Ti Oxides Research Articles

The Chromite Crisis in the Evolution of Continental Magmas and the Initial High δ26Mg Reservoir

Abstract Fractional crystallization of Fe–Ti oxides can induce detectable Mg isotopic changes during late-stage basalt differentiation. Because chromite and olivine are early crystallizing phases during basaltic melt differentiation, the effect of chromite crystallization on the fractionation of Mg isotopes during early-stage basalt differentiation is still poorly understood. Here, we examine the possibility of chromite induced Mg isotope fractionation with a Mg isotopic study of chromite–olivine pairs in dunites and chromitites collected from major types of basaltic intrusive rock suites formed by fractional crystallization in different tectonic settings. The chromite δ26Mg (= [(26Mg/24Mg)sample / (26Mg/24Mg)DSM3–1] × 1000) values range from −0.19‰ to 0.30‰ in the Luobusa ophiolite, −0.09‰ to 0.78‰ in the Kızıldağ ophiolite, −0.04 to 0.42‰ in the Gaositai Alaskan-type complex, similar to those previously reported from the Stillwater layered intrusion (−0.05 to 0.84‰; Bai et al., 2021). They are significantly higher than those of coexisting olivine (δ26Mg = −0.48 to −0.10‰). The Δ26MgChr-Ol (= δ26MgChr − δ26MgOl) values in the rock suites investigated here fall largely between equilibrium fractionation lines of spinel–olivine pairs and magnesioferrite–olivine pairs, indicating equilibrium Mg isotopic fractionation. Furthermore, the Δ26MgChr-Ol values increase with decreasing Cr content of chromite in the dunites and chromitites, showing that high 26Mg has a greater affinity to Al-rich chromite than Cr-rich chromite. Fractional crystallization of such isotopically high chromite is expected to progressively lower the Mg isotope values of the in the remaining magma. Furthermore, continental basaltic magmas typically experience early crystallization of olivine and Al-rich chromite. Their δ26Mg values correlate positively with MgO (FeO, Cr,) and CaO/Al2O3 ratios and negatively with total alkali contents (Na2O + K2O). This indicates that detectable Mg isotopic fractionation occurred in intra-continental basalt magmas, probably by fractional crystallization of olivine and chromite. The observed low-δ26Mg intra-continental basalts can be accurately modeled by olivine + chromite fractionation with fractionation factors (Δ26MgChr-Melt) of 0.20‰, 0.60‰, and 1.18‰ as observed in the chromitites investigated during this study. Therefore, the early-stage basaltic melt differentiation involving separation of olivine and chromite may induce resolvable Mg isotopic fractionation, and the δ26Mg values of continental basalts should be used with caution in petrogenetic studies.

Ambipolar Electrochemistry of Pre‐Intercalated Ti3C2Tx MXene in Ionic Liquid Electrolyte

AbstractCation intercalation with or without redox remains the dominant charge storage mechanism for two‐dimensional (2D) Ti3C2Tx MXene. Anion‐based charge storage remains unexplored due to intrinsic negative surface charge of MXenes preventing spontaneous intercalation of anions and irreversible oxidation of Ti at anodic potentials in aqueous electrolytes. In this work, we report on the ambipolar electrochemical behavior of the Ti3C2Tx in ionic liquid electrolyte over a 2.5 V electrochemically stable window. The experiments are conducted on a thin Ti3C2Tx film current collector coated with an electroactive layer of small flakes (∼150 nm) of Ti3C2Tx pre‐intercalated with 1‐ethyl‐3‐methylimidazolium bis‐(trifluoromethylsulfonyl)‐imide (EMIM‐TFSI) ionic liquid. Couples of redox peaks with a very small potential separation during the voltage sweep are observed at high negative (−0.75 V vs. Ag wire) and high positive (+0.75 V vs. Ag wire) potentials. Our experimental electrochemical data combined with density functional theory (DFT) calculations suggest feasibility of pseudo‐intercalation of TFSI anions between Ti3C2Tx flakes. This study provides a pathway for elucidating anion intercalation for different MXene chemistries in solvent‐free electrolytes, which can lead to development of MXene based energy storage devices with improved performance.

Investigation of Phase Formation in Ceramic Based on Zn, Sn, and Ti Oxides

Investigation of Phase Formation in Ceramic Based on Zn, Sn, and Ti Oxides

Distribution of trace elements between phases in the Carbonate–Phosphate System with Fluorine at 500 MPa

The distributions of Ti, Zr, Nb, La, Sm, Yb, and Y were experimentally studied between phosphate and carbonate melts with various Ca and Na concentrations and equilibrium solid phases: apatite (in 12 experiments) and buchwaldite, CaNaPO4 (in two experiments). The experiments were carried out in an internally heated pressure vessel at a pressure of 500 MPa in the CaCO3 + NaPO3 + NaF system with variable proportions of phosphate and carbonate, and with the addition of H2O, H2C2O4 and mixture of trace-element oxides. The temperatures in runs V-1-8 were conducted as 1000 °C for melting for 24 h, then for crystallization at 650 °C for 7 days, and quenching; the temperatures in runs VI-1-5 - 1000 °C for 1 day and immediate quenching. The proportion of phosphate and carbonate in the starting mixtures was expressed as χ(P2O5) (mol. %), where χP2O5=nP2O5nP2O5+nCaO×100%. The experimental products were analyzed by electron probe microanalysis. The following two types of quenched melts were obtained depending on χ(P2O5): (i) calcite-rich melt with 20 mol% Na2O at χ(P2O5) < 30% and (ii) sodic carbonate–phosphate melt with a low CaO concentration at χ(P2O5) > 30%. The solubilities of ZrO2, TiO2, and Nb2O5 in the calcite-rich quenched melts at 650 °C were low and limited by the crystallization of Zr, Ti, and Nb oxides. At the temperatures 1000 °C these oxides are dissolved in the melts, and their concentrations in the melts increased with increasing χ(P2O5). The TiO2 and ZrO2 distribution coefficients between apatite and melt are 0.06–0.2 and 0.4–1.0, respectively. The REE distribution coefficients between apatite and coexisting melt rich in Ca carbonate increase with increasing χ(P2O5) from 1.3 to 3.3 for La2O3, from 0.4 to 3.4 for Sm2O3, from 1.4 to 1.9 for Yb2O3, and from 0.8 to 2.9 for Y2O3. The REE distribution coefficients between apatite and the sodic carbonate–phosphate melt increase by a few orders of magnitude with increasing χ(P2O5), particularly significantly for La2O3 and Sm2O3, to 110 and 75, respectively, and to >32 and 20 for Yb2O3 and Y2O3. The TiO2 and ZrO2 distribution coefficients between buchwaldite and melt do not depend on χ(P2O5) and are 0.1 and 1.05, respectively. The REE distribution coefficients between buchwaldite and melt coexisting with it in the experiments are 1.5 times lower than the distribution coefficients between apatite and melt and increase from ∼1.1 for all REE at χ(P2O5) = 25.8%, to 3.6, 2.9, 3.2, and 2.0, respectively, for La2O3, Sm2O3, Yb2O3 и Y2O3 at χ(P2O5) = 41.7%.

Precision control of oxygen content in CP-Ti for ultra-high strength through titanium oxide decomposition: An in-situ study

Oxygen has been known as an effective strengthening element in titanium (Ti) and its alloys. However, an over-dose of oxygen can also lead to embrittlement of Ti alloys. To precisely control and push the limit of oxygen in Ti and its alloys, we studied the decomposition process of Ti oxides in pure α-Ti matrix using an in-situ high-temperature scanning electron microscope. The experimental results revealed that TiO particles decomposed in α-Ti at elevated temperatures and the oxygen atoms gradually diffused into the matrix, following the Fick’s second law. Then, the samples with different oxygen contents were produced using the aforementioned strategy, for which the oxygen content, microstructure, and mechanical properties were measured. The results revealed that the oxygen content can be precisely controlled, which can achieve an ultra-high tensile strength of close to 1100 MPa, at no expense of elongation-to-failure, with incorporating 0.87 wt% oxygen. An analysis showed that the strength contribution from oxygen follows the Labusch law. These findings offer a novel approach to design high-performance Ti alloys with non-toxic and cheap elements.

Thermodynamic Study on Initial Oxidation Behavior of TiAl-Nb Alloys at High Temperature

The initial oxidation behavior of TiAl-Nb alloys was systematically investigated against the composition, temperature, and partial pressure of O2 with the CALculation of PHAse Diagrams (CALPHAD) technique. The mole fraction of each oxidation product at the initial oxidation stage of the alloys at the corresponding temperatures was predicted. The initial oxidation products of the alloys are oxides of Al, Ti, and Nb, with the oxidation order of Al, Ti, and Nb. As P(O2) increases, the Ti and Nb oxidation products move towards a high oxygen content, and the mole fractions of the Al and Ti oxides gradually decrease and increase, respectively. It was found that the temperature and partial pressure of O2 determined the types of the oxides and the oxidation order, while the concentration of Nb and Al determined the mole fraction of the oxides. The CALPHAD results are in good agreement with the experiments.

Oxide ceramic coatings with amorphous/nano-crystalline dual-structures prepared by micro-arc oxidation on Ti–Nb–Zr medium entropy alloy surfaces for biomedical applications

Due to the presence of multi-principal elements, the multi-principal element alloys (MPEAs) are supposed to undergo competing oxidation reactions during micro-arc oxidation (MAO). In this work, Ti–Nb–Zr medium entropy alloy (MEA, MAO-Free) was MAO-treated at various applied voltage. For Ti–Nb–Zr MEA treated at 250 V (MAO-250 V), the coating microstructure was characterized by amorphous oxides of Ti, Nb and Zr from the substrate and amorphous compounds of CaO, Ca(OH)2, SiO2 and CaSiO3 from the electrolyte, which distributed homogeneously in coating matrix. Different from the microstructure of MAO-250 V group, tetragonal-ZrO2 nano-crystals dispersed in amorphous coating matrix were noticed for that treated at 300 V (MAO-300 V). For specimen treated at 350 V (MAO-350 V), the coating matrix exhibited higher crystallinity by composing of major tetragonal-ZrO2 and minor rutile-TiO2, with the presence of nano-sized amorphous regions. The pore size, porosity, surface roughness and hydrophilicity of coatings increased with the increase of applied voltage. An order of MAO-300 V > MAO-250 V > MAO-Free > MAO-350 V group was identified for the wear resistance. Moreover, the MAOed coatings exhibited comparable corrosion resistance and cyto-compatibility to MAO-Free group. Together, the results indicate that the MAO-300 V group with favorable wear resistance, corrosion resistance and cyto-compatibility is promising for biomedical applications.

Oxidation behavior of Ti2AlC MAX-phase foams in the temperature range of 600–1000 °C

The isothermal oxidation behavior of Ti2AlC gel-cast foams with an almost completely open porosity of 87 vol% was investigated in the temperature range of 600–1000 °C, in static air, and for exposure times of up to 6.5 h. It was found that the oxidation process obeyed the parabolic rate law. The determined parabolic oxidation rate constants were low, indicating that the material’s resistance to oxidation at high temperatures was very good, especially given its highly porous form. The nature of the scale formed on the strut surface of Ti2AlC foams changed significantly with increasing oxidation temperature. After oxidation at 600 °C, gaps/cracks were observed between Ti2AlC layers on the strut surface, and the oxidation products were mixed Ti and Al oxides. At 700–800 °C, the scales were integrated and composed of Ti and Al oxides. At 900–1000 °C, the oxidation products were composed of large elongated plates of TiO2 (rutile) and small, needle-like Al2O3 (corundum) grains.

Zinc isotope fractionation during mid-ocean ridge basalt differentiation: Evidence from lavas on the East Pacific Rise at 10°30′N

Zinc (Zn) isotope data for mid-ocean ridge basalts (MORB) are scarce. The possible effects of MORB differentiation and mantle compositional heterogeneity on MORB Zn isotope compositions are poorly understood. In this paper, we report Zn isotope data of MORB lavas from the East Pacific Rise (EPR) at 10°30′N, which are understood to have been derived by a similar extent of melting from a compositionally uniform mantle source but manifest significantly varying extents of magma differentiation (MgO = 7.38–1.76 wt%) to demonstrate unequivocal Zn isotope fractionation during MORB differentiation. These lavas have a small δ66Zn (relative to the JMC-Lyon standard) range of 0.21–0.32‰, with an average of 0.26 ± 0.07‰ (2SD, N = 24), overlapping with literature data. However, δ66Zn values show significant correlations with indices of magma differentiation (e.g., MgO and CaO), with the more differentiated samples having isotopically heavier Zn. We can thus conclude that MORB differentiation can lead to ∼0.1‰ δ66Zn elevation, which is similar to that observed in Hawaiian Kilauea Iki lava lake samples. Fractional crystallization of olivine and clinopyroxene at MgO > ∼3.5 wt% and clinopyroxene and Fe–Ti oxides dominated by ilmenite at MgO < ∼3.5 wt% results in the observed Zn isotope fractionation. The δ66Zn values for primitive N-MORB and MORB source mantle are estimated to be ∼0.22‰ and ∼0.17‰, respectively. Furthermore, we observe a positive correlation between δ66Zn and [La/Sm]N in primitive (MgO = 7.58–9.01 wt%) literature MORB, indicating the existence of possible Zn isotope heterogeneity in the oceanic upper mantle. We thus predict heavy Zn isotope enrichment in mantle sources for E-MORB samples with high [La/Sm]N, which requires future testing.

High-Pressure Synthesis, Synchrotron Single-Crystal XRD and Raman Spectroscopy of Synthetic K–Ba Minerals of Magnetoplumbite, Crichtonite and Hollandite Group Indicatory of Mantle Metasomatism

The paper summarizes the results of an experimental study of the formation of K–Ba high-Ti (and Cr) oxides synthesized in the chromite–rutile/ilmenite–K2CO3/BaCO3–H2O–CO2 systems at 1.8–5.0 GPa. Experiments confirm the conclusion that the formation of K–Ba high-Ti oxides characterizes the most advanced or repeated metasomatic stages in upper mantle peridotites, which lead first to the formation of simple Ti oxides and then to the formation of K–Ba high-Ti and Cr oxides. Relations between the oxides is a function of the activity of the K and Ba components in the fluid. The appearance of priderite corresponds to the highest activity of K in the mineral-forming media. Redledgeite is formed only in the Fe-poor chromite–rutile–H2O–CO2–BaCO3 system, and, in the system with ilmenite, minerals of the magnetoplumbite group preferably crystallize. A direct dependence of the Cr content in oxides on pressure is revealed. Raman spectra of K–Ba high-titanium oxides are presented. The structure of a potassium compound of a magnetoplumbite group with the chemical formula K0.90Ti5.16Cr2.94Fe2.54Mg0.87Al0.22Mn0.30O19 is studied by single-crystal X-ray diffraction using a synchrotron radiation. The obtained data can be used to specify the nomenclature of the magnetoplumbite mineral group.

Polydimethylsiloxane-assisted plasma electrolytic oxidation of Ti for synthesizing SiO2-TiO2 composites for application as Li-ion battery anodes

A SiO2-TiO2 composite electrode with the synergistic effects of a stable cycle performance of TiO2 and high theoretical capacity of SiO2 was prepared through the plasma electrolytic oxidation (PEO) of Ti. When a polydimethylsiloxane (PDMS) layer is spin-coated on a Ti substrate (PDMS@Ti), the PEO reaction effectuates immediately on the pristine Ti, where the bubble phase forms first and PEO occurs for an extended period of time at a low voltage. Significantly, compared to the composite film prepared on pristine Ti, the SiO2-TiO2 composite film with a thickness of 80.39 μm exhibits large pores, which are beneficial for facilitating the transportation of Li+ with large amounts of Si. Consequently, a higher areal capacity of 1505.35 μAh cm−2 at a current density of 500 μA cm−2 was achieved compared to that of pristine Ti.

Ultrashort Laser Texturing of Superelastic NiTi: Effect of Laser Power and Scanning Speed on Surface Morphology, Composition and Wettability

Among metallic biomaterials, near-equiatomic NiTi is one of the most promising intermetallic system applicable for biomedical applications, thanks to its high biocompatibility and unique superelasticity (or pseudoelasticity), offering a complete recoverable strain up to 8%. In the prospective uses for bio-devices, the surface processing of NiTi medical components plays a fundamental role for guaranteeing both a Ti oxide passivizing layer for avoiding Ni ion release into the human body and surface morphology for controlling the cell proliferation. Mechanical polishing, thermal, chemical or electro-chemical treatments are typically performed for surface modifications. Recently, laser texturing has been successfully applied for different materials, included NiTi shape memory alloys, and also for tuning the surface properties, such as wettability. In the present work, ultrashort laser surface modification was carried out, through the use of a femtosecond laser, for the surface texturing of commercial superelastic NiTi plates. The main goal is to investigate the correlation among morphology, chemical composition and wettability with the principal process parameters, such as average power and scanning velocity in high power ultrashort laser texturing. Laser patterned surfaces were characterized by means of scanning electron microscopy, 3D-profilometry, XPS analysis and wetting measurements. After the laser treatments, both surface morphology and Ni/Ti ratio were largely modified from the initial surface, depending on the adopted process parameters. The wettability of the laser textured surfaces can be also varied with respect to the initial surface, due to the roughness values and grooves induced by the laser beam scans. The laser texturing process induced a combination between micro and nano structures, depending on the input energy. In details, the surfaces were tuned to lower roughness values (from 0.4 μm to 0.3 μm) with a laser power of 1 W, while it was increased up to 0.65 μm with a laser power of 13 W. The laser surface modification promoted a change of the contact angle from 70° of the untreated condition up to 135° to the surface laser treated with a power of 13 W.

Origin of the post-collisional younger gabbroic rocks and the associated Fe–Ti oxide ores, Abu Ghalaga area, Southern Eastern Desert, Egypt: mineralogical and geochemical constraints

The Abu Ghalaga pluton in the southern eastern desert of Egypt (SED) consists of undeformed norite and hornblende gabbro intruding island arc metavolcanics, ophiolitic rocks, and syn-tectonic older granitic rocks. The Fe-Ti ore (mainly ilmenite) occurs in the form of lenses at the base of the norite. Based on microtextures, mineralogy, and chemical composition, three types of ilmenites are recognized: massive high-Mg type, disseminated high-Mg type, and disseminated low-Mg ilmenite. The three ilmenite types are chemically distinguished by their MgO, MnO, TiO2, Fe2O3, FeO, and V2O3 contents. The variations in the concentration of these oxides are interpreted as a function of variations in T, fO2, and the composition of the parental magma. Reconstruction of the orthomagmatic conditions shows that T and fO2 of the magma from which the norite and its Fe-Ti deposit formed decrease during the course of magmatic differentiation, whereas the hornblende gabbro and its Fe-Ti mineralization have formed from a more evolved magma under relatively lower T and fO2. The REE patterns and variation diagrams support a model of crystal fractionation as the primary means of formation of the Fe-Ti deposits. Chemical features also suggest that the parent magma of both types of gabbroic rocks was generated in the mantle, but in two different pulses. Subduction zone, MORB, and WPB chemical signatures for these gabbroic rocks suggest a complex tectonic history consistent with compression followed by within plate extension possibly contributing to the development of a back-arc/intra-arc basin.

Atomically selective oxidation of (Ti,V) MXene to construct TiO2@TiVCTx heterojunction for high-performance Li-ion batteries

In situ derivation of TiO2 from Ti2CTx and Ti3C2Tx MXenes is a promising strategy to construct TiO2-based heterostructure. How to precisely control the conversion depth of MXene and well maintain its lamellar structure are the top priority. Herein, double transition metal (Ti, V) MXenes (Ti2−yVyCTx) act as precursors to engineer TiO2/MXene heterostructure as anode materials for lithium-ion batteries. Due to the different oxidation tendency, vanadium atoms with higher oxidative tolerance can maintain the 2D lamella morphology and high electronic conductivity while titanium atoms can be selectively oxidized to well-dispersed TiO2 nanoparticles. Moreover, the content and dispersity of derived TiO2 nanoparticles can be well controlled by adjusting the molar ratio of Ti/V in the Ti2−yVyCTx precursors. The intensive interfacial interaction between derived TiO2 and vanadium dominated MXene layers protects TiO2 nanoparticles from pulverization and detachment from 2D MXene as well as the restacking of MXene layers during charge/discharge cycles. Benefiting from the synergistic effects, the TiO2@TiVCTx anode delivers a superior specific capacity of 741.2 mAh g−1 at 0.1 A g−1, which shows prominent advantage in current MXene-derived anode materials. This work innovatively realizes atomically selective oxidation of double metal transition MXenes and regulate the derivatives for high performance anode materials.

C-TiO2+Ni and ZnO+Ni Magnetic Photocatalyst Powder Synthesis by Reactive Magnetron Sputtering Technique and Their Application for Bacteria Inactivation

In the current study, a bi-layered magnetic photocatalyst powder consisting of a Ni layer on one side and carbon-doped TiO2 or ZnO photocatalyst layers on the other side was synthesized by magnetron sputtering technique. SEM, XRD, and XPS analysis of powders revealed that the photocatalytic TiO2 layer had a mixed anatase-rutile structure, was doped by carbon to approximately 3 at. % and had a fraction of Ti(III) oxide. Meanwhile, the ZnO layer was crystalized in a wurtzite structure and had a considerable number of intrinsic defects, which are useful for visible light photocatalysis. The activity of magnetic photocatalyst powder was tested by photocatalytic bleaching of dyes, as well as performing photocatalytic inactivation of Salmonella bacteria under UV and visible light irradiation. It was observed, that C-TiO2+Ni magnetic photocatalyst had relatively high and stable activity under both light sources (for five consecutive cycles dye degradation reached approximately 95%), but ZnO+Ni was generally lacking in activity and stability (over five cycles under UV and visible light, dye degradation fell from approximately 60% to 55% and from 90% to 70%, respectively). Photocatalytic treatment of bacteria also provided mixed results. On one hand, in all tests bacteria were not inactivated completely. However, on the other hand, their susceptibility to antibiotics increased significantly.

Achieving controlled topography and wettability through laser surface texturing of Ti6Al4V for bioengineering applications

The global rise of dental and orthopedic implant treatments in the twenty-first-century appeals to researchers for further investigations. The situation is worsening as the rate of failure and revision treatments are considerable. Inadequate osseointegration and infections are the significant causes of the problem. To address the issue laser surface texturing is proficient to modulate surface topography, morphology, wettability, and chemical characteristics. To date, the implant surface features are not configured to receive an optimal response for early bone healing through cell adhesion and proliferation. Experimental design to investigate optimal responses of Ti6Al4V surface by texturing it with nanosecond Nd: YAG 1064 nm laser is carried out. The evolved research surface methodology model resulted in an efficient parametric relationship with 98.5%, 98.87%, and 96.99% R2 values for ‘kerf width’, ‘Rz’, and ‘kerf width to Rz’ ANOVA analysis respectively. The ANN approach shows more accuracy than the RSM approach for the prediction of ‘kerf width’, ‘Rz’, and ‘kerf width to Rz’. The experiment was performed to attain control in the range of water contact angle 40° to 119° as hydrophilic (ϴ ≤ 90) nature is prominently favorable for cell adhesion and proliferation. The Lower ‘kerf width to Rz ratio’ and higher Rz inclined towards hydrophobicity. An increment in carbon content also assists in rising contact angle. LST improves the Ti oxide layer which is considered a more corrosion-resistive and biocompatible layer. This study will certainly help to develop improved stability and life of dental and orthopedic implant surfaces.

A Mantle Plume Connection for Alkaline Lamprophyres (Sannaites) from the Permian Tarim Large Igneous Province: Petrological, Geochemical and Isotopic Constraints

AbstractThe origin of lamprophyres associated with large igneous provinces (LIPs) remains controversial, particularly whether they are derived by direct melting of mantle plumes, or from previously metasomatized domains in thermally perturbed subcontinental lithosphere. Here, we report the petrological and geochemical characteristics of a recently identified suite of alkaline lamprophyres (sannaites) that represent the final pulse of magmatism in the Permian Tarim LIP in NW China. The sannaites display porphyritic texture with phenocrysts of olivine, clinopyroxene, hornblende, phlogopite, and titanomagnetite in a groundmass of plagioclase, clinopyroxene, nepheline, hornblende, biotite, and titanomagnetite with minor pyrite and apatite. Carbonate ocelli and almost pure albite in the groundmass are interpreted to have crystallized from immiscible carbonate and hydrous fluids, respectively, produced by late-stage magmatic segregation. The rocks show low to moderate SiO2 (37.7–49.3 wt.%) and MgO (2.74–9.91 wt.%), together with high Fe2O3T (up to 22.7 wt.%) and alkali contents (up to 9.02 wt.% Na2O + K2O). They are characterized by high incompatible element abundances, especially a marked enrichment in large-ion lithophile elements (Rb and Ba) and light rare-earth elements (e.g. La and Ce) relative to P and high-field-strength elements (e.g. Ti). They show a relatively restricted range of δ66Zn values between 0.22‰ and 0.46‰ with an average of 0.37 ± 0.04‰ (2SE, n = 10), which is marginally heavier than that of MORBs (0.27 ± 0.05‰). Their (87Sr/86Sr)t values range from 0.7035 to 0.7061, εNd(t) from −0.97 to +5.62, and δ26Mg from −0.36‰ to −0.17‰ (n = 8), the latter being consistent with those of global MORBs. Based on the correlation between Zn isotopes and TiO2–FeO concentrations, we infer that the heavy Zn isotopes in some of the sannaites resulted from fractional crystallization of Fe–Ti oxide minerals. The whole rock geochemical features of these rocks (negative K anomalies and enrichment in large-ion lithophile elements) and rhyolite–MELTS simulations suggest that the primary magmas of the sannaites were derived from an amphibole-bearing enriched lithospheric mantle source. Metasomatism and related formation of amphibole-bearing metasomatized mantle may be linked to sublithospheric melts/fluids derived from the Tarim plume in the earlier stages of plume activity, rather than slab-derived fluids or carbonate melts as suggested in previous studies for other alkaline mantle-derived magmas. Partial melting may have been triggered by the thermal input from the Tarim plume during a later stage. This study suggests that exotic, alkali-rich magmas can be produced during the multi-stage evolution of large mantle plumes, involving complex cycles of lithospheric mantle metasomatism and later melting of previously enriched domains.

Thermal stability and corrosion behavior of a novel Zr22.5Ti22.5Hf22.5Ni22.5Ta10 high-entropy amorphous alloy

The present study reasonably designed and prepared a novel Zr22.5Ti22.5Hf22.5Ni22.5Ta10 high-entropy amorphous alloy with excellent thermal stability and corrosion resistance. The hysteresis diffusion effect caused by the high mixing entropy of the multi-principal system affects the formation of the crystalline phase and thus improves thermal stability. The alloy exhibits excellent corrosion resistance compared to 316 L in 3.5 wt% NaCl solution. The XPS results indicate that the passive film of Zr22.5Ti22.5Hf22.5Ni22.5Ta10 passive film is rich in oxides of Zr, Ti, Hf, and Ta, which has excellent resistance to chloride ion attack.

Synthesis of Magnetron-Sputtered TiN Thin-Films on Fiber Structures for Pulsed-Laser Emission and Refractive-Index Sensing Applications at 1550 nm

In this work, a set of titanium nitrides thin-films was synthesized with the technique of reactive RF and DC magnetron-sputtering. To demonstrate the versatility and effectiveness of the deposition technique, thin films were deposited onto different fiber structures varying the deposition parameters for optical applications as saturable absorbers in passively q-switched fiber lasers and as lossy mode resonance fiber refractometers. After deposition, optical and electronical properties of samples were characterized by UV–Vis and XPS spectroscopies, respectively. Samples presented coexisting phases of Ti nitride and oxide, where the nitride phase was non-stoichiometric metallic-rich, with a band gap in the range of Eg = 3.4–3.7 eV. For all samples, glass substrates were used as templates, and on top of them, optical fibers were mounted to be covered with their respective titanium compounds.

Influence of Ti, Zn and Fe oxide nanoparticles on seed germination capability, photosynthetic pigment content and activity of photosystem II Triticum aestivum L.

Influence of Ti, Zn and Fe oxide nanoparticles on seed germination capability, photosynthetic pigment content and activity of photosystem II Triticum aestivum L.