+ phosphor. The excitation path of NIR emission is mainly through Er3+ from 2H11/2 to 4I9/2 energy level. What's more, the temperature-dependent near-infrared UCL properties of sample is explored in the temperature range from 323 K to 673 K. The enhancement of upconversion luminescence intensity shows a linear relationship with increasing temperature. The study paves a new way for non-contact optical temperature measurement with single near-infrared UCL emission.

Embedded high-quality ternary GaAs1−x Sb x quantum dots in GaAs nanowires by molecular-beam epitaxy

Semiconductor quantum dots are promising candidates for preparing high-performance single photon sources. A basic requirement for this application is realizing the controlled growth of high-quality semiconductor quantum dots. Here, we report the growth of embedded GaAs1−x Sb x quantum dots in GaAs nanowires by molecular-beam epitaxy. It is found that the size of the GaAs1−x Sb x quantum dot can be well-defined by the GaAs nanowire. Energy dispersive spectroscopy analyses show that the antimony content x can be up to 0.36 by tuning the growth temperature. All GaAs1−x Sb x quantum dots exhibit a pure zinc-blende phase. In addition, we have developed a new technology to grow GaAs passivation layers on the sidewalls of the GaAs1−x Sb x quantum dots. Different from the traditional growth process of the passivation layer, GaAs passivation layers can be grown simultaneously with the growth of the embedded GaAs1−x Sb x quantum dots. The spontaneous GaAs passivation layer shows a pure zinc-blende phase due to the strict epitaxial relationship between the quantum dot and the passivation layer. The successful fabrication of embedded high-quality GaAs1−x Sb x quantum dots lays the foundation for the realization of GaAs1−x Sb x -based single photon sources.

Copper oxides CuO and Cu2O processed by spark plasma sintering—Electrical characterization and photo-activated conductivity

Commercial powders made of two copper oxides were compacted with spark plasma sintering (SPS). Their dielectric properties were studied in a broad range of frequencies and temperatures. Various relaxation phenomena were documented. DC resistivity was measured as well. Microstructure and phase composition were studied, and phase purity was shown for CuO, whereas Cu2O was more sensitive to carbon contamination during the SPS processing. Influence of the sintering temperature on microstructure and electrical properties was described for both materials. Change of DC resistivity induced by visible light irradiation was monitored for 48h. The overall difference between CuO and Cu2O from the electrical standpoint was finally not so dramatic as the stoichiometry indicated. Both materials exhibited giant permittivity, but extremely dependent on frequency and temperature. Application could find such systems mainly in the branch of sensors.

Settlement stability, electrical properties, and magnetoelectric properties of Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 multiferroic fluids modulating by particle sizes

Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 (MZFO-PZT) multiferroic fluids with different MZFO particle sizes were prepared, and magnetoelectric coupling effects were observed to be enhanced at room temperature. The X-ray diffraction analysis (XRD) indicates that the MZFO and PZT particles are in the pure phases. Scanning electron microscopy (SEM) images illustrate a decrease in MZFO particle size with increased ball milling time. As the MZFO particle sizes decrease, the settlement stability of multiferroic fluids becomes worse. The dielectric constant displays a nonlinear variation, exhibiting a maximum value of 4.52 at 140 Hz when the MZFO particle size is 0.55 μm. The residual polarization strength decreases and increases as particle size decreases, while the saturation polarization strength decreases gradually. The application of magnetic field results in a notable enhancement of the dielectric characteristics and ferroelectric properties, which indicates the presence of magnetodielectric and magnetoelectric coupling effects. The magnetoelectric coupling coefficient (αME) is 15.14 V/(cm·Oe) when the MZFO particle size is 0.61 μm. By modifying the strength of the applied magnetic field, the αME attains a maximum value of 114.43 V/(cm·Oe). This approach offers an effective strategy for optimizing the magnetoelectric coupling effect of multiferroic materials. Therefore, it is expected to be used in new magnetoelectric devices such as magnetoelectric random memories and magnetic field sensors.

A novel fluoroapatite-type phosphor Ca2Y8(BO4)2(SiO4)4F2:Eu3+ with high quantum efficiency and good thermal stability for multimodal applications☆

A novel Eu3+ doped fluorapatite red phosphor Ca2Y8(BO4)2(SiO4)4F2:Eu3+ with pure phase was synthesized in this study. Density functional theory (DFT) calculation and diffuse reflection spectrum analysis reveal its potential as a matrix for phosphors excited by ultraviolet light. Eu3+ has a 7F0→5L6 transition at 394 nm, and the prepared phosphor exhibits a high emission intensity at 614 nm, which may be attributed to the 5D0-7F2 energy transition at the lower symmetry site of Eu3+. The optimal doping concentration of the phosphor is determined to be 11 mol%, with concentration quenching attributed to the exchange interaction mechanism. The overall color purity of the phosphor is up to 99.88%, with an internal quantum efficiency as high as 91.15%. Notably, Ca2Y8(BO4)2(SiO4)4F2:11 mol%Eu3+ (CYBSF:11 mol%Eu3+) phosphors exhibit good thermal stability, with a thermal quenching temperature (T1/2) of 552 K and the intensity of emission at 423 K still at 88.89% of that at 298 K. The activation energy of the phosphor is up to 0.30287 eV. Its comprehensive luminescence performance surpasses that of commercial red phosphor, making it suitable for near ultraviolet excited warm white light emitting diode (NUV-WLED) with a high color rendering index (Ra = 82) and a correlation color temperature (CCT) of 4339 K. Moreover, the phosphor achieves latent fingerprint visualization and anti-counterfeiting ink on different material surfaces: glass, aluminum foil, plastic and paper. Overall, the fluorapatite CYBSF:11 mol%Eu3+ phosphor holds great potential for multimodal applications due to its high quantum efficiency and good thermal stability.

Structural, dielectric and Magnetic properties of Samarium doped (Ni–Zn) based Spinel Ferrite (Ni0.5Zn0.5SmxFe2-xO4) nanomaterials

Samarium doped Ni-Zn ferrites (Ni0.5Zn0.5SmxFe2-xO4) were synthesized using sol-gel auto-combustion technique with Sm3+ doping concentrations varying as x = 0.00, 0.05, 0.10, 0.15, and 0.20. The prepared nanomaterials were examined using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), complex impedance spectroscopy (CIS) and vibrating sample magnetometer (VSM). The XRD examination verified the pure FCC spinel phase of all samples with no impurity peak. The FTIR analysis for spinel molecules formation identified two frequency bands at the octa and tetrahedral sites. The TEM analysis confirmed the shape, size and distribution of prepared nanoparticles. The different dielectric properties were analyzed with a frequency range of 1 MHz–3 GHz and the impact of doping was also studied simultaneously. Magnetic nature of prepared materials was investigated at room using the VSM. It is found that the prepared nanomaterials are suitable for high energy storage as well as magnetic applications.

Synergistic effect of YAG particulate reinforcement on microstructural and thermo-mechanical properties of pressureless sintered MgAl2O4 spinel ceramic composites

Yttrium aluminum garnet (YAG) powders, synthesized through a partial wet chemical process, exhibit controlled morphology, high phase purity, and uniform homogeneity etc. This process involves the precipitation of aluminum ions onto Y2O3 particles. The transformation process of the Al-compound/Y2O3 precursor structure leads to the direct crystallization of pure YAG at 900 °C, passing through an intermediate stage where hexagonal YAH phase forms. A comprehensive study was conducted on the impact of preformed YAG as a reinforcing phase on the densification, mechanical, and thermo-mechanical properties of MgAl2O4-YAG composite, sintered under pressureless sintering in temperature range of 1500 °C–1600 °C. The inclusion of YAG particulate up to 5.0 wt% significantly enhances the densification, hardness, fracture toughness, flexural strength and high-temperature mechanical behavior of magnesium aluminate spinel (MAS) ceramics, however, increasing the YAG content beyond 5.0 wt% causes a reduction in these properties. The optimized addition of YAG particulate contributes to reducing the average grain size and refining the microstructure of the spinel ceramic matrix.