Formation Of Crystalline Phases Research Articles

Novel titanium-based sulfur-containing BMG for PBF-LB/M

AbstractThis paper investigates the additive manufacturing route for a novel glass-forming titanium-based sulfur-containing alloy of the composition $${\text{Ti}}_{60} {\text{Zr}}_{15} {\text{Cu}}_{17} {\text{S}}_{8}$$ Ti 60 Zr 15 Cu 17 S 8 . This system is a promising candidate for medical devices since the lack of toxic components is combined with a high corrosion resistance and strength. Preliminary experiments and simulations show a general processability of bulk material by powder bed fusion technologies. TEM and XRD reveal an amorphous microstructure of laser-treated surfaces. Ultrasonic atomization is used to fabricate a flowable powder feed stock with spherical morphology and crystalline microstructure, which is suitable for processing in powder bed fusion. Correlations between detected crystalline phase formations and melt pool dynamics are revealed by SEM and EDX. It is shown that bulk samples with a high relative density and partially crystalline microstructure can be manufactured.

Z-Scheme heterojunction Cu2(OH)3F/Bi2WO6 with improved photocatalytic activity for uranium removal from wastewater under air atmosphere

The proper treatment of uranium-contaminated nuclear wastewater is important for uranium resource recovery and environmental protection. Photocatalytic strategies have emerged as promising approaches for improving uranium removal efficiency. In this study, a Z-scheme heterojunction Cu2(OH)3F/Bi2WO6 (CFO/BWO) was synthesized by directly depositing CFO onto a BWO semiconductor for highly efficient photocatalytic removal of uranium from wastewater. The CFO semiconductor contains abundant O–H bonds and a high conduction band position, which can couple with BWO to form a heterojunction via interactions between the O and W atoms. Owing to the high electronegativity of CFO, electrons easily transfer from BWO to CFO, resulting in enhanced electron-hole separation and promoted electron transmission. Importantly, introducing CFO narrowed the bandgap of CFO/BWO compared to that of BWO, providing an appropriate band position, which is more conducive to the photocatalytic immobilization of uranium. Moreover, the mechanism of CFO/BWO heterojunction for photocatalytic immobilization of uranium revealed the formation of a stable crystalline phase of (UO2)O2·2H2O during the photocatalytic process. As a result, CFO/BWO could remove 91 % of uranium from simulated wastewater under an air atmosphere. The findings of this study provide a promising strategy by regulating the band position of heterojunctions for photocatalytic immobilization of uranium.

Building Nitridic Networks with Phosphorus and Germanium-from GeIIP2N4 to GeIVPN3.

Nitridophosphates and nitridogermanates attract high interest in current research due to their structural versatility. Herein, the elastic properties of GeP2N4 were investigated by single-crystal X-ray diffraction (XRD) upon compression to 44.4(1) GPa in a diamond anvil cell. Its isothermal bulk modulus was determined to be 82(6) GPa. At 44.4(1) GPa, laser heating resulted in the formation of multiple crystalline phases, one of which was identified as unprecedented germanium nitridophosphate GePN3. Its structure was elucidated from single-crystal XRD data (C2/c (no. 15), a = 8.666(5), b = 8.076(4), c = 4.691(2) Å, β = 101.00(7)°) and is built up from layers of GeN6 octahedra and PN4 tetrahedra. The GeN6 octahedra form double zigzag chains, while the PN4 tetrahedra are found in single zigzag chains. GePN3 can be recovered to ambient conditions with a unit cell volume increase of about 12%. It combines PV and GeIV in a condensed nitridic network for the first time.

Manufacturing process and annealing influence on the dynamic mechanical properties and physical structure of LLDPE thin films

Thin films of Linear Low-Density Polyethylene are used for stratospheric balloon applications. They undergo tensile mechanical stress on a wide range of temperatures [-95; 55]°C. The aim of this study is to compare the influence of blown film and double-bubble manufacturing processes on the crystalline phase and mechanical properties of the films through their operating temperatures (flight, storage, and transportation temperatures). Dynamic Mechanical Analysis and Differential Scanning Calorimetry have been used to monitor the dynamic mechanical properties in tension mode and the crystalline phase of the films respectively. The films mechanical properties are dependent on their manufacturing process. The double-bubble process allows isotropic tensile mechanical properties regarding stretching direction, whereas the blown film process favors only transversal direction. To simulate different storage conditions, annealing has been performed. The influence of annealing on the tensile mechanical properties of the films depends mainly on the internal stress stored during manufacturing. The double-bubble process produces a biaxially stretched film with a higher stretching ratio than blown films. The dissipated internal stress can be associated with thermal shrinkage and goes up to 10 % for the biaxially stretched film. The more internal stress is stored, the more E′ and E″ increases. Annealing also favors the formation of a secondary crystalline phase that is dependent on annealing temperature and time, and exhibits αc relaxation. After annealing, the amorphous phase is less stretched, and the crystalline phase keeps its orientation.

Solution Processed Hybrid Lead Perovskite Films for White Light Emission and Lasing Applications

Abstract2D organic–inorganic hybrid lead halide perovskite films are fascinating optoelectronic materials for white‐light emission and lasing applications. Here, it is demonstrated that nano‐meter‐thick films of perovskites can be formed at room temperature using Langmuir–Schaefer (LS) deposition technique. In situ X‐ray measurements reveal a self‐assembly process of the 2D perovskite formation at the air–water interface. This formation process requires the presence of stearic acid monolayer on the water subphase having a solution of lead‐perovskite in dimethylformamide. Microscopy and X‐ray measurements of these nanofilms transferred onto substrates show crystalline phase formation that deviates from the known orthorhombic structure of the bulk crystals. The nanofilms exhibit novel broad optical emission with sharp band‐edge transition in temperature‐dependent photoluminescence studies. Also, their band‐edge emission is distinctly blue‐shifted compared to that of thicker 2D perovskite flakes prepared by the slow‐cooling chemical synthesis process. 2D flakes exhibit lasing that cannot be obtained in the LS nanofilms as their thicknesses are lower than the lasing wavelength prohibiting wave‐guide formation. The results show that the 2D single‐crystalline nature of the LS films and flakes are suitable materials to develop broad‐band white light emission across the entire visible range and to obtain lasing without external cavities, respectively.

Chemical looping reforming with water splitting (CLRWS) for syngas and hydrogen coproduction using the ternary metal-oxides (Ca-Fe-Cu–O) as oxygen carriers

In this work, chemical looping reforming with water splitting (CLRWS) using ternary metal oxides (Ca-Fe-Cu–O) as oxygen carrier (OC) was investigated for syngas and hydrogen coproduction. The introduction of Cu into the Ca-Fe-O system results in the formation of the main crystalline phases, which include Ca2Fe2O5, CuFe2O4, and a small amount of CaO. The presence of Cu enhances the oxygen transfer capacity (OTC) and reduces the reduction temperature of Ca-Fe-O oxides. When the ratio of Ca:Cu:Fe equals 0.5:0.5:2, the Ca0.5Cu0.5Fe2O4 exhibited the highest hydrogen yield and purity of 9.15 mmol/(g OC) and 96.80 %, respectively. The syngas yield, purity and fuel conversion were 66.48 mol/L, 74.76 % and 83.12 %, respectively. It can be attributed to the suitable ratio of brownmillerite Ca2Fe2O5 and the spinel CuFe2O4 in Ca0.5Cu0.5Fe2O4. The crystal phases of Ca2Fe2O5 and CuFe2O4 exhibit a synergistic effect in the Ca-Fe-Cu–O system, the formation of CuFe2O4 enhances the lattice oxygen activity, while the brownmillerite-structured Ca2Fe2O5 inhibits the sintering and agglomeration of CuFe2O4 due to the morphology effect. The Ca0.5Cu0.5Fe2O4 showed almost stable reactivity after 10 cycles.

Nanoparticles reinforced ceramic bonds derived from K-gel geopolymers composites at elevated temperature: Pore structure, micro and meso scale properties

The refractory alkaline activated materials gained attention in the various engineering and industrial applications due to its environmental and eco-friendly benefits. The present study deals with the evaluation of the effects of nano-ZrO2, nano-Al2O3, and nano-TiO2 particles reinforcement mechanism on the final properties of the geopolymer matrices subjected to thermal treatment from 900 to 1250°C. Three series of composite matrices were obtained by adding 2–8 wt% of nanoparticles content (Al2O3, TiO2 and ZrO2) within the activated mortar and were devoted RAi, RRi and RZi (i = 2, 3, 5 and 8%).The designed composite matrices were characterized using several analytical methods and techniques including the mechanical characterization, mercury intrusion porosimetry (MIP) as well as the microstructural characterization. The results revealed that the use of the high content of nanoparticles (8 wt%) favored formation of a cross-linkage chain around the crystalline phases present within matrices. Their resulting percolation-induced reinforcement acted as supplementary with the interlocked network from the crystalline phases within the matrices to rendering it denser and compact. The matrices with high content of the nanoparticles added exhibited high mechanical properties at 1250°C. Flexural strength and young modulus were 70.7, 52 and 78.4 MPa, and 28.15, 22.61 and 29.86 GPa for RA, RR and RZ series respectively. Furthermore, the formation of the new crystalline phase like cordierite, mullite and leucite contributed to hindering the crack propagation within the matrices and increased the level of crystallization of the matrices by providing a homogeneous and well-dispersed structure. The produced matrices emerged stable at high temperature treatment and therefore could be used as a potential candidate for the materials for elevated temperatures applications.

Optimized growth of LiZnBO3 monoclinic phase in lithium zinc borate glass ceramics for electrode material

Glass-ceramics (GCs) of glass composition 20ZnO.30Li2O.50B2O3 were prepared via controlled heat treatment at hold times of 2h, 4h, 6h and 8h at crystallization peak temperature (846K). The effect of the hold time of heat treatment on the physical, structural, optical, and electrochemical properties was studied. XRD study revealed the formation of a pure LiZnBO3 crystalline phase. FTIR study revealed the transformation of BO4 units to BO3 units with an increase in the time of heat treatment. Optical band gap energy has been estimated from Diffuse Reflectance spectroscopy and, its values range from 3.26eV–3.36eV. Electrochemical properties were studied using Cyclic Voltammetry and compared with parent glass composition. The GC 20ZnO.30Li2O.50B2O3 heat treated for 8h exhibits the highest value of specific capacitance (∼48 mAh/gV) and energy density (∼18 J/g) indicating that it can be used as an electrode material in Li-ion batteries.

Photocatalytic Degradation of Methylene Blue and Methyl Orange Dye by Using the Core-Shell Structure of Fe3O4@ZnS Nanoparticles

A straightforward and highly efficient method was developed for the synthesis of Fe3O4@ZnS core-shell nanoparticles (NPs). These synthesized materials were subsequently utilized for the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes. The structural characteristics of the prepared sample were meticulously investigated through X-ray diffraction (XRD) and field-effect scanning electron microscopy (FESEM). The XRD analysis confirmed the crystalline phase formation in the Fe3O4 nanoparticles, while a study in the Vibrating Sample Magnetometer (VSM) mode emphasized their strong ferromagnetic behavior. The degradation of dyes was comprehensively studied using UV-Vis analyses, taking into account factors such as pH and initial dye concentration in the decolorization process. The synthesized Fe3O4@ZnS core-shell nanostructure underwent thorough characterization using XRD, UV-Vis spectroscopy, SEM, Fourier-transform infrared spectroscopy (FT-IR), and VSM mode in PPMS. Furthermore, the reusability of the catalyst was explored, yielding promising results. The findings demonstrated the efficient photocatalytic degradation of MB and MO dyes under UV-visible irradiation, achieving significant results within 30-minute intervals.

Synthesis of Mo-Ta bimetallic oxide catalyst with crystal phase regulation strategy for efficient catalytic oxidation of 4,6-DMDBT in diesel

Oxidative desulfurization (ODS) technology mainly involves selectively oxidizing sulfides in diesel fuel into sulfone utilizing highly efficient catalysts to prepare clean fuel, especially using molecular oxygen as an oxidant. Bimetallic oxide is a feasible catalyst for the ODS process owing to its superior catalytic activity. Herein, a series of molybdenum-tantalum bimetallic oxide catalysts (MoTaOx) with different crystalline phases were successfully fabricated by co-precipitation combined with calcinating at different temperatures. The characterization experimental results manifested that the calcination temperature observably affected the formation of crystalline phase of MoTaOx as well as the catalytic activity. Meanwhile, the activity tests demonstrated that the MoTaOx-750 catalyst exhibited outstanding sulfur removal efficiency on 4,6-DMDBT in ODS system, achieving ultra-deep desulfurization (100 %) within 9 h at 120 °C. The excellent oxidative desulfurization activity was attributed to the synergistic effect of Mo-Ta bimetal exposing more active centers. Finally, a possible reaction mechanism was proposed and the obtained catalyst showed a long-life utilization without deteriorating rather noticeably in catalytic activity after 26 cycles.

Directing the formation of tunable superlattice crystalline phases from anisotropic nanoparticles

The ability to precisely control the self-assembly of colloidal nanoparticles into desired and tunable superstructures holds immense potential, but achieving this remains a challenge due to intricate interplay of various controlling factors that govern this process at the nanoscale. Here, we demonstrate the controlled fabrication of co-existing smectic and triangular crystalline phases of gold nanorods, separated by domain boundary, by fine tuning the interparticle and particle–substrate interaction. The interaction forces between nanorods is tailored via the addition of surfactant, cetyltrimethylammonium bromide (CTAB), which in turn affects the particle–substrate attraction through screened electrostatic potential due to surfactant adsorption on the substrate. The emergence of the resulting phases is discussed via simulation of a coarse-grained model which considers the nanorod superlattices as nematic liquid crystals. It accounts for the interplay of repulsive, attractive forces, and particle–substrate interactions. The co-existing superlattice structures are obtained at low particle concentration over a large length scale, paving the way for various potential applications that specifically require both smectic and vertical rods on the same substrate.

3D-printed polycaprolactone/tricalcium silicate scaffolds modified with decellularized bone ECM-oxidized alginate for bone tissue engineering

The treatment of large craniofacial bone defects requires more advanced and effective strategies than bone grafts since such defects are challenging and cannot heal without intervention. In this regard, 3D printing offers promising solutions through the fabrication of scaffolds with the required shape, porosity, and various biomaterials suitable for specific tissues. In this study, 3D-printed polycaprolactone (PCL)-based scaffolds containing up to 30 % tricalcium silicate (TCS) were fabricated and then modified by incorporation of decellularized bone matrix- oxidized sodium alginate (DBM-OA). The results showed that the addition of 20 % TCS increased compressive modulus by 4.5-fold, yield strength by 12-fold, and toughness by 15-fold compared to pure PCL. In addition, the samples containing TCS revealed the formation of crystalline phases with a Ca/P ratio near that of hydroxyapatite (1.67). Cellular experiment results demonstrated that TCS have improved the biocompatibility of PCL-based scaffolds. On day 7, the scaffolds modified with DBM and 20 % TCS exhibited 8-fold enhancement of ALP activity of placenta-derived mesenchymal stem/stromal cells (P-MSCs) compared to pure PCL scaffolds. The present study's results suggest that the incorporation of TCS and DBM-OA into the PCL-based scaffold improves its mechanical behavior, bioactivity, biocompatibility, and promotes mineralization and early osteogenic activity.

Immobilization mechanism of Mn2+ in electrolytic manganese residue using sintered ceramsites prepared by alkali-mechanical-roasting method

Currently, sufficient information is unavailable on using electrolytic manganese residue (EMR) to prepare sintered ceramsites for immobilization of manganese in EMR. This study used EMR, Na2CO3, and montmorillonite (MMT) as raw materials to prepare ceramsites with the influence of alkalinity, sintering temperature, and sintering time on the investigated ceramsite properties. Under the optimal conditions (i.e., C-2 h= EMR content: 50%, Na2CO3 content: 25%, sintering temperature: 1050℃, sintering time: 2 h), the cylinder compressive strength, porosity, bulk density and apparent density of the ceramsites reached 25.03 MPa, 54.72%, 0.748 g/cm3 and 2.056 g/cm3. The presence of mesoporous pores within the ceramsites made them suitable for adsorption as biocarriers. The leaching concentration of Mn2+ from the ceramsites was 2.26 mg/L, lower than the third grade in standard (GB 8978–1996), suggesting that heavy metals are stabilized within the ceramsite. The main immobilization mechanism in the ceramsites included the formation of a new crystalline phase including jacobsite (Fe2MnO4) and liquid phase encapsulation. The involvement of certain impurities such as Mg2+ in the formation of crystalline phases can influence Mn2+ immobilization. This research not only offers valuable insights into the safe and valuable utilization of EMR but also provides a novel method for preparing ceramsites.

Influence of zinc-containing compounds on the properties of ceramic materials based on the Li<sub>2</sub>O–MgO–Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> system

The results of a study the influence of magnesium oxide substitution with zinc oxide in the Li2O–MgO– Al2O3–SiO2 system, as well as the introduction of pre-synthesized ganite ZnAl2O4, on sintering, phase formation and thermal expansion of synthesized materials are presented. It was found that after substitution of 4 % magnesium oxide MgO with zinc oxide ZnO, the ceramic material synthesized at a temperature of 1 150 °C was characterized by higher values of apparent density (not less than 1 835 kg/m3), mechanical compressive strength (300 MPa), and heat resistance (more than 80 thermal cycles), as well as low values of LTEC (–0,25 ∙ 10–6 K–1), which is due to the formation of crystalline phases of spodumene, spinel, forsterite, corundum, ganite and quartz.

Effect of CaO on the shrinkage and microstructure of alkali-activated slag/fly ash microsphere

Alkali-activated materials (AAMs) are regarded as promising alternatives to Portland cement. However, the significant high shrinkage of AAMs, particularly in alkali-activated slag system, is a critical issue that hinders their wide application. This study investigated the effect of expansive admixture, i.e. CaO on the autogenous shrinkage and drying shrinkage of alkali-activated slag/ fly ash microsphere (AASFAM). The effect of CaO content on heat evolution, reaction products, microstructure development and compressive strength was systematically investigated. The results revealed that the addition of CaO can effectively reduce both the autogenous and drying shrinkage of AASFAM. Mixture with 3% and 5% CaO exhibited expansion within the first 24 hours after casting, while the drying shrinkage was reduced by 72% and 82%, respectively. The addition of CaO promoted the formation of crystalline phases including Ca(OH)2, hydrotalcite and calcite, leading to a lower free water content and coarser pore structure, which in turn reduced the capillary stress during the drying process. The results demonstrated the promising potential of CaO in effectively mitigating the high autogenous shrinkage and drying shrinkage of AAMs without compromising its mechanical properties.

Synthesis and Characterization of V2O5 Nanorods Using Hydrothermal Method for Energy Application

Background: Nanomaterials are very useful in energy harvesting and energy storage devices. Morphological features play a vital role in energy storage devices. Supercapacitors and batteries are examples of energy storage devices. The working of a supercapacitor is decided by the nature of the microstructure and other features of the electrode material. Vanadium Pentaoxide (V2O5) is one of the promising materials due to its attractive features, such as band gap, multiple oxidation state, and large conductivity transition from semiconducting to conducting domain. Objective: This study aimed to perform the tuning of structural, optical and morphological properties of V2O5 nanomaterials using the hydrothermal method. Methods: A low-cost hydrothermal method was used in this work. Hydrothermal synthesis was carried out at different concentrations of Ammonium Metavanadate (NH4VO3), varying from 0.06 M, 0.08 M, and 0.1 M in the aqueous medium. Moreover, the pH of the solution was maintained at 4 using drop-wise addition of H2SO4. Hydrothermal synthesis was carried out at 160° for 24 hours. The synthesized precipitate was annealed at 700° for 7 hours in ambient air. Structural, optical, morphological, and elemental probing was carried out. Result: XRD revealed the formation of monoclinic crystalline phase formation of V2O5. Crystallite size increased with an increase in the concentration of vanadium precursor. The band gap obtained using UV-Vis spectroscopy decreased upon an increase in concentration. SEM micrographs displayed nanosheet and nanorod-like distorted morphology. The presence of vanadium and oxygen was noticed in the EDS study. Conclusion:: Nanoparticles with attractive features are very useful as an electrode material for supercapacitors. Upon changing concentration, we can change the band gap of the material, adding an extra edge in the use of these materials.

Study of structural, X-ray photoelectron spectroscopy, Raman and temperature-dependent magnetic studies of NiFe2O4/CoCr2O4 nanocomposites

In recent years, cobalt chromites/nickel ferrites have been attractive candidates for significant applications as nanomagnets. In the present work, structural, electronic, vibrational and low-temperature magnetic properties of NiFe2O4, CoCr2O4, and NiFe2O4/CoCr2O4 nanocomposites were investigated. Refined XRD patterns and the Raman spectra confirm the formation of the pure crystalline spinel cubic phase. The estimated crystallite size is in the range of 14 - 29 nm. X-ray photoelectron spectroscopy (XPS) confirm the oxidation state of all elements present in the synthesized samples. The studies of the photoemission core level lines prove the cations distribution in the tetrahedral and octahedral sites with the expected valence states. The magnetic studies reveal the S-type hysteresis loops, confirming the ferrimagnetic nature. The remanent and saturation magnetization increase with increasing NiFe2O4 concentration and decrease with increasing temperature. The magnetization also increases with increase of crystallite size. The temperature-dependent magnetization curve of CoCr2O4 shows the ferrimagnetic phase transition at Curie temperature TC = 86 K. The performed density functional theory (DFT) calculations indicate a significant distribution of the density of states over the Fermi level in NiFe2O4/CoCr2O4 composites as compared to bare NiFe2O4 and CoCr2O4 materials, confirming the improved electronic properties. The overall magnetic analysis proved the magnetization enhancement by increasing x concentration.

Investigation of the migration of natural organic matter-iron-antimony nano-colloids in acid mine drainage

Colloids can potentially affect the efficacy of traditional acid mine drainage (AMD) treatment methods such as precipitation and filtration. However, it is unclear how colloids affect antimony (Sb) migration in AMD, especially when natural organic matter (NOM) is present. To conduct an in-depth investigation on the formation and migration behavior of NOM, iron (Fe), Sb and NOM-Fe-Sb colloids in AMD, experiments were performed under simulated AMD conditions. The results demonstrate significant variations in the formation of NOM-Fe-Sb colloids (1–3–450 nm) as the molar ratio of carbon to iron (C/Fe) increases within acidic conditions (pH = 3). Increasing the C/Fe molar ratio from 0.1 to 1.2 resulted in a decrease in colloid formation but an increase in particulate fraction. The distribution of colloidal Sb, Sb(III), and Fe(III) within the NOM-Fe-Sb colloids decreased from 68 % to 55 %, 72 % to 57 %, and 68 % to 55 %, respectively. Their distribution in the particulate fraction increased from 28 % to 42 %, 21 % to 34 %, and 8 % to 27 %. XRD, FTIR, and SEM-EDS analyses demonstrated that NOM facilitates the formation and crystallization of Fe3O4 and FeSbO4 crystalline phases. The formation of the colloids depended on pH. Our results indicate that NOM-Fe-Sb colloids can form when the pH ≤ 4, and the proportion of colloidal Sb fraction within the NOM-Fe-Sb colloids increased from 9 % to a maximum of 73 %. Column experiments show that the concentration of NOM-Fe-Sb colloids reaches its peak and remains stable at approximately 3.5 pore volumes (PVs), facilitating the migration of Sb in the porous media. At pH ≥ 5, stable NOM-Fe-Sb colloids do not form, and the proportion of colloidal Sb fraction decreases from 7 % to 0 %. This implies that as pH increases, the electrostatic repulsion between colloidal particles weakens, resulting in a reduction in the colloidal fraction and an increase in the particulate fraction. At higher pH values (pH ≥ 5), the repulsive forces between colloidal particles nearly disappear, promoting particle aggregation. The findings of this study provide important scientific evidence for understanding the migration behavior of NOM-Fe-Sb colloids in AMD. As the pH gradually shifts from acidic to near-neutral pH during the remediation process of AMD, these results could be applied to develop new strategies for this purpose.

Assessment of sand dunes in Missan Governorate, South-eastern Iraq: Implications for Extraction High Purity Silica

Sand dunes are widely spread in Missan Governorate, South-eastern Iraq in many areas including; Manziliyah, Khazina, Zubadiate, and Chailat. X-ray diffraction (XRD) results of sand samples of sizes 0.063-2 mm, 0.125-0.250mm, and 0.250-0.500mm, revealed that quartz is the main mineral phase, followed by calcite, feldspar and trace of gypsum. Chemically SiO2 is the main oxide in sand of an average 61.36 % while the rest oxides; CaO (14.08%), Al2O3 (6. 76%), Fe2O3 (3.05%), K2O+Na2O (2.30 %) are considered as impurities that could affect the properties of sand. XRD tests indicated the formation of crystalline phase of synthetic silica. XRF showed an increases in SiO2 to 85.37%, while all other oxides (impurities) were reduced to their minimum rate, particularly CaO (1.06 %). Field emission scanning electron microscope (FESEM) and Brunauer-Emmett-Teller (BET) tests indicated the existence of well compiled spherical particles of synthetic silica within the size of 8.55 nm and surface area of 66.51 m2\\g. The medium sand size (0.250-0.500mm) is the appropriate size to produce high purity crystalline silica as it contains the greatest percentage of silica and the low percent of impurities compared to other sizes of sand.

Polyvinylpyrrolidone – KNNLST lead-free ceramic composites for dielectric applications

Piezoelectric composites offer many advantages compared to piezoelectric ceramics or polymers because of their mechanical flexibility and relatively high stress-induced voltage. In this research, high-molecular weight polyvinylpyrrolidone (PVP) and lead-free piezoelectric (K0.45Na0.51Li0.04) (Nb0.85Ta0.1Sb0.05)O3 (KNNLST) ceramics have been used to produce composites. The possible range of composites from 0 to 100 wt% has been explored. The ceramics were produced using conventional processing methods, while the composites were solution-cast after being mixed with a magnetic stirrer. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and dielectric and piezoelectric characterization to determine their properties. The morphology of the composites indicates the homogeneous distribution of the ceramics in the polymer. The XRD patterns show that the dissolved amorphous PVP precipitates and the addition of KNNLST ceramics contributes substantially to the crystalline phase formation. The relative permittivity and loss tangent values increase with an increase in ceramic content. Acceptable polarization and strain hysteresis curves were obtained only for the KNNLST ceramics. The composites produced will be suitable for dielectric applications.