Paramagnetic Behavior Research Articles

Syntheses, crystal structures, and physical properties of non-centrosymmetric MgIn2Te4 and MnIn2Te4

In this study, we prepared two ternary tellurides, MgIn2Te4 and MnIn2Te4 (single crystals and bulk polycrystalline phases), by directly fusing the elements at high temperatures using the sealed tube synthesis method. Single crystal X-ray diffraction studies confirmed the non-centrosymmetric tetragonal structures (space group: I4‾ 2m) of the MgIn2Te4 and MnIn2Te4 phases with two formula units (Z = 2). Interestingly, the refined unit cell lengths of a = b = 6.2149(5) Å and c = 12.4240(19) Å for the MgIn2Te4 are slightly longer than those of the MnIn2Te4 structure (a = b = 6.1901(3) Å and c = 12.3877(7) Å). The asymmetric unit of these two MIn2Te4 (M = Mg and Mn) isostructural compounds contains three crystallographically independent sites: two disordered metal sites (M1/In1, M2/In2) and one Te1 site. Each metal atom in these structures is tetrahedrally coordinated with four Te1 atoms. Optical absorption studies for polycrystalline MgIn2Te4 and MnIn2Te4 samples showed bandgaps of 1.1(2) eV and 0.9(2) eV, respectively, consistent with these powders' black color. Seebeck studies confirm that holes are the majority of charge carriers for the MgIn2Te4 sample. The thermal conductivity (ktot) studies of the samples reveal ultralow values at 773 K: 0.37 Wm−1K−1 for the MgIn2Te4 and 0.44 Wm−1K−1 for the MnIn2Te4. Magnetic studies on the polycrystalline MnIn2Te4 show a paramagnetic behavior with a magnetic moment of 5.73 μB. Our theoretical studies indicate the possibility of achieving a high thermoelectric figure of merit (zT > 1.5) by optimizing the hole concentration in the MgIn2Te4 sample.

Tuning magnetic and optical properties in Mn x Zn1−x PS3 single crystals by the alloying composition

The exploration of two-dimensional (2D) antiferromagnetic (AFM) materials has shown great promise and interest in tuning the magnetic and electronic properties as well as studying magneto-optical effects. The current work investigates the control of magneto-optical interactions in alloyed Mn x Zn1−x PS3 lamellar semiconductor single crystals, with the Mn/Zn ratio regulating the coupling strength. Magnetic susceptibility results show a retention of AFM order followed by a decrease in Néel temperatures down to ∼40% Mn concentration, below which a paramagnetic behavior is observed. Absorption measurements reveal an increase in bandgap energy with higher Zn(II) concentration, and the presence of Mn(II) d-d transition below the absorption edge. DFT + U approach qualitatively explained the origin and the position of the experimentally observed mid band-gap states in pure MnPS3, and corresponding peaks visible in the alloyed systems Mn x Zn1‒x PS3. Accordingly, emission at 1.3 eV in all alloyed compounds results from recombination from a 4T1g Mn(II) excited state to a hybrid p-d state at the valence band. Most significant, temperature-dependent photoluminescence (PL) intensity trends demonstrate strong magneto-optical coupling in compositions with x > 0.65. This study underscores the potential of tailored alloy compositions as a means to control magnetic and optical properties in 2D materials, paving the way for advances in spin-based technologies.

Synthesis, Characterisation, Hirshfeld Surface Analysis, Magnetic Susceptibility, DFT Calculations, pkCSM Profile, and Biological Activities of Novel Mono‐, Di‐, and Multinuclear Cobalt (II) Complexes

AbstractThis study explores the synthesis and diverse properties of newly synthesised water‐soluble cobalt (II) complexes (1–3). Analysis of the complexes through various methods, including Hirshfeld surface analysis, reveals distinctive intermolecular interactions, particularly robust H‐bonding contributions to crystal packing. 2D fingerprint plots provide quantitative insights into supramolecular interactions, while TGA‐DSC analysis elucidates multi‐step decomposition processes, mainly involving organic moieties. FT‐IR and SCXRD confirm the structures of the complexes. Magnetic susceptibility measurements show paramagnetic behaviour in all complexes. FMO calculations expose HOMO‐LUMO gaps and charge transfer processes, with NBO analysis emphasizing the significance of chloride, nitrogen, and oxygen atoms in coordination. In addition, pkCSM profile was carried out. The biological properties of the complexes reveal potent antibacterial activity for 2 and 3 against Gram‐positive and Gram‐negative bacteria. Despite lower antibacterial efficacy compared to standard antibiotics, their water solubility suggests potential human pharmacological applications. In terms of anti‐inflammatory activity, all three complexes exhibit concentration‐dependent prevention of ovalbumin denaturation, with 2 being the most effective. Compound 3, despite having seven carboxyl groups, exhibits the weakest anti‐inflammatory effect, potentially attributed to complex formation obscuring these groups. Furthermore, all complexes display antioxidant activities; 1 and 2 are greater than BHT in the ferric thiocyanate assay.

Magnetic short-range order and Griffiths-like phase in the S-1/2 spin-dimer ferromagnet BaCu(SeO3)2

The polycrystals of S = 1/2 spin-dimer compound BaCu(SeO3)2 have been synthesized by using solid-state reaction. Without long-range order, the magnetic susceptibility χ(T) curve presents two anomalies at T1 = 5 K and TG = 58 K due to antiferromagnetic (AFM) short-range order and short-range ferromagnetic (FM) correlations, respectively, which is further supported by the specific heat and electron spin resonance data. The high-temperature χ(T) curve follows the Curie-Weiss law with θCW = 11.3 K, showing the dominant intradimer FM interaction. The magnetization M(H) curve at 2 K is characteristic of an AFM-FM transition at 0.4 T, suggesting the weak interdimer AFM couplings. The density function theory calculations and quantum Monte Carlo simulations allow an estimation of the intradimer and interdimer exchanges with J1/kB = 39.09 K, J2/kB = −1.51 K, and J3/kB = −1.68 K. Interestingly, the χ−1(T) curve within θCW <T <TG deviates downward from paramagnetic Curie-Weiss behavior, mimicking the Griffiths-like phase. This is further supported by the ac magnetic susceptibility and magnetic relaxation measurements. The competing intradimer FM and interdimer AFM exchanges with a subtle ratio between them are proposed to be responsible for the formation of Griffiths-like phase.

Induced ferromagnetism in Ni(II) doped ZnO monolayers via Al co-doping and their optical characteristics: ab initio study

For applications in magneto-electronic devices, diluted magnetic semiconductors (DMSs) usually exhibit spin-dependent coupling and induced ferromagnetism at high Curie temperatures. The processes behind the behavior of optical emission and ferromagnetism, which can be identified by complicated microstructural and chemical characteristics, are still not well understood. In this study, the impact of Al co-doping on the electronic, optical, and magnetic properties of Ni(II) doped ZnO monolayers has been investigated using first principles calculations. Ferromagnetism in the co-doped monolayer is mainly triggered by the exchange coupling between the electrons provided by Al co-doping and Ni(II)-d states; therefore, the estimated Curie temperature is greater than room temperature. The spin–spin couplings in mono-doped and co-doped monolayers were explained using the band-coupling mechanism. Based on the optical study, we observed that the Ni-related absorption peak occurred at 2.13–2.17 eV, showing a redshift as Ni concentrations increased. The FM coupling between Ni ions in the co-doped monolayer may be responsible for the reduction in the fundamental band gap seen with Al co-doping. We observed peaks in the near IR and visible regions of the co-doped monolayer, which improve the optoelectronic device’s photovoltaic performance. Additionally, the correlation between optical characteristics and spin–spin couplings has been studied. We found that the Ni(II)’s d–d transition bands or fundamental band gap in the near configuration undergoes a significant shift in response to AFM and FM coupling, whereas in the far configuration, they have a negligible shift due to the paramagnetic behavior of the Ni ions. These findings suggest that the magnetic coupling in DMS may be utilized for controlling the optical characteristics.

Real Structure, Magnetism and Chemical Bonding of SmSi3‐x

New metastable SmSi3‐x (x = 0‐0.05) is obtained by high‐pressure high‐temperature synthesis (9.5 GPa, 870‐1270 K). Powder diffraction data refinements reveal that the crystal structure of SmSi3 is isotypic to that of YbSi3 (space group I4/mmm, a = 7.23634(5) Å, c = 11.0854(1) Å). In the crystal structure, two types of Si2 dumbbells agglomerate into layers, which embed the samarium atoms. At ambient pressure, SmSi3 decomposes exothermally upon heating into Si and SmSi2‐x. Single‐crystal structure refinements of a specimen SmSi3‐x (x=0.05) reveal considerable electron density, which is not accounted for by the YbSi3 model. The additional maxima can be assigned to disorder which affects the samarium positions and induces silicon vacancies. Scanning transmission electron microscopy experiments evidence that the disorder can be attributed to extended defects. Magnetic measurements on SmSi3‐x reveal van Vleck paramagnetic behavior and antiferromagnetic ordering at low temperatures. Computations within the local spin density approximation (LSDA and LSDA+U) on the crystal structure of SmSi3 reproduce the anti­ferro­magnetic coupling as the favored long‐range order. Quantum chemical analysis of the chemical bonding in SmSi3 reveals two‐center two‐electron bonds within the Si2 dumbbells plus a total of a little less than four electrons in lone pairs at each silicon atom.

Syntheses, crystal structures, and magnetic behaviors of phenoxo-bridged manganese compounds based on tetradentate Schiff bases

Six Mn(II)/Mn(III) coordination compounds with tetradentate Schiff bases, [Mn(L1)(N3)]2 (1), [Mn(L2)(N3)]2 (2), [Mn(L1)(SCN)]2 (3), [Mn(L2)(SCN)]2[Mn(L2)(SCN)(C2H5OH)]2 (4), [Mn(L1)(CH3OH)]2 (5), and [Mn3(L2)2(CH3COO)2] (6) [H2L1 = N,N'-bis(5-chloro-salicylaidimine)-1,2-diaminop-ropane), H2L2 = N,N'-bis(5-chloro-salicylaidimine)-2,2-dimethylpropane-1,3-diami- ne], were structurally and magnetically characterized by X-ray single crystal diffraction, powder X-ray diffraction (PXRD), elemental analysis, infrared (IR) spectroscopy and magnetic susceptibility measurement. Structural analysis reveals that each manganese center displays a typical Jahn-Teller distortion. Compounds 1, 2, 3 and 5 are binuclear systems in which two central manganese atoms are connected by di-u2-phenoxo-bridging from two inverse tetradentate ligands. The asymmetric unit of compound 4 contains two moieties, which is composed of a dimeric unit [Mn(L1)(SCN)]2 and two monomeric units [Mn(L1)(SCN)(C2H5OH)]. Compound 6 is a linear homo-trinuclear structure. Dc variable-temperature magnetic susceptibility measurements show that compounds 1, 2, 4 and 5 exhibit paramagnetic behaviors with J = +0.202 cm−1 for 1, J = +0.203 cm−1 for 2, J = +1.03 cm−1 for 4 and + 0.152 cm−1 for 5, respectively, whereas compounds 3 and 6 show a strong antiferromagnetic interaction between the high-spin metal centers. In addition, we investigated the relationship between the structures and magnetic behaviour.

Iron(II)-induced defect luminescence and deconvolution of ferromagnetic and paramagnetic behaviour in Zn(1-x)FexO (x = 0.01, 0.03, 0.05) nanoparticles

Zn(1-x)FexO (x = 0.00, 0.01, 0.03, 0.05) nanoparticles (NPs) were prepared by co-precipitation method and the wurtzite phase was confirmed by x-ray diffraction (XRD). The average crystallite size changes from 36 nm to 26 → 23→22 nm as the Fe-doping level varies from 0 to 1% → 3% → 5 % and the lattice strain increases concomitantly. The pristine ZnO NPs exhibit well-defined peak at 370 nm in the UV–vis absorption spectra which gets broadened on Fe-doping. The photoluminescence (PL) spectra of the pristine ZnO NPs shows a dominant excitonic peak at 390 nm. On Fe(II)-doping, new PL peaks at 449, 490 and 525 nm appear that are attributed to Zn-interstitials (Zni), oxygen vacancies (VO) and Zn vacancies (VZn), respectively. For all the Fe-doped ZnO NPs, M vs H plots have a complex non-saturating appearance indicating combination of ferromagnetic (FM) and paramagnetic (PM) behaviors. The subtraction of PM contribution revealed the FM curves with saturation magnetization (Ms). On going from 1% to 5% Fe-doping, the Ms values increase substantially by 39 times (0.00361 → 0.1398 emu/g) whereas the paramagnetic susceptibility, χP, increased 35 times (0.28 × 10−6 → 9.72 × 10−6 emu g−1 Oe−1).

Deciphering Iberian Variscan Orogen Magmatism Using the Anisotropy of Magnetic Susceptibility from Granites

In this paper, we have synthesized the information derived from more than 20 papers and PhD theses on the anisotropy of the magnetic susceptibility (AMS) of 19 Variscan granite plutons, spanning the period between 320 Ma and 296 Ma. The AMS data are obtained from 876 sampling sites with more than 7080 AMS measurements and a re-interpretation is proposed. The studied granites exhibit a magnetic susceptibility (Km) ranging from 30 to 10,436 × 10−6 SI units. Most granites typically exhibit Km values below 1000 × 10−6 SI, indicative of paramagnetic behavior. Biotite serves as the main carrier of iron (Fe), emphasizing the reduced conditions prevalent during the formation of granite melts in the Variscan orogeny. The AMS fabrics of the studied granite plutons record the magma strain, expressing the chronologic evolution of the stress field during the orogeny. This chronologic approach highlights the magmatic events between around 330 and 315 Ma, occurring in an extensional regime, in which the Borralha pluton is an example of a suite that recorded this extensional AMS fabric. Plutons with ages between 315 and 305 Ma show AMS fabrics, pointing out their emplacement in a compressional tectonic regime related to the Variscan collision. The plutons, younger than 305 Ma, record AMS fabrics indicating that the tectonic setting for emplacement changes from a wrench regime to an extensional one at the end of the collision stage. This is evident as there is a chronological overlap between the granites that exhibit AMS fabrics indicating extension and the ones that have AMS fabrics indicating a wrench regime.

D0 ferromagnetic display of zirconia nanocrystallites and the impact of gold doping on their structural, optical, and magnetic properties

[Formula: see text] ferromagnetism is currently under extensive investigation as an alternative to transition metal-doped dilute magnetic semiconductors in the continuously evolving field of spintronics and optoelectronic applications. The literature contains numerous conflicting sources regarding its origin, specifically in materials such as oxides, making it a subject of ongoing controversy. This work mainly centers on the interplay among gold doping, oxygen concentration, and resulting changes in the structural, optical, and magnetic characteristics, with a specific focus on [Formula: see text] ferromagnetism and room temperature ferromagnetism in sol–gel synthesized zirconia nanocrystals. The powder samples crystallized in a mixed monoclinic-tetragonal phase. The weak absorbance band around 280[Formula: see text]nm and the O-1s peak in X-ray photoelectron spectroscopy provide insights into the metastable tetragonal phase’s stability, attributed to oxygen vacancies. The bandgap slightly increases from 4.6[Formula: see text]eV to 5.0[Formula: see text]eV due to the transformation from a tetragonal to a monoclinic phase. Magnetic studies reveal room-temperature ferromagnetism induced by oxygen vacancies in undoped zirconia, while a shift from ferromagnetic to paramagnetic behavior occurs in gold-infused zirconia samples.

Cr5.7Si2.3P8N24-A Chromium(+IV) Nitridosilicate Phosphate with Amphibole-Type Structure.

The first nitridic analog of an amphibole mineral, the quaternary nitridosilicate phosphate Cr5.7Si2.3P8N24 was synthesized under high-pressure high-temperature conditions at 1400 °C and 12 GPa from the binary nitrides Cr2N, Si3N4 and P3N5, using NH4N3 and NH4F as additional nitrogen source and mineralizing agent, respectively. The crystal structure was elucidated by single-crystal X-ray diffraction with microfocused synchrotron radiation (C2/m, a=9.6002(19), b=17.107(3), c=4.8530(10) Å, β=109.65(3)°). The elemental composition was analyzed by energy dispersive X-ray spectroscopy. The structure consists of vertex-sharing PN4-tetrahedra forming zweier double chains and edge-sharing (Si,Cr)-centered octahedra forming separated ribbons. Atomic resolution scanning transmission electron microscopy shows ordered Si and Cr sites next to a disordered Si/Cr site. Optical spectroscopy indicates a band gap of 2.1 eV. Susceptibility measurements show paramagnetic behavior and support the oxidation state Cr+IV, which is confirmed by EPR. The comprehensive analysis expands the field of Cr-N chemistry and provides access to a nitride analog of one of the most prevalent silicate structures.

Cr5.7Si2.3P8N24—A Chromium(+IV) Nitridosilicate Phosphate with Amphibole‐Type Structure

AbstractThe first nitridic analog of an amphibole mineral, the quaternary nitridosilicate phosphate Cr5.7Si2.3P8N24 was synthesized under high‐pressure high‐temperature conditions at 1400 °C and 12 GPa from the binary nitrides Cr2N, Si3N4 and P3N5, using NH4N3 and NH4F as additional nitrogen source and mineralizing agent, respectively. The crystal structure was elucidated by single‐crystal X‐ray diffraction with microfocused synchrotron radiation (C2/m, a=9.6002(19), b=17.107(3), c=4.8530(10) Å, β=109.65(3)°). The elemental composition was analyzed by energy dispersive X‐ray spectroscopy. The structure consists of vertex‐sharing PN4‐tetrahedra forming zweier double chains and edge‐sharing (Si,Cr)‐centered octahedra forming separated ribbons. Atomic resolution scanning transmission electron microscopy shows ordered Si and Cr sites next to a disordered Si/Cr site. Optical spectroscopy indicates a band gap of 2.1 eV. Susceptibility measurements show paramagnetic behavior and support the oxidation state Cr+IV, which is confirmed by EPR. The comprehensive analysis expands the field of Cr−N chemistry and provides access to a nitride analog of one of the most prevalent silicate structures.

On the correlation between mechanical, optical, and magnetic properties of co-substituted Sn1-x-yZnxMyOz metal-oxide ceramics with M = Fe, Co, Ni, and Mn

We report here the FTIR, optical, and magnetic properties of Sn1-x-yZnxMyOz ceramics with various x, y, and M. The pure samples are called S1, S2, and S3 for ZnO, SnO2, and SnZn. The co-substituted samples are called S4, S5, S6, and S7 for SnZnFe, SnZnCo, SnZnNi, and SnZnMn, with Zn = 0.50, Sn = 0.25, and M = 0.25. The Young's modulus, was decreased from 5.70 (D/cm2) for S3 to 4.59, 3.14, 2.59, and 3.05 (D/cm2) for S4, S5, S6, and S7. The Eg was decreased from 2.13 eV for S3 to 2.16, 2,2, and 1.6 eV for S4, S5, S6, and S7. The pure samples (S1–S3) exhibit ferromagnetic behavior at 300 K, and combination of paramagnetic and ferromagnetic behaviors at 10K. In contrast, the samples (S4–S7) exhibit a combination of paramagnetic and ferromagnetic behaviours at both temperatures. The Curie temperature (Tc) obtained through zero-field cooling (ZFC) and field cooling (FC) is close to 300 K for S1–S3, S5, S6, 200 K for S4, and 20 K for S7. The real saturated magnetization (Ms) of the ZnO sample was decreased by the addition of SnO2, and then increased by the addition of Mn, Ni, Fe, and Co sequentially. Ms was increased from 12.31 (emu/g) for S3 at 300 to 16.24, 31.04, 27.27, and 10.49 (emu/g) for S4, S5, S6, and S7, and from 16 (emu/g) to 87, 730, 83, and 29 at 10 K. Remnant magnetization (Mr) decreases with the addition of SnO2 to ZnO and is not affected by the addition of TMs, just in the case of Co, where it increases. The coercive field decreases, but the switching field increases markedly with the addition of Mn and Ni, transforming the system from a hard magnetization to a soft magnetization system.

Theoretical prediction of closed-shell paramagnetism for scandium and yttrium hydride.

Following chemical intuition, one would expect that all closed-shell molecules are diamagnetic. However, it is known that this is not the case for some second-row hydrides with low-lying unoccupied orbitals due to an unquenching of the total angular momentum in the presence of an external magnetic field. In this article, the transition-metal hydrides ScH and YH are investigated, assuming a similar unquenching effect involving low-lying unoccupied and orbitals formed from the metal orbitals rather than the orbitals. We are comparing results obtained with various quantum-chemical methods (HF, CCSD, CCSD(T), CCSDT) and basis sets. The obtained positive values for the magnetizabilities clearly indicate paramagnetic behavior. Vibrational effects on the magnetizability tensor are also considered, but these effects are small and do not change the overall conclusion that both ScH and YH are further examples for closed-shell paramagnetism.

Separating the contributions of the magnetic subsystems in antiferromagnetic ferrihydrite nanoparticles by analyzing the magnetization in fields of up to 250 kOe

Contributions of different magnetic subsystems formed in the systems of synthetic ferrihydrite nanoparticles (characterized previously) with an average size of < d>≈2.7 nm coated with polysaccharide arabinogalactan in different degrees have been separated by measuring the dependences of their magnetization M on magnetic field H of up to 250kOe on vibrating sample and pulsed magnetometers. The use of a wide measuring magnetic field range has been dictated by the ambiguity in identifying a linear M(H) portion for such antiferromagnetic nanoparticle systems within the conventional field range of 60–90 kOe. The thorough analysis of the magnetization curves in the temperature range of 100–250 K has allowed the verification of the contributions of (i) uncompensated magnetic moments µun in the superparamagnetic subsystem, (ii) the subsystem of surface spins with the paramagnetic behavior, and (iii) the antiferromagnetic susceptibility of the antiferromagnetically ordered ferrihydrite particle core. As a result, a model of the magnetic state of ferrihydrite nanoparticles has been proposed and the numbers of spins corresponding to magnetic subsystems (i)–(iii) have been estimated. An average magnetic moment μunof ∼ 145μB (μB is the Bohr magneton) per particle corresponds approximately to 30 decompensated spins of iron atoms in a particle (about 3 % of all iron atoms), which, according to the Néel’s hypothesis μun∼<d>3/2, are localized both on the surface and in the bulk of an antiferromagnetically ordered particle. The fraction of free (paramagnetic) spins is minimal in the sample without arabinogalactan coating of the nanoparticle surface (7 %) and is attained 20 % of all iron atoms in the sample with the highest degree of spatial separation of particles. According to this estimation, paramagnetic spins are located mainly on the edges and protruding areas of particles. Most magnetic moments of iron atoms are ordered antiferromagnetically and the corresponding magnetic susceptibility of this subsystem behaves as in an antiferromagnet with the randomly distributed crystallographic axes, i.e., increases with temperature.

A Study of the Magnetic Properties and Structure of Heusler Alloys Prepared by Arc-Melting Technique

Heusler alloys were prepared in this study using the Arc-Melting method in which 30 g of the Arc-melting pure elements were combusted in an Argon arc furnace. Saturation magnetization, X-ray diffraction (XRD) analysis, and scanning electron microscope (SEM) were used to characterize the prepared alloys in terms of the compositions (Co2TiZ), where Z= Al, Ge, Sb are related IVB sub-group metals. In this work, the specimens containing Ge and Ti have fully Ferro magnetically order and L21 chemical structure with magnetism due to the magnetic moments attributed to the Co site. The Heusler alloys containing IIB or IVB sub-group metals such as Al, Ti, or Ge behave ferromagnetism, with the magnetic moments being attributed to the magnetic moments of the Co sites. Heusler alloys containing the group IVB element such as Sb exhibited vacant chemical effects with Co sites, and they also contain some paramagnetic compounds. Heusler alloys with Sb element exhibited paramagnetic behavior with vacant chemical order. Alloys demonstrate different magnetic properties as a result of temperature change and exchange interaction with atomic structure.

Investigating acquisition of magnetic properties and biocompatibility of Gadolinium substituted Strontium phosphosilicate for magnetic imaging in orthopaedics

The ability to acquire in situ magnetic resonance properties in biological apatites to facilitate real time MRI was investigated by substituting a series of hierarchically increasing Gadolinium over Strontium in the study. Samples were synthesized using an aqueous sol–gel pathway to ensure maximum reactivity and favour Silica-based species. Structural features were investigated using diffraction and IR spectra followed by VSM to calculate magnetization as a function of the field revealing the paramagnetic behaviour of the samples when doped. Morphological features visualized through FE-SEM showed sustained structural integrity of parent material characteristic of the P63/M space group and the EDAX spectra confirmed the hypothesised substitution when sintered as well. When immersed with SBF a loss of secondary phases and formation of amorphous calcium phosphate flakes were confirmed by diffraction and morphological studies. Biocompatibility was evaluated against first contact cells i.e. RBC via haemolytic study and L929 cells wherein Alamar assay show the samples least toxic at 25 μg/ml beyond which cell viability decreases providing enough evidence of applicability of Strontium phosphosilicate as a bioactive ceramic.

Quadruple Beltrami field structures in electron–positron multi-ion plasma

Abstract A quadruple Beltrami (QB) equilibrium state for a four-component plasma that consists of inertial electrons, positrons, lighter positive (H +) ions and heavier negative ions O 2 − $\left({\mathrm{O}}_{2}^{-}\right)$ is derived and investigated. The QB relaxed state is a linear superposition of four distinct single Beltrami fields and provides the possibility of the formation of four self-organized vortices of different length scales. In addition, robust magnetofluid coupling characterizes this non-force-free state. The analysis of the QB state also shows that by adjusting the generalized helicities and densities of plasma species, the formation of multiscale structures as well as the paramagnetic and diamagnetic behavior of the relaxed state can be controlled.

Catalytic peroxidation of winery wastewater contaminants using activated carbon-supported magnetite nanoparticles

In this study, co-precipitation and hydrothermal synthesis methods were employed to prepare two types of magnetite nanoparticles (MNPs). An activated carbon derived from olive stones (OSAC) was used as MNPs-support. The physicochemical properties of the resulting OSAC-MNPs catalysts were determined using various characterization techniques. A more homogeneous distribution of larger and well-defined MNPs was obtained by hydrothermal synthesis, resulting in a more extensive blockage of the microporous structure of the support. Both catalysts exhibited paramagnetic behavior, but with relatively low magnetization due to the small size and low crystallinity of the Fe3O4 nanoparticles obtained. The catalytic peroxidation performance of OSAC-MNPs was studied using tyrosol (TY) as a model compound, but also real samples of winery wastewater (WW) were used in the optimized operational conditions, including pH, temperature, and doses of catalyst and hydrogen peroxide. The MNPs-based catalyst prepared by co-precipitation performed better in the range of experimental conditions tested because of the higher surface concentration of active phase that is easily accessible to the pollutant and was less prone to deactivation during successive reaction runs. The combination of active materials and optimized process enables to remove up to 92 % TPh, 35 % COD, and 26 % TOC, while the high stability of the samples associated to a low Fe-leaching (0.07 mg L−1) permits the reuse of materials in consecutive cycles.

A systematic look at structural diversity of metal phosphonates

AbstractHerein, we report the synthesis of three new copper phosphonate frameworks using a tetrahedral‐shaped organic building block, methane tetra‐p‐phenylphosphonic acid (H8‐MTPPA), and three different N‐ancillary ligands terpyridine (terpy), 2,2’‐bipyridine (2,2’‐bpy), phenanthroline (phen) to optimize the ligand binding modes on copper coordination sphere to generate molecular secondary building units (SBUs) in metal organophosphonates. We report the crystal structures of rod‐shaped one‐dimensional zig‐zag chain structure, [{Cu(terpy)}(H6‐MTPPA)(H2O)]⋅2H2O, three‐dimensional framework, [{Cu5(2,2’‐bpy)2}(H2‐MTPPA)(H4‐MTPPA)], and one‐dimensional structure [{Cu2(phen)2}(H4‐MTPPA)]⋅4H2O. Magnetic analysis of three‐dimensional copper phosphonate framework, namely [{Cu5(2,2’‐bpy)2}(H2‐MTPPA)(H4‐MTPPA)], showed paramagnetic behavior. Crystal structures were characterized by single crystal X‐ray diffraction, FT‐IR, and thermogravimetric analysis (TGA).