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Ultraviolet C (UVC) light has a great promising application in the field of sterilization. However, how to obtain efficient UVC emission with peak maximum at 265 nm that is called 'golden sterilization wavelength' remains a great challenge. Herein, we propose a defect-engineering strategy to obtain enhanced UVC emission at the golden sterilization wavelength of 265 nm through introducing oxygen vacancies into Pr3+ doped Ba 2 MgSi 2 O 7 melilite phosphors. Combined with X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) and thermoluminescence (TL) characterizations, it is confirmed that the calcination of Ba 2 MgSi 2 O 7 :Pr3+ in an inert atmosphere could efficiently increase oxygen vacancy concentration, promoting the efficient energy transfer from the melilite host to Pr3+ ions. It could lead to a significant enhancement of the luminescence intensity to 2.43 times of the initial one with less oxygen vacancies. The optimized Ba 2 MgSi 2 O 7 :0.4%Pr3+ phosphor could effectively inactivate 100 % of Staphylococcus aureus within 8 min, showing higher efficiency than commercially available mercury lamp. This work provides an effective solution for the design and preparation of UVC phosphors using defect engineering to achieve golden UVC emission. [Display omitted] [ABSTRACT FROM AUTHOR]

Praseodymium doped lanthanum arsenate, denoted as La 1-x Pr x AsO 4 , has been synthesized with different concentrations of the dopant (x = 0.5 %; 1 %; 2 %; 3 % and 5 %) via the combustion method and their optoelectronic properties have been investigated. A study of the crystalline structure and size of the compound by XRD confirms that both the pristine LaAsO 4 and Pr-doped LaAsO 4 are pure and maintain a monoclinic crystal structure, with the crystalline size ranging from 60 to 76 nm. The morphological study of the nanoparticles by SEM analysis reveals that all samples, regardless of the concentration of Pr3+, consist of homogeneously packed and irregularly shaped small particles. The optical studies by absorption and fluorescence spectroscopies highlight the unique optoelectronic characteristics of La 1-x Pr x AsO 4 , with absorption predominantly in the UV and blue regions and prominent emission peaks in the visible spectrum, most notably at 610 nm. The optimal luminescence is observed at a 0.5 % Pr3+ doping level, deviating from typical trends as higher concentrations lead to diminished emission intensity and lifetime due to concentration quenching effects. The application of Density Functional Theory (DFT) with GGA + PBE and GGA + PBE + U approximations has effectively elucidated the electronic structure and optical properties of the Pr-doped LaAsO 4. The incorporation of Pr's 4f states within the LaAsO 4 forbidden band significantly alters the material's electronic landscape, notably reducing the optical band gap from 4.45 eV to 2.299 eV. This modification in the band structure aligns favourably with the dielectric function curves and density of states analyses, corroborating the observed visible light emission in the doped samples. [ABSTRACT FROM AUTHOR]

The booming demand for electric vehicles, driven by the pursuit of enhanced efficiency, faces significant hurdles attributed to the costly integration of rare earth magnets like NdFeB. M-type strontium ferrite emerges as a promising alternative owing to its economic viability and exceptional magnetic characteristics, rendering it suitable for electric vehicle motor applications. This research focuses on the synthesis and characterization of SrFe 12 O 19 and Sr 1-x Pr x Fe 10 Al 2 O 19 (where x = 0.00 to 0.20) hexaferrites, with praseodymium (Pr) substitution. Magnetic particles were synthesized utilizing the sol-gel auto-combustion technique, employing a calcination temperature of 1100 °C for a duration of 4 h. Structural and magnetic studies of aluminium-praseodymium (Al–Pr) doped samples are performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating-sample magnetometry (VSM). The structural analysis reveals a decrease in both particle size from 42 nm to 31.76 nm and lattice parameter with increasing doping concentration. Magnetic analysis yields crucial insights: Al3+ doping induces a substantial rise in coercivity from 5500 Oe to 10,500 Oe which is quite comparable to NdFeB, while Pr doping shows a subtle impact, enhancing remanence from 17 emu/g to 23.05 emu/g. These findings underscore the potential for optimizing magnetic properties through meticulous control of dopant concentrations in M-type hexaferrites, thereby positioning them as promising substitutes for rare earth magnets. [ABSTRACT FROM AUTHOR]

Pr doped La 2 Zr 2 O 7 (LPZ) TBCs have been deposited by electron beam physical vapor deposition. This work concentrates on the thermophysical properties and microstructure evolution of LPZ/YSZ duplex TBCs before and after thermal cyclic so as to probe into the merit and the application feasibility. The thermal expansion, thermal conductivity and phase structure have been measured and analyzed in comparison to other classical TBCs materials. Typical feathery microstructure and intra-columnar gaps did not provide desired thermal cyclic counts for LPZ/YSZ TBCs. Two principal categories of degradation mechanism limited the cyclic lifetime. The first principal degradation mode is the pulverization of LPZ after thermal cyclic due to the Pr rare earth elements modification in lanthanum Zirconates. Pr instability created the pulverization degradation mode instead of spalling. The second degradation mode is the cracks extension paralleled to interface inside TGO due to the brittle spinel generated by excessive oxidation. This study of thermal properties and degradation mechanism might offer thought and inspiration for other advanced TBCs. [ABSTRACT FROM AUTHOR]

Samarium praseodymium (Sm–Pr) co-doped ceria was synthesized by the co-precipitation technique as an electrolyte for low-temperature solid oxide fuel cell (LT-SOFC) applications. The structural, morphological, compositional, and electrical characterization of the synthesized samples were evaluated via x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX) and impedance spectroscopy. The generation of a single-phase fluorite structure of co-doped ceria without any secondary phases has been verified by XRD analysis, exhibiting the successful incorporation of Sm and Pr ions into the ceria lattice. Vegard's law is utilized for Pr redox behavior explaining the variation in lattice constant values. SEM pictures show that the co-doped ceria powder has a homogeneous and well-dispersed microstructure, and has enhanced particle size. The impedance spectroscopy results indicate that Sm–Pr co-doped ceria has much higher ionic conductivity than single-doped ceria. The highest amount of ionic conductivity (σ i o n i c ) for the composition Ce 0.80 Sm 0.10 Pr 0.10 O 2 − δ recorded as 2.12 × 10 − 2 S / c m at 500 ° C , and 6.19 × 10 − 2 S / c m at 750 ° C with the lowest activation energy E a = 0.48 e V , which has been not reported earlier. Sm and Pr are chosen as dopants because of their capacity to generate oxygen vacancies and improve ceria's ionic conductivity. This study contributes to the enhancement in the ionic conductivity of co-doped ceria by co-precipitation technique and the temperature-dependent frequency exponent factor "s" is also explored to comprehend the conduction mechanism of the prepared samples. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive exploration of the electronic properties of hydroxyapatite (HA) doped with zinc (Zn), silver (Ag), and praseodymium (Pr). Five distinct compositions—0.4Pr-HA, 0.4Zn-0.4Pr-HA, 0.8Zn-0.4Pr-HA, 0.4Ag-0.4Pr-HA, and 0.8Zn-0.4Pr-HA were systematically investigated through Density of States (DOS) and band structure calculations. The computed band gap values, ranging from 4.4037 to 4.1554 eV, revealed a progressive decrease in band gap energy from 0.4Pr-HA to 0.8Ag-0.4Pr-HA, emphasizing the substantial impact of dopant composition on electronic properties. Additionally, the incorporation of Pr induced distinct bands and peaks in the density of states, signifying the emergence of specific energy levels associated with Pr and suggesting a clear effect on the electronic structure. Furthermore, the study explores the influences of dopant type and quantity on the electronic structure, microstructure, spectral, thermal, and in vitro cell viability properties of Pr-based HA samples. Theoretical results demonstrated a continuous decrease in the bandgap with Ag or Zn dopants, and the study observed controllable changes in LAC values based on co-dopant type and quantity. Experimental outcomes revealed significant effects on crystallinity, crystallite size, lattice parameters, and unit cell volume, confirmed through XRD, SEM, EDX, FTIR, and Raman analyses. These findings provide valuable visions into the tunability of the electronic properties of HA through controlled doping with Zn, Pr, and Ag. This knowledge is crucial for modifying materials with desirable electronic properties, and thus holds promise for various applications in electronic devices and biocompatible coatings. [ABSTRACT FROM AUTHOR]

We report a comprehensive investigation on customization process of Oxide Dispersion-Strengthened alloys through Sm 2 O 3 , Pr 2 O 3 , and Er 2 O 3 incorporation into 316L stainless steel matrix in terms of a desired enhancement in structural, physical, and nuclear radiation shielding properties. Oxide powders are incorporated into 316L stainless steel powder all with the same purity of 99.5%. These were Erbium oxide (Er 2 O 3), Praseodymium oxide (Pr 2 O 3), and Samarium oxide (Sm 2 O 3). First, X-Ray diffraction and Scanning Electron Microscope/Energy-dispersive X-ray spectroscopy analyses are conducted in order to investigate their physical and structural properties. Next, two different experimental setups are employed using a133Ba and 241Am/Be sources for the measurements of gamma-ray and neutron transmission properties of Oxide Dispersion-Strengthened alloys. The maximum density increment is achieved through Er 2 O 3 compared to other reinforced oxides. The detector counting value reached its minimum level when a 5% Er 2 O 3 oxide dispersion was introduced into the 316L SS matrix. Similarly, the most significant degree of photon absorption, the highest values of mass attenuation coefficient, lowest half value layer, and most effective atomic number, were all attained by the same sample. Based on the findings derived from the investigation, it can be concluded that incorporating Er 2 O 3 oxide into 316L steel can be considered as a viable option in terms of enhancing the critical properties of Oxide Dispersion-Strengthened alloys for extreme conditions such as nuclear reactors and other similar fields, where the behavioral attributes of the utilized materials are at utmost importance. [ABSTRACT FROM AUTHOR]

So far, overcoming thermal quenching remains a huge challenge in the application of phosphor materials. The intervalence charge transfer (IVCT) state has an inestimable role in the compensation of antithermal-quenching effects and is widely used in the research of applications in optical temperature sensing, yet little study has been reported on its modulation of thermal quenching properties. In this contribution, the thermal quenching properties of praseodymium-activated solid-solution substituted GdNb 1-x Ta x O 4 phosphors were investigated systematically for the inaugural time from the perspective of IVCT energy level positions. According to the empirical formula, the IVCT level positions in the phosphor increase sequentially from 32960.71 cm−1 to 33442.15 cm−1, the DFT calculates the extension of the substrate band gap from 3.6408 eV to 4.3066 eV, and the contributing energy level of the conduction band is determined. The variation in the position of the IVCT energy level explains the alteration of the luminescence intensity at room temperature for different composition phosphor 3P 0 and 1D 2 energy levels. More particularly, it was analyzed that in the variable temperature spectra, x = 0–0.75 exhibited different degrees of efficient antithermal-quenching properties at 303–523 K, while no antithermal-quenching was presented at x = 1. By analyzing the IVCT energy level position and other influencing factors such as band gap, the feasibility of the IVCT energy level position as a competing model for the compensation and quenching channels is established, and the internal mechanism of regulating thermal quenching property is revealed. Effective control of the phosphor resistance to thermal quenching performance was achieved, which directly determines whether enhanced or diminished thermal quenching can be obtained. This finding provides a new effective strategy for the tuning of thermal quenching luminescence of Pr3+-doped Nb/Ta system phosphors. [Display omitted] [ABSTRACT FROM AUTHOR]

Multifunctional ceramics with the 0.93(Na 0.5 Bi 0.5) 1- x Pr3+ x TiO 3 -0.07BaTiO 3 (abbreviated as BNBT- x Pr, x = 0.00, 0.002, 0.004, 0.006, 0.008) were synthesized using the solid-phase reaction method. This study systematically investigated the phase structure, microstructure, dielectric, ferroelectric, piezoelectric, and photoluminescence properties. As the value of x increased, the ceramics underwent a transition from a co-existing rhombohedral (R) and tetragonal (T) phases to a T phase with a slight R distortion. In addition, the grain size decreased, and the relative density increased. The Pr3+ doping led to a decrease in the coercive field and an improved reversible phase transition, accompanied by a reduction in the depolarization temperature (T d) from 91 °C to 41 °C. The ceramic with x = 0.006 showed excellent piezoelectric properties, with a d 33 = 201 pC/N and k p = 30.6%. Such properties were ascribed to the appropriate R/T phase ratio, increased relative density, decreased coercive field, and improved reversible phase transition. Moreover, under excitation at 451 nm, the ceramics exhibited bright red emission bands at 611 nm and 655 nm, corresponding to the transitions of 1D 2 →3H 5 and 3P 0 →3F 2 , respectively. After polarization, the relative intensity of the emission peak at 655 nm significantly increased due to the changed lattice environment caused by the electric field. These Pr-doped BNBT ceramics demonstrated great potential in applications requiring electro-optic integration and coupling devices as multifunctional materials. [ABSTRACT FROM AUTHOR]

In this work, MgGeO 3 :Pr3+ system is prepared by high-temperature solid phase method under the condition of different temperature and Pr content. MgGeO 3 :Pr3+ could emit 622 nm (red), 716 nm (red), 903 nm (NIR) and 1081 nm (NIR) lights under the external excitation of 251 nm and 425–500 nm. Due to the different excitation wavelengths, MgGeO 3 :Pr3+ has completely different electronic transition paths, resulting in a much larger emission intensity under 251 nm excitation than that excited by 425∼500 nm. When the incident light wavelength is 251 nm, the excitation process is VB→1D 2 level of Pr3+, and the emission is due to transition of 1D 2 →3H 4 , 1D 2 →3H 5 , 1D 2 →3H 6 (3F 2) and 1D 2 →3F 3,4. When the wavelength of incident light is 425∼500 nm, the excitation process is 3H 4 →CB, the emission is CB→1D 2 , and then 1D 2 →3H 4 , 1D 2 →3H 5 , 1D 2 →3H 6 (3F 2) and 1D 2 →3F 3,4. At the same time, the emission spectrum and X-ray diffraction measurements show that the most fundamental factor determining the emission intensity of the sample is the concentration of the luminescent center (Pr3+ that can emit light) in the MgGeO 3 grain. Increasing the sintering temperature and Pr element content in raw materials can increase the of Pr3+ concentration in the grain (increase the concentration of the luminescent center). However, if the concentration of Pr3+ in the grain is too high, Pr3+ would lose the function of the luminescence center, resulting in a decrease in the concentration of the luminescence center, thereby reducing the luminescence intensity. [ABSTRACT FROM AUTHOR]

CaMoO 4 :Pr3+ thermochromic phosphors with diverse thermal responses for temperature sensing were prepared by the traditional solid-phase reaction method. The typical CaMoO 4 :Pr3+ had scheelite structure belonging to tetragonal crystal system and space group of I 4 1 / a (88). Pr3+ ions can be easily substituted for Ca2+ ions of host CaMoO 4 because of similar ionic radius. CaMoO 4 : 1.5% Pr3+ have the block structure with mean size of 6.84 μm. The E g (∼3.93 eV) value of pure CaMoO 4 is bigger than that (∼3.65 eV) of CaMoO 4 : 1.5%Pr3+, attributing to the existence of intermediate defect energy levels. Appropriate Pr3+ doping concentration is 1.5%, and the concentration quenching phenomenon can be explained by the concrete electric multipole type of d-d interaction. The emission peak at ∼605 nm from 1D 2 →3H 4 transition have a good thermal stability of 99.452%@423 K, while the wide band centered at ∼490 nm from 3T 1,2 → 1A 1 transition in the MoO 4 2− complex and 3P 0 →3H 4 transition in Pr3+ have a poor thermal stability of 27.572%@423 K. Calculated activation energy is 0.239 eV. Temperature-dependent FIR for optical thermometry was constructed due to their diverse thermal responses. CaMoO 4 : Pr3+ phosphor had good relative sensitivities of 2.216%, 0.969% and 0.932% based on FIR of I 605 nm /I 490 nm with Boltzmann distribution, modified Boltzmann distribution and exponential equation fitting. Thermochromic behavior and thermal quenching mechanism are investigated. The obtained relative sensitivity is better than that of most phosphors, implying that CaMoO 4 : Pr3+ has a potential for application in optical thermometry. [ABSTRACT FROM AUTHOR]

Little information is published on the hardness and corrosion resistance properties of WC-Mn-Cu-Ni alloys infiltrated by an NdPrFeB alloy. Is iron-neodymium-praseodymium inter-metallic compound a desirable choice for a binder for liquid sintering or spontaneous infiltration at high temperatures? Also, is it an opportunity to study the effect of the particle size (d < 30 μm) and the percentage of addition (<5%) of neodymium and praseodymium on the mechanical and electrochemical properties of the composite WC-Cu-Ni-Mn/binder? These inter-metallic composites associating elements of different sizes and electronegativities make it possible to have metallic bonds, but also localized interactions, of the covalent type, between metals and semi-metallic element. The influence of the mechanisms of dissolution and progressive precipitation intervening in the process of densification in the liquid phase allows for obtaining micro-hardness with a value of 1580 HV0.3 and a relative density of 0.798. The micrographs reveal additional information concerning the strong chemical activity of Nd and Pr. The advantage of using the NdPrFe alloy is to take advantage of both the qualities of each element via the coupling of the conduction electrons of the two elements. The behavior of the composite sample in an aggressive (1 M NaOH) medium was examined. Electrochemical parameters determined from Tafel lines show a significant diminution of I corr when a grain size decreases. For the sample elaborated by spontaneous infiltration the polarization resistance increases to 3686 Ωcm2 and the addition of 4–5 wt% of rare earth (RE) is recommended. In relations to their composition and hardness, we can consider these materials as candidates for magnetic drilling tools. [ABSTRACT FROM AUTHOR]

The study investigates the ability of synthetic ZrSiO 4 to host the combined occupancy of Pr3+/PO 4 3− in its tetragonal crystal lattice. Sol-gel method has been utilized to synthesize a series of Pr3+/PO 4 3− additions in SiO 2 –ZrO 2 binary oxides and the feasibility of the resultant to transform into a ZrSiO 4 by the influence of thermal treatment were investigated through series of analytical techniques. The overall results indicated the feasibility of ZrSiO 4 lattice to host a maximum of 10 mol.% Pr3+/PO 4 3− to retain a unique solid solution beyond which the crystallization of PrPO 4 as a secondary phase is noticed. The temperature effect has played a pivotal role in the phase behaviour of SiO 2 –ZrO 2 binary oxides due the invariable range maintained in the Pr3+/PO 4 3− additions. The data obtained from the absorption spectra, luminescence, lifetime decay measurements, morphological, magnetic and mechanical analysis of the investigated systems ensured the significance of phase composition to yield the desired properties. Formation of ZrSiO 4 solid solution until 10 mol.% saturation occupancy limit of Pr3+/PO 4 3− beyond which the crystallization of PrPO 4 is witnessed. [Display omitted] [ABSTRACT FROM AUTHOR]

A new glass series with nominal molar composition of 60B 2 O 3 + 30NaF + 10Al 2 O 3 co-doped with Dy3+ and Pr3+, synthesized by melt quench was reported. The influence of Rare Earth (RE) ratio variation on prepared glasses was investigated by using Fourier Transform Infra-Red spectroscopy, UV–Vis–NIR absorption spectroscopy, Photoluminescence, Decay curves and Density measurements. Their X-Ray Diffraction and FTIR spectra revealed the glassy nature and confirmed that AlO 6 , AlO 4 , BO 3 and BO 4 units are the main structural units of that matrix. A non-linear variation following the same trend for tetragonal borate units (N 4), Band gap, non-linear optical properties, Density, Molar Volume etc. was observed. Different optical parameters were obtained by UV–Vis–NIR spectroscopy. The Bonding parameter obtained from Nephelauxetic study indicated ionic nature of Dy3+ and covalent nature of Pr3+ ions. Photoluminescence excitation and emission spectra were recorded under variety of excitation wavelengths and corresponding color parameters were calculated using 1931 CIE standards. A detailed yellow to blue ratio analysis was reported as a function of RE ion concentration and excitation wavelengths. Composition DPNAB(x = 0.7) displayed the best performance with CIE coordinates (0.33, 0.37). Existence of Energy transfer from Dy3+ and Pr3+ was evidenced by the spectral overlap diagram and lifetime values obtained from fitting of Decay curves. From the obtained results, prepared glasses can be suggested for solid-state lighting devices like WLEDs and display devices. • Dysprosium (Dy3+) and Praseodymium (Pr3+) co-doped alumino-borate glasses were prepared. • FTIR exploration confirmed the existence of AlO 6 , AlO 4 , BO 3 and BO 4 units in the structure. • Optical transitions of Dy3+ and Pr3+ were observed. • Photoluminescence investigations predict the applicability of prepared glasses in tunable visible lighting applications. • Yellow to Blue (Y/B) ratio was discussed as a function of Dy3+concentration and excitation wavelengths. [ABSTRACT FROM AUTHOR]

Transparent Pr3+ doped Ca 1-x Gd x F 2+x (x = 0, 0.01, 0.03, 0.06, 0.10, 0.15) polycrystalline ceramics with fine-grained microstructures were prepared by the hot-pressing method. The dependence of microstructure, optical transmittance, luminescence performances and mechanical properties on the Gd3+ concentrations for Pr3+:Ca 1-x Gd x F 2+x transparent ceramics were investigated. The Gd3+ ions show positive effects on the microhardness of Pr3+:Ca 1-x Gd x F 2+x transparent ceramics as a result of the decrease in the grain sizes. Excited by the Xenon lamp of 444 nm, typical visible emissions located at 484 nm, 598 nm and 642 nm were observed. Furthermore, the incorporation of Gd3+ ions can greatly enhance the photoluminescence performance owing to the improvement in the concentration quenching effect. The quenching concentration of Pr3+ ions in CaF 2 transparent ceramics increased to 1 at.% as a result of the positive effect of Gd3+ codoping. The energy transfer mechanism of Pr3+ in the Pr3+:Ca 1-x Gd x F 2+x transparent ceramics has been investigated and discussed. [ABSTRACT FROM AUTHOR]

Cobalt-free layered perovskite as a promising mixed ionic electronic conductor cathode has shown outstanding performance in conventional oxygen-ion conducting solid oxide fuel cells (O–SOFCs), but not in next-generation proton-conducting solid oxide fuel cells (H–SOFCs) due to insufficient oxygen vacancy so far. We propose a facile A-site doping strategy to enable higher-oxygen-vacancy cobalt-free layered perovskite cathode for higher-performing protonic ceramic fuel cells at reduced temperatures. As proof of concept, two different typical A-site doping of mixed-rare-earth Nd and alkali-metal K in PrBaFe 1.9 Zn 0.1 O 5+δ are chosen as potential H–SOFC cathode materials. Pr 0.8 Nd 0.2 BaFe 1.9 Zn 0.1 O 5+δ (PNBFZ) and PrBa 0.9 K 0.1 Fe 1.9 Zn 0.1 O 5+δ (PBKFZ) layered perovskite cathodes were synthesized using a nitrate-gel combustion method. Both PNBFZ and PBKFZ have a layered perovskite structure and are chemically compatible with protonic BaZr 0.1 Ce 0.7 Y 0.2 O 3−δ (BZCY) electrolyte. Both Nd and K doping dramatically improve the electrical conductivities under operation temperatures. Compared with PBKFZ, PNBFZ shows a lower average thermal expansion coefficient (TEC) of 13.9✕10−6 K−1, being thermally compatible with the BZCY electrolyte without cracks. A-site doping in Fe-based layered perovskite cathodes promotes the single-cell output performance by around 100-26% at 550–700 °C, especially for the mixed-rare-earth doped PNBFZ with high peak power densities of 401–650 mW cm−2. [ABSTRACT FROM AUTHOR]

Perovskite nanostructures of PrFe 1-x Mn x O 3 with and without Mn ions were hydrothermally processed and extensively studied as photocatalysts and photoelectrocatalysts. The significance of Mn ions on the intrinsic characteristics of perovskites were initially evaluated to be in orthorhombic pbnm structure. PrFe 1-x Mn x O 3 was also examined to be made up of fine particle like structures. The effective replacement of Mn ions was affirmed through several structural characterization routes. The bonding of Mn ions in the perovskite architecture and their capacity to replace the Fe sites was additionally studied using X-ray photoelectron spectroscopic (XPS) measurements. The absorbance spectra augmented the potential of PrFe 1-x Mn x O 3 to serve as an effective photocatalyst in treating organic pollutants. Mn ions were also found to improve the defect sites in the nanomaterials, which actually played a vital role in influencing the photocatalytic and photoelectrochemical activities. The photocatalytic efficacy of Mn based perovskites was noted to be much better than their pristine counterparts through the comparative photocatalytic studies. The density of photocurrent values studied via photoelectrochemical experiments also supported the active role of Mn ions in boosting the water splitting performance. The impedance data studied via electrochemical route suggested the aid of Mn ions in accelerating the migration of charges readily to result with the observed results. [ABSTRACT FROM AUTHOR]

The photoluminescence and temperature sensitivities of Ca 3 Y 2 Si 3 O 12 :Pr3+ thermo-phosphors with silico-carnotite structure obtained by solid state reaction method were investigated. Pr3+ ions were accommodated in the A sites having coordination number of 9 in AB 2 C 2 (SiO 4) 3 to replace Y3+ ions. The typical sample consisted of microcrystals with an irregular structure and the surface of particles was smooth, which could enhance the luminescence due to reducing the scattering and non-radiation produced by rough surfaces. The band gap value of typical sample was about 4.01 eV. Dipole-dipole interaction could account for concentration quenching. The two thermometry strategies including normalized intensities from 3P 0 →3H 4 transition and Fluorescence intensity ration (FIR) of 3P 0 →3H 4 /3P 1 →3H 5 transitions were employed for temperature sensing in 298–573 K. The results revealed that Ca 3 Y 2 Si 3 O 12 :Pr3+ thermo-phosphors had good temperature sensitivity performance with maximum S r of 0.59% K−1@573 K and 0.762% K−1@298 K in the above two methods, respectively. Hence, Ca 3 Y 2 Si 3 O 12 :Pr3+ would be a promising candidate in the field of optical thermometry. [ABSTRACT FROM AUTHOR]

Nanoparticles of ZrO 2 :Pr stabilized with ytterbium in the range 0.5%mol.-20%mol. were synthesized. Crystallite sizes depended on Yb concentration. Red luminescence resulting from 1D 2 →3H 4 transition of Pr3+ is present in all the samples. Additionally in the samples calcined at 1200 °C blue-green luminescence from 3P 0 level of Pr3+ was found. This emission was more intense than red one. Intensity of the 3P 0 →3H 4 luminescence depended on ytterbium content and was found to be the highest at 20% mol. Yb. Luminescence study had shown, that ytterbium introduced additional lattice defects. Some quantity of praseodymium activator ions were found to be present at +4 state and changed its valence to +3 as ytterbium content had risen. [ABSTRACT FROM AUTHOR]

Recognizing the crucial properties exhibited by FeAlO 3 perovskite, its stabilization with the inclusion of bigger sized Pr3+ (f -block ion) in place of Fe3+ (d -block ion) is examined by preparing the samples employing an epoxide mediated sol-gel route and characterizing them extensively. Up to 40 mol % substitution of iron, hexagonal PrAlO 3 with rhombohedral symmetry (R-3c spacegroup) was retained. At 50 mol % of iron substitution, it transformed into orthorhombic symmetry (Pnma spacegroup). At 80 mol % substitution of iron, X-ray pattern was amorphous. The metal-oxide bonding and symmetries were further verified by FTIR and Raman measurements. EPR and XPS measurements, performed at room temperature, confirmed the presence of Fe2+ and Fe3+ in the samples. Besides, praseodymium existed in III and IV oxidation states in these samples. Both field and temperature-dependent measurements showed ferromagnetic/ferrimagnetic behavior in the iron substituted samples. The ferrimagnetic transition occurred above room temperature (321 K) in 70 mol % iron substituted PrAlO 3. Such a high T F is not reported till now among the available polymorphs of PrAlO 3 or FeAlO 3. 50 and 70 mol % iron substituted PrAlO 3 samples showed ferroelectric behavior at room temperature, qualifying them to be multiferroics. [ABSTRACT FROM AUTHOR]

Improving the piezoelectric activity of lead zirconate titanate (PZT) ceramics is of great importance for practical applications. In this study, the influence of Pr3+ doping on the ferroelectric phase composition, microstructure, and electric properties on the A-site of (Pb 1-1.5x Pr x)(Zr 0.52 Ti 0.48)O 3 is extensively investigated. A dense and fine microstructural sample is obtained with the introduction of Pr3+. The results show that the morphotropic phase boundary (MPB) moves to the rhombohedral phase region. The rhombohedral and tetragonal phases exhibit an ideal coexistence in the 4 mol.% Pr3+ doped (PPZT4) samples. Lead vacancy and the reduction of the potential energy barrier are considered to be the key mechanisms for donor doping, which is upheld by the Pr3+ doping. Combining the I-E hysteresis loops with the P-E hysteresis loops, it becomes apparent that both contribution maximums of the domain switching and residual polarisation are in PPZT4. Moreover, the thermal aging resistance of PZT is improved by doping, and the temperature stability is optimised from 83% in PZT to 96% in PPZT4. Hence, an appropriate amount of Pr3+ doping can effectively improve the piezoelectric activity of PZT ceramics in the MPB area and optimise the performance stability of the material under application temperatures. [ABSTRACT FROM AUTHOR]

Nano-sized light rare-earth (La, Pr, Nd, and Sm) doped Ba 0.90 Ca 0.10 Ti 0.90 Zr 0.10 O 3 ceramics were synthesized to enhance the energy storage performance. The Rietveld study of bare and doped samples has shown tetragonal crystal symmetry and a single-phase perovskite structure. The rare-earth addition in Ba 0.90 Ca 0.10 Ti 0.90 Zr 0.10 O 3 has resulted in a remarkable change in the microstructure of the doped samples. The addition of Nd in Ba 0.90 Ca 0.10 Ti 0.90 Zr 0.10 O 3 lattice has resulted in optimum grain size and density among the five compositions. As a result of improvement in morphological characteristics in the Nd-doped sample, the dielectric, ferroelectric and piezoelectric characteristics were significantly enhanced. The Nd-doped sample has shown a relaxor behavior with a maximum dielectric constant of 10788 combined with a high saturation polarization of 41.88 μC/cm2. Further, the material has shown optimum electromechanical behavior with excellent aging characteristics. The obtained properties of Nd-doped Ba 0.90 Ca 0.10 Ti 0.90 Zr 0.10 O 3 sample justifies its potential application in multi-layer energy storage capacitors. [ABSTRACT FROM AUTHOR]

A versatile platform for the production of metal-oxide composites is reported in this work. A La 0.25 Ce 0.52 Nd 0.17 Pr 0.06 O 2 – 3Ni composite is selected for this study. The composite is fabricated in a two-step method including mechanical milling of the metals/alloys and thermal treatment in air and H 2. The mechanism of synthesis includes the structural transformation from cubic to hexagonal of the polymorphs present in the starting La 0.25 Ce 0.52 Nd 0.17 Pr 0.06 alloy. The transformation is induced by milling. As a part of the analysis, the enthalpy of formation of the La 0.25 Ce 0.52 Nd 0.17 Pr 0.06 O 2 compound is reported. The work reports a platform for the synthesis of composites. The microstructure of the composites is tunable for the use in different technological applications. • The original non-wet synthesis of a metal-oxide composite from metals/alloys as precursors is reported. • The original experimental value of the enthalpy of formation of the La 0.25 Ce 0.52 Nd 0.17 Pr 0.06 O 2 is reported. • The structural transformation from cubic to hexagonal of the La 0.25 Ce 0.52 Nd 0.17 Pr 0.06 alloy induced by milling is reported. • The crystallographic refinements of the cubic and the hexagonal structures of the La 0.25 Ce 0.52 Nd 0.17 Pr 0.06 alloy are reported. [ABSTRACT FROM AUTHOR]

In this work, Y 1 − x Pr x F e O 3 (0 ≤ x ≤ 0.16) ceramics were fabricated via the auto-combustion sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM) associated with EDS mapping, and Fourier transform infrared spectroscopy (FTIR) were employed for structural and morphology analysis. The substitution of praseodymium (Pr) modified the orthorhombic structure into a hexagonal structure. However, small traces of Fe 2 O 3 and Y 2 O 3 appeared in all samples. The lattice constant 'a' was increased from 3.523 to 5.530 Å upon substitution up-to x = 0.12, afterward this started to decrease from 5.530 to 5.529 Å. Pure orthorhombic YFeO 3 (o-YFeO 3) has cell volume 223.61 (Å3), while the cell volume of Pr substituted hexagonal YFeO 3 (h-YFeO 3) showed a decreasing trend (125.61–125.43 Å). Bulk density was thoroughly decreased from 5.009 to 4.634 (g/cm3) by increasing the Pr concentration. Frequency dependence of the dielectric behavior was investigated at room temperature in a comprehensive frequency range of 1 MHz ~ 3 GHz. SEM results exhibited the average grain size 149.28 nm, 66.78 nm, and 69.36 nm for the samples 0.00, 0.08, and 0.16, respectively. The identification of o-YFeO 3 was confirmed by two main absorption bands ν 1 (449.86 cm-1) and ν 2 (567.12 cm-1) and these bands indicate a clear shift upon the addition of Pr. The force constant of absorption bands at tetrahedral and octahedral sites showed increasing trend and this ranges from 1.633dyn/cm2x105 to 1.912dyn/cm2x105 and 2.818dyn/cm2x105 to 8.832dyn/cm2x105, respectively. The substitution of Pr significantly enhanced the dielectric constant. The shifting of peaks at higher frequencies demonstrates that an increase of dopant concentration resulted in the shifting of peaks that may follow the Maxwell-Wagner-Sillars polarization mechanism. Pr substituted YFeO 3 exhibited microwave frequency response in a range of 1.6 GHz–2.9 GHz which might be suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

Praseodymium-doped zirconolite ceramics targeting nominal composition Ca 1-x Pr x ZrTi 2-5x/3 Al 5x/3 O 7 (x ≤ 0.20, Δx = 0.05) were fabricated by a mixed oxide solid state reaction, at 1350 °C in air for 20 h. Praseodymium (Pr) was employed as a surrogate for neptunium (Np), with Al3+ co-accommodated to provide charge balance. High-resolution transmission electron microscopy and electron diffraction analyses confirmed that zirconolite crystallised as the 2M monoclinic polytype throughout the phase evolution, with no evidence of transformation to other polytype structures. Phase assemblage and microstructural data were consistent with zirconolite occupying a high fraction of the phase assemblage (> ca. 93 wt.%), alongside a minor secondary perovskite phase at all levels of targeted Pr incorporation. Despite this, it was demonstrated near theoretical density formed through a solid-state fabrication route, and we therefore propose that, through analogy with the corresponding Pr solid solution, zirconolite may be a suitable candidate for the immobilisation of Np-bearing wastes. [ABSTRACT FROM AUTHOR]

Recent developments of luminescence ratiometric thermometry have attracted much attention owing to its merits of fast response, non-invasiveness and high spatial resolution. In this work, the synthesis, crystal structure and luminescence properties has been carried out for Pr3+-activated SrMoO 4 phosphors as optical thermometry. The XRD results show that all the phosphors possess the scheelite type tetragonal structure with space group I4 1 /a. The efficient luminescence of Pr3+ can be observed under intra-configurational (4f-4f) and charge transfer band (Mo–O) excitations, respectively. Upon different excitations, the quenching concentration of Pr3+ is diverse due to the multi-phonon relaxation and cross-relaxation processes occurring in different excited states of Pr3+ ions. The fluorescence intensity ratio (FIR) techniques based on emissions of 3P 0 and 1D 2 excited states of Pr3+, and the FIR in the excitations of the charge transfer band (Mo–O) and 4f-4f transitions of Pr3+ were employed for the thermometric characterizations in the 298–498 K range. Both results show remarkable performance in temperature sensing with the maximum relative sensitivity of 0.45%K−1@489 K and 0.98 %K−1@298 K, respectively. Our study demonstrates that Pr3+-activated SrMoO 4 phosphors have a promising potential application in non-contact optical thermometry. [ABSTRACT FROM AUTHOR]

A modified Pechini method involving the formation of carbon shell was proposed and used for the synthesis of the unsubstituted lanthanum and praseodymium hexaaluminates with the magnetoplumbite structure. The peculiarities of the LaAlO 3 and LaAl 11 O 18 phases' formation were studied in a wide temperature range starting from their appearance at 700 °C and finishing at 1300 °C when the complete phase formation occurs. It was found that the size of the formed hexaaluminate's crystallites is a crucial factor affecting the phase purity of the final product. The critical size of the thermodynamic stability of the LaAlO 3 phase is supposed to be 10 nm, which corresponds to the specific surface area of 90 m2/g. The use of a carbon template approach leading to the formation of a core-shell structure during the synthesis procedure allows stabilizing the oxide particles in size and preventing their agglomeration at high temperatures. Depending on the carbon template nature, the carbon content in the samples was found to be 13 wt% (low-carbon-shelled samples) and 40 wt% (high-carbon-shelled samples). In the case of high carbon content, the resulting LaAl 11 O 18 and PrAl 11 O 18 hexaaluminates possess the surface areas as high as 160 m2/g. [ABSTRACT FROM AUTHOR]

The impact of the synthesis method and morphology of the LaFe 0.5 Sb 1.5 O 6 samples on their catalytic activity in CO oxidation was studied in detail. The samples obtained by solid-phase reaction and co-precipitation showed higher catalytic activity. The features of the morphology, which cause the lowering of catalytic activity, were revealed for the samples synthesized in molten salts with and without preliminary microwave-hydrothermal treatment. A comparative study of all synthesized rosiaites LnFe 0.5 Sb 1.5 O 6 , Ln = La–Pr, LaFe 0.5-x Ga x Sb 1.5 O 6 and also pyrochlore Pr 2 (Fe,Sb)O 7 using an in situ diffuse reflection IR spectroscopy method was undertaken to clarify the mechanism of CO oxidation. It was revealed that in the course of the reaction the intermediate complexes of metal carbonyls are formed on the surface. At the same time, inactive carbonyls, which exist on the of Ce- and Pr-containing samples surface before the reaction mixture is fed, were found. This feature gives rise to a decrease in their catalytic activity. A reaction mechanism occurring via intermediate carbonyl complexes on the active centers - [Sb3+ - V O - - Fe3+] – is proposed. The CO oxidation on completely gallium-substituted samples indicates the existing of an additional channel for proceeding of redox process, which is not associated with Fe3+. It is suggested that the nature of this channel is possibly associated with a rosiaite layered structure, which creates a unique environment conducive to complex adsorption phenomena. [ABSTRACT FROM AUTHOR]

Rare earths (Res) doped Mn spinel nanoferrites with nominal composition MnR 0.2 Fe 1·8 O 4 (REs = Tb, Pr, Ce, Y and Gd) were synthesized using sol gel method. FTIR, XRD and FESEM were employed to evaluate the structure, phase, vibrational bands, morphology, grain size and microstructure respectively. VSM was employed to investigate the magnetic features of the Mn nanoferrite and REs doped Mn nanoferrites. XRD confirmed the single-phase cubic structure of Mn nanoferrite whereas tetragonal phase was observed for all REs doped Mn nanoferrites. Unit cell software was used to determine the structural features such as lattice parameter, cell volume, 'da', 'db', 'dc' and 'dv' respectively. FTIR results demonstrated the absorption peaks of Mn and REs doped Mn ferrite at 647-674 cm−1. FESEM results depicted the irregular shapes of the particles with large agglomerations in the prepared samples. The grain size evaluated by LIM (line intercept method) found in the range of 94 to 213 nm respectively. Saturation magnetization was increased from 1.332 to 38.097 emu/g whereas remanence was increased from 1.096 to 25.379 emu/g respectively. In addition, other magnetic parameters such as initial permeability, magnetic anisotropy and magnetic moments were also increased. Moreover, Y–K angles showed significant response with REs doping in Mn ferrites. Furthermore, high frequency response and switching field distribution (SFD) of Mn ferrite and REs doped Mn ferrites were also determined. It is found that Y doped Mn ferrite depicted better high frequency and SFD response as compared to Mn ferrite and REs doped Mn ferrites. The coercivity of all these pure Mn ferrite and rare earth's substituted Mn ferrites (425–246 Oe) was higher as compared to the pure Mn and yttrium substituted Mn ferrite (107–217 Oe. Therefore, it was suggested that Y doped Mn ferrite was more suitable candidate for switching, and high frequency absorption applications in microwave regime. [ABSTRACT FROM AUTHOR]

Praseodymium (Pr3+) and dysprosium (Dy3+) co-doped mixed lanthanum/yttrium oxyorthosilicates (La 2- x Y x SiO 5 , x = 0.5, 1 and 2) phosphors were synthesized using urea-assisted combustion method. The X-ray diffraction (XRD) patterns showed the pure monoclinic phases of La 2 SiO 5 (x = 0) and Y 2 SiO 5 (x = 2) and mixed phases of La 2- x Y x SiO 5. The diffuse reflectance spectra of the phosphors showed a broad absorption peak with a maximum around 376 nm assigned to O2− → Pr4+ charge transfer band. The band gaps of the Pr3+/Dy3+ co-doped La 2- x Y x SiO 5 increased from 2.7 to 5.1 eV as the value of x increased from 0 to 2. The luminescent properties were measured when the samples were excited using three different sources, namely 450 W Xenon lamp, 325 He-Cd laser and electron beam. The photoluminescence (PL) emission spectra recorded using monochromatized Xenon lamp showed tunable emission for different excitation wavelengths. For example, when the PL spectra were recorded under 294 nm excitation, using Xenon lamp, emissions from self-trapped excitons (STE) in SiO 2 , f→f transitions of Dy3+ and Pr3+ were observed. The emission monitored under 349 nm excitation showed the STE peak and the four emission lines of Dy3+. However, when the phosphors were excited using a 325 nm He-Cd laser, the STE emission and four Dy3+ lines were observed in all the samples, but the four manifolds emission from the 1D 2 →3H 4 transition of Pr3+ were only observed for x = 1.5 and 2. Furthermore, the cathodoluminescence (CL) spectra showed the STE band, four emission lines of Dy3+ and four manifolds emission from the 1D 2 →3H 4 transition of Pr3+. The tunable colours of the phosphors were shown in International Commission on Illumination (CIE) coordinate diagram. [ABSTRACT FROM AUTHOR]

Photoluminescence materials with reversible luminescence regulation properties have great potential for applications in photoswitches, optical sensing, and high-density optical data storage devices. In this work, a series of Pr3+-doped Bi 4 Ti 3 O 12 (BiT) ceramics were synthesized by a high-temperature solid-phase reaction method. It is well known that BiT is the most famous one within the Aurivillius ferroelectric (FE) system. Previous works routinely focused on the FE-related properties of BiT-based compounds, but little attention has been devoted to the luminescence, especially the luminescence modulation performance. Here, a large and reversible photoluminescence modulation by alternating visible light irradiation and thermal stimulus based on photochromic (PC) process was achieved. Meanwhile, the influence of sintering temperature on the luminescence modulation behavior was also illustrated. The luminescence regulation properties of the Pr3+-doped BiT ceramics prepared at optimized sintering temperature were investigated in detail. The mechanisms connected to the luminescence, luminescence manipulation, and PC effect were discussed. It is believed that Pr3+-doped BiT materials can be utilized as a kind of ideal optical medium for future information storage device. [ABSTRACT FROM AUTHOR]

New complex oxides of the composition Ln 0.65 Sr 1.35 Co 0.5 Ti 0.5 O 4 (Ln = La, Nd, Pr) with the K 2 NiF 4 – type structure were synthesized using the citrate-nitrate method. Their crystal chemical characteristics and dielectric properties are researched. Different values of frequency-independent dielectric constants are observed in a wide frequency range of 103–107 Hz in ceramics prepared at a temperature of 1300 °C. The highest permittivity ε is about 102 (at ambient temperature) in the frequency range from 1 kHz to 1 MHz for La 0.65 Sr 1.35 Co 0.5 Ti 0.5 O 4 and Pr 0.65 Sr 1.35 Co 0.5 Ti 0.5 O 4 samples. Co3+ and rare earth elements (La, Nd, Pr) co-doping Sr 2 TiO 4 solid solution distorts the coordination polyhedra (Co,Ti)O 6 and SrO 9 , which leads to an Re ε increase by several times. The surface microstructure of ceramics was investigated. The samples relative density correlates with the dielectric constant value. A sample of the Nd 0.65 Sr 1.35 Co 0.5 Ti 0.5 O 4 composition has a lower relative density and, accordingly, a lower Re ε value. The results of dielectric properties researches show that the structure anisotropy and the samples morphology have a significant effect on the value of the dielectric constant. [ABSTRACT FROM AUTHOR]

In this study, bulk and thin films of the Pr and Ce co-doped yttrium iron garnet, Pr 0.5 Ce x Y 2.5-x Fe 5 O 12 , with various contents of Ce, x=0.25, 0.5 and 0.75, were synthesized and investigated. The solid-state method was used to synthesize the bulk samples and the films were deposited by the Pulsed Laser Deposition (PLD) method. The phase and structure analysis of the samples were investigated by the XRD, SEM, and AFM techniques. The results show that the bulk samples contain the secondary phases of cerium oxide (CeO 2) and iron oxide (Fe 2 O 3). After deposition, a single garnet phase is formed in the (444) orientation on GGG (111) substrate. The investigation of the magnetic properties was undertaken by VSM. The results of the VSM manifested the positive impression of the additives on the saturation magnetization from 33.47 e m u g in the un-doped sample to 37.07 e m u g in the sample containing 0.25 mol of Ce. The saturation magnetization plunged to 25.39 e m u g in a sample involving 0.75 mol of Ce due to the forming of the secondary phases. In order to find the co-dopant effect on the magneto-optical properties, the Faraday rotation of the films was measured. The Faraday rotation of the samples was found to be 0.74, 0.82 and 1.24 d e g μ m for x= 0.25, 0.5 and 0.75, respectively. Comparing the results with the literature manifests the synergistic effect of the two additives. [ABSTRACT FROM AUTHOR]

New effective luminescence thermometers based on novel host Ba 4 Y 3 F 17 doped with Pr3+ and Pr3+/Yb3+ in 80–320 K temperature range were studied. The absolute temperature sensitivity (S a) of both Ba 4 Y 3 F 17 : Pr3+(0.1 mol %) and Ba 4 Y 3 F 17 : Pr3+(0.1 mol.%): Yb3+(10.0 mol.%)nanothermometers based on luminescence intensity ratio (LIR) between two Pr3+ emission bands (3P 1 -3H 5 and 3P 0 -3H 5) demonstrate a notable value (0.011 K−1 at 300 K) in the 200–320 K range. The Ba 4 Y 3 F 17 : Pr3+(0.1 mol.%): Yb3+(10.0 mol.%)nanothermometers based on LIR between 3P 0 →3H 4 of Pr3+ and 2F 5/2 → 2F 7/2 of Yb3+ emission bands demonstrate high S a into the 80–200 K range with maximal S a = 0,0778 K−1 at 100 K. The stability of the phosphors was revealed by thermo-cycling experiments. [ABSTRACT FROM AUTHOR]

High permittivity Ba 4 (Pr 1-x Sm x) 28/3 Ti 18-y Al 4y/3 O 54 (0.4≤x ≤ 0.7, 0≤y ≤ 1.5) ceramics were synthesized using a standard solid-state method. The effects of Sm3+ substitution into the A-site and Sm3+/Al3+ cosubstitution into the A/B-sites on the microstructure, crystal structure, Raman spectra, infrared reflectivity (IR) spectra and dielectric characteristics were investigated in a Ba 4 Pr 28/3 Ti 18 O 54 solid solution. In the ceramic samples of Ba 4 (Pr 1-x Sm x) 28/3 Ti 18 O 54 (0.4≤x ≤ 0.7), Sm3+ partial substitution for Pr3+ could improve the quality factor (Qf) value and reduce the TCF value. Nevertheless, the quality factor (Qf ~10,000GHz) needed further improvement and the TCF values (+12.3~+35.4 ppm/°C) were still too large. Therefore, Al3+ was introduced for further optimization of the TCF values and Qf values of the Ba 4 (Pr 1-x Sm x) 28/3 Ti 18 O 54 ceramics. Sm/Al cosubstitution led to a good combination of high ε r (ε r ≥ 70), high Qf (Qf ≥ 12,000 GHz), and near-zero TCF (−10 < TCF < +10 ppm/°C) in a wide range (0.4≤x ≤ 0.7). Infrared reflectivity (IR) spectra indicated that A-TiO 6 vibration modes gave the primary contribution rather than Ti–O bending and stretching modes. The decrease in the degree of B-site cations order could be confirmed by Raman spectra. XPS results demonstrated that the improvement of quality factor (Qf) value was strongly related to the suppression of Ti3+. Excellent dielectric properties were achieved in Ba 4 (Pr 1-x Sm x) 28/3 Ti 18-y Al 4y/3 O 54 microwave ceramics with x = 0.5 and y = 1.25: ε r = 72.5, Qf = 13,900GHz, TCF = +1.3 ppm/°C. [ABSTRACT FROM AUTHOR]

Rare earths RE's (Pr, Y, Gd, Ho, Yb) substituted MnZn spinel ferrites with composition of Mn 0.5 Zn 0.5 M 0.02 Fe 1.98 O 4 (M = Pr, Y, Gd, Ho, Yb) are prepared by sol gel combustion approach. Low sintering temperature (500 °C) is used to sinter the RE's doped MnZn samples. MnZn samples are further characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to measure the cubic crystalline structure, particle size, morphology, porosity and grain size. Cubic crystalline phase of prepared RE's doped MnZn ferrites is confirmed by x-ray diffraction (XRD). The morphology, porosity and grain size are observed using FESEM. The magnetic properties of RE's doped MnZn nanoferrites are analyzed by vibrating sample magnetometer (VSM). Coercivity (H c), remanence (M r) and saturation magnetization (M s) are calculated from the magnetic loops. The saturation and remanence of the nanoferrites are increased by the substitution of RE's metal ions and varies from 14.76 to 26.36 emu/g and 9.98–22.48 emu/g respectively. Bohr magneton and anisotropy constant are calculated from the recorded magnetic data. The conductive analysis of the prepared samples is studied at 40 °C −300 °C temperature, leading to the conductivity measurements from 1.12 × 10-2 Ω-1-cm-1 to 9.52 × 10-2 Ω-1-cm-1. UV–Vis spectroscopy is used to determine the semi conducting nature of RE's doped MnZn spinel ferrite samples. The magnetic, conductive and optical study of the RE's doped MnZn nanoferrites sintered at low temperature suggests the use of these materials for microwave absorption, supercapacitor, lithium ion batteries and nanoelectronics industrial applications. [ABSTRACT FROM AUTHOR]

A Pr-doping strategy was used to improve traditional strontium-doped lanthanum ferrite oxides for proton-conducting solid oxide fuel cells (SOFCs). Three different samples, La 0.5 Sr 0.5 FeO 3- δ , La 0.25 Pr 0.25 Sr 0.5 FeO 3- δ , and Pr 0.5 Sr 0.5 FeO 3- δ ,were successfully prepared. The Pr content was shown to have an obvious influence on the hydration ability of the materials. Hydration was improved at higher Pr-contents, suggesting a promising cathode performance. However, the improved hydration ability did not always lead to an increased fuel cell performance, and it was found that the fuel cell performed best when an appropriate Pr-doping amount was used that resulted in a good compromise between protonic and oxygen-ion conduction. As a result, the optimized composition La 0.25 Pr 025 Sr 0.5 FeO 3- δ generated a high peak power density of 616 mW cm−2 and a low polarization resistance of 0.09 at Ω cm2 at 700 °C, which is an encouraging performance for a traditional cathode material. [ABSTRACT FROM AUTHOR]

The substitution of Ca for Sr in the LnSr 3-x Ca x Fe 3 O 10-δ (x = 0–1.5, Ln = La, Pr, and Sm), Ruddlesden-Popper (RP) intergrowth structure was investigated to determine how the physical and electrochemical properties of this potential cathode material in solid oxide fuel cells (SOFCs) are impacted. A small amount of Ca incorporated into the structure reduced the thermal expansion coefficient, improved the electrical conductivity, and increased power density by up to 30% of a La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 electrolyte-supported single cell. The microstructure and oxygen permeability of the materials were independent of Ca substitution. A phase transformation of LaSr 3-x Ca x Fe 3 O 10-δ to perovskite was observed when the Ca composition of x > 1.0. Among the substitution of Pr and Sm for La in LaSr 2.7 Ca 0.3 Fe 3 O 10-δ , only PrSr 2.7 Ca 0.3 Fe 3 O 10-δ was pure with no phase transformation found. The co-substitution of Pr and Ca promoted the reduction of Fe, enhanced the oxygen permeation and active surface, and diminished the contact resistance at the cathode-electrolyte interlayer. The co-substitution of Ca and Pr delivered good electrochemical performance of approximately 354 mWcm−2 at 800 °C on a 0.3 mm thick La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 electrolyte-supported cell and the lowest area specific resistance (ASR). [ABSTRACT FROM AUTHOR]

This paper has focused on the structural and magnetic properties of Ce 0.25 Bi x Pr y Y 2.75-x-y Fe 5 O 12 (x = 0.15, 0.20, 0.25) and (y = 0.25, 0.5) prepared by the solid-state method. The structural and microstructural evaluations were carried out by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), Raman Spectroscopy (RS) and Fourier-transform infrared spectroscopy (FTIR). Furthermore, the magnetic properties were studied through a vibrating sample magnetometer (VSM). As it can be obtained from the XRD patterns, a single garnet phase with high purity has been formed in all samples in the sintering condition. Also, the FTIR analysis confirmed the formation of the garnet phase and related inorganic bonding. Raman spectroscopy reveals the dominant garnet phase with good incorporation of the Bi, Pr and Ce dopants into the garnet structure. XPS confirmed the presence of Ce4+ and also its value was measured from the peak areas. The results showed that the amount of Ce4+ in all the samples is lower than 10%. According to the results, by increasing the Bi content from x = 0.15 up to x = 0.25, saturation magnetization (M s) increased from 29.31 to 37.79 emu/g, and by enhancing the Pr concentration from x = 0.25 to x = 0.5, this magnetic characteristic enhanced from 29.31 to 33.16 emu/g. Furthermore, the Ce-solubility limit was enhanced from x = 0.2 to x = 0.25 by the charge compensation mechanism. An increase in the Ce-solubility limit and also the saturation magnetization led to an enhancement in the magneto-optical and magnetic properties of YIG for telecommunication applications and memory storages, respectively. [ABSTRACT FROM AUTHOR]

The electrical properties of La 2 Ti 2 O 7 (LTO) ceramics have been enhanced through the substitution of La3+ ions by Pr3+ ions. Almost all doped Pr3+ ions will get at A - site without causing a change on monoclinic phase of LTO. The average grain size is 17.8 μm for La 1.9 Pr 0.1 Ti 2 O 7 ceramics. The relaxation activation energy which is contributed by defect dipoles that are formed from TiO 6 oxygen octahedrons' distortions in grains is 1.6 eV for La 1.8 Pr 0.2 Ti 2 O 7 ceramics. This kind of defects will be activated from 520 °C and completely be activated until 650 °C. The piezoelectric coefficient d 33 = 3.0 pC/N of La 2- x Pr x Ti 2 O 7 ceramics maintains stable when the Pr3+ doping content x ranging from 0.1 to 0.3. [ABSTRACT FROM AUTHOR]

In this paper, we present the fabrication of Ln 2 Zr 2 O 7 (Ln = Nd, Pr) ceramic nanostructures with green tea extract (GrTeEx) as novel and efficacious fuel through easy and repeatable route as well as their application in propane-selective catalytic reduction of NO x process (propane-SCR-NO x), for the first time. As-fabricated samples with green tea extract have been examined via diverse kind of techniques. Our outcomes represented the successful production of the pure nanostructured Ln 2 Zr 2 O 7 (Ln = Nd, Pr) in presence of green tea extract as novel and efficacious fuel. Moreover, the nanostructured samples can be utilized as a potential novel kind of catalysts with desirable efficiency for propane-SCR- NO x. It was found that Pr 2 Zr 2 O 7 denoted better performance than Nd 2 Zr 2 O 7 for NO x abatement so that the conversion of NO x in to N 2 for Pr 2 Zr 2 O 7 was 67% and for Nd 2 Zr 2 O 7 was 56%. Also the concentration of CO production for Pr 2 Zr 2 O 7 which is inevitable and undesirable product in SCR-NOx process with hydrocarbons such as propane was lower than Nd 2 Zr 2 O 7. [ABSTRACT FROM AUTHOR]

We elucidated the penetration depth of the ultraviolet excitation light for oxide-phosphor: Pr-doped Ca 0.6 Sr 0.4 TiO 3 epitaxial film. Pr-doped Ca 0.6 Sr 0.4 TiO 3 films with thicknesses of 50, 100, 200, 500, and 1000 nm were grown on single-crystal SrTiO 3 (001) substrates. The penetration depth was estimated from the film-thickness dependence of photoluminescence intensities and analyzed by using the exponential Box-Lucas equation. It was found that Pr-doped Ca 0.6 Sr 0.4 TiO 3 achieves nearly maximal intensity when the thickness is above approximately 200 nm. The combination of highly transparent oxide-phosphor films and the simple analysis make the precise measurement of penetration depth possible. This approach could be applicable to other phosphor ceramics. Our methods and results are quite helpful in the fundamental technologies for information devices and security printings, and also realizes significant resource savings of rare-earth ions. [ABSTRACT FROM AUTHOR]

Ceramic dual-phase oxygen transport membranes with the composition of 60 wt% Ce 0.9 Pr 0.1 O 2- δ -40 wt%Pr 0.6 Sr 0.4 Fe 1- x Al x O 3- δ (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0) (60CPO-40PSF 1- x A x O) based on 60Ce 0.9 Pr 0.1 O 2- δ -40Pr 0.6 Sr 0.4 FeO 3- δ doped Al was successfully synthesized through a modified Pechini method. Crystal structure, surface microtopography and oxygen permeability are investigated systematically. The cell parameters of perovskite phase first increased and then decreased with the increase of Al content, which is related to the radius of the Al3+ and the formation of impurity phase. As x ranges from 0.1 to 0.8, the oxygen permeability of the materials first increases and then decreases, and the maximum value of oxygen permeation rate for 60CPO-40PSF 1- x A x O membranes with 0.4 mm thickness at 1000 °C is 1.12 mL min−1 cm−2 when x = 0.4. XRD measurements revealed high temperature stability and CO 2 -tolerant property of the dual-phase composites. The partial replacement of Fe3+/Fe4+ by Al3+ causes the material not only to exhibit good stability, but also to increase the oxygen permeability of the membranes. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Sol-gel method was used to prepare the Pr3+ ions-doped (1- x)Na 0.5 Bi 0.5 TiO 3 - x CaTiO 3 (Pr-NBT- x CTO) (x = 0, 0.04, 0.06, 0.08, 0.1, 0.12, and 0.16) thin films on Pt/Ti/SiO 2 /Si and fused silicon substrates. The structure phase of thin films was evolving from rhombohedral (R 3 c) to orthorhombic (Pnma) with increasing CTO content. Owing to the morphotropic phase boundary (MPB), the improved ferroelectric and dielectric properties were obtained at x = 0.06–0.1. The MPB was formed from the concomitant phase of rhombohedral (R 3 c) and orthorhombic (Pnma). The Pr-NBT-0.08CTO thin film showed the best ferroelectric and dielectric properties, as well as strong relaxor behavior (the diffusion factor is γ = 1.79). In addition, all the films exhibited strong red emission as excited by UV light, and wide optical band-gap (3.44–3.47 eV), which might be influenced by grain size and structural variation. Our results indicate that Pr-NBT- x CTO thin films may have potential applications in ferroelectric-luminescence multifunctional optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract This study presents the successful synthesis of praseodymium oxide, Pr 6 O 11 and hausmannite manganese oxide, Mn 3 O 4 nanoparticles, along with a novel synthesis of (Pr 6 O 11 /Mn 3 O 4) nanocomposites by employing the hydrothermal route followed by post thermal annealing. X-ray Diffraction, Field Emission Scanning Electron Microscopy and Energy Dispersive X-ray characterization techniques are being adapted to analyze the physical characteristics of all the synthesized materials. XRD results reveal the crystalline nature of the synthesized materials. FE-SEM results display the irregular nanograins of Mn 3 O 4 and a regular network of interconnected Pr 6 O 11 nanoparticles. Nitrogen adsorption/desorption tests confirm the mesoporous nature of all the synthesized electrode materials. The Pr 6 O 11 /Mn 3 O 4 − 2 electrode material exhibits an outstanding specific capacitance of 794.58 F/g at a current density of 0.5 A/g, as compared to the 521.24 F/g for the Pr 6 O 11 electrode material. These investigations provide an easy and efficient method to develop nanocomposites (Pr 6 O 11 /Mn 3 O 4) with better electrochemical characteristics, as electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Abstract Gadolinium based luminescent materials have been researched due to their unique optical and magnetic properties with excellent chemical stability, which are useful to apply in both magnetic resonance imaging (MRI) and fluorescence imaging (FI). In this work, red emitting Gd 2 O 3 :Pr3+ nanospheres were successfully fabricated by a facile co-precipitation method. The change of reaction time influenced the size of Gd 2 O 3 :Pr3+ nanospheres and exhibited the sizes between 110 and 250 nm. The size of the Gd 2 O 3 :Pr3+ nanospheres influenced the luminescence and MR imaging signal intensity. Therefore, it can be applied for bi-functional contrast agents. [ABSTRACT FROM AUTHOR]

Abstract Gd 0.2-x Pr x Ce 0.8 O 1.90 , (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) has been synthesized by means of a simple co-precipitation route based on ammonium carbonate as the precipitating agent. The as-synthesized precursors are cerium-gadolinium-praseodymium amorphous hydroxycarbonates, which are nanometric in size with highly homogeneous morphology, leading to reactive doped and co-doped nanocrystalline (≈13 nm) ceria after a mild thermal treatment (2 h at 600 °C). The obtained results highlight the very positive effect of Pr on the powders' sintering behaviour, which favour a better densification of the final pellets, thus improving both their microstructure (with relative densities of 97–99% after sintering at 1250 °C for 3 h) and electrochemical properties (up to 1.25·10–1 S cm−1 at 800 °C for sample 6Pr) compared to the state-of-art ceria-based electrolytes. Through a comprehensive characterization, a relation was formed between the Pr content and the microstructural features of the sintered pellets and their electrical behaviour. The amount of Pr doping was investigated over a wide range and 6 mol% has been established to be optimal (possessing the lowest electronic conductivity contribution). Definitely, these results indicate that Gd 0.2-x Pr x Ce 0.8 O 1.90 has an excellent set of characteristics, both microstructural and electrical, and a convenient fabrication process, thus making it perfectly suitable for IT-SOFC practical applications. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract 0.2–5.0 at% Pr3+-doped CaF 2 transparent ceramics were fabricated by hot-pressed processing for the first time. The phase compositions, microstructure and optical characteristics of the presented transparent ceramics were examined systematically. The average in-line transmittance of Pr:CaF 2 transparent ceramics (2.0 mm thick) with high Pr3+ doping concentrations (1.0–5.0 at%) exceeds 86% at the wavelength of 1200 nm. The absorption spectrum manifests that the prepared Pr:CaF 2 transparent ceramics contain some absorption peaks overlapped with emission bands of the commercial InGaN laser diodes. Further, a detailed investigation on the visible emission properties as a function of Pr3+ concentrations in CaF 2 transparent ceramics was reported. The emission spectra presented two main characteristic peaks at 496 nm (bluish green) and 656 nm (red) corresponded to the transitions of 3P 0 →3H 4 and 3P 0 →3F 2 for Pr3+ activator ions. With the increase of the Pr3+ doping concentrations, the emission intensity and decay lifetimes decreased generally attributed to the concentration quenching effect. Details on energy transfer mechanism of Pr3+ in CaF 2 transparent ceramics were demonstrated and discussed. [ABSTRACT FROM AUTHOR]

Abstract Double perovskite Pr 2 NiMnO 6 (PNMO) and Pr 2 CoMnO 6 (PCMO) ceramics have been synthesized and their crystal structure, microstructure, as well as cryogenic magnetic properties and magnetocaloric performance have been investigated. The crystal structure of PNMO and PCMO ceramics was determined to be monoclinic with space group of P21/n at room temperature. A ferromagnetic to paramagnetic (FM-PM) phase transition (second-order) occurred in PNMO and PCMO around 208 and 170 K, respectively. Significant reversible magnetocaloric effect (MCE) was found and the values of the maximum magnetic entropy change (-Δ S M max) were 3.15 and 3.91 J/kg-K under the magnetic field change (Δ H) of 0–7 T in PNMO and PCMO, respectively. The corresponding relative cooling power (RCP) values were 241.9 and 229.9 J/kg. [ABSTRACT FROM AUTHOR]

The formation of Bi 2 O 3 -based compounds with the general formula (Bi 2 O 3 ) x (Pr 2 O 3 ) y (MoO 3 ) z ( x  +  y  +  z  = 1) in the ternary system Bi 2 O 3 –Pr 2 O 3 –MoO 3 has been studied using samples prepared by solid-state reactions in air, followed by slow cooling. The results demonstrate that, in this system, phases with a monoclinic, tetragonal, or cubic fluorite structure can be stabilized, when bismuth oxide is co-doped with molybdenum and praseodymium. Two stability fields of cubic phases have been identified: 0.6 ≤  x  ≤ 0.93, 0.02 ≤  y  ≤ 0.2, and 0.02 ≤  z  ≤ 0.26 (δ-phase); 0.33 ≤  x  ≤ 0.55, 0.27 ≤  y  ≤ 0.45, and 0.11 ≤  z  ≤ 0.22 (δ'-phase). The δ- and δ'-phases have identical X-ray powder diffraction patterns but differ in properties. Two tetragonal phases exist in the system, with 0.94 ≤  x  ≤ 0.97 (β-phase) and with 0.45 ≤  x  ≤ 0.6, 0.14 ≤  y  ≤ 0.25, and 0.21 ≤  z  ≤ 0.34 (β'-phase). On heating to 900–1030 °C, the β'-samples undergo a transition to a cubic phase with the δ-Bi 2 O 3 structure, which is accompanied by a lambda-type anomaly in permittivity, characteristic of ferro- or antiferroelectrics. The electrical conductivity of the samples increases with Bi 2 O 3 concentration. The highest conductivity in the Bi 2 O 3 –Pr 2 O 3 –MoO 3 system (0.4 S/cm at 800 °C) is offered by the cubic material (Bi 2 O 3 ) 0.8 (Pr 2 O 3 ) 0.1 (MoO 3 ) 0.1 . A monoclinic phase isostructural with Bi 3.24 La 2 W 0.76 O 10.14 have been found in a narrow region near the cubic δ-Bi 2 O 3 phase. [ABSTRACT FROM AUTHOR]