Effect Of Pr3 Research Articles

Manipulating the ferroelectric, dielectric and photoluminescence performance of Ba0·77Ca0·23TiO3 ceramics through Pr3+ ions doping

The Pr3+-doped Ba0·77Ca0·23TiO3 ferroelectric ceramics, which were sintered by means of a high-temperature solid-state reaction technology, were prepared. The Rietveld X-ray diffraction refinement and Raman spectrum proved that the resultant compounds had tetragonal phase. With the addition of Pr3+ ions, the highest remanent polarization of the resultant ceramics was nearly two times higher than that of the pure Ba0·77Ca0·23TiO3 ceramics. With the aid of a theoretical calculation based on the temperature-dependent dielectric constant, it is found that the synthesized compounds pertained to the relaxor-like ferroelectrics. Furthermore, through the piezoresponse force microscopy technique, the effect of Pr3+ ions doping on the domain structure of the Ba0·77Ca0·23TiO3 ferroelectric ceramics was studied. Additionally, the prepared ferroelectric ceramics can exhibited the characteristic emissions of Pr3+ ions when excited by 450 nm light. The strongest emission intensity was achieved when the dopant content was 0.5 mol% and the dipole-quadrupole interaction contributed to the relevant concentration quenching mechanism.

The effects of Pr3+ doping on the dielectric and photoluminescence properties of BaTi0.9(Yb0.5Nb0.5)0.1O3 ceramic

The praseodymium Pr3+ doped BaTi0.9(Yb0.5Nb0.5)0.1O3 (BTYN01) ceramic, under low concentration (0.1%), was prepared by a conventional ceramic fabrication technique and its phase structure, microstructure, dielectric, vibrational and photoluminescence (PL) properties was studied. Both X-ray diffraction (XRD) and Raman studies confirmed the incorporation of Pr3+ into A-site lattice of BTYN01. The structure of Ba0.9985Pr0.001□0.0005Ti0.9(Yb0.5Nb0.5)0.1O3 (BTYN01-Pr) shows the coexistence of Pm3¯m-cubic symmetry (∼10%) and P4mm-tetragonal symmetry (∼90%) at room temperature. The dielectric study reveals that the maximum of the dielectric constant of BTYN01-Pr occurred at 283 K. The incorporation of Pr3+ has not change significantly the temperature of transition of BTYN01, but makes its transition peak more broadened. Contrary to BTYN01, doping with the Pr3+ allowed us to accommodate a PL response with a strong single red emission localized at about 648 nm. The temperature dependence on up-conversion emissions of BTYN01-Pr ceramic, obeying an Arrhenius law with a weak energy activation (Ea = 0.04 eV), indicates that the mechanism of PL emission is probably related to the vibrational property of the lattice. The Pr3+ doped BTYN01 red emission material with dielectric properties might have important technological promise in novel multifunctional devices.

A multicolor persistent luminescent phosphor Sr2Ga2GeO7:Pr3+ for dynamic anticounterfeiting

AbstractPersistent luminescence (PersL) phosphor is a glow‐in‐the‐dark material that has been widely applied. Here, we report a multicolor PersL phosphor Sr2Ga2GeO7:Pr3+. The PersL color can be tuned from deep red to blue. It reveals that the luminescent color modulation of the Sr2Ga2GeO7:Pr3+ phosphor is essentially associated with the cross‐relaxation effect of Pr3+ in the host with low‐phonon assistance energy. The PersL lifetime of the multicolor phosphors can be also tuned. Based on the unique features of Sr2Ga2GeO7:Pr3+ phosphor, some simple PersL images are fabricated to emit dynamic multicolor information, and it shows that the PersL image even depicts dynamic multicolor anticounterfeiting.

The structure and photoluminescence of a ZnO phosphor synthesized by the sol gel method under praseodymium doping.

This work outlines some interesting results regarding the effects of Pr3+ substitution on the structural and optical properties of (x = 0 and 0.02) samples. Our samples were synthesized using the Pechini sol–gel method. The structural study using Rietveld refinement of XRD patterns showed a hexagonal structure with the P63mc space group for all the samples and also the existence of a secondary phase attributed to the praseodymium oxide (Pr6O11) for 2% wt Pr-doped ZnO. The refinement results revealed that both the lattice parameter and the unit cell volume increase with the increase of Pr content. X-ray peak broadening analysis was used to evaluate the crystallite size and lattice strain by the Williamson–Hall (W–H) method and size–strain plot method (SSPM). The physical parameters such as strain, stress and energy density values were also calculated using the W–H method with different models, namely uniform deformation model (UDM), uniform stress deformation model (USDM) and uniform deformation energy model (UDEDM). The obtained results showed that the mean particle size of the ZnO and Pr0.01Zn0.97O estimated from W–H analysis and the SSPM method are highly intercorrelated. Shifting of the absorption edge to lower wavelength and blue shift of the band gap are observed in the UV-visible spectra of Pr-doped ZnO samples. Particular emphasis was put on the PL measurements of such composites. A noticeable decrease of the maximum intensity of PL response was found after adding Pr3+ to ZnO. This finding is discussed in terms of the photo excited limitation of electron–hole pairs in such nanocomposites.

Effect of Pr3+ on Site Preferences of Eu2+ in NaBaScSi2O7 and Its Optical Properties

NaBaScSi2O7 with Eu2+ doped phosphors are prepared by high temperature solid state reaction. It is found that there are two different sites for Eu2+ occupied, which is responsible for different emission color of NaBaScSi2O7: Eu2+ with increasing Eu2+concentration. Pr3+ ions are introduced to regulate the Eu2+ ions occupied sites. When Pr3+ ions content climbs, conversion of blue to green emitting light can be realized because of the location migration of Eu2+ ions. Meanwhile, the defect structure of NaBaScSi2O7: Eu2+ has been adjusted by introducing Pr3+ ions, the shallow and deep traps generated benefits the long persistent luminescence (LPL) and photo-stimulated luminescence (PSL) phenomenon. It is interesting to note that NaBaScSi2O7: Eu2+, Pr3+ demonstrates different LPL and PSL color compared to NaBaScSi2O7: Eu2+. The controllable optical properties are realized on the basis of Eu2+ site preferences assisted by doping Pr3+, which provides guidance for the development of electron trapping materials.

Photoluminescence characteristics of Pr3+ doped PbGdB7O13 as a new red emitting phosphor

A red phosphor Pr3+ doped PbGdB7O13 was synthesized by high temperature solid state reaction. The effect of Pr3+ doped concentration on the luminescent properties of the phosphor was investigated. The emission spectrum includes an apex at about 607 nm, corresponding to the 3P0→3H6 transition of the Pr3+ ion activator. For PbGd1-xB7O13:xPr3+, the emission peak intensity first increases with the increase of Pr3+ concentration, and reaches the maximum when the Pr3+ concentration is 0.02, and then decreases with the increase of Pr3+ concentration. The CIE coordinates of the PbGdB7O13:0.02Pr3+ phosphor was calculated to be (0.6332, 0.3651), falling into the red color. Therefore, there is a potential application on display, indication or illumination.

Effect of Pr3+doping on key properties of CdO thin films deposited by spray pyrolysis using perfume atomizer

High quality Cadmium oxide thin films doped with Praseodymium (Pr) were prepared using perfume atomizer based spray pyrolysis technique at substrate temperature near 350 °C. Structural analysis of films was examined by XRD and confirmed that the films are cubic in structure. All un-doped and doped films were good crystalline in nature with smooth and flat surface without significant modifications owed to doping. Optical transmittances of doped films was decrease in the visible and IR range with increasing Pr doping concentration. Band gap widened from 2.42 to 2.20 eV when doped with Pr from 0 to 5 at. %. In addition, the photoluminescence property of the films was also observed. Further, the electrical studies were performed on pure and doped samples Viz., the electrical resistivity, carrier concentration (ρ) and Hall mobility (μ). It confirmed that the deposited films has good structural environments in terms of grain size, absolute stress correspond and low resistivity. Current-voltage measurements on the nanostructured Al/Pr-nCdO/p-Si/Al device showed a non-linear electric characteristics indicating diode like behavior.

Corrosion Inhibition Performance and Healing Ability of a Hybrid Silane Coating in the Presence of Praseodymium (III) Cations

In this study, combinations of two environmentally friendly compounds including a silane-based organic-inorganic coating and a rare earth (RE) salt have been investigated for mitigation of corrosion activity of mild steel. Bilayer silane coatings based on methyl triethoxy silane (MTES) and tetraethyl orthosilicate (TEOS) were reinforced by different amounts of praseodymium cations (Pr3+). The effects of Pr3+ loading on the hydrophobicity and surface properties of the coating were studied by contact angle measurements. Fourier Transform Infrared (FT-IR) spectroscopy was done to scrutinize the curing process and possible structural changes of silane network in the presence of inhibitor. Despite the decrease in the hydrophobic nature of silane coating, the Pr3+ cations did not change the curing of the coating. Electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) measurements confirmed the high corrosion inhibition power for the mild steel sample immersed in 400 ppm Pr3+ containing the saline solution. The results of EIS, polarization and salt spray tests besides the scanning electron microscopy (SEM) images confirmed the silane coating healing ability and corrosion protection properties enhancement in the presence of Pr3+ cations.

Very low loss tangent, high dielectric and non-ohmic properties of Ca1−1.5xPrxCu3Ti4O12 ceramics prepared by the sol–gel process

In this work, Ca1−1.5xPrxCu3Ti4O12 (0.00, 0.02, 0.04 and 0.06) ceramics were prepared by the sol–gel process. Very low loss tangent (tanδ) ∼0.016–0.022 and high dielectric constant (e ′) ∼6174–8469 with temperature coefficients less than ±15% over the temperature range of −75 to 135 °C were observed in all Pr3+-doped CaCu3Ti4O12 ceramics. e ′ decreased with increasing Pr3+ ion due to the decrease of oxygen vacancies and grain size, resulting from the substitution of small ionic radius Pr3+ ion in the structure. X-ray absorption near edge spectroscopy (XANES) confirmed the decrease of Ti3+/Ti4+ and Cu+/Cu2+ ratios with increasing Pr3+ ions. In addition, all Ca1−1.5xPrxCu3Ti4O12 ceramics displayed non-linear characteristics. Non-linear coefficient (α) and breakdown field (E b) of all ceramic samples can be enhanced by Pr3+ doping with the highest α value of ~14.74 and E b of ~5640 V/cm−1 in sample with x = 0.02. Effect of Pr3+ doping on phase composition and microstructure of samples were studied using X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-rays spectroscopy.

Enhanced 286 μm emission of Ho^3+,Pr^3+-codoped LaF_3 single crystal

A novel Ho3+,Pr3+-codoped LaF3 mid-IR laser crystal was successfully grown and analyzed. Enhanced emission at ~2.86 μm was observed for the first time. The effect of Pr3+ co-doping on the ~2.86 μm photoluminescence of Ho3+ was investigated. Compared with Ho3+ singly-doped LaF3 crystal, the Ho3+,Pr3+-codoped LaF3 crystal possessed stronger emission intensities at ~2.86 μm. It was also found that the energy transfer efficiency of Ho3+: 5I7 → Pr3+: 3F2 (71%) is much greater than that of Ho3+: 5I6 → Pr3+: 3F4 (28%), which almost restrained the self-termination problem in this Ho3+:Pr3+:LaF3 crystal. All the results indicated that Ho:Pr:LaF3 crystal is an attractive laser medium for ~2.86 μm laser applications.

Effect of Pr3+ ions concentration on the spectroscopic properties of Zinc telluro-fluoroborate glasses for laser and optical amplifier applications

A new series of Pr3+ ions doped Zinc telluro-fluoroborate (PrZTFB) glasses have been prepared by adding up to 2wt% Pr2O3. Spectroscopic properties were explored through X-ray diffraction, Raman, optical absorption, photoluminescence and decay measurements. The Raman spectra reveal the presence of different vibrational bonds of the borate and tellurite network(s). The bonding parameters have shown the ionic nature of the bonding Pr–X (X=O,F). The optical band gap energy and Urbach energy have been determined to understand the electronic band structure. The Judd-Ofelt parameters Ωλ (λ=2, 4 and 6) have been calculated to explore the bonding environment around the Pr3+ ions. The luminescence spectra exhibit emission bands in the visible region attributed to the 3P0→3H4, 3F2, 3F3, 3F4 and 3P1→3H5 and 1D2→3H4, 3H5 transitions and a broad near infrared emission band at around 1330nm corresponding to the 1G4→3H5 transition with a FWHM ≈70nm. The glasses lying in the reddish orange region of CIE 1931 chromaticity diagram have been found suitable for light emitting diode applications. The decay curves of 3P0 and 1D2 levels of Pr3+ exhibit non exponential behavior for all the glasses and experimental lifetime value is found to decrease while increasing the Pr3+ ions due to cross-relaxation mechanisms. The radiative parameters corresponding to the prominent 3P0→3H4, 1D2→3H4 and 1G4→3H5 emission transitions have been determined to elucidate the suitability of the studied glasses for the fabrication of photonic devices that includes laser materials and broad band optical amplifiers.

Synthesis and photoluminescence study of narrow-band UVB-emitting LiSr4(BO3)3:Gd3+, Pr3+ phosphor

A series of Pr3+, Gd3+ and Pr3+–Gd3+-doped inorganic borate phosphors LiSr4(BO3)3 were successfully synthesized by a modified solid-state diffusion method. The crystal structures and the phase purities of samples were characterized by powder X-ray diffraction. Surface morphology of the sample was studied by scanning electronic microscopy (SEM). The optimal concentrations of dopant Gd3+ ions in compound LiSr4(BO3)3 were determined through the measurements of photoluminescence (PL) spectra of phosphors. Gd3+-doped phosphors LiSr4(BO3)3 show strong band absorption in UV spectral region and narrow-band UVB emission under the excitation of 276 nm was only due to 6P J → 8S7/2 transition of Gd3+ ions. The effect of Pr3+ ion on excitation of LiSr4(BO3)3:Gd3+ was also studied. The excitation of LiSr4(BO3)3:Gd3+, Pr3+ gives a broad-band spectra, which show very good overlap with the Hg 253.7 nm line. The photoluminescence spectra of LiSr4(BO3)3 with different doping concentrations Pr3+ and keeping the concentration of Gd3+ constant at 0.03 mol have also been studied. The emission intensity of LiSr4(BO3)3:Pr3+–Gd3+ phosphors increases with increasing Pr3+ doping concentration and reaches a maximum at 0.01 mol. From the photoluminescence study of LiSr4(BO3)3:Gd3+, Pr3+ we conclude that there was efficient energy transfer from Pr3+→ Gd3+ ions in LiSr4−x−y Pr x Gd y (BO3)3 phosphors.

Enhanced visible to near infrared downshifting in Ce3+/Yb3+-co-doped yttrium aluminum garnet through Pr3+ doping

Novel YAG:Ce3+, Pr3+, Yb3+ phosphors were synthesized using a high temperature solid state reaction method. The XRD patterns revealed that the obtained samples belong to the single phase YAG. The optical spectra demonstrated that Pr3+ could be a bridge to facilitate the energy transfer from Ce3+ to Yb3+ in the YAG host. Blue light excited Ce3+ and a yellow emission from Ce3+ together with a near infrared emission of Yb3+ was obtained. The effect of Pr3+ doping on the energy transfer efficiency was explored. When the doping concentration of Pr3+ increased, the yellow emission intensities of Ce3+ decreased and the near infrared emission intensity of Yb3+ increased monotonously. Hence, the efficiency of energy transfer from Ce3+ to Yb3+ is enhanced by the addition of Pr3+, implying that the YAG:Ce3+, Pr3+, Yb3+ phosphors are promising downshifting materials and have the potential to be used in Si-based solar cells.

Effect of Pr3+ doping on structural, electrical, and optical properties of BaTi0.925(Yb0.5Nb0.5)0.075O3 ceramics

The effect of Pr3+ addition on structural, electrical, and optical properties of Ba1−xPr2x/3Ti0.925(Yb0.5Nb0.5)0.075O3 (0.3% ≤ x ≤ 1%) ceramics was investigated. X-ray studies have allowed the identification of a continuous solid solution with P4mm-tetragonal symmetry of all prepared samples. Incorporation of Pr3+ was found to improve ferroelectric and piezoelectric properties with an optimum at the critical concentration of 0.005. Photoluminescence properties revealed that the introduction of Pr3+ ions gives rise to the green and red photoemissions and permitted to shed more light on the created structural disorder and shallow defects. This effect was confirmed by Raman spectroscopy investigation. The presence of Pr element in such materials may have significant technological promise in novel multifunctional devices.

Correlation of structural distortion with magnetic properties of Pr-YIG system

The structural and magnetic measurements are carried out to interpret the effect of substitution of Pr3+ into Y3Fe5O15 system. The evolution of the microstructure and magnetic properties of Y3-xPrxFe5O12 (x = 0.0–0.8) series were characterized by the X-ray diffraction technique (XRD), Far-Fourier Transform Infrared Spectroscopy (Far-FTIR), Vibrating Sample Magnetometer (VSM) and Mössbauer spectroscopy. The Rietveld refinement of the X-ray data indicated that single-phase garnet structure was achieved for all the obtained samples. The observed absorption bands in Far-FTIR spectra shows the substitution structural effects. The effect of Pr3+ on magnetic properties have been analyzed based on associating a specific superexchange interaction to configurations of iron ions with fixed number of Pr3+ at their vicinity. A random cation distribution model is used to discussed the results in detail. The Mössbauer analyses are consistent with the explanation of the magnetization behavior and interestingly revealed that how different configurations with different superexchange interactions contribute in saturation magnetization variation.

Photoluminescence Properties of Er/Pr‐Doped K0.5Na0.5NbO3 Ferroelectric Ceramics

Er/Pr‐doped K0.5Na0.5NbO3 ceramics have been fabricated and the effects of Pr3+ on their photoluminescence properties have been investigated systematically. The visible upconversion emissions, near‐infrared and mid‐infrared downconversion emissions of Er3+ ions under the excitation of 980 nm have been studied in detail. The effects of Pr3+ on PL properties and energy‐transfer processes have also been elucidated. By selecting an appropriate excitation source, simultaneous visible downconversion emissions of Er3+ and Pr3+ ions can be realized, and the emission colors of the ceramics can be tuned via the concentration of Pr3+ ions in a wide range from yellowish green to yellow. Our results also reveal that the photoluminescence emissions of the ceramics can be enhanced by the alignment of polarization of the ferroelectric host.

Effect of Pr3+ substitution on the microstructure, specific surface area, magnetic properties and specific heating rate of Ni0.5Zn0.5PrxFe2−xO4 nanoparticles synthesized via sol–gel method

A series of Ni–Zn ferrite nanoparticles with a nominal composition of Ni0.5Zn0.5PrxFe2−xO4 (x=0.000–0.100 with steps of 0.025) has been synthesized by a sol–gel method. The effect of composition and calcination temperature on the morphology, specific surface area, magnetic properties and specific heating rate has been studied. The Ni–Zn–Pr ferrites have a single spinel (NZF) phase at Pr loadings below 5at%. A minor amount of an orthorhombic PrFeO3 phase is present in the Ni–Zn–Pr ferrites at Pr loadings above 5at%. At a Pr loading of 10at%, the specific surface area increases six-fold as compared to that of the non-doped Ni0.5Zn0.5Fe2O4 sample. As the Pr loading increases, the saturation magnetization, remnant magnetization and coercivity increase and reach the maximum at x=0.05 and then decrease. The maximum values of these parameters are 67.0emu/g, 9.7emu/g and 87.2Oe, respectively. Under radiofrequency field (frequency: 295kHz, intensity: 500Oe), the highest heating rate of 1.65K/s was observed over the sample with x=0.025 which is 2.5 times higher than that of Ni0.5Zn0.5Fe2O4.

Effects of Pr3+-deficiency on structure and properties of PrBaCo2O5+δ cathode material–A comparison with Ba2+-deficiency case

Double-layered perovskite oxides of Pr1−yBaCo2O5+δ (P1−yBCO) with A-site Pr3+-deficiency contents of y = 0.00–0.10 have been studied with respect to phase structures, oxygen content, high-temperature chemical stabilities as well as electrical and electrochemical properties as cathode materials of intermediate-temperature solid oxide fuel cells (IT-SOFCs). The Pr3+-deficiency content in P1−yBCO is limited by ∼8 mol%, and the Pr3+-deficiency hardly changes lattice parameters of P1−yBCO. Content of oxygen vacancies increases while that of Co4+ decreases with the higher Pr3+-deficiency content. P1−yBCO is chemically stable with the Gd0.1Ce0.9O1.95 (GDC) electrolyte at 1100 °C and below in air. Introduction of Pr3+-deficiency decreases electrical conductivities and significantly improves electrochemical performance of P1−yBCO. Among the studied oxides, P0.95BCO with 5 mol% Pr3+-deficiency shows the best electrochemical performance with low ASR values of 0.113 Ω cm2 at 600 °C, 0.054 Ω cm2 at 650 °C and 0.028 Ω cm2 at 700 °C respectively, demonstrating it a promising cathode material of IT-SOFCs. The results of P1−yBCO have also been compared with those of Ba2+-deficient PrBa1−xCo2O5+δ (PB1−xCO, x = 0.00–0.10) oxides and major differences have been found in lattice parameters, oxygen content, chemical defects, electrical conductivities and ASR results. Factors contributing to these differences have been discussed.

A hydrothermal synthesis of Pr3+ doped mesoporous TiO2 for UV light photocatalysis.

Pr3+ doped mesoporous TiO2 photocatalysts with a different molar ratio of Pr to Ti were prepared by a hydrothermal method using triblock copolymer as the template. The as-prepared samples were systematically characterized by X-ray diffraction, N2 adsorption-desorption, X-ray photoelectron spectra, transmission electron microscopy and UV-visible diffuse reflectance spectroscopy. The characterizations indicated all the samples had mesoporous structure and narrow pore size distribution. Pr3+ doping enlarged the surface area and decreased the crystallite size. The surface area of the samples varied from 136 to 170 m2/g, and the average crystallite size ranged between 5.04 and 7.60 nm. The effect of Pr3+ doping amount on the photocatalytic activity of mesoporous TiO2 was evaluated by the degradation of methyl orange under UV light irradiation. The results showed that the suitable amount of Pr3+ doped samples exhibited the higher photocatalytic activity than mesoporous TiO2. Among the samples, 1 at.% Pr3+ doped mesoporous TiO2 showed the highest photocatalytic activity.

The neutrophil serine protease PR3 induces shape change of platelets via the Rho/Rho kinase and Ca2 + signaling pathways

IntroductionProteinase 3 (PR3) is released from neutrophil azurophilic granules and exerts complex effects on the inflammatory process. PR3 catalyzes the degradation of a number of macromolecules, but the consequences on blood cells are less well defined. In the present study, the effect of PR3 on human platelets was thoroughly investigated. MethodsThe experiments were performed on washed platelets freshly isolated from blood donated by healthy human volunteers. Platelets shape change and aggregation was measured on a Chrono-Log aggregometer. The phosphorylated form of MYPT1 was visualized by immunostaining. Platelet activation was further evaluated by flow cytometry. ResultsPR3 induced platelet shape change but not aggregation. Flow cytometry analysis showed that PR3 induced no P-selectin expression or binding of fibrinogen to the platelets, and it did not change the activation in response to PAR1- or PAR4-activating peptides or to thrombin. Furthermore, Fura-2 measurement and immuno-blotting analysis, respectively, revealed that PR3 stimulated small intracellular Ca2+ mobilization and Thr696-specific phosphorylation of the myosin phosphatase target subunit 1 (MYPT1). Separate treatment of platelets with the Rho/Rho kinase inhibitor Y-27632 and the intracellular Ca2+ chelator BAPTA/AM reduced the shape change induced by PR3 whereas concurrent treatment completely inhibited it. ConclusionThe data shows that the neutrophil protease PR3 is a direct modulator of human platelets and causes shape change through activation of the Rho/Rho kinase and Ca2+ signaling pathways. This finding highlights an additional mechanism in the complex interplay between neutrophils and platelets.