Amorphous Phase Research Articles

Optimizing structure and magnetic softness of low-Nb-content Fe-Si-B-Nb-Cu nanocrystalline alloys by regulating Si/B ratio and Cu content

The influences of Si/B ratio and Cu content on the melt-spun and crystallized structures and magnetic properties of low-Nb-content Fe-Si-B-Nb-Cu alloys have been studied. The results show that increasing the Si/B ratio in Fe78SixB19.5-xNb1.5Cu1 (Cu1Six) alloys deteriorates amorphous-forming ability, and gradually transforms the melt-spun structure from an amorphous phase (x = 9.5–10.5) to amorphous phase plus α-Fe texture (x = 11.5–13.5). An appropriate rise in Cu content eliminates the α-Fe texture in melt-spun structure and Fe77.5SixB19.5-xNb1.5Cu1.5 (Cu1.5Six) alloys all appear amorphous within x = 9.5–13.5. After annealing, the average α-Fe grain size (Dα-Fe) and coercivity (Hc) of the Cu1Six nanocrystalline alloys initially decrease and then increase with rising the Si/B ratio, reaching their minimums at x = 11.5. For the Cu1.5Six nanocrystalline alloys, both the Dα-Fe and Hc consistently decrease with increasing the Si/B ratio, and remain significantly lower than those of the Cu1Six alloys. The increased Si/B ratio also steadily reduces the saturation magnetic flux density (Bs) of both alloy series. The Cu1.5Six nanocrystalline alloys with x = 12.5–13.5 exhibit the optimized nanostructure and soft magnetic properties featuring the Dα-Fe, Hc, Bs, and effective permeability at 100 kHz of 24.8–25.2 nm, 10.5–11.0 A/m, 1.50–1.52 T, and 7300–7500, respectively. The increase in the Si/B ratio facilitates α-Fe nucleation whereas hinders grain growth, and a higher content of Cu promotes high-number-density α-Fe nucleation and strengthens the competitive growth among the α-Fe grains, further inhibiting their overgrowth. The synergistic effect leads to a refined nanostructure and improved magnetic softness.

Facile synthesis of novel bismuth oxide/bismuth molybdate nanocomposites as advanced anodes for high performance Li‐ion batteries

In this study, a novel nanocomposite material consisting of Bi2O3 and Bi2MoO6, named as Bi2O3@Bi2MoO6, was successfully fabricated by co-precipitation method in ethylene glycol solvent. Morphological analysis of the heat-treated sample at 400 °C for 12 h in Ar atmosphere (Bi2O3@Bi2MoO6 _400 °C) showed that it contained nano-sized particles of Bi2O3 and Bi2MoO6; in addition, an amorphous phase along with a crystalline structure was also observed. When used as an anode for Li-ion batteries (LIBs), Bi2O3@Bi2MoO6 _400 °C anode exhibits excellent electrochemical properties such as high Coulombic efficiency, high specific capacity, excellent capacity retention, and outstanding rate capacity. Specifically, the Bi2O3@Bi2MoO6 _400 °C anode presented a reversible capacity of 786 mAh g−1 at the beginning cycle at 0.1 A g−1 and retained about 90 % of the charging capacity value after 80 cycles. The advanced electrochemical properties of the nanocomposite anode are related to the combination of many aspects such as nanostructure, existence of amorphous phase, and pseudo-behaviour of metal-based components. The structural stability and electrochemical performance of the anode material, therefore, are improved. These results demonstrate Bi2O3@Bi2MoO6 _400 °C as a promising material for establishing high-performance LIB anodes.

A composite photoluminescent probe based on Er/Yb co-doped tellurite glass powder for dual-parameter measurement of temperature and UV radiation

To cope with the cross-sensitivity of simultaneous measurement of ultraviolet (UV) irradiance and temperature, we propose and experimentally demonstrate a miniature composite photoluminescent probe that is formed by thoroughly mixing Er/Yb co-doped tellurite glass powder into a resin adhesive substrate. Utilizing tellurite glass in form of powder not only guarantees its thorough mixing into the liquid resin base, but also retains its amorphous glass phase for hosting Er/Yb ions, thus breaking the limitations of studying tellurite glass only in bulk or fibrous form. Co-excited by UV radiation and NIR pumping, the composite probe produces a superimposed fluorescence emission spectrum, where the intensity change rate of the 488 nm dip can be used for UV irradiance measurement, and the fluorescence intensity ratio (FIR) of the 524 nm and 545 nm peaks for temperature measurement. Based on the sensitive specificity of the resin substrate and the Er/Yb co-doped tellurite glass, we have realized the simultaneous measurement of UV and temperature without cross-sensitivity.

Soret-Effect Induced Phase-Change in a Chromium Nitride Semiconductor Film.

Phase-change materials such as Ge-Sb-Te (GST) exhibiting amorphous and crystalline phases can be used for phase-change random-access memory (PCRAM). GST-based PCRAM has been applied as a storage-class memory; however, its relatively low ON/OFF ratio and the large Joule heating energy required for the RESET process (amorphization) significantly limit the storage density. This study proposes a phase-change nitride, CrN, with a much wider programming window (ON/OFF ratio more than 105) and lower RESET energy (one order of magnitude reduction from GST). High-resolution transmission electron microscopy revealed a phase-change from the low-resistance cubic CrN phase into the highly resistive hexagonal CrN2 phase induced by the Soret-effect. The proposed phase-change nitride could greatly expand the scope of conventional phase-change chalcogenides and offer a strategy for the next-generation of PCRAM, enabling a large ON/OFF ratio (∼105), low switching energy (∼100 pJ), and fast operation (∼30 ns).

Microstructural evolution and phase transformation of cansas 3303 SiC fibers during thermal shock at 1200 °C

A self-built automatic platform was built to evaluate the thermal shock performances of Cansas-III SiC fibers at 1200 °C in air up to 500 cycles, the corresponding oxidation and damage mechanisms were then revealed. The results showed that oxide scale was formed during thermal shock with a thickness of about 1 μm, the core was not oxidized via its protection. The fiber roughness increased before 100 cycles due to the decomposition of the amorphous SiCxOy phase, and then decreased as the formation of oxide scale. Within Cansas-III SiC fibers, structural defects of free carbon increased as the increasing ID/IG values, in addition, the TO peak shifted to the left, which both demonstrated that the relative movements occurred among SiC grains and residual stresses were then emerged. To clarify the axis and radial cracking of the oxide scale, a modified formulation considering nonzero shear strain components was then proposed to calculate the related residual stresses. The peeling and cracking of the oxide scale was ascribed to the residual stresses of GPa level among SiC grains and the thermal expansion mismatch between the oxide scale and the core.

Microstructure, mechanical properties and cutting performance of CVD Ti(B,N) coatings

TiB0.19N1.06, TiB0.70N0.66, and TiB1.23N0.19 coatings were deposited on cemented carbide via the chemical vapor deposition (CVD) method based on the calculated phase diagrams of the Ti–B–N system. The microstructures, mechanical properties and cutting performances of the Ti(B,N) coatings were systematically studied via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), nanoindentation, etc. The coating compositions obtained via thermodynamic calculations show the same trend as the experimental values. The XRD and selected area electron diffraction (SAED) results of the coatings reveal that the phase assemblages transform from a dominant cubic structure of TiB0.19N1.06 to a hybrid of cubic and hexagonal structure of TiB0.70N0.66 and finally to a dominant hexagonal structure of TiB1.23N0.19. According to the XPS results, the TiB0.19N1.06 and TiB0.70N0.66 coatings consist of the crystalline phases TiN and TiB2 as well as amorphous BN and TiB, and the TiB1.23N0.19 coating mainly consists of the crystalline phases TiB2 and TiN. The hardness values of the TiB0.19N1.06, TiB0.70N0.66, and TiB1.23N0.19 coatings are 33.6, 35.1, and 39.1 GPa, respectively. The content of amorphous phase in the Ti(B,N) coatings decreases while the hardness increases as the B content increases and N content decreases. The TiB0.19N1.06 coating exhibits a composite structure of nanocrystallite embedded in amorphous matrix. The TiB1.23N0.19 coated tool prepared in this study demonstrates excellent performance in milling titanium alloy TC18 with a long cutting life up to 56.1 min, an increase of ∼9 % and ∼28 % compared to the TiB1.98 coated tool and commercial grade deposited with CVD TiB2 coating, respectively.

Spontaneous heterophase atomic structure engineering of NiMo(S)/NiMoP for enhanced overall electrochemical water splitting in neutral media

Hydrogen/oxygen evolution reactions catalyzed by transition metals have sluggish kinetics during prolonged water electrolysis in neutral media. Covering the surface with an amorphous protecting layer can improve the reactivity and stability of these catalysts; however, the rational design of crystalline–amorphous electrocatalysts for efficient and stable water electrolysis in neutral media has been challenging. Here, we present a unique and facile strategy for the in situ synthesis of the heterophase-structured cNiMo(S)/aNiMoP catalyst with a crystalline–amorphous phase boundary. The high-density active sites present on the surface and at the interface of the heterophase is responsible for the excellent electrochemical activity and operational stability of water electrolysis in neutral media. For the overall water splitting reaction, the cNiMo(S)/aNiMoP || cNiMo(S)/aNiMoP system displays a low cell voltage of 1.67 V to achieve a current density of 100 mA cm−2. Moreover, negligible performance degradation was observed during a continuous long-term stability test for 100 h.

The effect of chromium on the corrosive performance of novel high manganese steel frogs in a simulated industrial atmosphere

Abstract The corrosion behavior of three novel high manganese steel frogs with different Cr contents in a simulated industrial corrosive atmospheric environment is studied through the corrosion weight gain, x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and electrochemical testing. The results indicate that the content of Cr in the steel affects the phase composition, density, and electrochemical stability of the rust layer. For instance, as the Cr content increases, the content of the amorphous phase in the rust layer continuously increases while that of γ-FeOOH decreases, leading to enhanced density and electrochemical stability of the rust layer. The study reveals that Cr exists in the rust layer in the form of Cr2O3 and Cr(OH)3, providing nucleation cores to nanoscale colloidal rust particles. Consequently, a higher Cr content leads to more nucleation cores, which improves the density of the rust layer and enhances the corrosion resistance of the novel high manganese steel frogs in industrial corrosive atmospheric environments.

Valorization of Grass Clipping Waste: A Sustainable Approach to Cellulose Extraction and Paper Manufacturing

This study investigates the physical, mechanical, and structural characteristics of handmade paper samples derived from cellulose extracted from grass clippings using two distinct methods as follows: (1) alkali treatment and (2) alkali treatment followed by bleaching, coupled with the incorporation of barium sulfate as a mineral filler. Our investigation revealed that the handmade paper samples’ densities, moisture contents, and thicknesses varied within the ranges of 0.436 to 0.549 g/cm3, 5.60 to 2.51%, and 0.41 to 0.50 mm, respectively. The tensile strength and folding endurance of the papers produced through alkali treatment with barium sulfate were notably superior to those produced from bleached pulp and barium sulfate. Our analysis indicates that several critical factors, including paper density, thickness, the crystallinity index, and the microfibrillar structure of cellulose, intricately influence the mechanical and strength properties of the samples. Using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques, we identified characteristic cellulose bonds and examined cellulose’s crystalline and amorphous phases. Additionally, the crystallinity index of the samples was determined using both the Segal and peak deconvolution methods. Scanning electron microscopy (SEM) micrographs revealed interconnected networks of cellulose fibers with varying thicknesses and lengths, along with incorporated mineral filler within the cellulose fiber structure. Variations in mineral particle retention were attributed to the presence or absence of cellulose microfibrils. These findings contribute to our understanding of the observed strength characteristics of the paper samples and underscore the potential applications of cellulose derived from grass clippings, especially when combined with barium sulfate as a mineral filler in paper production.

Amorphous-Crystalline Heterostructured Nanoporous High-Entropy Alloys for High-Efficiency pH-Universal Water Splitting.

Developing high-efficiency durable electrocatalysts in wide pH range for water splitting is significant for environmentally-friendly synthesis of renewable hydrogen energy. Herein, a facile method by dealloying designable multicomponent metallic glass precursors is reported to synthesize amorphous-crystalline heterostructured nanoporous high-entropy alloys (AC-HEAs) of CuAgAuPtPd, CuAgAuIrRu, and CuAgAuPtPdIrRu, heaped up by nanocrystalline particles with an average size of 2-3nm and the amorphous glued phase. The synthesized AC-HEA-CuAgAuPtPd owns highly catalytic performances for hydrogen evolution reaction (HER), with 9.5 and 20mV to reach 10 mA·cm-2 in 0.5m H2SO4 and 1.0m KOH, and AC-HEA-CuAgAuIrRu delivers 208 and 200mV for oxygen evolution reaction (OER). Moreover, a two-electrode electrolyzer made of the AC-HEA-CuAgAuIrRu bifunctional electrodes exhibit a low cell voltage of 1.48 and 1.49V in the acidic and alkaline conditions at 10 mA·cm-2 for overall water splitting. Combining the enhanced catalytic activities from nanoscale amorphous structure and atom-level synergistic catalyst in AC-HEAs provides an effective pathway forpH-universal electrocatalysts of water splitting.

Highly Ionic Conductive, Self-Healing, Li10GeP2S12-Filled Composite Solid Electrolytes Based on Reversibly Interlocked Macromolecule Networks for Lithium Metal Batteries with Improved Cycling Stability.

Ceramic-polymer composite solid electrolytes (CSEs) have attracted great attention by combining the advantages of polymer electrolytes and inorganic ceramic electrolytes. Herein, Li10GeP2S12 (LGPS) particles are incorporated into poly(ethylene oxide) (PEO)-based reversibly interlocked polymer networks (RILNs) derived from the topological rearrangement of two PEO networks cross-linked by reversible imine bonds and disulfide linkages. A series of highly ionic conductive, self-healing CSEs are obtained accordingly. The interlocking architecture successfully inhibits PEO crystallization, increasing the amorphous phase for Li ion transportation, and stabilizes the conductive pathways of LGPS particles by its unique confinement effect. Meanwhile, the LGPS particles cooperate with the RILN matrix, forming a filler-polymer interfacial phase for additional Li ion transportation and strengthening and toughening the resultant CSEs via the strong intermolecular Li+-O2- interactions. Furthermore, the dynamic characteristics of the included reversible bonds ensure a multiple intrinsic self-healing capability. Consequently, the CSEs containing 15 wt % LGPS deliver a high ionic conductivity (1.06 × 10-3 S cm-1) and high Li ion transference number (∼0.6) at 25 °C, a wide electrochemical stability window (>4.9 V), good mechanical properties (0.63 MPa, 377%), and a stable CSE/Li anode interface. The integrated Li/CSE/LiFePO4 battery exhibits a specific discharge capacity of 110.8 mAh g-1 at 1 C (25 °C) and a capacity retention of 76.9% after 200 cycles. Thanks to the healability, the damaged CSEs can regain the structural integrity, ion conductive capability, and cycling performance of the assembled cells. The present work provides an effective strategy to fabricate CSEs for lithium metal batteries that are workable at ambient temperature.

Spray-Flame Synthesis of NASICON-Type Rhombohedral (α) Li1+xYxZr2-x(PO4)3 [x = 0-0.2] Solid Electrolytes.

Since solid electrolytes have a broad electrochemical stability window, are exceptionally electrochemically stable against Li metal, and function as a physical separator to prevent dendrite growth, they are at the forefront of alternate possibilities, further increasing the stability and energy density of Li-ion batteries. NASICON-type electrolytes are a promising candidate due to their negligible moisture sensitivity, which results in outstanding stability and a lower probability of Li2CO3 passivity under the ambient atmosphere. However, one of the most promising representatives, Li1+xYxZr2-x(PO4)3 (LYZP), has multiple stable phases with significant variation in their corresponding Li-ion conductivity. In this paper, we have successfully synthesized the highly ionically conductive rhombohedral phase of LYZP via spray-flame synthesis. Two different solvent mixtures (e.g., 2-ethyl hexanoic acid/ethanol, propanol/propanoic acid) were chosen to explore the effect of precursor composition and combustion enthalpy on the phase composition of the nanoparticle. The as-synthesized nanoparticles from spray-flame synthesis consisted of the crystalline tetragonal zirconia (t-ZrO2) phase, while lithium, yttrium, and phosphate were present on the nanoparticles' surface as amorphous phases. However, a short annealing step (1 h) was sufficient to obtain the NASICON phase. Moreover, we have shown the gradual phase conversion from orthorhombic β phase to rhombohedral α phase as the annealing temperature increased from 700 °C to 1300 °C (complete removal of β phase). In this context, Y3+ doping was also crucial, along with the appropriate solvent mixture and annealing temperature, for obtaining the much-desired rhombohedral α phase. Further, 0.2 at% Y3+ doping was added to the solvent mixture of 2-ethyl hexanoic acid/ethanol, and annealing at 1300 °C for 1 h resulted in a high ionic conductivity of 1.14∙10-5 S cm-1.

Physical Vapor Deposition of Indium-Doped GeTe: Analyzing the Evaporation Process and Kinetics

Chalcogenide glasses have broad applications in the mid-infrared optoelectronics field and as phase-change materials (PCMs) due to their unique properties. Chalcogenide glasses can have crystalline and amorphous phases, making them suitable as PCMs for reversible optical or electrical recording. This study provides an in-depth analysis of the evaporation kinetics of indium-doped chalcogenides, GeTe4 and GeTe5, using the physical vapor deposition technique on glass substrates. Our approach involved a detailed examination of the evaporation process under controlled temperature conditions, allowing precise measurement of rate changes and energy dynamics. This study revealed a significant and exponential increase in the evaporation rate of GeTe4 and GeTe5 with the introduction of indium, which was particularly noticeable at higher temperatures. This increase in evaporation rate with indium doping suggests a more complex interplay of materials at the molecular level than previously understood. Furthermore, our findings indicate that the addition of indium affects the evaporation rate and elevates the energy requirements for the evaporation process, providing new insights into the thermal dynamics of these materials. This study’s outcomes contribute significantly to understanding deposition processes, paving the way for optimized manufacturing techniques that could lead to more efficient and higher-performing optoelectronic devices and memory storage solutions.

Effects of Cr and Mo content on the microstructure and properties of Fe-based amorphous composite coatings by laser cladding

In this study, we successfully produced Fe-based amorphous composite coatings on the surface of 45 steel using laser cladding technology, and the impact of the relative content of Cr and Mo elements on the microstructure, hardness, and wear resistance of composite coatings has been investigated. The results show that the microstructure of the coating changes from dendrite to amorphous nanocrystalline when the content of Cr and Mo is 20 and 15 wt. %, respectively. However, when the Mo element continues to be added, elemental segregation will be caused, resulting in a large number of brittle Fe–Cr–Mo intermetallic compounds and MoSi2 ceramic phases in the coating. Therefore, the appropriate element ratio can not only increase the amorphous phase content in the coating but also prevent elemental segregation. Among the three types of amorphous composite coatings studied, the Fe45Cr20Mo15B10Si10 (wt. %) composite coating exhibited the most favorable performance, primarily due to its highest amorphous content (43.33%). Through the interaction of the amorphous phase, α-Fe, Fe–Cr solid solution, and a small proportion of intermetallic compounds, this coating achieved a hardness of 1282.8 HV0.2, approximately five times that of the 45 steel substrate, and demonstrated superior wear resistance.

Unusual nanoscale amorphization of metallic chromium interfacing with SiC under high energy irradiation

Layered metal/silicon carbide (SiC) materials systems are becoming increasingly relevant to solve materials challenges in advanced fission and fusion nuclear energy systems, necessitating a deeper understanding of how interfaces between dissimilar materials behave under high energy irradiation. In this work, we use a Cr-SiC bilayer system as a model to study the behavior of such interfaces under high energy ion irradiation (80 MeV Xe26+ ions) at elevated temperatures (∼350 °C). Through high resolution characterization of the interface, we observed the formation of a nanoscale Cr-rich amorphous layer adjacent to crystalline SiC. We explain this phenomenon through a multi-scale computational approach incorporating ballistic mixing simulations, density functional theory calculations, and CALPHAD-based non-equilibrium modeling that shows the localized amorphization of Cr to be driven by the synergistic action of irradiation-induced point defects within Cr and transport of Si and C atoms across the interface. In particular, the accumulation of radiation damage results in the thermodynamic destabilization of the point-defect containing, metastable Cr-Si-C solid solution with respect to an amorphous phase of identical composition. This study advances the understanding of how metal/SiC interfaces behave under irradiation and establishes a modeling framework that can be applied to interfacial systems to understand irradiation-induced amorphization.

Design of High‐Entropy Relaxor Ferroelectrics for Comprehensive Energy Storage Enhancement

AbstractFor an ideal electrostatic energy storage dielectric capacitor, the pursuit of simultaneously high energy density and efficiency presents a formidable challenge. Typically, under an applied electric field, an increase in energy density is usually accompanied with a deteriorated energy storage efficiency due to the escalated hysteretic loss, which is harmful to the reliability of the capacitor. Thus, a well‐balanced performance of improved energy density and maintained high efficiency is highly demanded. In this work, a structure with amorphous phases embedded in polycrystalline nanograins using the entropy tactic, leading to a higher transport barrier of carrier is constructed. Hence, the hysteretic loss is largely suppressed at a high electric field and the high polarization is still sustained in the high‐entropy film. Consequently, an ultrahigh energy density of 139.5 J cm−3 with a high efficiency of 87.9%, and a high figure of merit of 1153 are simultaneously achieved in the high‐entropy Ba2Bi4Ti5O18‐based relaxor ferroelectric. This work offers a promising avenue in materials structure design for advanced high‐power energy storage applications.

Synchronous or selective removal of nitrate and Cr(VI) by montmorillonite supported sulfidized nanoscale zerovalent iron: Role of Fe(II) and S0

The reduction process of Cr(VI) and NO3−-N by sulfidized nanoscale zerovalent iron (S-nZVI) under coexistence conditions has yet to be investigated. This study innovatively confirmed that NO3−-N and Cr(VI) could be reduced synchronously or selectively by synthesizing diverse montmorillonite-supported S-nZVI (S-nZVI@MMT) to meet different remediation requirements. Concretely speaking, S-nZVI@MMT at low S/Fe could synchronously reduce NO3−-N and Cr(VI) to NH4+-N and Cr(III). S-nZVI@MMT at high S/Fe selectively removed Cr(VI). The vital roles of Fe(II) and S0 in S-nZVI@MMT were clearly revealed. Fe(II) mainly involved in the generation of Fe3O4 during the reaction at low S/Fe, while participating in the transformation of amorphous phases of Fe3O4, FeS, and FeS2 at high S/Fe. The Fe0 and converted Fe3O4 were the primary reactive sites for the synchronous removal of NO3−-N and Cr(VI) while the surface-bound Fe(II) and converted amorphous phases of Fe3O4 and FeSx determined the selective removal of Cr(VI). Meanwhile, the high contents of S0 in S-nZVI@MMT at high S/Fe mediated the generation of FeSx during the reaction and blocked the adsorption and reduction of NO3−-N which was critical for the selective removal of Cr(VI). The variations in the reactive species of S-nZVI@MMT at different S/Fe led to discrepant Cr(VI) reaction pathways. The findings provided new insights and strategies for the practical applicability of S-nZVI. SynopsisStudy provides a new insight into the synchronous/selective removal of Cr(VI) and NO3−-N by S-nZVI to meet the remediation requirements for different application scenarios.

Influence of phosphates on phase formation in alkali‐activated MgO‐Al2O3‐SiO2‐P2O5 cements

AbstractThe impact of phosphates on phase formation in low Ca alkali‐activated materials (AAMs) is investigated using a polymer‐assisted sol‐gel process to fabricate MgO‐Al2O3‐SiO2‐P2O5 cement precursors covering a broad range of compositions activated with sodium hydroxide. X‐ray diffraction and magic angle spinning‐nuclear magnetic resonance are used to examine the crystalline and amorphous phases that form over 470 days of curing (35°C, 90% relative humidity). The results confirm that Al is preferentially incorporated into hydrotalcite‐like layered double hydroxides (LDH) over zeolites. Zeolites form when more Al is present than can be incorporated into the LDH. Little evidence of phosphate incorporation into aluminosilicate networks (such as zeolites or disordered aluminosilicate hydrate) was observed. The phosphates present in the precursor favor reaction with sodium to form water‐soluble sodium phosphate phases. In most cases, the remainder of the phosphates become adsorbed to the surface of other phases and are not intercalated into the LDH, though at high phosphate concentrations (26.6 wt. % P2O5) and extended curing times (470 days), phosphates are observed to intercalate into LDH phases. These results provide preliminary evidence that phosphates are compatible with low Ca AAMs, which is consequential as there is a growing interest in both the use of AAM and phosphate‐based corrosion inhibiter in steel‐reinforced concrete.

The synthesis and characterization of alkaline niobate-based ceramic composites containing L-lysine Hydrochloride

Some lead-free piezoelectric ceramics are known to have high dielectric and piezoelectric properties but are limited by their brittle nature. A few amino acids have recently been reported to exhibit rather low dielectric and piezoelectric properties but have the advantage of being biocompatible and flexible. It would therefore be interesting to form a composite that will combine the inherent advantage of high dielectric properties from the ceramics and flexibility from the biomolecule. In this research, the properties of lead-free (K0.45Na0.51Li0.04)(Nb0.85Ta0.1Sb0.05)O3 (KNNLST) ceramics and L-lysine hydrochloride (L-LHCl) have been combined to produce dielectric composites. The samples were produced by mixing the constituents from 0 wt.% to 100 wt.%, pelletising and heat-treating them. Bulk density, X-ray diffraction, scanning electron microscopy, and dielectric characterisation were techniques used to determine the density, phases, morphology, and dielectric properties of the produced composites. The results show an increasing bulk density value from 1.2 g/cm3 for L-LHCl to 4.67 g/cm3 for the KNNLST ceramics. The morphology of the composite shows very tiny grains when small amounts of the ceramics were introduced. The L-LHCl transforms from an amorphous phase to a crystalline phase having the orthorhombic-tetragonal structure with the introduction of the KNNLST ceramics. The dielectric constant values increased with increasing KNNLST ceramics content from 10 @1 kHz to 200 for the composite with 80 wt%. KNNLST content. The dielectric loss values decreased for L-LHCl from 0.9 @1 kHz to 0.2 @1kHz. The electrical conductivity values increased with increasing KNNLST ceramics content. The results show that the composites produced from these constituents may be suitable for dielectric applications.

Highlighting amorphous phase separation process on cooling borosilicate melts using impedance spectroscopy

Four samples of sodium borosilicate glasses of composition (100 - x)(SiO2 - B2O3) - xNa2O with x = 4, 7, 10 and 25 mol% were synthesized and studied in a wide temperature range (up to 1673 K) using impedance spectroscopy, from the molten to the solid states. During melt cooling of three compositions (x = 4, 7 and 10), a clear transition was observed on the conductivity behavior at a critical temperature (Tcrit ≈ 973 K), highlighting the onset of an amorphous phase separation, in agreement with both Differential Scanning Calorimetry thermograms and literature. The amorphous nature of the phase separated samples was verified by in situ X-Ray Diffraction measurements performed under the same thermal conditions. Furthermore, Scanning Electron Microscopy micrographs taken on these three samples at room temperature after the impedance measurement confirmed the presence of two different phases, whose size and morphology vary with composition. As expected, the x = 25 sample did not show phase separation and remained homogeneous down to room temperature.