Conventional Solid-state Synthesis Method Research Articles

Effects of sintering temperatures on crystal structures, dielectric properties, and phonon characteristics of Sr2V2O7 microwave ceramics

Sr2V2O7 (SVO) microwave dielectric ceramics were fabricated through a conventional solid-state synthesis method and sintered at 900–1000 °C for 10 h. The crystal structures and morphologies of the SVO samples were examined via X-ray diffraction and scanning electron microscopy. These analyses revealed that the SVO sample sintered at 950 °C exhibited high crystallinity and a triclinic crystal system. Through the lens of lattice dynamics, the phonon characteristics of the SVO samples were investigated via Raman spectroscopy and far-infrared spectroscopy to elucidate the dielectric response mechanics and microstructural origins of these responses. Raman spectra were classified into three sections corresponding to the vibration of Sr2+ ions, the V–O or V–O–V telescopic vibration, and the internal elongation of the tetrahedral structure composed of V–O, respectively. The inherent dielectric properties obtained from the far-infrared spectra were analyzed using a four-parameter semi-quantum model with the assistance of the Focus software. This analysis aligned with the measured property values. The relationships between the crystal structures and the dielectric properties were established using the Raman modes. Particularly, the SVO sample sintered at 950 °C exhibited excellent dielectric properties, characterized by a dielectric constant (εr) of 9.49, a quality factor (Q × f) of 35,189 GHz, and a resonant frequency (f) of 12.48 GHz.

Influence of the La0.2Sr0.7Ti0.95Ni0.05O3 (LSTN) Synthesis Method on SOFC Anode Performance

Solid oxide fuel cells are characterized by a high efficiency for converting chemical energy into electricity and fuel flexibility. This research work focuses on developing durable and efficient anodes for solid oxide fuel cells (SOFCs) based on exsolving nickel from the perovskite structure. A-site-deficient La- and Ni-doped strontium titanates (La0.2Sr0.7Ti0.95Ni0.05O3−δ, LSTN) were synthesized using four different techniques and mixed with Ce0.8Gd0.2O2−δ (GDC) to form the SOFC anode. The synthesis routes of interest for comparison included solid-state, sol-gel, hydrothermal, and co-precipitation methods. LSTN powders were characterized via XRD, SEM, TPR, BET and XPS. In situ XRD during reduction was measured and the reduced powders were analyzed using TEM. The impact of synthesis route on SOFC performance was investigated. All samples were highly durable when kept at 0.5 V for 48 h at 800 °C with H2 fuel. Interestingly, the best performance was observed for the cell with the LSTN anode prepared via co-precipitation, while the conventional solid-state synthesis method only achieved the second-best results.

Investigation of crystal structural and magnetic properties of titanium doped Pr0.67Ba0.33MnO3 perovskite manganites

Pr0.67Ba0.33Mn1-xTixO3 (x = 0 and 0.02) were synthesized using a conventional solid-state synthesis method to investigate the effect of Ti substitution on their magnetic and electrical transport properties. All the samples were structurally evaluated by XRD diffraction Rietveld refinement method which showed an increase in unit cell volume with increasing Ni content, indicating that Ti is partially substituted at Mn. Scanning electron microscopy (SEM) and energy dispersive X-tray (EDX) are used to examine the surface morphology and identified elements in the samples' compounds. Fourier transform infrared spectroscopy (FTIR) reveals that all the samples exhibit a transmission band in the range of 590 cm-1 - 610 cm-1 . For x = 0, magnetization measurements showed paramagnetic (PM) to ferromagnetic (FM) transition at the transition temperature, TC ∼ 213 K. For Ti-substituted samples, ferromagnetic (FM) to PM transition was reduced with Curie temperature (TC), decreasing from 213 K (x = 0) to 205 K (x = 0.02). On the other hand, the M(H) showed the presence of a linear graph for x = 0 and x = 0.02 which may be related to the presence of paramagnetic at room temperature.

The interaction between Co and Mn ions on the magnetic frustration and the inducement of the double-exchange mechanism in hole-doped La0.6Dy0.1Ca0.3Co1-xMnxO3 (x = 0–1.0) cobaltite

This study investigates the interaction between Co and Mn ions on spin state behaviour and magnetic frustration in hole-doped La0.6Dy0.1Ca0.3Co1-xMnxO3 (x = 0–1.0) cobaltite. It aims to understand the inducement of the double-exchange (DE) mechanism in this system. The samples were synthesised using the conventional solid-state synthesis method, and their crystal structure and magnetic properties were analysed. Rietveld refinement of X-ray diffraction data confirmed that La0.6Dy0.1Ca0.3Co1-xO3 (x = 0.0 and 0.2) samples had rhombohedral crystals structure with R c − 3 space group. An orthorhombic (Pbnm) perovskite structure was observed for the La0.6Dy0.1Ca0.3Co1-xMnxO3 (x = 0.4 –1.0) accompanied by increasing cell volume in the samples as the substitution level of Mn increases. Temperature dependence of resistivity ρ(T) shows semiconducting behaviour in the whole temperature and composition range of x = 0.0–0.8. However, further substitution with x = 0.9 and x = 1.0 give remarkable induced MI behaviour where the MI transition temperature (TMI) increased from 75 K and 132 K, respectively. The result suggests that Mn ions play an important role in the magnetic properties of the cobaltite, and the system can be tuned by adjusting the Mn concentration.

Optimizing the Mechanoluminescent Properties of CaZnOS:Tb via Microwave-Assisted Synthesis: A Comparative Study with Conventional Thermal Methods.

Recent developments in lighting and display technologies have led to an increased focus on materials and phosphors with high efficiency, chemical stability, and eco-friendliness. Mechanoluminescence (ML) is a promising technology for new lighting devices, specifically in pressure sensors and displays. CaZnOS has been identified as an efficient ML material, with potential applications as a stress sensor. This study focuses on optimizing the mechanoluminescent properties of CaZnOS:Tb through microwave-assisted synthesis. We successfully synthesized CaZnOS doped with Tb3+ using this method and compared it with samples obtained through conventional solid-state methods. We analyzed the material's characteristics using various techniques to investigate their structural, morphological, and optical properties. We then studied the material's mechanoluminescent properties through single impacts with varying energies. Our results show that materials synthesized through microwave methods exhibit similar optical and, primarily, mechanoluminescent properties, making them suitable for use in photonics applications. The comparison of the microwave and conventional solid-state synthesis methods highlights the potential of microwave-assisted methods to optimize the properties of mechanoluminescent materials for practical applications.

Ba2–xLaxSnO4+δ layered barium stannate materials: Synthesis, electronic transport, and chemical stability

The design and synthesis of new solid oxide materials are important areas in both fundamental and applied chemistry. In the present work, we consider weakly studied Ba2SnO4 layered materials for high-temperature applications. The Ba2–xLaxSnO4+δ (x = 0.05 and 0.1) samples were prepared according to the conventional solid-state synthesis method followed by sintering at 1150–1200 °C. Although a single-phase state was achieved for all the studied compositions, the decomposition of the layered phases into individual oxides (BaO, SnO2/SnO and La2O3) following their long-term storage even under ambient conditions can be explained in terms of their interactions with gas components (H2O and CO2). Nevertheless, the chemical stability of Ba2–xLaxSnO4+δ was slightly improved by La-doping. The electrical characterisation indicated that Ba2SnO4 at 700–900 °C is an n- and p-type conductor with negligible oxygen ionic conductivity. Ba2SnO4 thus represents a relevant research object for fundamental and applied sciences when solving issues with its unsatisfactory chemical stability.

Ferroelectric properties and large electric field-induced strain of Eu3+-doped Na0.5Bi0.5TiO3–BaTiO3 lead-free ceramics

Eu3+-doped lead-free piezoelectric ceramics, 0.937Na0.5Bi0.5−xEuxTiO3-0.063BaTiO3 (abbreviated as NBExT-BT, where x = 0, 0.003, 0.005, 0.01, 0.013, 0.015, 0.017, and 0.02), were synthesized using a conventional solid-state synthesis method. All the component samples were crystallized in a pure perovskite structure without a secondary phase. The introduction of Eu3+ caused the evident variation of the dielectric, ferroelectric and luminescence properties. The remanent polarization and coercive field of the pure NBT-BT are Pr ∼29.24 μC/cm2, Ec∼39.33 kV/cm, respectively. The maximum of the remanent polarization Pr of ∼38.02 μC/cm2 at room temperature and the highest dielectric constant of 6899 with a frequency of 1 kHz were obtained for NBE0.003T-BT. The maximum bipolar strain Smax of ∼0.91% and the minimum of coercive field Ec ∼18.45 kV/cm were achieved by the NBE0.015T-BT, resulting from the formation of a double hysteresis loop. For all the components, Eu3+ doping stabilized the antiferroelectric phenomenon at high temperature. Furthermore, the polarized NBE0.015T-BT had the strongest fluorescence luminescence intensity as well as a fluorescence lifetime reaching 785.98 μs.

The Ba(Mg1/3Ta2/3)O3 ceramic based X-band filter

The microwave dielectric Ba(Mg1/3Ta2/3)O3 ceramics with different sintering temperatures were prepared by conventional solid-state reaction synthesis method. The ordering degree and lattice distortion related to high quality factor were investigated systematically with XRD. In accordance with the observed morphology and grain distribution, compact and uniform microstructure with large grain size has a good effect on the high Q × f value. Surprisingly, in the case of the 1:2 ordered structure, the shorter bond length associated to Mg-O at 1670 ℃ also contributes to the high-Q, as compared with that of samples sintered at low temperature. Finally, Ba(Mg1/3Ta2/3)O3 ceramic based filter (center frequency: 10.29 GHz, bandwidth: 216 MHz, insertion loss: 0.86 dB) was designed for X-band high frequency application.

Tailoring the properties of Ni-Mn based NTC thermistors by Cu and Li addition

The influence of Cu and Li doping in the structural and R-T characteristics of Ni-Mn-based spinel oxide negative temperature coefficient (NTC) thermistors prepared using the conventional solid-state synthesis method was investigated in this study. The doping of Cu and Li in nickel manganite plays an important role in tailoring the thermistor parameters. The structural characterization of the prepared samples using XRD revealed that the basic structure of the samples is not altered by the addition of the dopants Cu and Li. The particle size of the samples was obtained at less than 50 nm. R-T characteristics showed a decrease in resistance with temperature. It was observed that the addition of dopant Cu in a minimal amount helps to tune the resistance of the thermistor in the required range and Li addition, as a dopant, stabilized the thermistor parameters B and alpha.

Preparation of Li3PS4–Li3PO4 Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

A solid solution of a 100Li3PS4·xLi3PO4 solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li2S, P2S5 and Li3PO4 was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li3PO4 were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li3PO4 remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS33− unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0.

Structural, optical, and dielectric investigations in bulk PrCrO3

The polycrystalline powder samples of PrCrO3 have been prepared using conventional solid-state synthesis method. Structural investigations are carried out using Raman spectroscopy and synchrotron X-ray diffraction (SXRD) followed by Rietveld refinement of diffraction data. Investigations of diffraction data suggest that these samples possess centrosymmetric orthorhombic structure with space group $$Pnma$$ $$(or\;Pbnm)$$ . The valence (charge) state of Cr in PrCrO3 has been determined from X-ray absorption near edge spectroscopy (XANES). Optical properties are studied using diffuse reflectance spectroscopy technique. Optical absorption study reveals that absorption in PrCrO3 ceramic is dominated by d–d electrons of chromium cation (Cr3+). The synthesized compound found to have energy bandgap of 3.20 eV. Based on the results observed, energy level diagram for PrCrO3 has been presented. High dielectric permittivity $$(\varepsilon {^{\prime}})$$ of the order $$3\times {10}^{3}$$ is observed for the studied sample. Impedance spectroscopy measurement at room temperature on sintered pellet indicates electronic inhomogeneity in the samples as demonstrated by the presence of dielectric relaxation processes associated with highly conducting grain and low conducting grain boundaries. The relaxation mechanism has been explained on the basis of Cole–Cole model. Observed high dielectric permittivity $$(\varepsilon {^{\prime}})$$ and optical energy bandgap $$({E}_{g})$$ indicates that PrCrO3 may find promising application in optoelectronic devices.

Enhanced piezoelectric properties in M (M = Co or Zn)-doped Ba0.99Ca0.01 Ti0.98Zr0.02O3 ceramics

In this study, (Ba0.99Ca0.01)(Ti0.98Zr0.02)O3-x mol% M (M = Co or Zn) (0 ≤ x ≤ 1.0) (BCZT-xM) piezoelectric ceramics with enhanced piezoelectric properties were prepared by a conventional solid-state synthesis method. The effects of different doping amounts of M on the phase structure, microstructure, dielectric properties, and piezoelectric properties of the BCZT-xM ceramics were studied systematically. Results showed that Co doping markedly decreased the average grain size, whereas Zn doping slightly decreased the grain size. The piezoelectric coefficient of the BCZT-xM ceramics increased by 30% after appropriate M doping. The mechanisms of enhancing the piezoelectric properties of the BCZT ceramics by Co and Zn doping differed. For the BCZT-xCo ceramics, Co doping induced drastic lattice distortion and enhanced the crystal disorder distribution, thereby enhancing the piezoelectric properties. For the BCZT-xZn ceramics, the enhancement of piezoelectric properties could be attributed to the large grain size and dense microstructure. The optimum ferroelectric properties (Pr = 15.9 μC/cm2, Ec = 5.7 kV/cm) were obtained in the BCZT-0.2Co ceramics. This study provides a novel paradigm for designing high piezoelectric materials.

Quantitative assessment of degradation, cytocompatibility, and in vivo bone regeneration of silicon-incorporated magnesium phosphate bioceramics

Abstract

Effect of La3+ Substitution at Bi-Site on Transport Properties of Bi0.3-xLaxPr0.3Ca0.4Mn0.1Cr0.9MnO3

Magnetic and electronic transport properties of Bi0.3-xLaxPr0.3Ca0.4Mn0.1Cr0.9O3 (0≤x≤0.2) manganites have been investigated by measurements of AC-susceptibility, resistivity and magnetoresistance. The samples were prepared using conventional solid-state synthesis method. Magnetic susceptibility versus temperature measurements showed all samples exhibit ferromagnetic to paramagnetic transition with Curie temperature, Tc enhanced from 111 K (x=0) to 174 K (x=0.2). Electrical resistivity measurements of the samples in zero field showed increase of metal-insulator (MI) transition temperature from 58 K(x=0) to 88 K(x=0.2). The increase in both Tc and TMI indicates enhancement of double exchange (DE) interaction involving Mn3+ and Mn4+ ions as a result of weakening of the hybridization effect between Bi3+ 6s2 lone pair with O orbital due to La3+ substitution. La substitution in the Bi-based compound is suggested reduce MnO6 octahedral distortion hence increasing delocalization of charge carriers. The observed variation in MR behavior due to La substitution indicates the substitution influence the MR mechanism of extrinsic and intrinsic behavior in Bi0.3-xLaxPr0.3Ca0.4Mn0.1Cr0.9O3 .Â

Effect of Fe3+ for Ru4+ substitution in disordered Na1.33Ru0.67O2 cathode for sodium-ion batteries: Structural and electrochemical characterizations

Sodium ruthenium oxides (Na2RuO3 and Na1.33Ru0.67O2) belong to a special Na-rich type of cathode material which show high specific capacities and structural stability. Even though these Na-rich materials possess attractive electrochemical properties, owing to the low abundance of ruthenium (Ru) within the Earth’s crust, commercialization of sodium ruthenium oxide (NRO) cathodes is extremely difficult. To mitigate this disadvantage, we have substituted Ru in NRO using Fe, which is electrochemically active in many cathode materials for sodium-ion batteries (SIBs), Earth-abundant and cheap. Herein, a series of Fe-substituted (Fe% = 5 mol. %, 10 mol. %, 20 mol. %, and 30 mol. %) sodium ruthenium iron oxide (NRFOx) phases were synthesized using a conventional solid-state synthesis method. When used as a cathode material, among these novel Fe substituted phases, the composition with the lowest Fe mol. % displays the highest specific discharge capacities of 115 mAh g−1 and 61 mAh g−1, at 0.2C and 2C rate respectively, within a 2.0–3.7 V potential range. It was seen that the Fe substitution level significantly influences structural stability and discharge capacities. Cyclic voltammetry displays that Fe3+ is surprisingly electrochemically inert inside the NRO matrix and only plays a structural role.

Molten salt assisted growth of lead-free BCZT crystals: effects of synthesis conditions and sintering on structural and electrical properties

An attempt of preparing lead free [(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3] (BCZT) crystals by molten salt synthesis (MSS) method and the influence of MSS process parameters on the morphology, phase structure, dielectric and ferroelectric properties of BCZT ceramic have been reported in this investigation. A reduction in reaction temperature of 350 °C (1000 °C/4 h in MSS method versus 1350 °C/4 h in conventional solid state method) has been achieved in MSS method. Among various alkali metal salts NaCl–KCl salt mixture has been found most effective in producing phase pure and anisotropic platelet like BCZT crystals. Powder X-ray diffraction pattern and Raman spectra of the BCZT crystals confirm the room temperature tetragonal structure of the BCZT ceramic. Finally, BCZT template prepared by alkali metal salts (Na2SO4, NaCl, KCl, NaCl–KCl and NaBr) at 1000 °C/4 h were compacted and sintered at 1450 °C/2 h to achieve pellets with good sintered densities. The crystal structure, microstructural and electrical properties were compared with randomly-oriented BCZT ceramics prepared by conventional solid-state synthesis method, and the results are presented in this paper.

Effects of the Sintering Temperature on RF Complex Permeability of NiCuCoZn Ferrites for Near-Field Communication Applications

The effect of bismuth oxide (Bi 2 O 3 ) and sintering temperature on NiCuCoZn ferrite powders has been investigated for the near-field communication applications. The powders were prepared by conventional solid-state synthesis method. The microstructure and frequency-dependent complex permeability were investigated. Employment of Bi 2 O 3 as a sintering aid promotes uniform grain growth and densification in sintered powders, which in turn has affected complex permeability spectra. It has been observed that the addition of Bi 2 O 3 decreases permeability and magnetic loss from 147 to 110 and from 0.03 to 0.02, respectively, which were both sintered at 1100 °C and measured at 13.56 MHz frequency as compared to undoped sample (without Bi 2 O 3 ). Also, permeability and magnetic loss were increased with sintering temperature. Complex permeability and resonance frequency follow the Globus model.

The Effects of Bismuth Oxide on Microstructures and Magnetic Properties of Mn-Mg-Al Ferrites

In the present paper, the effects of bismuth oxide as an additive on microstructure and magnetic properties of Mg0.9Mn0.1Al0.4Fe1.6O4 were investigated. Mg-Mn-Al ferrite powders were prepared by the conventional solid state synthesis method. Two different amounts of bismuth oxide (2.5 wt.% and 5 wt.%) were utilized as the sintering aid and their microstructure and physical properties were compared to those of the sample without additives. X-ray diffraction (XRD) analysis indicated that crystal lattice distortion due to the microstructural constraints as the result from incorporation of bismuth oxide into the microstructure was developed by adding bismuth oxide. XRD Rietveld refinement was used to define the cation distribution and to refine the lattice parameter and oxygen parameter for the sample without bismuth oxide as (Mg0.16Mn0.02Al0.15Fe0.77)A(Mg0.74Mn0.08Al0.25Fe0.83)BO4 and 8.3308 A and 0.2542, respectively. Microstructure studies show that a bismuth rich liquid phase forms during the sintering at 1250°C, which enhances the densification of sintered bodies up to 13% (a relative density of 93%). Magnetization of sintered samples were increased from 21.1 emu/g to 26.2 emu/g upon addition of 2.5 wt.% bismuth oxide and then decreased to 24.9 emu/g when 5 wt.% bismuth oxide was added.

Revival of Metal-Insulator and Ferromagnetic-Paramagnetic Transitions by Ni Substitution at Mn Site in Charge-Ordered Monovalent Doped Nd0.75Na0.25MnO3 Manganites

Nd0.75Na0.25Mn1−xNi x O3 (x = 0 − 0.07) were synthesized using a conventional solid-state synthesis method to investigate the effect of Ni substitution on their magnetic and electrical transport properties. XRD analysis using the Rietvield refinement method showed an increase in unit cell volume with increasing Ni content, indicating the possibility of substituting Ni for the Mn site. For x = 0, magnetization measurements showed paramagnetic (PM) to antiferromagnetic (AFM) transition at the transition temperature, TN ∼ 185 K, which may be related to the presence of charge-ordering (CO) state. For Ni-substituted samples, ferromagnetic (FM) to PM transition was induced with Curie temperature (TC), increasing from 91 K (x = 0.01) to 115 K (x = 0.03), followed by decreases in TC to 60 K (x = 0.07). Electrical resistivity measurements showed that samples for x ≤ 0.01 exhibited insulator behavior while both x = 0.03 and 0.05 samples exhibited metal-insulator transition suggesting that the CO state is weakened. For x = 0.07, the sample shows re-entrant of insulating characteristic. Inducement of FM metallic (FMM) state, as well as increased of TC for x = 0.03 is suggested to be related to FM SE between Ni2+ and Mn4+, which suppressed the CO state, hence inducing double-exchange (DE)-like mechanism. In addition, an increase in resistivity was observed as temperature decreased below the resistivity minimum (Rmin) at Tmin ∼ 40 K for x = 0.05 is possibly due to the Kondo-like effect mechanism. On one hand, the M(H) curve showed the presence of a hysteresis loop for x = 0 and 0.01 at T= 60 and 80 K, indicating the presence of an unstable phase, which may be related with the CO-AFM phase. For x = 0.03, no hysteresis loop was observed, indicating the suppression of the CO-AFM. Intriguingly, for x = 0.05 and 0.07, small hysteresis loop was observed, indicating the possible presence of a minor AFM component. Further, the observed MR behavior in present studies can be understood as a result of a decreased scattering mechanism in the presence of magnetic field.

Enhanced strain sensitivity in magnetostrictive spinel ferrite Co1−xZnxFe2O4

We report the magnetic and magnetoelastic properties of spinel oxide system Co1−xZnxFe2O4 (CZF series) where x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5. All the composition were prepared by conventional solid state synthesis method and exhibited pure spinel phase formation. The lattice parameters showed gradual increase indicating uniform distribution Zn ions in cobalt ferrite lattice. The magnetic properties such as saturation magnetization and coercive field were drastically affected with Zn substitution showing enhanced saturation magnetization and a sharp decrease in the coercivity. The room temperature magnetostrictive properties showed a promising 30% enhancement in the slope of magnetostriction curve for x = 0.2 composition and a reasonable magnetostrictive strain of 110 ppm indicating its suitability as a promising magnetostrictive material.