Phase Transformation Research Articles

Piezoelectric-enhanced MoS2@PVDF-HFP composite for photocatalytic degradation of tetracycline

In this work, composite films of molybdenum disulfide (MoS2) with poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) were fabricated using aqueous phase transformation and hydrothermal methods, aiming at efficiently degrading tetracycline hydrochloride (TC). The findings revealed that the degradation efficiency of TC by MoS2@PVDF-HFP, when subjected to a combined photocatalysis process involving a simulated pressure electric field and aeration, reached a remarkable 96.11% within 1 hour-surpassing the performance observed under individual conditions. The changes in the electron density cloud on the films surface induced by the pressure electric field and the acceleration of electron transfer rate between contact interfaces were evident. Notably, the composite films exhibited a stable performance with a TC removal rate of 90.23% after five cycles, including a relatively stable degree of mineralization. We employed Density Functional Theory (DFT) to investigate the changes in the state density of MoS2@PVDF-HFP under different conditions, such as compressive stress, tension, and no force. This further clarified the mechanism of piezoelectric coupling photocatalysis promoting induced charge transfer on the films surface. The research findings presented in this paper provide a promising avenue for the application of piezoelectric field-assisted photocatalysis in enhancing material performance.

Microstructure instability of additively manufactured alloy 718 fabricated by laser powder bed fusion during thermal exposure at 600-1000 ℃

Microstructure and precipitation behavior of alloy 718 produced by laser powder bed fusion (L-PBF) and its recrystallized counterpart were evaluated after thermal exposure at a temperature range of 600-1000 ℃ for up to 1000h. The as-built 718 featured a microstructure of columnar grains, and dislocation cell structures (DCSs) with chemical segregations (rich in Nb, Ti, Mo and depleted in Cr, Fe) and precipitates (Laves phase and carbonitride). The DCSs remained thermally stable for up to 1000h at 600 ℃ or 100h at 700 ℃, but only 10h at 800 ℃. With the temperature increasing to 900 ℃ and 1000 ℃ for 1h duration, the DCSs tended to partially disassemble, and the chemical segregations were removed. The chemical segregations at cell boundaries of the as-built 718 promoted the formation of γ', γ″ and δ phases during aging, leading to a spatially heterogeneous distribution of γ' and γ″ phases between the cell boundaries and interiors during short exposure time or at lower temperatures. Meanwhile, the coarsening of γ' and γ″ phases and the phase transformation of γ″ to δ at 700-800 ℃ were facilitated in the as-built 718 compared to the recrystallized ones. A unique precipitation distribution was observed at 700 ℃ that γ' and γ″ phases precipitated both at the cell boundaries and within cell interiors, while only γ' formed in the vicinity of cell boundaries. Time-temperature-transformation curves for additively manufactured and recrystallized 718 were constructed based on the microstructure analyses. This study indicates that conventional heat treatment procedures may be suboptimized for additively manufactured 718 in high temperature applications.

Altered microstructure, phase transformation behaviors and shape memory response of CuAlMn shape memory alloys fabricated by selective laser melting

In this paper, nearly defect-free CuAlMn SMAs were successfully fabricated by selected laser melting (SLM). The result of microstructure show that only one type of thermal-induced martensite was detected in the prepared specimens, and the process parameters play a vital role in phase transformation behaviors. The alloy shows excellent ultimate tensile strength of 820 MPa and elongation of 11.5 %. Furthermore, the high shape memory response, i.e. shape recovery rate of 91.4 %–99.6 %, shape memory strain of 2.59 %–5.46 %, was presented under compressive strain not exceeding 8 %.

Density functional theory study on vanadium selective leaching separation from iron in stone coal via Fe2O3 (001) surface passivation

When vanadium is extracted from stone coal, iron impurities readily precipitate and reduce the purity of the vanadium product. Thus, separating vanadium from iron impurities at source is essential. The mechanism of surface passivation of Fe2O3 (001) for the selective leaching separation of vanadium from iron in stone coal was established in the present work. Analysis of mineral phase transformation and microscopic morphology indicates that Fe2O3 in stone coal can undergo a reaction with HF and F-. Subsequently, the hematite surface was covered with FeF3 passivation layer, resulting in the inhibition of hematite dissolving reaction. The results of density functional theory (DFT) computations demonstrate that the HF and F- can reform the Fe2O3 (001) surface via sedimentary behavior at mineral interface, and the adsorption energy can be down to -99.93kJ/mol for the F- adsorption configuration. During sulfuric acid leaching with CaF2 as an aiding agent, the transfer of electrons from Fe atoms to F atoms can weaken the stable Fe-F bonds and decrease the reactive activation of Fe atoms in Fe2O3. This study demonstrates the separation of vanadium from iron by means of hematite passivation in the attendance of fluoride at the atomic level of analysis.

Exceptional strength-ductility synergy in the novel metastable FeCoCrNiVSi high-entropy alloys via tuning the grain size dependency of the transformation-induced plasticity effect

In-depth knowledge of the coupling between grain refinement and the transformation-induced plasticity (TRIP) effect in metastable alloys is a viable approach for the improvement of strength-ductility synergy, which needs systematic research with consideration of commercial austenitic stainless steels and novel high-entropy alloys (HEAs). Accordingly, in the present work, two Si-containing metastable HEAs in the Fe47Co30Cr10Ni5V8-xSix system (x = 3 and 6 at.%) were designed, and the TRIP-assisted AISI 304L stainless steel was also considered for comparison. The alloys were processed by cold rolling and annealing to obtain different grain sizes. Reducing the stacking fault energy (SFE) through adjusting chemical composition contributes to minimizing the detrimental effect of grain refinement on the ductility of TRIP alloys, while extremely low SFE must be avoided owing to the fast kinetics of deformation-induced martensitic phase transformation, which leads to the deterioration of ductility. In contrast to AISI 304L stainless steel, a strong TRIP effect was maintained upon grain refinement in the Fe47Co30Cr10Ni5V2Si6 HEA due to the remaining apparent SFE in the appropriate TRIP range. The tuned kinetics of martensitic transformation was found to be responsible for the exceptional ductility (∼65%) of Fe47Co30Cr10Ni5V2Si6 HEA at an ultrahigh tensile strength of 1250 MPa. Therefore, considering the identical trend of SFE with grain size, an appropriate initial SFE value is important for tuning the grain size dependency of the TRIP effect. Moreover, the ultrahigh strength was attributed to the high volume fraction of α΄-martensite as well as the high strength of the martensite phase due to the high Si content. Accordingly, for achieving strong-yet-ductile HEAs, a high Si content is recommended to benefit from solid solution strengthening in the martensite phase, a specially-designed chemical composition is needed for attaining a high volume fraction of α΄-martensite, and SFE should be in a desirable range to tune the kinetics of martensitic phase transformation.

High speed impact induced dehydrogenation of titanium hydride and formation of cellular structure via cold spray

In this study, it is revealed for the first time that ultra-high-speed impact can trigger in-situ dehydrogenation at the impact interface of titanium hydride (TiH). This phenomenon leads to a phase transformation from brittle TiH to ductile Ti, causing a shift in the ductile-to-brittle transition from the impact interface to the particle interior. Inspired by this unique behavior, and considering the mechanical interactions between particles during the spray process, TiH powders were used as feedstock to successfully produce a large-scale random cellular structure through cold spray. A systematic investigation of the deposition process revealed that unbroken TiH particles interact with dehydrogenated ones, resulting in only the ductile portion of the TiH particle being deposited, while the brittle interior is spalled off, consequently forming the “walls” of the cellular structures. This work highlights the potential of TiH powders to advance cold spray technology, particularly in the creation of complex cellular structures.

Sintering behavior and thermal shock resistance of MgO-Mg2SiO4 refractories by co-doped silica fume and quicklime

To solve the serious environmental pollution of low-grade magnesite tailings, MgO-Mg2SiO4 refractories were prepared by low-grade magnesite tailings, materials and silica fume and quicklime as raw materials. The effects of calcium-silicate ratio (mol ratio) on the phase composition, microstructure, sintering behavior and thermal shock resistance of MgO-Mg2SiO4 refractories were investigated. When calcium-silicate ratio was 5/5, the samples showed the optimum bulk density and apparent porosity of 2.81 g/cm3 and 16.37 %, respectively. Controlled the calcium-silicate ratio of samples to 5/5 significantly improved the thermal shock resistance of samples, the residual compressive strength rate of 69.78 % and the residual flexural strength rate of 19.86 %, while the thermal parameter R was 34.45. The improvement in the thermal shock resistance can be attributed to the bonding phase transformation from monticellite phase to forsterite phase, thereby enhancing the bond strength between aggregate and matrix.

Advancing laser powder bed fusion with non-spherical powder: Powder-process-structure-property relationships through experimental and analytical studies of fatigue performance

This study investigates the multifaceted interdependencies among powder characteristics (i.e., non-spherical morphology and particle size ranging 50-120 or 75-175µm), laser powder bed fusion (L-PBF) process condition (i.e., contouring), post-process treatments (i.e., hot isostatic pressing (HIP) and mechanical grinding) on the pore, microstructure, surface finish, and fatigue behavior of additively manufactured Ti-6Al-4V samples. Microstructure analysis shows a phase transformation α′ → α+β microstructure after HIP treatment (at 899±14 °C for 2h under the applied pressure of 1034±34bar) of the as-built Ti-6Al-4V parts. The findings from pore analysis using micro-computed tomography (μ-CT) show an increase in sub-surface pores when relatively smaller powders are L-PBF processed including contouring. Surface optical profilometry reveals a decrease in surface roughness when fine powder is L-PBF including contouring. Pore analysis conducted through μ-CT reveals that the presence of lack-of-fusion pores within the L-PBF processed coarse powder is more pronounced when compared to the fine powder. Furthermore, HIP treatment does not eliminate these pores. The fracture failure in as-printed parts occurs at the surface, while the combination of HIP and mechanical grinding alters crack initiation to subsurface pore defects. Fractography reveals that HIP and as-built samples followed the facet formation and pseudo-brittle fracture mechanisms, respectively. Fatigue life assessments, supported by statistical analysis, indicate that mechanical grinding and HIP significantly enhanced fatigue resistance, approaching the benchmarks set by wrought Ti-6Al-4V alloy. A fatigue prediction model which considers the surface roughness as a micro-notch has been used.

Eco-friendly synthesized zeolitic imidazolate framework-8 enables one-step cerium recovery from water

The rapid pace of technology advancement has quickly depleted valuable rare earth elements (REEs), which are critical for the function and performance of electric and electronic components, and there is thus a need for REE extraction from secondary sources rather than from virgin mines. This study presents an approach involving the ball-milling-induced construction of zeolitic imidazolate framework-8 (ZIF-8) that integrates REE extraction and recovery processes. ZIF-8 demonstrates remarkable extraction capacities for various REEs, and notably promotes nanoscaled CeO2 formation. Ball-milling-prepared ZIF-8 (ZIF-8-BM) effectively concentrates cerium (III) ions (CeIII), and a purity of 99.34% is achieved by controlling the processing parameters, offering a comprehensive solution for efficient Ce retrieval from wastewater. The superior Ce extraction performance is attributed to the greater numbers of structural defects and surface hydroxyl (–OH) groups and the enhanced phase transformation efficiency. Moreover Ce extraction by ZIF-8-BM is found to be efficient in both low and high Ce concentration ranges. ZIF-8-BM nanoparticles spontaneously oxidize CeIII in solution to insoluble CeO2, thereby facilitating the efficient extraction and subsequent recovery of cerium from complex matrices. The findings of this study provide an environmentally benign approach for the safe and efficient recovery of REEs from waste streams, supported by a scientifically sound and economically feasible processing strategy.

Thermophysical properties of AlxCoCrCuFeNi high entropy alloys

The AlxCoCrCuFeNi (x = 0.25, 0.5, 1, 2) high entropy alloys (HEAs) were prepared by arc melting and spray casting techniques. Their microstructures, hardness, and thermophysical properties such as fusion enthalpy, entropy, thermal diffusion coefficients, thermal expansion coefficients, were investigated. XRD results indicated that AlxCoCrCuFeNi (x = 0.25 and 0.5) alloys were composed of a high-entropy FCC phase and Cu-rich nanophase. As the Al content increased to 1 and 2, the phase structures included the AlNi-rich B2 phase, FeCr-rich A2 phase and Cu-rich nanophase. With the increased Al content, the microstructures of AlxCoCrCuFeNi HEAs transitioned from coarse dendrites to petal-like dendrites, and the grains were continuously refined. Moreover, the Al additions reduced the density whereas increased the Vickers hardness of the alloys. The maximum hardness observed in Al2CoCrCuFeNi HEA was approximately 2.4 times greater than that of the Al0.25CoCrCuFeNi HEA. The thermal diffusion coefficients of alloys initially increased and subsequently decreased as the temperature elevated. The phase transformation induced by Al content was an effective method for rapidly homogenizing the internal temperature of alloys. Furthermore, the crystal structure, elemental segregation, lattice distortion, enthalpy and entropy of fusion, and lattice vibration frequency all mutually affected the thermal diffusion and expansion coefficients of AlxCoCrCuFeNi HEAs.

Effect of ionic soil stabilizer on the properties of lime and fly ash stabilized iron tailings as pavement base

The large use of iron tailings is in urgent need given its huge emissions and pollution to environment. This paper sought to utilize a large quantity of iron tailings with fly ash and lime to prepare road base materials, and use ionic soil stabilizer (ISS) to improve its pavement performance. Different dosage ISS content of was added to the lime-fly ash stabilized iron tailing materials to improve the mechanical strength, frost resistance properties and decrease the dry shrinkage. The results show that the UCS of the specimen with 0.67 % ISS represents enhancement of 195.5 % compared to the control sample at 7 d. After undergoing 15 freeze-thaw cycles, the residual UCS ratio remains at 76.6 %, whereas the control sample exhibits signs of failure. Additionally, the dry shrinkage strain at 30 d was 66.3 % lower than that of the control sample without ISS. The mechanisms underlie that the adsorbed ISS onto iron tailings can reduce the repulsion between total fine particles by lowering the general zeta potential, thus decreasing the porosity of the road base materials. Besides, the ISS can hinder the phase transformation from ettringite (AFt) to monosulfoaluminate (AFm) and its hydrophobic groups can prevent the infiltration and migration of water. The findings reveal that ISS significantly enhances the pavement performance of the stabilized iron tailings, thereby presenting a novel approach for the incorporation of iron tailings in road construction endeavors.

Influence of different rolling passes and deformation amounts on the microstructure evolution and strengthening mechanism of Cu-Ni-Si alloy

Under the condition of controlling the total rolling deformation to 80.0%, the effects of multi-pass rolling, the ratio of deformation between the first and second stages in two-stage rolling, and aging parameters on the microstructural evolution and property enhancement of Cu-Ni-Si alloy were investigated. The results showed that the second-stage rolling promotes the formation of high-density dislocations, significantly enhancing dislocation strengthening. Simultaneously, the high-density dislocations facilitate the precipitation of the second phase during aging, and concurrently improving the strength and electrical conductivity of the alloy. In the two-stage rolling and aging process, a ratio of first-stage to second-stage rolling deformation less than 1 yields superior comprehensive properties. Specifically, when the first-stage rolling deformation is 35.0% and the second-stage deformation is 68.8%, the alloy achieves an optimal electrical conductivity of 49.53% IACS, hardness of 272.9 HV0.1, tensile strength of 773.0 MPa, and yield strength of 723.3 MPa. This is because a rolling ratio less than 1 results in higher dislocation density; the δ-Ni2Si precipitates have a coherent relationship with the Cu matrix, the interparticle spacing of precipitates is smaller. The average grain size is refined from 1.29 μm to 1.08 μm, significantly enhancing grain boundary strengthening. Dislocation strengthening and second-phase strengthening are the primary strengthening mechanisms of the alloy, and the calculated alloy strength agrees well with the experimental values, with errors less than 3.4%. Additionally, the Avrami equation in phase transformation kinetics was utilized to study the variation law of the volume fraction of the δ-Ni2Si phase with aging time.

OPTIMIZATION OF HEAT TREATMENT REGIME FOR A NEW BIODEGRADABLE Mg-Zr-Nd ALLOY WITH ENHANCED MECHANICAL PROPERTIES

Purpose. To develop a rational heat treatment regime for a new biodegradable magnesium alloy of the Mg-Zr-Nd system, to ensure enhanced mechanical properties throughout the entire treatment period. Research methods. Differential thermal analysis (DTA) was used to determine phase transformation temperatures. Microstructure analysis was conducted using optical microscopy (“Neophot 32” and “OLYMPUS IX 70”) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SELMI RЕМ-106I). Mechanical properties were determined using an INSTRON 2801 testing machine. The influence of cooling rate on microstructure and properties was studied using ProCAST simulation software. Heat treatment was carried out in a Bellevue type shaft furnace and a PAP-4M furnace. X-ray analysis was used to detect internal defects in samples. Results. A new heat treatment regime was developed for the biodegradable Mg-3.15Nd-1.25Zr-0.6Zn (wt%) alloy. Using differential thermal analysis and microstructure studies at various quenching temperatures, the optimal quenching temperature was established at 560 °C. Empirical relationships describing the influence of heat treatment parameters on the alloy's microstructure were calculated. The new heat treatment regime (quenching from 560 °C for 8 hours, air cooling + aging at 200 °C for 16 hours) resulted in improved mechanical properties (UTS = 276–282 MPa, δ = 5.2–5.8%) compared to the standard T6 regime. Scientific novelty. For the first time, a comprehensive study of the influence of heat treatment parameters on the structure and properties of a new Mg-3.15Nd-1.25Zr-0.6Zn (wt%) alloy with increased content of alloying elements was conducted. New dependencies describing the influence of quenching temperature on the alloy's grain size were established. Practical value. A new heat treatment regime for the biodegradable magnesium alloy was developed, which ensures complete dissolution of the pseudoeutectic phase and formation of strengthening phases, resulting in improved mechanical properties compared to the standard alloy Mg-2.5Nd-0.4Zn-0.5Zr (wt%) and the standard T6 regime.

Tillandsia-Inspired Ultra-Efficient Thermo-Responsive Hygroscopic Nanofibers for Solar-Driven Atmospheric Water Harvesting.

Sorption-based atmospheric water harvesting (SAWH) is a promising approach for supplying water in off-grid arid regions. However, it is difficult to improve the SAWH efficiency because water undergoes multiple phase transformations, such as water vapor-water (desorption and condensation) in the desorption phase. To address this issue, an ultrahygroscopic temperature-responsive hydrogel nanofiber inspired by Tillandsia is developed, comprising poly N-isopropylacrylamide, poly N-dimethylacetamide, and carbon nanotubes and impregnated with lithium chloride (PCP@LiCl). The hydrophobicity of the nanofiber membrane is enhanced with increasing temperature, facilitating water separation from the hydrogel in liquid form. Moreover, PCP@LiCl exhibits unique kinetics at 25 °C and 15%-30% relative humidity, capable of adsorbing moisture to saturation within 2h, and oozing liquid water within 5min under sunlight. Through global potential modeling, it is demonstrated that PCP@LiCl has potential applications in arid and semiarid regions. This study provides new insights into the design of high-performance composites for solar-powered atmospheric water harvesting.

Identifying patterns in the structural-phase transformations when processing oxide doped waste with the use of carbon reducer

The object of this study is the structural and phase transformations during the carbon reduction of tungsten high-speed steel slag in order to obtain a resource-saving alloying additive. The problem is the loss of precious elements when obtaining and using alloying material from man-made raw materials. Solving the problem is related to the definition of technological parameters to enable the reduction of losses of the corresponding elements. As a result of increasing the degree of scale reduction from 33 % to 72 % and 85 %, the strengthening of the manifestation of the solid solution of carbon and alloying elements in α-Fe relative to FeWO4, FeO and Fe3O4 was revealed. Fe3C, WC, W2C, FeW3C, Fe3W3C, Fe6W6C, VC, V2C, Cr3C2, Cr7C3 and Cr23C6 also appeared. Along with this, rounded and multifaceted particles with different chemical composition and the formation of a spongy microstructure were found. It was established that the most acceptable degree of recovery is 85 %. But achieving a recovery rate of 72 % is also sufficient. This is explained by the fact that the residual carbon in the carbides provides an increased reducing capacity, which is realized during the further reduction of oxides in the liquid metal during alloying. The spongy microstructure results in faster dissolution in contrast to standard ferroalloys, which provides a reduction in melting time while reducing spent resources. No phases with an increased tendency to sublimation were found in the obtained alloying material. That is, no additional conditions are needed that restrain the loss of alloying elements during evaporation with a gaseous phase, which provides an increase in the degree of extraction of the corresponding elements. The properties of the resulting alloying material make it possible to use it in metallurgical production when smelting alloyed steel grades in an electric arc furnace, the composition of which does not have strict restrictions on the carbon content

Temperature stable (1-x)BaAl2Si2O8-xBa3V2O8 (0.2 ≤ x ≤ 0.5) microwave dielectric composite ceramics for LTCC applications

BaAl2Si2O8 microwave dielectric ceramics possess dielectric properties of low permittivity (εr) and low loss, coupled with low synthesis cost, making them promising for commercialization. However, the hexagonal structure undergoes high-temperature phase transitions that deteriorate thermal shock resistance and durability, hindering its practical use. In this work, we report temperature-stable BaAl2Si2O8-Ba3V2O8 low temperature co-fired ceramics (LTCC). The combination of Ba3V2O8 and G9 glass achieved a near-zero τf and a thermal expansion coefficient of ∼ 8.5 ppm/℃, significantly enhancing the temperature stability of BaAl2Si2O8 ceramics. By employing ion substitution and enhancing lattice disorder, the components of G9 glass were strategically designed to successfully induce hexagonal-to-monoclinic transformation of BaAl2Si2O8 phase. The dielectric properties of 0.5BaAl2Si2O8-0.5Ba3V2O8-9 wt% G9 sintered at 900 ℃ were εr ∼9, Q×f ∼22,000 GHz and τf ∼ +1.9 ppm/℃. Good chemical compatibility with silver powders was confirmed by further investigation of the co-firing behavior. This work provides attractive candidate for BaAl2Si2O8-based LTCCs and an available approach for modifying BaAl2Si2O8 ceramics.

High-Density Atomic Level Defect Engineering of 2D Fe-Based Metal-Organic Frameworks Boosts Oxygen and Hydrogen Evolution Reactions.

Electrocatalysts based on metal-organic frameworks (MOFs) attracted significant attention for water splitting, while the transition between MOFs and metal oxyhydroxide poses a great challenge in identifying authentic active sites and long-term stability. Herein, we employ on-purpose defect engineering to create high-density atomic level defects on two-dimensional Fe-MOFs. The coordination number of Fe changes from 6 to 4.46, and over 28% of unsaturated Fe sites are formed in the optimized Fe-MOF. In situ characterizations of the most optimized Fe-MOF0.3 electrocatalyst during the oxygen evolution reaction (OER) process using Fourier transform infrared and Raman spectroscopy have revealed that some Fe unsaturated sites become oxidized with a concomitant dissociation of water molecules, causing generation of the crucial *OH intermediates and Fe oxyhydroxide. Moreover, the presence of Fe oxyhydroxide is compatible with the Volmer and Heyrovsky steps during the hydrogen evolution reaction (HER) process, which lower its energy barrier and accelerate the kinetics. As a result, the optimized Fe-MOF electrodes delivered remarkable OER (259 mV at 10 mA cm-2) and HER (36 mV at 10 mA cm-2) performance. Our study offers comprehensive understanding of the effect of phase transformation on the electrocatalytic process of MOF-based materials.

Deriving 2D in-plane heterostructures in TMDC nanosheets via electron beam irradiation

2D in-plane heterostructures can enhance the electronic performance of hybrid systems, allowing for a variety of electronic device applications. However, precisely achieving uniform in-plane heterostructures with seamless interfaces at the same atomic planes remains a challenge. In this work, 2D in-plane heterostructures were successfully fabricated through electron beam irradiation-induced phase transformation in transition metal dichalcogenides (TMDCs). The transformed phases were seamlessly connected to the pristine TMDCs, forming ultraclean and atomically sharp interfaces of heterostructures. The phases were stable and determined to be novel tetragonal-like atomic structures by experimental and theoretical analyses. In situ transmission electron microscopy revealed that the phase transition involved atomic loss, lattice contraction, and then significant structural reconstruction in the pristine TMDCs. These results demonstrate that electron irradiation can efficiently achieve precise manufacturing of 2D in-plane heterostructures, offering new opportunities for the development of high-quality 2D in-plane heterostructures and novel 2D devices with high performance.

Synergistic contributions of the poling field-induced changes in local structure on the piezoelectric properties of modified BaTiO3 system

Abstract Local structural heterogeneity is a key factor in improving the piezoelectric properties of non-centrosymmetric piezoelectric systems. This work investigates electric field-induced structural and microstructural changes at localized and average scales to elucidate the structure-property correlations that enhance piezoelectric performance in Sn-doped BaTiO3 systems exhibiting coexisting phase boundaries. Despite showing field-induced structural phase transformation, the sample displays variations in piezocoefficient values with the nature of phase boundary compositions. Raman spectroscopy measurements reveal that the TiO6/SnO6 octahedra near the tetragonal-orthorhombic phase boundary exhibit significantly greater poling field-induced structural heterogeneities in local structure compared to those near the orthorhombic-cubic phase boundary. X-ray absorption spectroscopic results on Ti and Sn K-edge in unpoled and poled samples reveal that the dipolar contribution responsible for the piezoelectricity originates from field-induced distortion associated with both TiO6 and SnO6 octahedra. Near the vicinity of the tetragonal-orthorhombic phase boundary, both the TiO6 and SnO6 contributions are cumulative and exhibit better piezoelectricity. On the other hand, at the orthorhombic-cubic phase boundary, the dipolar contributions from these octahedra are counterintuitive, resulting in a reduction of piezoelectricity. These results could provide a pathway to design materials with an enhanced piezoelectric response by considering various phase boundary aspects before applying a poling field prior to making them piezoactive.

Correction: Phase Selection During Solidification and Solid-State Phase Transformations in an Al-10Ce-8Mn (wt pct) Alloy

Correction: Phase Selection During Solidification and Solid-State Phase Transformations in an Al-10Ce-8Mn (wt pct) Alloy