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Currently, a widely accepted solution to reduce gypsum precipitation in acid leaching of low-grade uranium ore has not yet been identified. This study aims to delve into the impact of different flow rates on gypsum precipitation in ore through column leaching experiments. Complementary methods such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to characterize slag samples. The results indicate that as the flow rate surged from 63.69 Lh−1m−2 to a whopping 254.76 Lh−1m−2, the gypsum content and types in the slag decreased gradually. This can be attributed to two factors: (1) the elevation of flow rates maintains the ore heap in a lower pH environment, promoting the conversion of SO42− to HSO4−; (2) higher flow rates contribute to increased ore heap porosity, providing more migration pathways for solutions containing high concentrations of Ca2+, SO42−, and HSO4−, thus facilitating the separation of gypsum from the ore. This study affirms the feasibility of employing high-flow pre-leaching to address gypsum clogging issues, offering a new perspective for acid pre-leaching. [ABSTRACT FROM AUTHOR]

The scalable and low-cost room temperature (RT) synthesis for pure-iodine all-inorganic perovskite colloidal quantum dots (QDs) is a challenge due to the phase transition induced by thermal unequilibrium. Here, we introduce a direct RT strongly confined spontaneous crystallization strategy in a Cs-deficient reaction system without polar solvents for synthesizing stable pure-iodine all-inorganic tin-lead (Sn-Pb) alloyed perovskite colloidal QDs, which exhibit bright yellow luminescence. By tuning the ratio of Cs/Pb precursors, the size confinement effect and optical band gap of the resultant CsSnxPb1-xI3 perovskite QDs can be well controlled. This strongly confined RT approach is universal for wider bandgap bromine- and chlorine-based all-inorganic and iodine-based hybrid perovskite QDs. The alloyed CsSn0.09Pb0.91I3 QDs show superior yellow emission properties with prolonged carrier lifetime and significantly increased colloidal stability compared to the pristine CsPbI3 QDs, which is enabled by strong size confinement, Sn2+ passivation and enhanced formation energy. These findings provide a RT size-stabilized synthesis pathway to achieve high-performance pure-iodine all-inorganic Sn-Pb mixed perovskite colloidal QDs for optoelectronic applications. Photoactive pure-iodine all-inorganic colloidal perovskite quantum dots (QDs) are attractive for optoelectronic applications, however their synthesis at room temperature is challenging. Here the authors report a room temperature strongly confined strategy to synthesize CsSnxPb1-xI3 QDs. [ABSTRACT FROM AUTHOR]

Jarosite has shown excellent adsorption capacity in heavy metal adsorption processes. In this study, jarosite was synthesized using different methods, including the bio-oxidation by Acidithiobacillus ferrooxidans (BAF), rapid addition of H2O2 (RAH), and slow addition of H2O2 (SAH). The synthesized jarosite samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The influence of pH, adsorption time, and adsorbent dosage on the adsorption performance of U(VI) by jarosite was investigated through static adsorption experiments. The results revealed that jarosite with petal-like, granular, and spherical morphologies was obtained using the BAF, RAH, and SAH methods, respectively. Among jarosite synthesized by the three methods, bio-synthesized jarosite exhibited the best adsorption performance, with a maximum adsorption capacity of 96.2 mg/g for U(VI). Under the conditions of pH 7 and an adsorbent dosage of 0.8 g/L, the adsorption equilibrium was reached within 80 min. The adsorption process of U(VI) by jarosite synthesized through three methods all followed the Langmuir model. Adsorption kinetics follow a pseudo-second-order rate expression, indicating a chemical interaction between the adsorbent and the presence of U(VI). These results suggest that bio-synthesized jarosite has great potential for adsorbing U(VI) from U(VI)-contaminated wastewater. [ABSTRACT FROM AUTHOR]

Highlights: The (001)-oriented ferromagnetic La0.67Sr0.33MnO3 films are stuck onto the (011)-oriented ferroelectric single-crystal 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 substrate with 0° and 45° twist angle. By applying a 7.2 kV cm−1 electric field, the coexistence of uniaxial and fourfold in-plane magnetic anisotropy is observed in 45° Sample, while a typical uniaxial anisotropy is found in 0° Sample. Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering. In recent years, lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations. Moreover, twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures. A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process, which could provide some insight in to the physical phenomena. In this work, the La0.67Sr0.33MnO3 (001)/0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (011) (LSMO/PMN-PT) heterostructures with 45º and 0º twist angles were assembled via water-etching and transfer process. The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO < 110 >. A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO [110] easy axis is observed for the 45° Sample by applying a 7.2 kV cm−1 electrical field, significantly different from a uniaxial anisotropy with LSMO [100] easy axis for the 0° Sample. The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45° twist angle causes different lattice distortion of LSMO, thereby enhancing both the fourfold and uniaxial anisotropy. This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures. [ABSTRACT FROM AUTHOR]

Epitaxial BiEuFeO (BEFO) thin films are deposited on Nb-doped SrTiO (NSTO) substrates by pulsed laser deposition to fabricate the Pt/BEFO/NSTO (001) heterostructures. These heterostructures possess bipolar resistive switching, where the resistances versus writing voltage exhibits a distinct hysteresis loop and a memristive behavior with good retention and anti-fatigue characteristics. The local resistive switching is confirmed by the conductive atomic force microscopy (C-AFM), suggesting the possibility to scale down the memory cell size. The observed memristive behavior could be attributed to the ferroelectric polarization effect, which modulates the height of potential barrier and width of depletion region at the BEFO/NSTO interface. The continuously tunable resistive switching behavior could be useful to achieve non-volatile, high-density, multilevel random access memory with low energy consumption. [ABSTRACT FROM AUTHOR]

Ceramic film capacitors with high dielectric constant and high breakdown strength hold special promise for applications demanding high power density. By means of chemical solution deposition, we deposited ≈2-μm-thick films of lanthanum-doped lead zirconate titanate (PLZT) on LaNiO-buffered Ni (LNO/Ni) foils and platinized silicon (PtSi) substrates. The dielectric properties and energy storage performance of the resulting samples were determined under a high level of applied electric field. X-ray diffraction stress analysis revealed that PLZT on LNO/Ni bears a compressive stress of ≈370 MPa while PLZT on PtSi endures a tensile stress of ≈250 MPa. Compressive stress was found to lead to heightened polarization, improved tunability, increased irreversible domain wall motion, and enhanced breakdown strength for PLZT deposited on the LNO/Ni as compared with the PtSi substrate. We observed a tunability of ≈55 and ≈40 % at room temperature under 100 kV/cm applied field, remanent polarization of ≈23.5 and ≈7.4 µC/cm, coercive electric field of ≈25.6 and ≈21.1 kV/cm, and dielectric breakdown strength of ≈2.6 and ≈1.5 MV/cm for PLZT deposited on LNO/Ni foils and PtSi substrates, respectively. A high recoverable energy density of ≈85 J/cm and energy conversion efficiency of ≈65 % were measured on the PLZT film grown on LNO/Ni. [ABSTRACT FROM AUTHOR]

Piezoelectric 0.365BiScO-0.635PbTiO (BSPT) ceramics are promising for high temperature actuator applications due to their high Curie temperature and high piezoelectric coefficient. However, relatively low mechanical quality factor (Q ≈ 25) and high dielectric loss (tan δ ≈ 0.04) would lead to self-heating and property degradation if BSPT ceramics are used in piezoelectric actuators that work at resonant frequency. In this work, Mn-doped BSPT ceramics were prepared by conventional solid state reaction to modify the electrical properties. Excellent hard piezoelectric properties of d ≈ 200 pC/N, Q ≈ 210, and tan δ ≈ 0.015 were measured in the BSPT ceramics doped with 1.2 wt% of Mn. Further, Mn-doped BSPT ceramics showed a depoling temperature of 360 °C, about 100 °C higher than that of commercialized hard PZT ceramics. These results indicate that piezoelectric actuators fabricated with Mn-doped BSPT ceramics would exhibit enhanced thermal stability and higher energy efficiency in a wide temperature range. [ABSTRACT FROM AUTHOR]

In our experiment, the influence of growth parameters of the spin-spray technique upon the microstructure and magnetic/microwave properties of NiZn spinel ferrite thin film was studied. By varying the pH value of precursor and oxidizer, the microstructure of NiZn ferrite thin film can be manipulated, further, bringing varying magnetic/microwave properties. High permeability μ′ > 200 at 0.5 GHz with low loss tanδ ~0.027 at 3-5 GHz range was achieved at precursor pH value of 4.6 and oxidizer pH value of 9.6. These magnetic/microwave properties are ideal for GHz range microwave application, for example, inductors, antennas, and electromagnetic interference suppression. [ABSTRACT FROM AUTHOR]

Ordered BiFeO (BFO) and BiFeCoO (BFC) nanotubes arrays were successfully synthesized by a sol-gel anodic aluminum oxide template method. Both kinds of nanotubes had straight and smooth profiles with diameters of about 200 nm and wall thicknesses of about 20 nm. A perovskite-type structure of BFO was confirmed in these nanotubes by high-resolution transmission electron microscopy. The dielectric properties of these nanotube arrays were measured and larger permittivity was obtained for the BFC nanotubes via adopting a columnar composite structure model. Ferromagnetic measurement showed enhanced ferromagnetism for the sample with Co doping. These improvements in dielectric constant and ferromagnetism of the nanotubes by Co doping may be mainly attributed, respectively, to the lattice distortion and the breakage of the spin cycloid period of the BFC nanotubes. [ABSTRACT FROM AUTHOR]

-site Ce and B-site Zr codoped BiCeFeZrO (BCFZ) thin films with different compositions were successfully prepared on the Pt/Ti/SiO/Si substrates by chemical solution deposition. The influence of the A-site Ce and B-site Zr codoping on the structure, surface morphology, electrical and magnetic properties of BFO films were investigated, respectively. The comparative study suggested that the A-site Ce doping with various contents have notable influences on the electrical properties of the BFO films, while the B-site Zr doping with different contents affect mainly the magnetic properties of the BFO films. Compared with the other BCFZ films studied here, the BiCeFeZrO film showed the lowest dielectric loss and leakage current density, a well-squared P- E loop and fatigue-free characteristics as well as the strong magnetization. [ABSTRACT FROM AUTHOR]