Solid-state Reaction Synthesis Research Articles

Beta radiation excited thermoluminescence of solid-state synthesized SrZrO3 phosphors

In this work, we report on the solid-state reaction synthesis of SrZrO3 phosphors, and their beta particle irradiation excited thermoluminescence (TL) characterization. X-ray diffraction data confirmed the obtention of the orthorhombic phase of SrZrO3. Through computational glow curve deconvolution, the whole glow curve was resolved into six individual first order kinetics peaks. This is the first report concerning the usefulness of SrZrO3 as TL dosimeter. The synthesized phosphors exhibit TL emission from below 100 °C up to above 300 °C, being the most intense TL between 200 and 300 °C, as well as a remarkable reproducibility of the TL response in repeated irradiation-TL readout cycles.

Effect of co-precipitation and solid-state reaction synthesis methods on lithium-rich cathodes Li1.2Ni0.2Mn0.6O2

Effect of co-precipitation and solid-state reaction synthesis methods on lithium-rich cathodes Li1.2Ni0.2Mn0.6O2

Solid-State Reaction Synthesis of Nanoscale Materials: Strategies and Applications.

Nanomaterials (NMs) with unique structures and compositions can give rise to exotic physicochemical properties and applications. Despite the advancement in solution-based methods, scalable access to a wide range of crystal phases and intricate compositions is still challenging. Solid-state reaction (SSR) syntheses have high potential owing to their flexibility toward multielemental phases under feasibly high temperatures and solvent-free conditions as well as their scalability and simplicity. Controlling the nanoscale features through SSRs demands a strategic nanospace-confinement approach due to the risk of heat-induced reshaping and sintering. Here, we describe advanced SSR strategies for NM synthesis, focusing on mechanistic insights, novel nanoscale phenomena, and underlying principles using a series of examples under different categories. After introducing the history of classical SSRs, key theories, and definitions central to the topic, we categorize various modern SSR strategies based on the surrounding solid-state media used for nanostructure growth, conversion, and migration under nanospace or dimensional confinement. This comprehensive review will advance the quest for new materials design, synthesis, and applications.

Excellent energy storage and hardness performance of Sr0.7Bi0.2TiO3 ceramics fabricated by solution combustion-synthesized nanopowders

Relaxor ferroelectric Sr0.7Bi0.2TiO3 ceramics were prepared by two types of powders synthesized by solid-state reaction (SSR) and solution combustion synthesis (SCS). The effects of the synthesis techniques of precursor powders on the microstructure, dielectric and energy storage performance of the ceramics were investigated. Compared with the SSR-derived samples, the SCS-derived ceramics show purer phase, more refined grain size, more uniform and denser morphology. Consequently, higher insulating resistivity and activation energy are obtained, thus inhibiting the carrier migration and improving the breakdown field. For the 0.1 mm-thickness ceramics via using SCS nanopowders in place of SSR powders, the critical electric field and recoverable energy density are enhanced from 320 kV/cm and 2.60 J/cm3 to 380 kV/cm and 3.60 J/cm3, respectively. Particularly, a high recoverable energy density of 5.21 J/cm3 with a high efficiency of 91.55% at 543 kV/cm is realized in the 0.04 mm-thickness SCS-derived ceramics. Meanwhile, the Vickers hardness of ceramics is promoted from ∼ 7.15 GPa to ∼ 7.80 GPa by using SSR instead of SCS method. This work suggests that SCS is an effective method to obtain precursor powders for sintering the dielectric ceramics with excellent energy storage and hardness performance.

Microwave Absorbing Material of Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) with Broadband Characteristic at X-band Frequency

In this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition.

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.

Solid-state reaction synthesis and characterization of Mn-doped LiFePO4 cathode material

Olivine type LiFePO4 has great advantages for Li-ion batteries due to its non-toxicity, high safety, and good cycle life performance. However, its low-rate capability and low energy density make some challenges for this LiFePO4. Several methods like doping with transition metals were used, and Mn ion was used in this work to improve the overall electrochemical properties. LiMn x Fe1-x PO4 is promising cathode material owing to high voltage, structural and chemical stability. However, the electrochemical performance of these materials depends on phases and structures obtained from synthesis. In this work, the effect of solid-state reaction conditions, including calcination temperature and duration, on morphology, structure, and electrochemical properties of LiMn x Fe1-x PO4 cathode materials with the composition of x = 0.5 was investigated. The morphology, crystallography and local structure of the synthesized materials were examined by field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD) and Fourier-transform infrared spectrometer (FTIR), respectively. The surface area was also determined by the Brunauer-Emmett-Teller (BET) model. The effect of calcination temperature and reaction time upon the morphology, structures of the synthesized cathode materials were studied and discussed. The results could be essential for further development and employment of LiMn x Fe1-x PO4 in Li-ion batteries.

Solid-state reaction synthesis of amorphous/nanostructured Si@SiOx-Cu3Si composites by mechanical milling for lithium-ion anodes

In present study we developed an effective way to obtain amorphous/nanocrystalline Si in high-capacity Si-based composites for improving their cycle stability as lithium-ion anodes. Amorphous/nanostructured Si@SiOx-Cu3Si composites were synthesized via solid-state reactions using mechanical milling with bulk Si and CuO as starting materials. The microstructural characterization of Si@SiOx-Cu3Si composites demonstrated the phase transformation during the synthesis process of mechanical milling. The ratio and fine-scale distribution of amorphous Si in Si@SiOx-Cu3Si composites were quantitatively analyzed by confocal μ-Raman spectroscopy. The electrochemical properties indicated that Si@SiOx-Cu3Si composites exhibited enhanced cyclability due to containing a highly disordered amorphous Si. Calculated in a full-cell stack model, the lithium-ion cell using Si@SiOx-Cu3Si anodes could provide higher energy density over commercial graphite.

Comparative study on SrAl2O4 formation using different approaches

A comparative study on SrAl2O4 synthesis via solid-state reaction and combustion synthesis was performed, based on thermodynamic calculations and resulted sample characteristics. We proposed a first-time approach of the combustion synthesis using metal perchlorates and a fuel mixture of urea and glycine. The calculated adiabatic temperature of the combustion reaction was 2807 °C and the standard enthalpy of reaction was - 6093 kJ/mol SrAl2O4. The recorded temperature during the highly exothermic combustion reaction was 1757 °C. The solid-state reaction was endothermic, with a standard enthalpy of reaction of 330 kJ/mol SrAl2O4. The precursor mixtures and obtained samples were characterized and compared in terms of temperature behavior, phase composition, crystallite size, specific surface area and morphology. The results prove the superiority of the proposed approach in terms of thermal efficiency and open a new perspective upon the use of strontium and aluminum perchlorates in the combustion synthesis of highly crystalline SrAl2O4-based materials, such as SrAl2O4: Eu, Dy phosphors.

Structure and magnetic properties of Bi-doped calcium aluminosilicate glass microspheres

Abstract Bi-doped CaO–Al2O3–SiO2 glass microspheres with Ca2Al2SiO7 (gehlenite) composition were prepared by combination of solid-state reaction and flame synthesis. The concentration of Bi was 0.0, 0.5, 1 and 3 mol%. The chemical composition of prepared glass microspheres was determined by X-ray fluorescence (XRF). The structural and magnetic properties of prepared glass microspheres and their polycrystalline analogues were studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscopy and SQUID magnetometry. The closer inspection of glass microspheres surface by SEM confirmed smooth surface and revealed no features indicating presence of crystalline phases. All Bi-doped microspheres are X-ray amorphous, however in case of undoped microspheres XRD detected traces of crystalline gehlenite. XRD analysis of samples crystallized at 1273 K for 10 h revealed the presence of gehlenite as the main crystalline phase. The presence of gehlenite in crystallized samples were also confirmed by Raman spectroscopy. All samples (glass microspheres and their crystalline analogues) showed diamagnetic or weak ferromagnetic behavior at room temperature, whereas paramagnetic or weak ferromagnetic behavior was observed at 2 K.

Investigation of structural and magnetic properties of Al substituted Ba0.9La0.1Fe12-xAlxO19 hexaferrites prepared by solid-state reaction method

The structural and magnetic properties in the Ba0.9La0.1Fe12-xAlxO19 hexaferrite compound were studied as a function of Al3+ concentration (x = 0.0 to 1.3). The samples were obtained by solid-state reaction synthesis and sintered by the conventional ceramic method. The Rietveld refinement method analysis showed the predominance of barium hexaferrite phase with hexagonal structure characterized by P63/mmc space group. The secondary phase of hematite (α-Fe2O3), with rhombohedral system and R-3c space group, was found. For the principal phase, the lattice parameters a, c, and the cell volume (V) reached a minimum value in the concentration x = 0.7 of Al3+ ion. Variations in the average bond length and distortion index of the oxygen polyhedra were observed at the Ba(2d) site and at the Fe (2b, 4fIV, 4fVI, and 12 k) sites. The Raman spectra showed all bands related to FeO bonds at different crystallographic sites. The saturation magnetization reached the minimum value for the composition x = 0.7. The coercive field increased until reaching the maximum value at x = 1.0 of Al3+ concentration. The magneto-crystalline anisotropy field decreased from x = 0.1 to 0.7 and increased at higher concentrations. At room temperatures the total magnetic moment decreases from μ = 10.74 to 4.33 μB for Al3+ concentration range of 0.1 ≤ x ≤ 0.7 and oscillates with μ = 8.18 and 9.44 μB at compositions of x = 1.0 and 1.3, respectively. The present study is important to understand the impact of Al and La addition on the structural and magnetic properties of barium hexaferrite.

Structure and magnetic properties of Ni- doped gehlenite glass microspheres

The structural and magnetic properties of undoped and Ni-doped aluminate glass microspheres with gehlenite (Ca2Al2SiO7) composition and of their polycrystalline analogues were studied. The concentration of Ni was 0.0, 0.5 and 3.0 mol. %. Glass microspheres were prepared by combination of solid-state reaction and flame synthesis. The detailed examination of morphology of the glass microspheres of all prepared composition by scanning electron microscopy (SEM) revealed no features indicating presence of crystalline phases. X-ray powder diffraction (XRD) confirmed amorphous character of prepared Ni-doped gehlenite glass microspheres. In samples crystallized at 1273 K for 10 h, XRD revealed the presence of gehlenite as the main crystalline phase. Raman spectroscopy of crystallized samples also confirmed the presence of gehlenite. Raman spectra of as-prepared glass microspheres differed significantly from the spectra of their crystallized counterparts. These indicate the role of aluminum as a network-forming element. Magnetic properties of the Ni-doped gehlenite microspheres and of their polycrystalline analogues were measured by SQUID magnetometer. Properties of the measured samples showed a more complex magnetic behaviour. Diamagnetic, paramagnetic and ferromagnetic components can be observed depending on whether Ni-doping is used or not, as well as depending on temperature and applied magnetic field values, both for glass microspheres and crystalline samples.

Surface optical phonon and multi – phonon transitions in YVO4:Eu3+ nanopowders

In this paper two methods of preparation of yttrium orthovanadate nanopowders were presented: Solid State Reaction (top – down approach) and Solution Combustion Synthesis (bottom – up approach). For starting structural characterization, X – Ray Powder Diffraction (XPRD) and Field Emission Scanning Electron Microscopy (FESEM) were used. We report the change in reflection spectra in europium doped YVO4 nanopowders with comparison to its bulk analog. In UV–Vis reflection spectra we consider the change in values of band gap in these structures, after resizing it from bulk to nanomaterial. In Far – Infrared (FIR) reflection spectra, we registered the existence of Surface Optical Phonon (SOP) and different multi – phonon processes which alter the reflection spectra of bulk YVO4. The influence of Eu ions is reflected through multi – phonon processes that occur and are connected with energy transfer from YVO4 lattice to Eu ions. All IR spectra were modeled using classical oscillator model with Drude part added which takes into account the free carrier contribution. Since our samples are distinctively inhomogeneous materials, we use Effective Medium theory in Maxwell Garnett approximation to model its effective dieletric function.

Ionic Conductivity and Dielectric Relaxation of NASICON Superionic Conductors at the Near-Cryogenic Regime

With a crystal lattice structure first characterized in the 1970s, NASICON sodium-based superionic conductors have recently found renewed interest as solid electrolytes in sodium-ion and seawater flow batteries due to their exceptional ionic conductivity being on the same scale as liquid electrolytes. Since sodium ions in the crystal lattice move among interstitial positions through site-specific bottlenecks, the overall conductivity is strongly dependent on the NASICON composition. In this work, we report on the synthesis protocols and processing parameters of Na3Zr2Si2PO12 prepared from Na2CO3, SiO2, ZrO2, and NH4H2PO4 precursors by the conventional solid-state reaction (SSR) route. We critically evaluated important observations made in the extended literature on the topic including: (i) the importance of precursor particle size concerning the SSR synthesis, focusing on effective ball-milling protocols; and (ii) the onset of excess zirconia contamination, expanding on the effects of both thermal and pressure processing—the latter often overlooked in the available literature. In approaching the cryogenic regime, the dataset availability concerning ionic conductivity and dielectric permittivity measurements for NASICON was extended, starting from elevated temperatures at 200 °C and reaching into the very low temperature zone at −100 °C.

EFFECT OF CALCINATION TEMPERATURE ON F-DOPED LiFePO4 CATHODE MATERIAL ON FORMATION OF OLIVINE PHASE

Olivine single phase of LiFePO4 was successfully synthesized by solid-state reaction (SSR) method through the formation of Fe2P2O7 from precursors of Li2CO3, F2O3, NH4H2PO4, and LiF as materials doping. Variations at temperatures of calcination 670 0C, 700 0C and 750 0C with doped 0.1F. TGA-DSC test results show that the LFP sample undergoes decomposition in the temperature range 0-600 0C. The olivine phase formed at temperatures of more than 650 0C and the oxidation process on the LiFePO4/C sample was completed, and the sample mass was constant. The olivine phase formed was determined by comparing the 2𝜃 value obtained through characterization with the ICDD LFP (01-081-1173), and accordingly with experiment. The increase of the temperature results from a dominant LFP phase with a larger grain size. The effect of increasing the calcination temperature at 0.1F has resulted in an enlargement of the particle size.

Magnetic Property Anomalies in Rutile-type Spin Glass CrNbO4: Bulk vs. Nanoparticle Aggregates

Spin glasses are of fundamental interest in the field of magnetism. CrNbO4 that crystallizes in a rutile structure is known as an antiferromagnetic oxide exhibiting a spin glass transition due to cationic disorder. The present study compares the magnetic properties of CrNbO4 synthesized by two different methods: high-temperature solid state reaction and sol-gel synthesis. The morphologies of these materials were found to be different. In the sample synthesized by solid state reaction, competing antiferromagnetic interactions and cluster spin glass states were observed. In contrast, the sample obtained by the sol-gel method clearly showed only the cluster spin glass transition at 7 K. The partial ordering of Cr3+ ions in the structure and microstructural differences between these samples are responsible for the observed anomalies in the magnetic properties of CrNbO4.

Facile synthesis of MgO–Mg2SiO4 composite ceramics with high strength and low thermal conductivity

The recycling of solid waste is a win-win solution for humans and nature. For this purpose, magnesite tailings and silicon kerf waste were employed to prepare MgO–Mg2SiO4 composite ceramics by solid-state reaction synthesis in the present work. Then, effects of sintering temperature and raw material ratio on as-prepared ceramics were systematically studied. As-prepared ceramics showed improvement in their relative density (from 47.55%–68.12% to 90.96%–95.25%) and cold compressive strength (from 7.34–118.66 MPa to 303.39–546.65 MPa) with the increase in sintering temperature from 1300 to 1600 °C. In addition, it was found that Si promoted synthesis process of Mg2SiO4 phase through transient liquid phase sintering and Fe2O3 accelerated sintering process through activation sintering. Consequently, the presence of Mg2SiO4 phase effectively improved the density and strength of MgO–Mg2SiO4 composite ceramic, while reducing its thermal conductivity. This work provides a potential reutilization strategy for magnesite tailings, and as-prepared products are expected to be applied in fields of construction, metallurgy, and chemical industry.

Solid State Reaction Synthesis and Characterization of Cu doped TiO2 Nanomaterials

In this work, copper-doped titanium dioxide (TiO2) nano-powder with of different doping concentration, weights were successfully fabricated with a classical method. This method authorizes obtaining pellets from powder in nonmetric scale with a small quantity. The best conditions for fabrication these pellets are acquired. Different quantities of Cu concentrations (0%, 3%, 5%, and 7%) are mixed with TiO2 (NPs) nano-particles. Then, the mixed powders are transformed into pellets using hydraulic press and sintered by a traditional furnace at temperature of about 1100 °C. The following apparatus demonstrates the structural, morphological, mechanical, optical properties and the composition of elements of materials for those as-prepared samples: X-ray diffraction (XRD), optical microscope, scanning electronic microscope (SEM), Shore D hardness instrument, roughness test Instrument, Lee’s Disc, Fourier-transform infrared spectroscopy (FTIR) and Energy-dispersive X-ray spectroscopy (EDS) respectively. The effects of Cu doped concentrations on the properties of TiO2 NPs based on the above instruments are examined. Crystalinality of these materials revealed by XRD patterns and have a grain size between (20-30) nm. A roughness measurement points that TiO2 NPs values decreases with the addition of Cu weights because of hardness values of the samples. Moreover, results showed that the thermal conductivity increased with the increasing the weight fraction of Cu element. The main goal of the present research is to demonstrate the annealing temperature dependent behavior of the broadening parameter and the properties of Cu doped TiO2 NPs.

UV and X-ray excited red persistent luminescence in Mn2+ doped MgGeO3 material synthesized in air and reducing atmosphere

Materials with long persistent luminescence (PersL) have caused widespread interest among scientists and industry for decades. Currently, there is widely available information on the long persistent luminescence materials with emission in the blue and green spectral range, while the number of publications on the afterglow in the red and near-infrared spectral range is considerably lower. In the course of this work MgGeO3 material doped with 0.1 mol% Mn2+ was produced using solid-state reaction synthesis in ambient and reducing atmospheres. The material exhibits a broad luminescence band with a peak around 680 nm, excited by either X-rays or UV. After cessation of irradiation, the afterglow up to 6 h when excited by UV and 15 h in the case of excitation by X-rays can be observed. Decay kinetics of the samples indicate that persistent luminescence in this material is a complex process that includes several different traps. Different thermally stimulated luminescence (TSL) techniques, such as Tstop – Tmax and Hoogenstraaten's methods were employed to draw conclusions about the nature of the traps and properties of the material. It was concluded that multiple traps with activation energy between 0.60 and 1.55 eV are present in the samples, furthermore the synthesis in reducing atmosphere promotes creation of additional closely overlapping deep traps, which, based on electron paramagnetic resonance (EPR) measurements, most likely are related to oxygen vacancies.

Growth and characterization of crystalline BaSnO3 perovskite nanostructures and the influence of heavy Mn doping on its properties

Solid state reaction synthesis of BaSn1-xMnxO3 (x = 0.0–0.3) nanostructures is presented in this article. Heavy transition metal doping in powdered BaSnO3 is accomplished to investigate the structural, morphological, chemical and dielectric properties of synthesized samples. Single phase, cubic crystal formations are revealed from the structural properties. Transmission electron micrographs (TEM) display the formation of polygonal discs with nanoscale (~50 nm) dimensions. Elemental composition of the synthesized samples has been confirmed from the x-ray photoelectron spectroscopy (XPS). Optical properties demonstrate the pristine BaSnO3 as an ultraviolet active material with a band gap of 3.2 eV. The enhancement in visible light active mode is achieved via band gap tuning by proportional Mn-doping in the parent material.