Terbium Addition Research Articles

Effect of the Rare Earth Metals (Tb, Nd, Dy) addition for the modification of nickel catalysts supported on alumina in CO2 Methanation

In the current research, a group of rare-earth metals functionalized mesoporous Ni-M/Al2O3 (M = Tb, Dy, Nd) composite oxides were prepared by the one-pot sonochemical pathway and applied in the CO2 methanation procedure. Promoters can partially influence the textural and catalytic characteristics of Ni–Al2O3 catalysts. Physicochemical characteristics of the as-fabricated catalysts were identified utilizing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDS), Temperature Programmed Reduction (H2-TPR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) analyses. Among the specimens, the catalyst modified by Terbium (Tb) manifested better catalytic performance and CH4 selectivity, particularly at low temperatures (350–400 °C). The influence of reaction temperature (200–500 °C) was scrutinized below space velocity (GHSV) of 25,000 ml/gcath, atmospheric pressure, and stoichiometric ratio of CO2 to H2 (1: 4). The impact of the desired content of nickel and terbium was examined. The 25Ni–5Tb–Al2O3 operates the best function for CO2 methanation, which can attain the highest CO2 conversion of 66.93% at 400 °C at atmospheric pressure. The superior catalytic performance of 25Ni–5Tb–Al2O3 could be assigned to the appropriate fabrication method and the promotion effect of Terbium. The synthesis effect could be assigned to its large surface area, obtaining by the hot spot mechanism. The addition of Terbium promotes the Ni distribution on the supports as well as accelerates the positive reaction due to the oxygen vacancies of Terbium. Besides, these outcomes could be defined with the maximum distribution of active nickel sites on the catalyst and improvement in the catalyst reduction ability at low temperatures.

Synthesis and Characterization of Magnetic Drug Carriers Modified with Tb3+ Ions.

The study aimed to synthesize and characterize the magnetic drug carrier modified with terbium (III) ions. The addition of terbium extends the possibilities of their applications for targeted anticancer radiotherapy as well as for imaging techniques using radioisotopes emitting β+, β−, α, and γ radiation. The synthesis of iron oxide nanoparticles stabilized with citrates using the co-precipitation method (IONP @ CA) was carried out during the experimental work. The obtained nanoparticles were used to synthesize a conjugate containing terbium ions and guanosine-5′-monophosphate as an analog of drugs from the thiopurine group. Conjugates and their components were characterized using Transmission Electron Microscopy, infrared spectroscopy, X-ray microanalysis, spectrofluorimetry, and thermogravimetric analysis. The hybrid was also investigated with Langmuir layers to check the interaction with analogs of biological membranes.

Tb–Al–Si systems

There are presently limited information regarding the liquid–solid equilibria at the (Al)-rich region of the different R–Al–Si systems (R = rare earth elements). These data, along with the ternary systems isothermal section, are needed to outline the design, plan and develop new Al–Si-based alloys. The effect of the lanthanide terbium addition to the Al–Si system, in the Al-rich corner, has been experimentally studied. The constitution of the alloys and the liquidus surface projection have been determined by means of differential thermal analysis, scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. In the system investigated have been identified five regions of primary crystallization: TbAl(3 − x)Six, Tb2Al3Si2, TbAlxSi2 − x, (Al) and (Si).

Phase transition and magnetocaloric effect of Ni50Mn29Ga21−xTbx (0 ⩽ x ⩽ 1) alloys

Ni50Mn29Ga21−xTbx (0⩽x⩽1) alloys were studied with the microstructure, phase transition, and magnetocaloric effect. Dual-phase microstructure containing the martensite matrix and Tb-rich precipitations were formed. The martensitic transformation was observed over the whole composition range, with the transformation temperature TM significantly increased by the addition of terbium. The magnetic transition temperatures of the austenite and martensite, i.e. TCA and TCM, were monitored for 0⩽x⩽0.16 and 0.27⩽x⩽1, respectively. Both TCA and TCM were slightly decreased by the addition of terbium. For 0.16⩽x⩽0.27 the martensitic transformation was coincided with the magnetic transition in case of TM=TC, giving rise to the coupled magneto-structural transition from ferromagnetic martensite to paramagnetic austenite. Sizable magnetic entropy change was induced by magnetic field in the vicinity of the coupled magneto-structural transition.

Determination of fluoroquinolone antibiotics by microchip capillary electrophoresis along with time-resolved sensitized luminescence of their terbium(III) complexes

We report on the time-resolved detection of the three fluoroquinolone (FQs) antibiotics ciprofloxacin (CIP), enrofloxacin (ENR) and flumequine (FLU). On addition of terbium(III) ions, the terbium(III)-FQs chelates are formed in-situ in an on-capillary derivatization reaction of a microfluidic system. The laser-induced terbium(III)-sensitized luminescence of the chelates is measured at excitation/emission wavelengths of 337/545 nm. The analytes can be separated and quantified within less than 4 min. A solid phase extraction step for analyte preconcentration can be included prior to chelation and microchip capillary electrophoresis. The analytical ranges of the calibration graphs for CIP, ENR and FLU are from 10.6 to 60.0, 10.3 to 51.0, and 11.5 to 58.8 ng mL−1, respectively, and the detection limits are 3.2, 3.1 and 3.6 ng mL−1, respectively. The precision was established at two concentration levels of each analyte and revealed relative standard deviations in the range from 3.0 to 10.2 %. The method was applied to the analysis of FQ-spiked water samples.

Effect of Tb3+ substitution on structural, electrical and magnetic properties of sol–gel synthesized nanocrystalline nickel ferrite

Abstract A series of NiTb x Fe 2− x O 4 ( x = 0.0, 0.1, 0.2, 0.3) nanoparticles with small size have been prepared using sol–gel technique. The effect of Tb 3+ substitution on the crystalline phase, crystallite size and magnetic, electrical and dielectric properties has been investigated in detail. The lattice constant shows an increasing trend with increase in Tb 3+ ion concentration. The high frequency tetrahedral vibration band ν 1 and the low frequency octahedral vibration band ν 2 in the FTIR spectra are in the reported range. The observed shift in ν 2 towards lower wave number side with increase in terbium concentration suggests the occupation of Tb 3+ ions predominantly on octahedral sites. Saturation magnetization is found to decrease with terbium addition. Magnetic hysteresis loss is observed to decrease up to x = 0.2 and then increases. The room temperature resistivity values are found to increase with terbium content. The observed dielectric dispersion with frequency is explained on the basis of Maxwell–Wagner two-layer model and electron hopping mechanism which is responsible for conduction and polarization. Dielectric constant and dielectric loss are found to decrease by terbium addition and is explained in terms of the decrease in hopping rate due to the substitution of Fe 3+ ions by Tb 3+ ions on the octahedral sites. The increased resistivity and reduced dielectric loss attained in terbium doped ferrite is promising as it is desirable for high frequency applications.

Effect of Terbium addition on the coercivity of the sintered NdFeB magnets

The effects of Tb addition on the microstructure and magnetic properties of the NdFeB magnets prepared by HD method were investigated by X-ray diffraction (XRD) and BH magnetometers. The results of the microstructure showed that both the Tb-doped and undoped permanent magnets were composed mostly of Tetragonal phase Nd 2Fe 14B (space group P42/ mnm) and a trace amount of Nd-rich phase. Accordingly, addition of Tb led to a decrease of the pole density factor of (004), (006) and (008) crystal plane of the Nd 2Fe 14B phase calculated by Horta formula, but the coercivity of the magnets increased from 2038 kA/m up to 2302 kA/m as a consequence of Tb addition. The study of the H c( T)/ M s( T) versus H min N/( M s( T) behavior showed that the nucleation was the dominating mechanism for the magnetization reversal in both sintered magnets, and the microstructural parameters of α k and N eff were obtained also. The Kronmüller-plot showed an increase of the α k responsible for an increase of the coercivity.

Electrical behavior against current impulse in ZnO–Pr 6O 11-based varistor ceramics with terbium addition

Tb 4O 7 addition effect on electrical behavior against current impulse in the Zn–Pr–Co–Cr-based varistors was investigated. The Tb 4O 7 did have a significant effect on electrical behavior against current impulse. Increasing Tb 4O 7 content improved the clamp ratio ( K), reaching nearly 2 at 1.0 mol%. The best stability against current impulse of 100 A/cm 2 was obtained at 0.25 mol% Tb 4O 7, where % Δ E 1 mA/c m 2 = − 0.8 % and %Δ α = +1.1%. In addition, the varistor doped with 0.5 mol% Tb 4O 7 were no less stable against current impulse than varistor doped with 0.25 mol% Tb 4O 7. Furthermore, the varistor doped with 0.5 mol% Tb exhibited the best surge withstand capability at a current impulse of 900 A. Conclusively, Tb 4O 7 content was optimized at 0.5 mol% in terms of the nonlinearity and surge withstand capability.

Effects of Tb addition on the microstructure and properties of a Ni-Mn-Ga ferromagnetic shape memory alloy

The effects of terbium addition on the microstructures and properties of polycrystalline Ni48.8Mn29.7Ga21.5 alloy (numbers indicate at.%) were investigated. The results show that the grain size of Ni-Mn-Ga alloy decreases significantly with the addition of Tb, and Tb elements are found to exist in the grain boundary region and form a (Ni, Tb)-rich quaternary phase. The compressive ductility and fracture toughness increased with the addition of Tb. The improvement of mechanical properties and the slight change of martensitic transformation temperature and the magnetic properties of the Tb-added alloys are discussed in terms of the modification of microstructures with the addition of Tb.

Structure and properties of Ni–Mn–Ga magnetic shape memory alloys containing minor addition of terbium

Effect of terbium addition in the range of 0–2 at% on the structure, phase constitution and hardness of the Ni 49Mn 29Ga 22 alloy was studied. The Tb addition substantially refined the grain size, which dropped from 200 to 400 μm, for the Tb-free alloy, down to 30–50 μm for the 2 at% Tb material. The terbium exhibited negligible solubility in the matrix phase and formed grain boundary layer. The mean composition of the boundary layer was: Tb, 16 at%; Ni, 55 at%; Mn, 7 at%; and Ga, 22 at%. The phase analysis revealed the presence of the following major phases in the alloys: Ni 2MnGa and Ni 3Ga. All the alloys exhibited martensitic structure at room temperature. The Tb addition did not affect the Curie temperature, however, the A s temperature (martensite-to-austenite transformation starting temperature) and M s temperature (martensite-to-austenite starting temperature) grew slightly for low Tb concentrations and subsequently decreased for the higher Tb contents. The Tb-containing alloys exhibited increased hardness, by about 40%, which was apparently caused by the grain refinement. No significant effect of the Tb addition on the magnetic shape memory effect was observed.

Optical response of thiosalicylic-capped CdS nanocrystals to terbium ions

The effects of terbium ion addition on the optical spectra of CdS nanocrystals capped with thiosalicylic acid were investigated by means of absorption and steady-state photoluminescence spectroscopy. Upon terbium addition, the CdS absorption was modified around the first exciton peak while the CdS photoluminescence experienced selective enhancing and quenching processes. The results indicated that, most probably, the two types of changes are decoupled. The interpretation considered the key role played by the capping ligand in the optical response of nanocrystals to the lanthanide ions.

Capillary electrophoresis with post‐column addition of terbium and sensitized lanthanide‐ion luminescence detection for the determination of diflunisal and salicylic acid

AbstractA detection scheme based on the Post‐column addition of terbium followed by sensitized luminescence detection has been developed. Two model Compounds‐ saliculic acid and diflunisa‐ were separated by capillary electophoresis in an alkaline phosphate buffer. A Solution containing terbium and CTAB was added post‐column via a “home‐built” reactor resulting in the rapid fromation of the strongly luminescent terbium‐salicylic acid and terbium‐diflunisal complexes in a reaction capillary. Following complexationn in the reaction capillarty, the 325 nm line from a HeCd laser was used to excite the analytes which efficiently transfer their energy to terebium. Resuulant luminescence of terebium was liner of 2 orders of magnitude. This novel and practical system enables the detection of micromolar concentrations of diflunisal and salicylic acid‐ a 10 fold improvement over UV absorbance detection in the same system. Post‐column addition of terbium also eliminates the problems associated with strong adsorption of the lanthanide ion to the silica walls of the separation capillary and the formation of metal‐ligand complexes with different coordination numbers.