Terbium Concentration Research Articles

Influence of Terbium Ions and Their Concentration on the Photoluminescence Properties of Hydroxyapatite for Biomedical Applications

A new generation of biomaterials with terbium-doped hydroxyapatite was obtained using a coprecipitation method. The synthesis of new materials with luminescent properties represents a challenging but important contribution due to their potential applications in biomedical science. The main objective of this study was to revel the influence of terbium ions on the design and structure of hydroxyapatite. Different concentrations of terbium, described by the chemical formula Ca10−xTbx(PO4)6(OH)2, where x is in the range of 0 to 1, were considered. The consequence of ion concentration on hydroxyapatite morphology was also investigated. The morphology and structure, as well as the optical properties, of the obtained nanomaterials were characterized using X-ray powder diffraction analysis (XRD), Fourier Transform Infrared spectrometry (FTIR), SEM and TEM microscopy, UV-Vis and photoluminescence spectroscopies. The measurements revealed that terbium ions were integrated into the structure of hydroxyapatite within certain compositional limits. The biocompatibility and cytotoxicity of the obtained powders evaluated using MTT assay, oxidative stress assessment and fluorescent microscopy revealed the ability of the synthesized nanomaterials to be used for biological system imaging.

Use of Terbium Doped Phosphate Glasses for High Dose Radiation Dosimetry—Thermoluminescence Characteristics, Dose Response and Optimization of Readout Method

The phosphate glass samples doped with Tb2O3 oxide (general formula: P2O5-Al2O3-Na2O-Tb2O3) were synthesized and studied for usage in high-dose radiation dosimetry (for example, in high-activity nuclear waste disposals). The influence of terbium concentration on thermoluminescent (TL) signals was analyzed. TL properties of glasses were investigated using various experimental techniques such as direct measurements of TL response vs. radiation dose, Tmax–Tstop and VHR (various heating rate) methods, and glow curve deconvolution analysis. The thermoluminescence dosimetry (TLD) technique was used as the main investigation tool to study detectors’ dose responses. It has been proved that increasing the concentration of terbium oxide in glass matrices significantly increases the thermoluminescence yield of examined material. For the highest dose range (up to 35 kGy), the dependence of the integrated thermoluminescent signals vs. dose can be considered as a saturation-type curve. Additional preheating of samples improves linearity of signal vs. dose dependencies and leads to a decrease of the signal loss over time. All obtained data suggest that investigated material can be used in high-dose radiation dosimetry. Additional advantages of the investigated dosimetric system are its potential ability to re-use the same dosimeters multiple times and the fact that reading dosimeters only requires usage of a basic TL reader without any modifications.

Visible emission characteristics in Tb3+-doped KNa3Al4Si4O16 phosphor

The citrate sol-gel method was used to synthesize a set of KNa3Al4Si4O16:xTb3+ phosphors (x = 0.005, 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, 0.13 mol). Powder X-ray diffraction (XRD) was carried out for structural investigations and Fourier transform infrared (FT-IR) spectra for identification of functional groups. The crystallite size of the phosphors was estimated by employing the well-known Debye-Scherer equation. Scanning electron microscopy (SEM) was performed to gather the morphological information. For photoluminescence (PL) studies, excitation and emission spectra were recorded for different concentrations of trivalent terbium (Tb3+) ion. Commission International de I′Eclairage (CIE) coordinates were calculated. The results confirmed the green emission from the prepared samples and the potential of this candidate as a green emitter for lighting applications.

Oxygen vacancy-based Tb-doped SnO2 nanotubes as an ultra-sensitive sensor for ethanol detection

In this work, different concentrations of terbium (Tb) doped SnO2 nanotubes (NTs) were synthesized via simple uniaxial electros-pinning and high-temperature calcination. The mapping results show that Tb elements are uniformly distributed on SnO2 NTs. X-ray photoelectron spectroscopy (XPS) was used to characterize the changes of oxygen ion species of pristine SnO2 and 7 mol% Tb-doped SnO2. In terms of gas sensitive performance, the sensor prepared by this method has low operating temperature, excellent selectivity and ultra-high sensitivity. Notably, compared with other obtained SnO2 samples, the 7 mol% NTs presented the best sensing performance, and the response to 100 ppm ethanol reached 53.6 at 200 °C. Combined with the study of gas sensitivity, it can be confirmed that doping Tb increases the number of active sites (such as oxygen vacancies (VO)) on the surface of SnO2, thus enhancing the gas sensitivity and electrical responsiveness of SnO2. Hence, the research in this work will be helpful to the development of new high performance gas sensors based on dopant metal oxide semiconductor.

Structural, electrical properties and photoluminescence analyses of the terbium doped barium titanate

Multifunctional materials integrating optical and electric properties into a composite or into a doped single–phase material have attracted much attention from scientists for future optoelectronic devices. In this work, polycrystalline Ba1–xTbxTiO3, x = 0.00, 0.01 and 0.05 materials were synthesized by hydrothermal route and their photoluminescence and dielectric properties were studied. The as–prepared powders showed a microstructure consisting of grains with the shape of cube; and average particle size ranging from 75 nm to 150 nm. The investigated temperature dependence of dielectric permittivity of Ba1–xTbxTiO3 ceramics revealed a decrease of the Curie temperature (Tc) with increasing terbium content, and a more pronounced degree of diffuseness of phase transition. The resistivity at room temperature was discussed in terms of positive temperature coefficient of resistance (PTRC) effect. UV–vis reflectance spectra of Ba1–xTbxTiO3 samples showed a decrease of the band gap energy with the increase of Tb amount, due to the band–gap narrowing effect. The photoluminescence spectra recorded for Tb doped BaTiO3 materials, at 80 K, evidenced the typical f–f luminescence lines of the Tb3+ accompanied the broad luminescence band at about 425 nm due to self–trapped exciton recombination. These results demonstrated that the terbium enhances the dielectric properties and photoluminescence simultaneously, being suitable for electronic applications.

Optical properties of ZnO:SiO2:Tb3+ films: the effect of DNA

Thin films of zinc oxide and those doped with terbium (at concentrations of 0.1–5.0 mol%) were synthesized on glass substrates using the sol–gel method. The UV–Vis transmission spectra showed that transparency increases from 60% to 86% with an increase of Tb content. All terbium-doped samples exhibit a rise in Eg from 3.37 eV for zinc oxide to 3.827 eV for doped films. The photoluminescence (PL) of zinc oxide doped with terbium in the UV (260 nm) region and the fluorescence of terbium in the visible region (330 nm) were studied. The intensity of green luminescence with an increase in the amount of terbium increases by an average of 6%. The yield of green fluorescence relative to PL also goes up with an increase in the concentration of terbium concentration of terbium from 5% to 7.4%. DNA deposited on the surface of the plate extinguishes PL by an average of 5.5% and has a weak effect (<3%) on terbium fluorescence in the visible region. SEM images without DNA consist of spherical structures—0.5–2.0 μm in diameter, assembled in the form of pentagons. The presence of DNA on the surface is expressed as ‘stars’ of white color of regular and irregular shapes, located on the surface inside these pentagons.

Tailoring Dy3+/Tb3+-doped lead telluride borate glasses for gamma-ray shielding applications

Glass–ceramics of composition (39.5–x) PbO–20 B2O3–20 TeO2–20 MgO–0.5 Dy2O3–x Tb2O3 (where x = 0, 0.5, 1, 1.5, 2, and 2.5 mol%) have been prepared by controlled heat treatment. XRD confirms the crystalline phases present in the network. The structural and vibrational bonds present in the network structure were estimated using the FTIR technique. The band-gap values for the direct and indirect decrease from 3.209 to 3.025 eV and 3.006 to 2.637 eV as terbium concentration increases. The gamma-ray shielding features for the fabricated samples were examined with the help of the MCNP5 code. The relative difference between the linear attenuation coefficients (LAC) obtained by MCNP5, and validated by XCOM, is less than 6%. The addition of Tb2O3 affects the LAC values, especially at the lower energies (0.347 and 0.662 MeV), where a notable decrease in the LAC was recorded as more Tb2O3 was added to the glasses. For the TNNS0-TNNS2.5 glasses, and with the simulated LAC's help, we reported the half-value layer (HVL). For all six of the prepared TNNS0.0–TNNS2.5 glasses, HVL positively correlated with energy. For TNNS0.5, its HVL increased from 0.3770 cm at 0.284 MeV, to 0.9929 cm at 0.511 MeV, 1.6241 cm at 0.826 MeV, and 2.367 cm at 1.332 MeV. From the HVL results, we found that when using these glasses to absorb low energy radiation, a smaller thickness is required to properly absorb most of the photons, while a much greater thickness is required in high energy applications. The ratio between the HVL of TNNS0.0 and TNNS0.5 glasses was calculated. The HVL ratio between TNNS0.0 and TNNS2.5 was also calculated to understand the glass composition's effect on the HVL values. In both cases, the ratios at all energies were greater than one, which means that TNNS0.0 has the greatest HVL at all energies. These results prove that TNNS0 has the greatest potential in radiation-shielding applications, as a lower HVL signifies a better shield, while TNN2.5 has the least potential. The transmission factor (TF) of the investigated glasses at four different thicknesses and four energies was examined. The results revealed that its TF decreases as the thickness of the glass increases for anyone glass, which proves that increasing the thickness of the glasses improves their shielding ability.

Influence of terbium (III) ions on the photocatalytic activity of TiO2 and CeO2 for the degradation of methylene blue in industrial effluents.

This study reports the preparation of TiO2 and CeO2 doped with different quantities of terbium and discusses the influence of this dopant on the photocatalytic activity of the semiconductors, with respect to the degradation of methylene blue, under ultraviolet and solar radiations. The oxides obtained were characterized by X-ray diffraction, infrared vibrational spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy, and dispersive energy spectroscopy. The results indicate that the presence of the dopant in TiO2 favored the formation of the anatase crystalline phase to the detriment of rutile, increased the band gap energy, and decreased the size of the nanoparticles. Doping CeO2 with Tb resulted in a fluorite-type crystalline structure, reduced band gap, and smaller particle size. The photocatalytic activity decreases as the concentration of terbium increases regardless of the radiation source and nature of the oxide. Furthermore, a better performance was observed for all semiconductors excited by solar radiation in comparison to ultraviolet light. The samples of pure TiO2 and TiO2 doped with 0.5 and 1% terbium showed total removal of the dye after less than 120min of reaction, while the samples of pure CeO2 and CeO2 doped with 0.5% terbium showed approximately 80% and 57% of dye removal after 120min, suggesting that these materials can be promising for the treatment of industrial effluents.

Generation of cold white light by using energy transfer process in single phase Ce3+/Tb3+ co-doped CaSrAl2SiO7 phosphor

Single phased CaSrAl2SiO7 phosphor singly doped with different concentrations of trivalent cerium and terbium; and co-doped with varying Tb3+ concentration were prepared by standard solid state reaction (SSR) method. The crystallinity and particle morphology of the product samples were analysed by using XRD and TEM characterizations. Photoluminescence characterizations of singly doped and co-doped samples were studied in detail. CaSrAl2SiO7:Ce3+,Tb3+ phosphor exhibit a broad blue emission band at 410 nm and some sharp emission bands in blue green and yellow regions, which originate from Ce3+ and Tb3+ ions, respectively. By increasing the concentration of Tb3+ ions while fixing Ce3+ concentration in the host lattice energy transfer takes place from Ce3+ to Tb3+ ions which create luminescence emission in white region. CaSrAl2SiO7:Ce3+,Tb3+ phosphors are proved to be promising candidates for white lighting for outdoor illumination.

Concentration-wavelength dependence of magneto-optical properties in Tb3+-doped BGAP Glass

B2O3-GeO2-Al2O3-P2O5 (BGAP) magneto-optical (MO) glasses with different Tb2O3 doped concentrations were prepared by melt quenching process. The effects of different Tb2O3 concentrations on structure, physical properties, MO properties and fluorescence properties of the BGAP glasses and the effect of wavelength on Verdet constant of BGAP glass were tested and analyzed. The results show that [BO3] in the glass network structure gradually converts to [BO4] and the glass density increases with the increase of Tb2O3 concentration according to FTIR spectra. The reported T35 glass exhibits an absolute negative Faraday rotation of, 140.15 rad/T/m at 632.8 nm. The Figure of Merit (FoM) which is the ratio of Verdet constant to transmittance can reach -2.93 °/dB at 420 nm for the T40 glass, the Tb3+ concentration of ~11.568 × 1021/cm3 over the visible light range. With the increased concentration of terbium, the excitation, emission intensity and fluorescence lifetime of glasses drop for the concentration quenching of terbium ions.

A study of the structure, luminescence and cytotoxicity of new green-emitting terbium-doped CaS nanophosphors

CaS nanoparticles have attracted significant attention due to their wide range of optoelectronic applications. The synthesis of CaS nanophosphors doped with different terbium concentrations through a simple wet chemical co-precipitation method using triethanolamine (TEOA) as a capping agent is reported here. X-ray diffractogram ensured that the nanoparticles were crystallized in the cubic phase with space group $$Fm\overline{3}m$$ . Morphology and particle size of the TEOA-capped CaS:Tb nanophosphors were determined using scanning electron microscopy and transmission electron microscopy. The optical properties of the samples were studied by photoluminescence spectroscopy and UV–Vis absorption measurements. The prepared nanoparticles exhibited green luminescence, which is attributed to 5D4–7FJ transitions of terbium ions incorporated into the CaS lattice. The existence of various functional groups in the synthesized products was identified by Fourier transform infrared spectroscopy. The lifetime decay measurements showed that the lifetime of the samples was in the nanosecond range. Cytotoxicity analysis of the nanoparticles was carried out on L929 fibroblast cells, which confirmed that the nanoparticles are biocompatible across a wide range of concentrations. Our findings indicate that CaS:Tb nanophosphor could be a potential candidate as a green-emitting phosphor in optoelectronics and biomedical field.

Films of (Gd1 –xTbx)2O2S Solid Solutions Produced by Oxide Sulfidation in NH4SCN Vapor and Their Optical Properties

(Gd1 – xTbx)2O3 (x = 0.04–0.22) films 115 to 150 nm in thickness have been grown on Si and SiO2 substrates by metal organic chemical vapor deposition (MOCVD) using Ln(dpm)3 precursors. After annealing in air at 800°C for removing carbon-containing impurities, the films were sulfided in NH4SCN vapor at temperatures from 700 to 1000°C in an Ar atmosphere until the formation of (Gd1 – xTbx)2O2S oxysulfides. The surface of the films is formed by grains 60 to 200 nm in size. The measured refractive index of the films is 2.2–2.4 and their estimated optical band gap (Eg) is 4.7–5.0 eV. The optical transmission of the films in the visible spectral region (400–750 nm) reaches 78–84%. The highest photoluminescence (PL) intensity in the oxysulfide films produced under identical conditions has been observed at x = 0.05. The blue component of their PL decreases with increasing terbium content and the emission shifts to the green spectral region.

Enhancement of the sensitivity of single band ratiometric luminescent nanothermometers based on Tb3+ ions through activation of the cross relaxation process

The description of luminescent processes and their thermally induced changes, that may be also influenced by the optically active ions concentration, and thus by the various inter-ionic processes, is the key to the improved development of luminescence thermometry. A phosphor doped with only trivalent terbium ions was described, which, by using two excitation lines fitted to the 7F6 → 5D3 and 7F5 → 5D3 transitions, shows a luminescent signals with the opposite characteristics of intensity changes as a function of temperature. By modifying the concentration of Tb3+ ions, the probability of {5D3, 7F6} ↔ {5D4, 7F0} cross-relaxation was being altered, which turned out to have a beneficial effect on the properties of the described nanothermometers. The ratio of intensities for both excitations was found to be temperature dependent, which resulted in high relative sensitivities of temperature readout reaching 3.2%/°C for 190 °C and not reaching values below 2%/°C in the broad range of the temperature. Extensive decay time measurements for 5D3 and 5D4 emissive levels were presented and the variability of both rise- and decay times as a function of terbium concentration and temperature was investigated. Thanks to this, conclusions were drawn regarding thermally dependent optical processes occurring in a given and similar systems.

Acid-Base and Luminescent Properties of Gd&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt;S: Tb Luminescent Phosphors Synthesized in a Reducing Atmosphere

Gd2O2S:Tb phosphors with different terbium content are prepared in a reducing atmosphere at various synthesis conditions. The effect of an activator and Na4P2O7 flux concentrations upon photo-and X-ray induced luminescence of the synthesized samples as well as on their acid-base properties and morphology is studied. The addition of Na4P2O7 flux into the charge mixture leads to a significant increase of the phosphor particle size. A positive correlation is found between the particle size and pH value of the phosphor aqueous slurry. The photoluminescence intensity is found to mostly depend on the activator concentration, while X-ray luminescence intensity primarily depends on the particle size and crystal structure perfectness of the phosphor matrix. Charge mixture compositions and synthesis conditions providing Gd2O2S:Tb phosphors with the highest photo-and X-ray luminescence intensity are determined. A Gd2O2S:Tb phosphor with X-ray luminescence intensity exceeding the values for the commercial phosphor KEP-45 of a similar composition is developed. The obtained phosphors can be used for the manufacture of intensifying screens applied in industrial X-ray flaw detection.

Growth and Characterization of (Tb,Yb) Co-Doping Sprayed ZnO Thin Films

Structural, optical and electrical properties of (ytterbium/terbium) co-doped ZnO thin films deposited on glass substrates using the spray pyrolysis method were investigated. The films exhibited the hexagonal wurtzite structure with a preferential orientation along (002) direction. No secondary phase was observed in the X-ray diffraction detection limit. Atomic force microscopy (AFM) was performed and root means square roughness (RMS) of our samples decreased with terbium content. Photoluminescence measurements showed a luminescence band at 980 nm which is characteristic of Yb3+ transition between the electronic levels 2F5/2 to 2F7/2. This is experimental evidence for an efficient energy transfer from the ZnO matrix to Yb. Hall Effect measurements gave a low electrical resistivity value around 6.0 × 10−3 Ω.cm. Such characteristics make these films of interest to photovoltaic devices.

Fluorophosphate Glasses with High Terbium Content for Magneto-optical Applications

Fluorophosphate glasses are investigated following the composition law (1 – x)(70NaPO3 – 30BaF2) – xTbF3 with x = 35, 40, 45, and 50 mol %. Bubble-free vitreous rods of 5 cm length and 4 mm in diameter are obtained without crystallization from 35 to 50 mol % of TbF3 by using the conventional melt-quenching process. The maximum content of Tb3+ ions successfully dissolved in these glasses corresponds to an ionic density of 8.88 × 1021 ions cm–3, which is the highest value ever reported in a fluorophosphate glass matrix, to our knowledge. Thermal, structural, and optical properties were characterized respectively by DSC, Raman spectroscopy, prism coupling technique, UV–visible-NIR, and Verdet constant measurement. The increase of the terbium content from 35 to 50 mol % in the glass results in an increase of its glass transition temperature (Tg) from 352 to 390 °C, a decrease of its thermal stability against crystallization (ΔT) from 153 to 73 °C, and an increase of both its refractive index and Verdet consta...

Influence of Tb3+ doping on the structural and down-conversion luminescence behaviour of SrLaAlO4 nanophosphor

Different concentrations of terbium activated strontium lanthanum aluminates (SLA:Tb3+) were synthesized by adopting urea-aided solution combustion route at the sintering temperature of 1330 °C. XRD based Rietveld refinement technique confirms that SLA:Tb3+ nanophosphors have a perovskite-based structure with I4/mmm space group symmetry. Morphological information is collected on scanning and transmission electron microscopes (SEM & TEM) however, the energy dispersive mode of SEM (EDS) provides an idea about the distribution of existing elements throughout the host lattice. The band-gap studies for SrLaAlO4 (5.00 eV) and SrLa0.98Tb0.02AlO4 (4.50 eV) compositions are carried out using diffuse reflectance (DR) measurements via Kubelka-Munk relations. The down-converted photoluminescence (PL) studies reveal that an intense green emission is obtained at 545 nm due to 5D4 → 7F5 transition under 279 nm UV-excitation. Further, Dexter's theory helps in explaining the concentration quenching mechanism in SLA:xTb3+ nanocrystals (d-q interactions, s = 8.13). Moreover, the radiative lifetime (1.17 ms), non-radiative rates (194.28 s−1) and quantum efficiencies (81%) of 5D4 term are calculated using Auzel's model. Finally, the Commission International de I'Eclairage (CIE) color coordinates confirm the emission in green region; which approves the role of Tb3+-activated SLA nanophosphors as a green component in RGB based white light emitting diodes (WLEDs).

Terbium concentration effect on magneto-optical properties of ternary phosphate glass

Ternary phosphate glass doped with different terbium concentration (up to 35 wt.%) is synthesized via standard melt-quenching technique. The effect of terbium content on physical, optical, and magneto-optical properties is investigated. Two glass transition regions on DSC curve at 35 wt.% Tb2O3 demonstrate phase-separation process. Transmittance spectra demonstrate maximum 0.2 cm−1 level in optical transmittance window of 400–1600 nm limited by standard absorption bands for terbium-containing materials. Metaphosphate groups in as-synthesized glass structure are predominant over polyphosphate complexes with no ultraphosphate units regardless to composition changes. After the additional heat treatment the partial depolymerization of glass structure occurs resulting in formation of big amount of Q0 and Q1 units. Glass refractive index varies from 1.5872 to 1.5814 with terbium content increase. The concentration dependence of Verdet constant is non-linear due to the presence of Tb4+ ions, which was confirmed by the XPS analysis results. The value of 15 rad/T/m at 1064 nm is reached for 35 wt.% Tb2O3-doped glass. The results indicate the viability of the considered glass series with high terbium oxide concentration to be attractive media for magnetooptical devices working in VIS and near IR ranges.

Spectroscopic investigations on Se/RE doped sol gel derived silica matrices

Selenium and rare earth ions co-doped inorganic luminescence silica matrices are synthesized through sol gel route. The incorporation of cubic Se quantum dots within the porous silica frame is confirmed from TEM analysis. The successful entrapment of green as well as blue color emitters within the silica frame generates evident luminescence bands in the visible region. Obtained Se/Tb3+ ions doped silica glasses give characteristic sharp emission peaks of terbium ions at 488 nm, 543 nm, 584 nm, 619 nm wavelength under UV excitations. A broad blue emission band from selenium nanodots centered at 421 nm wavelength is observed in the emission spectrum. Colorimetric studies are done with the aid of 1931 chromaticity diagram. CIE indices of the co-doped glasses are found to lie in between the CIE indices of selenium doped silica glasses (0.18, 0.21) and terbium doped silica glasses (0.28, 0.46). For a fixed concentration of Se and terbium in silica glasses, tunable luminescence without shift in peak wavelength is observed under the excitation wavelength of 340 nm to 380 nm. Varying blue to green luminescence intensity ratio (B/G) with the excitation wavelength reveals the possibility of tunable emission of the glassy matrix for their applicability in solid lighting systems.

Magneto-optical properties of terbium-doped metaphosphate and borate glasses

The paper shows the results of Faraday Effect study of borate and metaphosphate glasses doped with various concentrations of terbium under uniform longitudinal magnetic field. The Verdet constant of glass under study is obtained based on the experimental data for several wavelengths. The optical and spectral properties of glasses are also studied.