Cobalt Phosphates and Applications

Cobalt phosphates with open framework present various physical performances in relation to their structures. In fact, the development of new materials that could potentially be ionic conductors or ion exchangers led us to examine the Co-P-O and A-Co-P-O crystallographic systems (A: monovalent cation) and their different methods of synthesis. This work consists first of all in highlighting the crystalline phases of cobalt phosphates. Indeed, many works related to the discovery of some of these materials with interesting properties, in particular ionic conductivity, motivated our research and encouraged us to collect several cobalt phosphates and to correlate structure-physical properties in particular electrical properties

Correlation between Structure, Electrical, and Magnetic Properties of Some Alkali-Oxide Materials

In this chapter, the correlation between structure and electrical properties of Na2MP1.5As0.5O7 (MII = Co and Cu) are treated. The structural study shows that the cobalt and copper isotype materials can be crystallized in the tetragonal and monoclinic systems, respectively. The electrical study using impedance spectroscopy technique showed that these mixed diphosphate diarsenates are fast electrical conductors; however, the cobalt material exhibited more conductive property than the copper compound. In addition, the powder perovskite manganites La0.7M0.2M’0.1MnO3 (M = Sr, Ba and M’ = Na, Ag and K) have been prepared using the conventional solid-state reaction. The structural, magnetic, and magnetocaloric properties of these perovskite manganites compounds were studied extensively by means of X-ray powder diffraction (XRD) and magnetic measurements. These samples were crystallized in the distorted rhombohedral system with R3c space group. The variation of magnetization (M) vs. temperature (T) reveals that all compounds exhibit a second-order ferromagnetic to paramagnetic phase transition in the vicinity of the Curie temperature (TC). A maximum magnetic entropy change, ΔSMMax, of 4.07 J kg−1 K−1 around 345 K was obtained in La0.7Sr0.2Na0.1MnO3 sample upon a magnetic field change of 5 T. The ΔSMMax values of La0.7Ba0.2M’0.1MnO3 are smaller in magnitude compared to La0.7Sr0.2M’0.1MnO3 samples and occur at lower temperatures

Polycrystalline Powder Synthesis Methods

The synthesis of polycrystalline powder is a key step for materials sciences. In this chapter, we present the well-known methods of preparation of powders such as: solid-state reaction, sol–gel, hydrothermal, combustion, co-precipitation. Moreover, synthesis methods by arc furnace, by heating in a “high frequency” induction furnace and by high energy grinding are presented. The obtained powders could be defined by their purity, gain size, crystallinity, and morphology, which are influenced by the synthesis method. In addition, each method is dependent on some parameters like pH, concentration and temperature

Effects of Steel Fibers (SF) and Ground Granulated Blast Furnace Slag (GGBS) on Recycled Aggregate Concrete

[EN] Recycled aggregate is a good option to be used in concrete production as a coarse aggregate that results in environmental benefits as well as sustainable development. However, recycled aggregate causes a reduction in the mechanical and durability performance of concrete. On the other hand, the removal of industrial waste would be considerably decreased if it could be incorporated into concrete production. One of these possibilities is the substitution of the cement by slag, which enhances the concrete poor properties of recycled aggregate concrete as well as provides a decrease in cement consumption, reducing carbon dioxide production, while resolving a waste management challenge. Furthermore, steel fiber was also added to enhance the tensile capacity of recycled aggregate concrete. The main goal of this study was to investigate the characteristics of concrete using ground granulated blast-furnace slag (GGBS) as a binding material on recycled aggregate fibers reinforced concrete (RAFRC). Mechanical performance was assessed through compressive strength and split tensile strength, while durability aspects were studied through water absorption, acid resistance, and dry shrinkage. The results detected from the different experiments depict that, at an optimum dose (40% RCA, 20%GGBS, and 2.0%), compressive and split tensile strength were 39% and 120% more than the reference concrete, respectively. Furthermore, acid resistance at the optimum dose was 36% more than the reference concrete. Furthermore, decreased water absorption and dry shrinkage cracks were observed with the substitution of GGBS into RAFRC.SIThe authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through a group research program under grant number RGP. 2/129/42 and Taif University Researchers Supporting Project grant number [TURSP-2020/324]

Recent advancements in surface modification, characterization and functionalization for enhancing the biocompatibility and corrosion resistance of biomedical implants

Metallic materials are among the most crucial engineering materials widely utilized as biomaterials owing to their significant thermal conductivity, mechanical characteristics, and biocompatibility. Although these metallic biomedical implants, such as stainless steel, gold, silver, dental amalgams, Co-Cr, and Ti alloys, are generally used for bone tissue regeneration and repairing bodily tissue, the need for innovative technologies is required owing to the sensitivity of medical applications and to avoid any potential harmful reactions, thereby improving the implant to bone integration and prohibiting infection lea by corrosion and excessive stress. Taking this into consideration, several research and developments in biomaterial surface modification are geared toward resolving these issues in bone-related medical therapies/implants offering a substantial influence on cell adherence, increasing the longevity of the implant and rejuvenation along with the expansion in cell and molecular biology expertise. The primary objective of this review is to reaffirm the significance of surface modification of biomedical implants by enlightening numerous significant physical surface modifications, including ultrasonic nanocrystal surface modification, thermal spraying, ion implantation, glow discharge plasma, electrophoretic deposition, and physical vapor deposition. Furthermore, we also focused on the characteristics of some commonly used biomedical alloys, such as stainless steel, Co-Cr, and Ti alloys

Synthesis Methods in Solid-State Chemistry

The synthesis of single crystal is an area of intense activity in the materials science. The obtaining of the single crystal with sufficient dimension for X-ray diffraction depends on several factors including the chemical composition, crystal structure of the reagents, and physical parameters (temperature and pressure). In this context, this chapter is dedicated to the description of the most common synthesis methods of single crystal in the solid-state chemistry: solid-state method, hydrothermal, and slow evaporation at room temperature. Same other materials can be obtained at high pressure. There are also some physical techniques to grow single crystal, each technique is specific for specific materials

Surface-enhanced Raman scattering to realize the phonon processes in Ag nanoparticles-decorated CdS thin film

Surface-enhanced Raman spectroscopy (SERS) technique can achieve an ultra-high sensitivity (i.e., down to the single-molecule level) via coinage-metal nanostructures such as silver, gold, copper, etc. In this work, a geometry is proposed that consists of silver nanoparticles (AgNPs) decorated on cadmium chloride (CdCl2) annealed cadmium sulfide (CdS) thin film on a glass substrate. A strong SERS enhancement in AgNPs on CdCl2 annealed CdS thin films is achieved, which is twelve times larger than the scattering from the bare CdCl2 annealed CdS thin film. The improved SERS signal allows us to observe fundamental phonon processes in CdCl2 annealed CdS thin film. Moreover, a finite difference time domain (FDTD) method is used to understand the underlying SERS physics. By using the FDTD method, robust electromagnetic field localization in the nanogap between AgNPs and at the contact point of Ag NPs and CdS thin film is studied.The authors from King Khalid University extend their appreciation to the Deanship of Scientific Research at King Khalid University, Saudi Arabia, for funding this work through the Research Groups Program under grant number R.G.P-2/259 /44.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe

The Cuprate Ln₂CuO₄ (Ln: Rare Earth): Synthesis, Crystallography, and Applications

This chapter is concerned with a study of undoped and doped cuprates of the general formula Ln2CuO4 (Ln = rare-earth metal) and Ln2–xMxCuO4±δ (Ln = rare earth and M = Sr, Ba, Ca, Ln’, Bi, and 3d metal). The crystal structures of the undoped and doped cuprates having the notations (T, T′, T*, S, and O), significantly depend, however, on the synthetic route. The topotactic synthesis is a specific method, which allows the transformation of the cuprate from the T to T′ structure. The importance of these materials originates from the discovery of the unconventional superconductors of the Ce-doped Ln2CuO4. The cuprate materials could function as insulators or semiconductors which are valuable tools in optoelectronic applications. The doped cuprate materials are good ionic conductors and are found useful as electrodes in fuel cell applications. The undoped cuprates reveal high dielectric properties

Photocatalytic Reduction of Hexavalent Chromium Using Cu_3.21Bi_4.79S₉/g-C₃N₄ Nanocomposite

The photocatalytic reduction of hexavalent chromium, Cr(VI), to the trivalent species, Cr(III), has continued to inspire the synthesis of novel photocatalysts that are capable of achieving the task of converting Cr(VI) to the less toxic and more useful species. In this study, a novel functionalized graphitic carbon nitride (Cu3.21Bi4.79S9/gC3N4) was synthesized and characterized by using X-ray diffraction (XRD), thermogravimetry analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and scanning electron microscope (SEM). The composite was used for the photocatalytic reduction of hexavalent chromium, Cr(VI), under visible light irradiation. A 92.77% efficiency of the reduction was achieved at pH 2, using about 10 mg of the photocatalyst and 10 mg/L of the Cr(VI) solution. A pseudo-first-order kinetic study indicated 0.0076 min−1, 0.0286 min−1, and 0.0393 min−1 rate constants for the nanoparticles, pristine gC3N4, and the nanocomposite, respectively. This indicated an enhancement in the rate of reduction by the functionalized gC3N4 by 1.37- and 5.17-fold compared to the pristine gC3N4 and Cu3.21Bi4.79S9, respectively. A study of how the presence of other contaminants including dye (bisphenol A) and heavy-metal ions (Ag(I) and Pb(II)) in the system affects the photocatalytic process showed a reduction in the rate from 0.0393 min−1 to 0.0019 min−1 and 0.0039 min−1, respectively. Finally, the radical scavenging experiments showed that the main active species for the photocatalytic reduction of Cr(VI) are electrons (e−), hydroxyl radicals (·OH−), and superoxide (·O2−). This study shows the potential of functionalized gC3N4 as sustainable materials in the removal of hexavalent Cr from an aqueous solution