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Sodium-cerium molybdate, NaCe(MoO4)2, belongs to the family of double alkaline rare-earth molybdate, and it holds significant importance across various technological domains, such as environmental remediation and energy conversion. Despite its importance, the behavior of NaCe(MoO4)2 under high-pressure conditions remains unexplored. This study uses synchrotron x-ray diffraction and Raman spectroscopy to investigate NaCe(MoO4)2in situ under high-pressure conditions. We observed a pressure-induced phase transition from the scheelite to the M ′ -fergusonite structure type on a double molybdate at approximately 10 GPa. These findings contribute to a deeper understanding of the structural stability of NaCe(MoO4)2 and shed light on the broader field of high-pressure studies of double molybdates. [ABSTRACT FROM AUTHOR]

Sodium-cerium molybdate, NaCe(MoO4)2, belongs to the family of double alkaline rare-earth molybdate, and it holds significant importance across various technological domains, such as environmental remediation and energy conversion. Despite its importance, the behavior of NaCe(MoO4)2 under high-pressure conditions remains unexplored. This study uses synchrotron x-ray diffraction and Raman spectroscopy to investigate NaCe(MoO4)2in situ under high-pressure conditions. We observed a pressure-induced phase transition from the scheelite to the M ′ -fergusonite structure type on a double molybdate at approximately 10 GPa. These findings contribute to a deeper understanding of the structural stability of NaCe(MoO4)2 and shed light on the broader field of high-pressure studies of double molybdates. [ABSTRACT FROM AUTHOR]

Abstract: In this work we investigate the vibrational properties of anhydrous and hydrated yttrium molybdate as a function of hydrostatic pressure. An analysis of vibrational modes suggests that the anhydrous material experiences a phase transformation from orthorhombic to a lower symmetry phase (probably monoclinic) about 0.3GPa, and to a highly disordered phase above 2.4GPa. The structural transformation to the high-pressure disordered phase is not reversible and suggests the onset of a pressure-induced amorphization process. The vibrational mode dependence on pressure is discussed considering lattice dynamics calculations. [Copyright &y& Elsevier]

Abstract: Temperature-dependent Raman spectroscopy studies of K2WO4 and MgMoO4 polycrystals were performed in order to obtain information about vibrational and structural changes in these materials as a function of temperature. The stability of the monoclinic phase for both K2WO4 and MgMoO4 samples was assessed and our results indicated that this phase is stable in the 295–723K and 300–770K ranges for K2WO4 and MgMoO4, respectively. It was observed that both samples underwent two phase transformations above room temperature. The first phase transformations which occur at about 633K and 640K for K2WO4 and MgMoO4, respectively, is most likely connected with weak tilting and/or rotations of WO4/MoO4 tetrahedral units that lead to a disorder in the oxygen sublattice. Raman spectroscopy data also indicated that K2WO4 and MgMoO4 exhibited a first-order phase transition at around 723K and 770K, respectively, changing from monoclinic to hexagonal symmetry. [Copyright &y& Elsevier]

Abstract: High pressure Raman scattering experiments were performed on RbFe(MoO4)2. These experiments revealed that two phase transitions take place in RbFe(MoO4)2 at very low pressures, i.e. between ambient pressure and 0.2GPa and between 0.4 and 0.7GPa. Raman results showed that at the first phase transition the room temperature P3̄m1 phase transforms into the P3̄ phase, which is also observed at ambient pressure below 190K. The second pressure-induced phase transition occurs into a low symmetry phase of unknown symmetry. The performed lattice dynamics calculations for the P3̄m1 phase and ab initio calculation of the structural changes under hydrostatic pressure helped us to get better insights into the mechanism of the observed phase transitions. [Copyright &y& Elsevier]

Abstract: In this paper, we present results of high-pressure Raman scattering studies in β-MgMoO4 from atmospheric to 8.5GPa. The experiments were carried out using methanol–ethanol as pressure medium. By analyzing the pressure dependence of the Raman data (change in the number of lattice modes, splitting of bands and wavenumber discontinuities) we were able to observe a phase transition undergone by the β-MgMoO4 at 1.4GPa, which is only completed at ∼5GPa. The transition was observed to be irreversible and the modifications in the Raman spectra were attributed to the changes in coordination of Mo ions from tetrahedral to octahedral. The transition possibly changes the original C2/m symmetry to C2/m or to P2/c. Implication on the phase transition for similar molybdate structures, such as α-MnMoO4, is also highlighted. [Copyright &y& Elsevier]

Magnetic nanoparticles, such as magnetite (Fe 3 O 4 ), exhibit superparamagnetic properties below 15 nm at room temperature. They are being explored for medical applications, and the coprecipitation technique is preferred for cost-effective production. This study investigates the impact of synthesis temperature on the nanoparticles' physicochemical characteristics. Two types of magnetic analysis were conducted. Samples T 40, T 50, and T 60 displayed superparamagnetic behavior, as evidenced by the magnetization curves. The experiments verified the development of magnetic nanoparticles with an average diameter of approximately dozens of nanometers, as determined by various measurement methods such as XDR, Raman, and TEM. Raman spectroscopy showed the characteristic bands of the magnetite phase at 319, 364, 499, and 680 cm -1 . This was confirmed in the second analysis with the ZFC-FC curves, which showed that the samples' blocking temperatures were below ambient temperature. ZFC-FC curves revealed a similar magnetization of about 30 emu/g when applying a magnetic field of 5 kOe., Competing Interests: All authors declare that there are no financial and personal relationships with other people or organizations that could inappropriately influence (bias) our paper., (© 2024 The Authors.)

The present study reports the synthesis, characterization, and antibacterial properties of silver trimolybdate (Ag 2 Mo 3 O 10 .2H 2 O) nanorods. The synthesis was performed using a conventional hydrothermal method. The sample was characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-Vis-NIR diffuse reflectance, thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC). The direct antibacterial activity was evaluated using the microdilution method to determine the minimum inhibitory concentration (MIC). To assess the ability of Ag 2 Mo 3 O 10 .2H 2 O nanorods to modulate antibacterial resistance, the MIC of aminoglycosides was established in the presence of a subinhibitory concentration of this substance alone and associated with LED light exposure. The characterization of the sample indicated that the synthesis of silver trimolybdate generated nanometric crystals with rod-like morphology, without secondary phases. The treatment with Ag 2 Mo 3 O 10 .2H 2 O nanorods alone or combined with visible LED lights exhibited clinically relevant antibacterial activity against both Gram-negative and Gram-positive bacteria. This nanostructure presented a variable antibiotic-modulating action, which was not improved by visible LED light exposure. Nevertheless, LED lights showed promising antibiotic-enhancing activities in the absence of Ag 2 Mo 3 O 10 .2H 2 O nanorods. In conclusion, silver trimolybdate dihydrate nanorods have antibacterial properties that can be photocatalysed by visible-light exposure. While showing the potential use to combat antibacterial resistance, the simultaneous combination of silver trimolybdate, visible LED lights, and antibacterial drugs should be carefully analysed to avoid antagonist effects that could impair the effectiveness of antibiotic therapy., Competing Interests: The authors declare that there are no conflicts of interest., (Copyright © 2022 Maria Karollyna do Nascimento Silva Leandro et al.)

This study aimed to systematically understand the magnetic properties of magnetite (Fe 3 O 4 ) nanoparticles functionalized with different Pluronic F-127 surfactant concentrations (Fe 3 O 4 @Pluronic F-127) obtained by using an improved magnetic characterization method based on three-dimensional magnetic maps generated by scanning magnetic microscopy. Additionally, these Fe 3 O 4 and Fe 3 O 4 @Pluronic F-127 nanoparticles, as promising systems for biomedical applications, were prepared by a wet chemical reaction. The magnetization curve was obtained through these three-dimensional maps, confirming that both Fe 3 O 4 and Fe 3 O 4 @Pluronic F-127 nanoparticles have a superparamagnetic behavior. The as-prepared samples, stored at approximately 20 °C, showed no change in the magnetization curve even months after their generation, resulting in no nanoparticles free from oxidation, as Raman measurements have confirmed. Furthermore, by applying this magnetic technique, it was possible to estimate that the nanoparticles' magnetic core diameter was about 5 nm. Our results were confirmed by comparison with other techniques, namely as transmission electron microscopy imaging and diffraction together with Raman spectroscopy. Finally, these results, in addition to validating scanning magnetic microscopy, also highlight its potential for a detailed magnetic characterization of nanoparticles.

Nano-heterostructures of titanate nanotubes were synthesized and they revealed a complex structure with the formation of TiO 2 (anatase), CeO 2 , Ag 2 O and metallic silver nanoparticles on the outer walls and intercalation of Ce 4+ and Ag + into the interlayer spaces of the nanotubes by microwave-assisted hydrothermal process and subjected to ion exchange reactions. To the best of our knowledge, this is the first reported silver and cerium co-exchanged titanate nanotubes for bio-applications. The co-ion exchange processes preserved the original tubular structure of titanate nanotubes with significant changes of the superficial as well as interlamellar environment. This study opens up possibility of synthesizing complex, functional nano-heterostructure with the scope of modification of the final structure, especially the amount and oxidation state of the intercalated cation (Ce 4+ , Ce 3+ and Ag + ) as well as the quantity and variety of the decorating nanoparticles (CeO 2 , Ag 2 O or metallic Ag). The interplay of which, in turn, can lead to important biological properties and applications, owing to their ion-liberation capacity. The samples were tested in antibacterial activity with two different kind of bacteria (gram positive and negative), cell cytotoxicity and adhesion, and it was found that the nano-heterostructure formed shows high antibacterial activity with low cytotoxicity and high cell adhesion, which makes it a promising material for further health applications., Competing Interests: Declaration of competing interest On behalf of the authors of the article “Synthesis of Silver-Cerium Titanate Nanotubes and their surface properties and antibacterial applications”, I certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Scanning magnetic microscopy is a tool that has been used to map magnetic fields with good spatial resolution and field sensitivity. This technology has great advantages over other instruments; for example, its operation does not require cryogenic technology, which reduces its operational cost and complexity. Here, we presented a spatial domain technique based on an equivalent layer approach for processing the data set produced by magnetic microscopy. This approach estimated a magnetic moment distribution over a fictitious layer composed by a set of dipoles located below the observation plane. For this purpose, we formulated a linear inverse problem for calculating the magnetic vector and its amplitude. Vector field maps are valuable tools for the magnetic interpretation of samples with a high spatial variability of magnetization. These maps could provide comprehensive information regarding the spatial distribution of magnetic carriers. In addition, this approach might be useful for characterizing isolated areas over samples or investigating the spatial magnetization distribution of bulk samples at the micro and millimeter scales. This technique could be useful for many applications that require samples that need to be mapped without a magnetic field at room temperature, including rock magnetism.

We improved a magnetic scanning microscope for measuring the magnetic properties of minerals in thin sections of geological samples at submillimeter scales. The microscope is comprised of a 200 µm diameter Hall sensor that is located at a distance of 142 µm from the sample; an electromagnet capable of applying up to 500 mT DC magnetic fields to the sample over a 40 mm diameter region; a second Hall sensor arranged in a gradiometric configuration to cancel the background signal applied by the electromagnet and reduce the overall noise in the system; a custom-designed electronics system to bias the sensors and allow adjustments to the background signal cancelation; and a scanning XY stage with micrometer resolution. Our system achieves a spatial resolution of 200 µm with a noise at 6.0 Hz of 300 nT rms /(Hz) 1/2 in an unshielded environment. The magnetic moment sensitivity is 1.3 × 10 -11 Am². We successfully measured the representative magnetization of a geological sample using an alternative model that takes the sample geometry into account and identified different micrometric characteristics in the sample slice.