Ta2O5 Content Research Articles

Neutron attenuation features and elastic properties of silicate glasses containing Ta2O5, and Li2O

In this investigation, the elastic properties and neutrons attenuation factors for some optical glasses containing Ta2O5, SiO2, and Li2O were reported. The present glasses were also consisted of ZrO2 and Nb2O5 in very small concentrations. The glasses are chemically defined as 26.47Li2O-5.88ZrO2-(20-x)Ta2O5-xNb2O5-47.06SiO2, where, x takes the values: 0, 2.94, 5.88, and 11.77 mol%. The elastic properties of these glassy specimens were determined by employing Makishima-Mackenzie's theory (M.M.T). By using the same method, moreover, the micro-hardness and Poisson's ratio were assessed. Cross sections for slow, moderated, and fissile neutrons were computed through standard expressions and models. In addition, the influence of the partial replacement of Ta2O5 by Nb2O5 on the parameters were also analysed. The glass with the lowest Nb2O5 content presented the highest cross sections for fast, moderated, and slow neutrons. The neutron-absorption ability of included glasses declined as glass density declined and Nb2O5 molar concentration increased in the glasses. Therefore, the sample with the highest Ta2O5 content is recommended for neutron absorption applications.

The petrogenesis and mineralization of Zhaojinggou Nb–Ta deposit, Inner Mongolia: Evidence from geochronology, rock, and mineral geochemistry

The Zhaojinggou Nb–Ta deposit is one of large rare metal deposits newly discovered in the northern margin of the North China Craton in recent years. This paper reports petrography, petrochemistry, columbite‐group minerals U–Pb chronology study of the amazonite granitic pegmatite (AGP) exposed in this deposit, and composition of columbite‐group minerals and biotite are obtained by electron probe microanalyzer and LA‐ICP‐MS. Eighteen analyses of columbite‐group minerals yielded weighted mean 206Pb/238U age of 116.9 ± 1.4 Ma. The crystallization temperature of biotite is 630–650°C, and the oxygen fugacity is 10−17–10−18 bars. The biotite has low MgO contents and high Rb, Rb/Sr, and FeOT/(FeOT + MgO) ratios. The AGP has extremely low MgO, Cr, Co and Ni contents, with Nb/Ta ratios range from 1.63 to 9.05 and Rb/Sr ratios range from 303.30 to 648.90, and obvious ‘M’ type tetrad effect of rare earth element indicating that the formation of the AGP is related to crust‐derived magma. The contents of Nb2O5 and FeO decrease, while the Ta2O5 and WO3 contents, Mn# and Ta# values increase gradually from the core to the rim of columbite‐group minerals. Some columbite‐group minerals have unobvious oscillatory zoning, and some have a clear bright zoing with high Ta contents on the rim, indicating that the genesis of Zhaojinggou Nb–Ta deposit is mainly magmatic crystallization differentiation, accompanied by hydrothermal autometasomatism in the late stage.

Genesis of the Huanggangliang Fe-Sn polymetallic deposit in the southern Da Hinggan Range, NE China: Constraints from geochronology and cassiterite trace element geochemistry

The Huanggangliang Fe-Sn deposit is located in the southern Da Hinggan Range (NE China), and it’s one of the most important deposits within the Huanggangliang-Ganzhuermiao Sn polymetallic metallogenic belt. Nearly 90% of the orebodies (stratiform/lenticular) at Huanggangliang are hosted in the Lower Permian andesite or marble. Three ore deposit types were proposed, including: 1) stratabound skarn-type (Yanshanian); 2) exhalative sedimentary (SEDEX)-type (Hercynian); and 3) SEDEX (Hercynian)-hydrothermal (Yanshanian) superimposing-type. Two generations of cassiterite (Cst-1 and Cst-2) were identified based on their microscopic features and CL images: Cst-1 is dark brown with distinct banded texture (euhedral-subhedral), whilst Cst-2 is light brown in color and cut Cst-1 (as veins) or distributed on the Cst-1 margin. They are both replaced by chlorite and quartz. The Huanggangliang cassiterite has relatively high Fe (median 4828 ppm) and W (median 273 ppm), but low Nb2O5 (<0.08 wt%) and Ta2O5 (<0.09 wt%) contents, distinct from SEDEX-type cassiterite but similar to granite-related cassiterite.Cst-1 has higher Fe-W-U contents than Cst-2, which reflects that Cst-1 was formed under relatively high temperature. Meanwhile, Cst-2 is relatively HFSEs-enriched, suggesting that the metallogenic environment had become more acidic. The cassiterite, zircon and garnet samples were U–Pb dated to be 137.10 ± 3.65 Ma, 138.45 ± 0.45 Ma, and 136.03 ± 1.22 Ma, respectively. Considering the Huanggangliang geology, cassiterite geochemistry and published ages from Sn-polymetallic deposits in the southern Da Hinggan Range, we suggest that the regional Sn mineralization occurred mainly in 139–134 Ma, and that the Huanggangliang deposit is best classified as skarn-type, closely related to Yanshanian magmatic-hydrothermal activity.

Melt‐quenched oxide glasses with ultrahigh Young's modulus and small thermal expansion coefficient

AbstractThe well‐known Makishima–Mackenzie relationship, consisting of two terms of the dense packing structure and dissociation energy regarding bonding in constituent oxides, enables fabricating oxide glasses with ultrahigh Young's modulus (∼140 GPa) and a small coefficient of thermal expansion (CTE) (∼4 ppm/K). The effects of increasing MgO and Ta2O5 contents in an MgO–Ta2O5–Al2O3–SiO2–B2O3 glass system using a conventional melt‐quenching method are revealed. The essential oxides of Al2O3 and Ta2O5 are primarily suitable for dense packing structures dominated by a large coordination number of oxygens. The substitution of CaO by MgO results in high dissociation energy when the glass composition falls in the peraluminous regime (Al2O3/[MgO + CaO] &gt; 1). A small CTE is realized by increasing the molar ratio of Al2O3/MgO. According to magic‐angle spinning‐nuclear magnetic resonance spectra, mechanically and thermally functional oxide glasses depend on their structures. These findings facilitate the development of glass substrate applications without thermal dilatation.

Effect of Ta2O5 addition on the structure, crystallization mechanism, and properties of CaO–B2O3–SiO2 glasses for LTCC applications

CaO–B2O3–SiO2–Ta2O5 (CBST) glass-ceramics, with different Ta2O5 content, (up to 6 mol%), have been prepared by using glass melt quenching followed by heat treatment between 800 and 880 °C. The Fourier Transform Infrared (FTIR) results showed that the stronger the attraction of Ta5+ to the oxygens in the BO33− and SiO32− structures, the more easily the B–O and Si–O bonds will be destroyed. The underlying reason is most probably the high field strength of Ta5+, which results in a weakening of the vibration intensities of the [BO3] and [SiO4] units. Moreover, the Differential Scanning Calorimetry (DSC) results showed that the softening point (Tg), crystallization starting temperature (Tc1), and exothermic crystallization peak temperature (Tp1), of the CaSiO3 phase, shifted to higher values with the addition of Ta2O5. Also, the crystallization activation energy (Ea) and the glass stability factor (ΔT) of the CaSiO3 phase increased, which indicated that the CaSiO3 phase of the glass became inhibited by the addition of Ta2O5. It was, thus, obvious that there was a need of glass characterization. The results of the crystallization kinetics showed that the critical cooling rate decreased with the addition of Ta2O5, which indicated that the viscosity of the system had increased. The CBST glass-ceramics, containing 1 mol% Ta2O5, that were sintered at 875 °C for 15 min showed excellent dielectric properties: εr = 6.22 and tanδ = 1.19 × 10−3 (1 MHz). To sum up, CaO–B2O3–SiO2–Ta2O5 glass-ceramics are potential low temperature co-fired ceramic substrate materials.

Study on properties of Hf6Ta2O17/Ta2O5 system: A potential candidate for environmental barrier coating (EBC)

Ta2O5 doped Hf6Ta2O17 system (Hf6Ta2O17/Ta2O5) is considered to have potential application prospect in the field of aero-engine. We herein focus on the thermo-physical, mechanical properties and CMAS corrosion resistance of Hf6Ta2O17/Ta2O5 to systematically evaluate the possibility for the application of environmental barrier coating (EBC). By changing the content of Ta2O5, the gradient adjustment of thermal expansion coefficient can be realized while maintaining low thermal conductivity (1.5–2.2 W/(m·K)). The introduction of Ta2O5 significantly reduces the modulus and improves the fracture toughness. Single-phase Hf6Ta2O17 shows excellent corrosion resistance against molten calcium-magnesium-alumina-silicate (CMAS). The crystallization of CaTa2O6 and HfSiO4 is the important factor to prevent further corrosion. The introduction of Ta2O5 weakens the ability to prevent Si penetration and greatly increases the thickness of the corrosion layer. The results highlight the merit of Hf6Ta2O17/Ta2O5 system as potential candidate for multi-layer gradient coating on the surface of ceramic matrix composites.

Effect of TiO2 and Ta2O5 co-doping on phase stability, fracture toughness, and sintering behavior of ZrO2 stabilized by 10mol%(Y0.4Gd0.3Yb0.3)2O3

The effect of TiO2 and Ta2O5 co-doping on the phase structure, fracture toughness, and sintering behavior of 10mol%(Y0.4Gd0.3Yb0.3)2O3-stabilized zirconia was investigated using X-ray diffraction, scanning electron microscopy, microindentation, and pressureless sintering. The results showed that 10mol%(Y0.4Gd0.3Yb0.3)2O3–ZrO2 had a single cubic phase structure, and an increase in the Ta2O5 (≥6 mol%) and TiO2 doping concentrations resulted in a simultaneous increase in the content and stability of the tetragonal phase. The fracture toughness of TiO2 and Ta2O5 co-doping 10mol%(Y0.4Gd0.3Yb0.3)2O3–ZrO2 decreased with an increase in the Ta2O5 content. On the other hand, the TiO2 content had no significant effect on the fracture toughness of 10mol%(Y0.4Gd0.3Yb0.3)2O3–ZrO2. The sintering resistance of the specimens increased with an increasing in the Ta2O5 content; however, an increase in the TiO2 content accelerated the densification of the specimens. When the Ta2O5 content was 10 mol% and the TiO2 content was in the range of 4–8 mol%, a single non-transformable tetragonal phase structure with fracture toughness similar to that of 6–8 wt% Y2O3 stabilized ZrO2 and excellent anti-sintering properties could be obtained. This structure can be explored as a thermal barrier coating material for high-temperature applications.

Elastic Modulus and Hardness of Potassium Tantalum Germanate Glasses and Glass-Ceramics

Whilst the optical and structural properties of the glasses containing tantalum oxide have been considerably investigated, research into their mechanical properties is not substantially established. This work reports on the mechanical characterization of transparent germanate glass samples, obtained via the melt-quenching technique, with a molar content of Ta2O5 ranging from 0% to 20%. The introduction of Ta2O5 in the samples is related to significant improvements in the mechanical properties. The transition from glass to transparent glass-ceramic via the controlled crystallization of Ta2O5 proved to be a tool to increase both the elastic modulus and the hardness while keeping the transparency of the material. The average elastic modulus of the studied compositions ranged from 69.2 GPa to 99.1 GPa, while the average hardness of the same samples varied from 5.10 GPa to 7.34 GPa.

Effects of Ta2O5 content on mechanical properties and high‐temperature performance of Zr6Ta2O17 thermal barrier coatings

AbstractZr6Ta2O17/YSZ double ceramic top coat thermal barrier coatings (TBCs) with different Ta2O5 content are prepared by atmospheric plasma spraying (APS). The effects of Ta2O5 content on mechanical properties and high‐temperature performance of Zr6Ta2O17 TBCs are investigated. With the decrease in Ta2O5 content, the hardness and fracture toughness of the Zr6Ta2O17 coating increases from 12.833 to 15.117 GPa and from 3.3592 to 3.7753 MPa m1/2, respectively. The Zr6Ta2O17 coating specimens with different Ta2O5 content do not delaminate from the substrate except the edge peeling after 180 h of oxidation or 2000 thermal cycles at 1150°C. The Zr‐12Ta specimen (the molar ratio of ZrO2/Ta2O5 of 0.88:0.12) presents the more excellent mechanical properties and high‐temperature performance. The reduction in Ta2O5 content will improve the mechanical properties, high‐temperature oxidation, and thermal cycle performance of Zr6Ta2O17/YSZ double ceramic top coat TBCs.

Hot corrosion of SiO2-Ta2O5 binary scale on MoSi2-based ceramics

The SiO2-Ta2O5 binary scales with different Ta2O5 contents were prepared on MoSi2-based ceramics by pre-oxidation. Hot corrosion with Na2SO4 was carried out at 1000 °C for 8 h. The pre-oxidized SiO2-Ta2O5 scale on ceramics with 10 % Ta2O5 has an excellent hot corrosion resistance. Ta2O5 reacted preferentially with Na2SO4 forming solid sodium tantalates to retard the dissolution of SiO2. A dense reaction layer can be formed to prevent the further infiltration of Na2SO4. Compared to the pure SiO2 scale without Ta2O5, fewer Na2MoO4 and no obvious corrosion hole can be observed.

Control optical characterizations of Ta+5–doped B2O3–Si2O–CaO–BaO glasses by irradiation dose

Borosilicate glasses within 25B2O3–15Si2O–10CaO-(50-x)BaO-xTa2O5 system at different Ta2O5 contents (x = 0, 4, 8, 12, and 15 wt%) were synthesized via quenching technique. The effect of irradiation doses of both 10, and 40 kGy, as well as the Ta2O5 ratio on the structural and optical characteristics of the prepared glasses were studied. The investigations were carried out using UV–Vis–NIR spectrophotometer, differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) techniques. Physical parameters such as density, molar volumes, refractive index, optical bandgap, Urbach energy, optical density, extinction coefficient, optical sheet resistance, and thermal emissivity of 25B2O3–15Si2O–10CaO-(50-x)BaO-xTa2O5 samples with different irradiation doses were investigated. The results show that irradiation does not affect the crystal structure for the present samples even at 40 kGy. The optical aspects reveal the indirect allowed optical transition for the studied samples. The evaluated optical parameters show an effective influence towards both Ta2O5 content and irradiation does which forces the optical applications.

Origin of high piezoelectricity in low-temperature sintering PZT-based relaxor ferroelectric ceramics

Multilayer piezoelectric devices need to co-sinter the piezoelectric ceramic layers and the Ag-rich Ag–Pd internal electrode layers at a low temperature (less than the Ag melting point of 961.78 °C), and need to use Sn–Zn-based lead-free solder to weld the components at 260 °C. This requires low-temperature sintering of high-performance piezoelectric ceramics with a Curie temperature (Tc) higher than 260 °C. Thereby low-temperature (940 °C) sintering 0.09 Pb(Ni1/3Nb2/3)O3‒ 0.03 Pb(Mg1/2W1/2)O3‒0.88 Pb(Zr0.5Ti0.5)O3 ceramics are prepared via the solid-state reaction method. Samples added with different Ta2O5 contents are fabricated and compared in terms of phase structure, microstructure, piezo-/ferro-electric properties, and dielectric relaxation. High piezoelectric properties (d33 = 640 pC/N, d33∗ = 676 p.m./V, Tc = 303 °C) are achieved in the 0.70 wt% Ta2O5 added ceramic with a minimum activation energy of domain wall movement (Ea) of 0.025 eV. Rietveld refinement and Raman spectroscopy show that all the ceramics exhibit rhombohedral-tetragonal (R-T) coexistence and the distortion degree of crystal structures increases with the increase of Ta2O5 content. Our results show that the larger the content of the tetragonal phase (CTP), the lower the Ea, the smaller the domain, and the higher the piezoelectric response. Low Ea favors orientation and extension of polar regions and facilitates the formation of the nanometer-size domain structure (polar nanoregions) which is observed by using piezoresponse force microscopy, thus resulting in high piezoelectric properties. This mechanism associated with the CTP, the Ea and the domain structure reveals the origin of the high piezoelectricity in the low-temperature sintering PZT-based relaxor ferroelectric ceramics.

Tantalum-Containing Bioactive Glass-Ceramics: A Mechanism of Suppression of the Biological Activity of the 45S5 Bioglass by Doping with Ta2O5

Methods for the synthesis of radiopaque tantalum-containing glass and glass-ceramics by doping 45S5 bioglass with tantalum oxide are presented. Bioactive glass has been obtained by pyrolysis of a mixture of organic precursors: tetraethoxysilane, tributyl phosphate, sodium oleate, and calcium oleate. Bioglass has been doped with tantalum oxide by three different methods. The mechanism of suppression of the biological activity of materials with an increase in the Ta2O5 content has been studied. The bioactivity of samples containing 1–40 wt % Ta2O5 has been evaluated in vitro using a model medium—an SBF solution. The samples have been studied by 31P NMR, XRD, SEM, and EDS. A decrease in the concentration of calcium in the glass phase due to the formation of insoluble CaTa2O6 crystals has been considered the major cause of the suppression of the bioactivity of glasses. Samples containing up to 10 wt % Ta2O5 can be used in modern medicine as materials that restore bone tissue. The radiopaque substance in the composition of the biomaterial makes it possible to monitor the process of bone tissue regeneration. Samples containing more than 20 wt % Ta2O5 failed in vitro tests. Due to the dissolution of one of the phases of glass-ceramics in a model solution, the prognosis for the use of such materials in vivo is unfavorable.

The Effect of Ta&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; on the Densification Behaviour and Mechanical Properties of Zirconia-Toughened Alumina (ZTA) Composites Prepared by Two-Stage Sintering

By 2050, 130 million people are estimated to suffer from osteoarthritis worldwide which would require patients to undergo total hip replacement procedure which have a lifespan of 20 years and failure rates of ~1%. In this research, Zirconia Toughened Alumina (ZTA) which is the main biomaterial used for total hip arthroplasty were doped with varying vol % of Tantalum Oxide (Ta2O5) from 0 to 0.4 vol % were produced through conventional two-stage sintering with first stage sintering temperature, ranging between 1400°C and 1550°C, heated at 20°C/min, followed by second stage sintering temperature of 1350°C and hold for 12 hours. The efficacy of two-stage sintering on the microstructure and mechanical properties of the sintered samples were then evaluated. Addition of Ta2O5 combined with two-stage sintering were able to produce ZTA composites with enhanced grain size and mechanical properties compared to undoped ZTA composites. The samples with 0.3 vol% Ta2O5 content and above sintered at T1 ≥1450°C achieved density &gt; 99% T.D., Vickers hardness &gt; 19 GPa, Young’s modulus &gt; 400 GPa and fracture toughness &gt; 6 MPam1/2 when compared to undoped ZTA composites. This would enable production of ZTA with improved mechanical properties and lifespan ensuring the well-being of people suffering from osteoarthritis.

Ta2O5-incorporated in photoinduced electrocatalyst of TiO2-RuO2 decorated by PPy-NrGO nanocomposite for boosting overall water splitting

In the current work, the heterostructures highly PEC activity photoelectrodes composed of mixed metal oxides (TiO2-RuO2-Ta2O5 (TRT)), polypyrrole- N doped reduced graphene oxide (PPy-NrGO) were prepared by electrodeposition of PPy-NrGO films on the TRT- coated titanium (Ti) plates as substrates. The TRT coatings were deposited on Ti plates via the sol-gel technique. The effects of the Ta2O5 molar ratios were followed using physical and PEC measurements. Morphology studies showed that the surface structure of photoelectrodes alters remarkably by changing the Ta2O5 content in the mixture of metal oxides. TRT/PPy-NrGO photoelectrodes indicated to have a decreasing impact on the charge transfer resistance at the photoelectrode/electrolyte interfaces. The overall PEC water splitting performances of photoelectrodes were compared by measuring photocurrent density at 0 and 1.23 V vs. RHE, Tafel slopes, charge carrier density, stability, hydrogen evaluation reaction (HER) and oxygen evaluation reaction (OER) efficiencies. The highest HER (43.68% at −0.4 V) and OER (17.51% at 0.45 V) efficiencies were obtained in photoelectrodes comprising of 20 mol% Ta2O5 which possessed charge carrier density (5.9 × 1018) of about 1.7 times higher than that considered for TRT (0%)/PPy-NrGO with no Ta2O5 in the mixture of metal oxides.

Composition and probable ore igneous rocks source of columbite from alluvial deposits of Mayoko district (Republic of the Congo)

The article presents the results of optical, electron microscopic and electron microprobe studies of columbite group minerals, collected during heavy mineral concentrate sampling of alluvial deposits in the Mayoko region (Republic of the Congo). The aim of the study is revealing tantalum niobates ore body in this region. We found that these minerals in loose deposits are represented by two grain-size groups: less than 1.6 mm (fine fraction) and 1.6-15 mm (coarse fraction). The grains of both fractions belong mainly to columbite-(Fe), less often to columbite-(Mn), tantalite-(Mn) and tantalite-(Fe), contain impurities of Sc, Ti, and W. The crystals have micro-scaled zoning (zones varies slightly in the Ta/Nb ratio values) and contains a lot of mineral inclusions and veins represented by zircon, pyrochlore supergroup minerals and others. Columbite-(Fe) and columbite-(Mn) are characterized by an increased content of Ta2O5 up to the transition to tantalite-(Fe) and tantalite-(Mn). This allows us to exclude the formation of subalkaline rare-metal granites, their metasomatites (albitites and greisenes) and carbonatites, from the list of possible columbite ore rocks source in the Mayoko district. Thus, beryl type and complex spodumene subtype rare-element pegmatites of the mixed petrogenetic family LCT-NYF (according to P.Černý) should be considered as a probable root source. The results of the research should be taken into account when developing the methodology for prospecting in this area.

Niobium–tantalum oxide minerals in alluvial placer deposits from the Ngoura area, East-Cameroon

This work presents a preliminary mineralogical characterization of Nb–Ta oxide minerals from alluvial placers located in the Ngoura area, eastern Cameroon. The heavy minerals are characteristic of short hydromechanical transport and highlight the stability of Nb–Ta oxides during the weathering and transport. Nb–Ta mineralization in placer deposits from the Ngoura area may derive from local sedimentation. The assemblage of Nb–Ta oxides in the studied placers consists of tapiolite-(Fe) and tantalite-(Mn). Tapiolite-(Fe) exhibits high concentrations in Ta2O5 (78.07–80.46 wt%) and FeO (12.18–13.66 wt%) and plots within a narrow range of Ta* (0.900–0.933) and Mn* (0.037–0.119), which correspond to the ranges typically observed in tapiolite-(Fe) worldwide. Tantalite-(Mn) shows Ta2O5 contents ranging from 62.17 to 69.45 wt%, Nb2O5 from 12.09 to 17.37 wt%, MnO from 7.63 to 12.49 wt% and FeO from 1.48 to 6.62 wt%. It is also characterized by a wider range of Mn* (0.538–0.891) and relatively homogeneous Ta/(Ta + Nb) (0.683–0.779) ratios. Texturally, the studied Nb–Ta minerals exhibit oscillatory zoning characterized by bright Ta-rich zones alternating with dark Nb-rich zones. This oscillatory zoning is progressive in some minerals and the alternating bands may appear regular to wavy with gradual transitions. Oscillatory zoning in Nb–Ta oxides from the Ngoura placers is considered to be a primary magmatic feature and is tentatively explained as a result of magmas mixing, rapid cooling or degassing/decompression of the igneous system. The geomorphology and the tropical humid climate of the eastern region offer suitable conditions for the deposition of alluvial placers. Therefore, niobium-tantalum minerals from the Ngoura placers must have been sourced from the weathering and erosion of alkaline granites and pegmatites widespread in the study area.

Sulfonated porous surface of tantalum pentoxide/polyimide composite with micro-submicro structures displaying antibacterial performances and stimulating cell responses

To improve the surface bio-performances of polyimide (PI), tantalum pentoxide (Ta2O5)/PI composites (TPC) were prepared, and concentrated sulfuric acid was utilized to modify TPC surface. The results revealed that sulfonated TPC (STPC) exhibited microporous surface with pores size of about 3 μm, and sulfonic acid (-SO3H) groups were introduced onto the microporous surface. In addition, many Ta2O5 submicro particles appeared on the microporous surface, which formed micro-submicro structures. Compared with PI, the surface roughness, hydrophilicity, surface energy and protein adsorption as well as apatite mineralization of STPC in simulated body fluid were obviously enhanced, which increased with Ta2O5 content increasing. In addition, STPC exhibited antibacterial performances due to the presence of -SO3H groups and Ta2O5. Furthermore, the responses (adhesion, proliferation and differentiation) of rat bone marrow mesenchymal stem cells to STPC were remarkably promoted with the increase of Ta2O5 content. In short, STPC with 50w% Ta2O5 content (STPC 50) with sulfonated microporous surface contained micro-submicro structures, which exhibited antibacterial performances and stimulated cell responses. STPC50 with improved surface properties and cytocompatibility might have large potentials for bone repair applications.

Structural, dielectric, and multiferroic properties of Ta2O5-modified BiFeO3–BaTiO3–LaFeO3 solid solutions

In this work, a series of Ta2O5-doped 0.675BiFeO3–0.3BaTiO3–0.025LaFeO3−x mol% Ta2O5 (x = 0, 0.25, 0.50, 0.75, 1.0, 1.25) multiferroic ceramics were synthesized by solid-state reaction. The effects of Ta5+ doping on their phase structure, morphology, dielectric, ferroelectric, magnetic, and magnetoelectric properties were assessed. All samples were found to crystallize in perovskite structures, and the grain size was remarkably decreased by Ta5+ doping. Ta2O5 was beneficial to the dielectric properties, with the dielectric constant rising from 829 for undoped ceramic to 1149 for x = 1.25 at 100 Hz. The remnant polarization Pr and coercive field Ec decreased as x increased, indicating the worsening of ferroelectric behavior. In comparison, the ferromagnetism was evidently enhanced with increasing content of Ta2O5, and the remanent magnetization Mr peaked at 0.035 emu/g for x = 0.75. The magnetoelectric coefficient αME reached the maximum (418.68 mV/cm·Oe) for x = 0.25 at 200 Oe and 105 Hz.

Transparent glass and glass‐ceramic in the binary system NaPO3‐Ta2O5

AbstractTransparent and homogeneous tantalum phosphate glasses were prepared in the binary system (100‐x)NaPO3‐xTa2O5 with x varying from 10 to 50 mol%. Thermal, structural, and optical properties, as well as crystallization mechanisms, were investigated by thermal analysis, X‐ray diffraction, Fourier‐transform infrared spectroscopy (FTIR) and Raman spectroscopies, optical absorption, transmission electron microscopy in terms of Ta2O5 content. FTIR and Raman results support the tantalum insertion in the phosphate chains with [TaO6] polyhedra cross‐linking the phosphate units. At higher Ta2O5 content, [TaO6] clusters are formed and connected to the phosphate network by P‐O‐Ta bonds. This structural evolution is in good agreement with the thermal features measured by differential scanning calorimetry (DSC) with a strong increase of the Tg temperatures up to 920°C, high thermal stability against crystallization for low Ta2O5 content and increasing of crystallization tendency for the most Ta‐concentrated samples. Besides, due to the progressive insertion of [TaO6] units, the precipitation of Na2Ta8O21 perovskite‐like phase was identified in the sample with 50 mol% of Ta2O5. The optimal heat treatment conditions were identified using DSC measurements and a transparent glass‐ceramic from 50NaPO3 to 50Ta2O5 composition was prepared. The obtaines glass‐ceramic has great potential for optical applications, such as host for rare‐earth ions, nonlinear optical materials, and ferroelectric domain.