Doped Samples Research Articles

Structural and photoluminescent properties of Gd3+ doped barium aluminate phosphor

Gd3+-doped barium aluminate was synthesized using a conventional solid-state technique and annealed at 1200 °C. The X-ray powder diffraction results confirmed the formation of a hexagonal structure with the space group of P6322 for the studied phosphors. The average crystallite size of 75 nm was calculated using Scherrer's equation based on the X-ray line broadening of all the major diffraction peaks. The shape, distribution, and level of agglomeration of the synthesized samples were confirmed using a field emission scanning electron microscope and energy-dispersive X-ray spectroscopy. The distribution of various ions in the host and doped sample was confirmed using time-of-flight secondary ion mass spectroscopy equipped with a Bi+ ion gun. UV–Visible spectroscopy was employed to record the reflectance of the studied samples, and bandgaps were calculated using the Kubelka-Munk function. The bandgaps were found to be in the range of 3.96–4.75 eV, confirming the formation of a room-temperature wide bandgap semiconductor. Photoluminescence spectroscopy was used to record the excitation and emission spectra of all the samples, which displayed an intense peak at 314 nm attributed to the 6P7/2 → 8S7/2 transition. Moreover, all samples displayed an additional peak in the emission spectrum at a wavelength of 627 nm, which was subsequently confirmed to be generated by second-order diffraction. The decay time for all the Gd3+ doped samples was calculated for λex of 274 nm and λem of 314 nm and was observed to be a few microseconds. The strong emission peak in the wavelength range of Ultraviolet-B has the potential to be utilized for phototherapy to treat skin problems that respond to photons in the range of 312–315 nm.

Effect of adding Er3+ on the precipitated crystalline phase of SrF2–ZnO–B2O3 glass and upconversion luminescence

Elucidating the relationship between nucleation and its structure in glasses is essential for the efficient development of new glass-ceramics. In this study, we developed new oxyfluoride nanocrystallized glass-ceramics with potential for upconversion luminescence, phosphor for LEDs, and fiber laser hosts. We investigated the glass-forming region in the SrF2–ZnO–B2O3 system and the crystallization behavior, glass structure, and optical properties of the xSrF2–(50−x)ZnO–50B2O3 system with the lowest quantity of glass-forming oxides. Whereas both the x = 10 and x = 20 samples precipitated more than 100 nm diameter of Zn4B6O13 by heat treatment, the Er3+-doped samples with x = 10 and x = 20 precipitated SrF2 nanocrystals of less than 20 nm. The resulting SrF2 nanocrystallized glass was transparent, and upconversion luminescence was observed by irradiating with a 980-nm LD. We found that the addition of Er3+ ions has a significant impact on crystallization, and the proposed mechanism for this is that the bond selectivity arising from the polarizability forms fluoride-rich domains, and Er3+ further assists the nucleation of SrF2 by serving as a crystal nucleation site. This study is expected to provide a guideline for the development of new transparent nanocrystallized glasses.

Enhanced bipolar fatigue resistance by few oxygen vacancies of PZN-PNN-PZT ceramics near MPB

The bipolar fatigue behavior for Mn-doped PZN-PNN-PZT ceramics with composition near the MPB region was investigated at both 0.6 Ec and 2 Ec (where Ec is a coercive field). It was found that fatigue behavior depends on both the Mn doping content (or oxygen vacancies and the amplitude of the applied electric fields. Compared to no Mn doping ceramics, enhanced bipolar fatigue resistance was observed in 0.1 wt% Mn doping samples by nearly no variation of remnant polarization up to 106 cycles. The enhanced fatigue behavior is proposed to the weak pinning effect of few oxygen vacancies on domain walls, which hinders the microcrack propagation and stabilizes the domain structure. As Mn doping content increased, rich oxygen vacancies exist in ceramics, and the remnant polarization deteriorated due to the severe pinning effect of defect dipoles. Besides, different fatigue behaviors at 0.6 Ec and 2 Ec indicate that fatigue behavior can be controlled by the orientation of defect dipoles under repeated fatigue cycling.

Improvement of leakage, magnetic and magnetodielectric properties in cobalt doped gallium ferrite

Gallium ferrite (GFO) is a magnetoelectric (ME) material, capturing growing attention due to its strong ME coupling at room temperature. However, the application of the material in practical use is hindered due to its high leakage. In this work, the effects of cobalt (Co) substitution at the iron (Fe) sites of GaFe1−x Co x O3 (0.0 ⩽ x ⩽ 0.1) polycrystals on the structure, electric and magnetic properties are investigated in detail. 5 at. wt.% substitution (x = 0.05) with cobalt ions achieves a reduction in leakage current density by four orders of magnitude due to reduced hopping between Fe3+ and Fe2+ ions and suppression of the oxygen vacancy formation. This is supported by higher dielectric constant and lower dielectric loss, as well as a significant difference between grain and grain boundary resistances. Two-phase-like magnetic behavior in magnetic hysteresis loop with enhanced magnetization and two magnetic transition temperatures are observed in the doped samples. All samples exhibited an increase in the magnetodielectric factor, indicating enhanced coupling between magnetic and electrical parameters. By concurrently increasing dielectric, magnetic, and coupling between them, this study describes a viable technique for lowering the most significant impediment to GFO’s usage as a ME device.

Polymer nanocomposite films of Sr-doped BiVO4 for photodegradation of malachite green

Nanosized m-BiVO4 and Sr-doped derivatives were prepared by solid state reactions, to produce Bi1-xSrxVO4 (X = 0%, 4%, 8% & 12%). XRD and Raman investigations confirmed the formation of BiVO4 phase. 8% and 12% doped samples contained a small fraction of secondary t-BiVO4 phase. SEM images exhibited flat and irregular nanoparticles (64–70 nm). Estimated band gaps were in visible region (2.34–2.42 eV). The materials were used to photodegrade malachite green and BVO-12 showed maximum efficiency ˜ 88% in 180 min. The catalyst was stable and effective for three cycles. Radical scavenging experiments proved the role of holes and hydroxyl radicals. Polymer nanocomposite films made of EOC and photocatalyst were prepared. 0.15 g catalyst loaded film showed maximum activity and recyclability.

Synthesis and investigation of structural, morphological and dielectric properties of Ba‐ordered BaTiO3 perovskite oxide

AbstractThe samples with A‐site cation ordering Ba1−x/2Ti1−xNbxO3 (BTN) with 0 ≤ x ≤ 0.010 were synthesized via the conventional ceramic route by calcining at 1200°C and sintered at 1350°C. The preliminary study of the phase of prepared samples was determined through X‐ray diffraction (XRD) analysis. The Rietveld refinement analysis indicates the tetragonal phase in BTN0 sample, whereas the doped samples exhibit a combination of tetragonal and cubic phases. Presence of Raman band at 308 cm−1 suggests the presence of tetragonal in all samples. The dielectric constant was observed to be 1500 (BTN0), 3000 (BTN5) and 1680 (BTN10) while tangent loss found 0.6 (BTN0), 0.04 (BTN5) and 0.07 (BTN10). All the sample shows same Curie temperature (120°C) due to Ba‐site cation ordering in the sample. Ferroelectric nature in all samples was also confirmed by modified Curie‐Weis law. Based on the current studies, the present materials can be explored as a potential candidate for ferroelectric‐memory devices, dielectric capacitor and energy harvesting applications.

Preparation of RE/g-C3N4 Photocatalysts by Thermal Polycondensation Method and Its Properties

Graphite phase carbon nitride photocatalysts (RE/g-C3N4) doped with different rare earths (RE=La, Ce, Sm, Nd, Eu) were prepared by thermal polycondensation method using rare earth metal nitrate and melamine as raw materials. The photocatalytic performance of RE/g-C3N4 was studied through using photo-degradation reaction of methylene blue (MB) as the evaluation model. The effects of calcination temperature, rare earth elements type and doping ratio on the photocatalytic performance of g-C3N4 were studied. The microstructure of the samples were characterized by FESEM, XRD, UV-Vis, etc. The results show that RE doping can refine the grains and enhance the absorption of visible light. The performance of rare earth doped samples have a significantly improved compared with pure g-C3N4. The performance of La doped samples was better than that of Ce, Sm, Nd and Eu doped g-C3N4. As the temperature increases, the photocatalytic activity of La/g-C3N4 samples increases. When the La doping ratio is 4.0%, the calcination temperature is 590 °C, the degradation rate of The La/g-C3N4 photocatalyst to MB is up to 98.0% within 4 h under visible light irradiation.

High-Performance Zr-Doped P3-Type Na0.67Ni0.33Mn0.67O2 Cathode for Na-Ion Battery Applications

Sodium-ion battery (SIB) technology started to bloom along with lithium-ion batteries (LIBs) as a supportive energy source to alleviate the cost of lithium sources for the development of energy storage devices and electric vehicles. Layered cathode materials are considered potential candidates to produce high-energy-density batteries. Among the layered cathode materials, P3-type cathodes are the least investigated in spite of their capacities, which are comparable to those of P2-type cathodes. P3-type cathodes show high polarization, leading to a poor cycle life, which impedes their extensive use in practical applications. In this work, we report on zirconium doping as an effective strategy to improve cycling stability and reduce voltage fading, another serious issue of layered cathode materials. It is found that an optimum composition of the P3-type cathode with Zr doping at the Mn site, leading to a composition of Na0.67Ni0.33Mn0.64Zr0.033O2, shows good electrochemical performance in terms of retention (89% after 100 cycles) when compared to Na0.67Ni0.33Mn0.60Zr0.067O2 (85% after 100 cycles) and an undoped sample (83% after 100 cycles). Also, remarkable performance is delivered by the Na0.67Ni0.33Mn0.64Zr0.033O2 sample, with a retention rate of 72% after 450 cycles. This result is also supported by an analysis of the amount of polarization for undoped and doped samples, which found that doping helps in improving the diffusion of ions, and the least polarization is obtained for the Na0.67Ni0.33Mn0.64Zr0.033O2 sample.

Magnetic, morphological, and photocatalytic studies of Cu2+ doped Mg-Zn ferrite nanoparticles

Due to their distinctive characteristics, including their optical, catalytic, electrical, and magnetic properties, spinel ferrite nanoparticles attract more interest. Also, the substitution of transition metals like copper in ferrites has the potential to control their physical characteristics and could improve their catalytic and magnetic capabilities. Cu2+ doped Mg-Zn ferrite samples show a change in behaviour from superparamagnetic to soft ferrimagnetic. The photocatalytic studies for the CuxMg0.5Zn0.5-xFe2O4 (x= 0.1 to 0.5, and Δx= 0.1) nano-ferrites are conducted in visible light to investigate the methylene blue photodecomposition capability. The Cu-Mg-Zn nano-ferrites displayed unique behaviour in terms of Magnetic, and photocatalytic activity. These outcomes show that the Cu-Mg-Zn ferrite samples are apply to water remediation.

Thermoluminescence studies of Sm3+ doped ZnB2O4 phosphor

Solid-state reaction method was used to prepare the rare earth Sm3+ doped ZnB2O4 phosphors. The structural characterization of Sm3+ doped ZnB2O4 samples was recorded by X-ray diffraction (XRD) technique. A single phase structure similar to the standard JCPDS files-39-1126 was recorded using XRD. The graph plotted between TL intensity a nd temperature for different UV dose was recorded. The highest TL intensity was recorded for 20 minutes of UV dose. On further increase in the exposure dose, decrease in TL intensity was observed. The thermo-luminescence was recorded with varying percentage of Sm3+. The at most TL intensity was obtained with 3 mol% of Sm3+. The thermo-luminescence spectra of ZnB2O4 and Sm3+ doped ZnB2O4 phosphors were also studied.

Influence of Ag and/or Sr Dopants on the Mechanical Properties and In Vitro Degradation of β-Tricalcium Phosphate-Based Ceramics.

β-tricalcium phosphate has good biodegradability and biocompatibility; it is widely perceived as a good material for treating bone deficiency. In this research, different contents of strontium (Sr) and silver (Ag) ion-doped β-tricalcium phosphate powders were prepared using the sol-gel method. After obtaining the best ratio of pore-forming agent and binder, the as-synthesized powders were sintered in a muffle for 5 h at 1000 °C to obtain the samples. Then, these samples were degraded in vitro in simulated body fluids. The samples were tested using a series of characterization methods before and after degradation. Results showed that the amount of Sr and/or Ag doping had an effect on the crystallinity and structural parameters of the samples. After degradation, though the compressive strength of these samples decreased overall, the compressive strength of the undoped samples was higher than that of the doped samples. Notably, apatite-like materials were observed on the surface of the samples. All the results indicate that Sr and/or Ag β-TCP has good osteogenesis and proper mechanical properties; it will be applied as a prospective biomaterial in the area of bone repair.

Green-light emitting Tb(III) doped Gd2Si2O7 nanocrystals: Structural and optical measurements for NUV excitable cool LEDs

Cool-green light-emitting Gd2-xTbxSi2O7 (x = 1–6 mol%) doped phosphors were synthesized through the self-sustained solution combustion synthesis (SCS) method. The prepared nanomaterials were characterized via different structural and optical analysis. XRD measurements revealed that the doped samples were structured into a stable triclinic structure. The percentage difference in ionic radii (Dr) between Gd3+ and Tb3+ ions is 1.59%, which authorizes the replacement of Gd3+ ions via the Tb3+ ions. Williamson-Hall (W-H) method, retaining the Scherrer formula, is applied to calculate the average crystallite size of doped phosphors. A Kubelka-Munk function is used to deduce the energy band gap (Eg) values for pure Gd2Si2O7 and representative doped Gd1.96Tb0.04Si2O7 nanophosphors. The morphological studies revealed the random dispersion of agglomerated particles in the nano-range. The electric dipole (ED) 5D4→7F5 transition at 543 nm is accountable for relevant green-light emission. The obtained coordinates fall in the green region of the CIE (1931) triangle and replicate the potency of designated nanomaterials in the design and architecture of R-G-B phosphor-based LEDs.

Superior energy storage performance and excellent multiferroic properties of BaTi1-xGdxO3 (0 ≤ x ≤ 0.06) ceramics

Ceramic based capacitors with superior energy storage performance and high storage energy density play an important role in modern electronic devices. Several ferroelectric materials with high dielectric constant and relaxor behavior become the most promising systems for realizing higher energy storage performance. In the present work, environmentally lead-free BaTi1-xGdxO3 (0 ≤ x ≤ 0.06) nanostructures were synthesized using the sol-gel auto-combustion process. The doping of Gd at the Ti site causes the transformation of the ferroelectric behavior to the relaxor ceramics, which is important for finding the large energy storage efficiency of the material. The surface morphology of undoped and doped samples was examined through the SEM studies. Ferroelectric study evidence that the system is going to a more symmetric phase due to a reduction in the polarization parameters and enhancement in the leakage current density. Moreover, the energy discharge density and energy storage efficiency were boosted in x = 0.02 and x = 0.04 samples with energy storage efficiencies reaching ∼81% and 83%, respectively. The linear enhancement in the magnetic moment and the dielectric constant in the doped sample make the system favorable for multifunctional applications. The samples' piezoelectric constant (d33) remains preserved under Gd doping. Hence, the present study opens a propagable and feasible route to synthesize novel lead-free ferroelectric material for energy storage applications.

Mechano-Chemical Synthesis and Characterization of Undoped and Mn2+ Doped Cspb(Br1-xClx)3 Halide Perovskite for Light Source Application

All-inorganic halide perovskites (HPs) continue to be of current interest for light source applications (e.g. lasers, LED’s) because of their high emission quantum yields and wide wavelength tunability due to compositional engineering [1]. The development of red and near-IR emitting lead halide perovskites, however, has been hampered by low emission efficiency and instability of iodine based compositions at room temperature. Recent studies employing transition metal or lanthanide doping have demonstrated an alternative approach to achieve red and near-IR emitting HPs structures [2-4]. In this study we report results of the mechano-chemical synthesis of undoped and manganese (Mn) doped CsPb(Br1-xClx)3 halide perovskites as emitting materials for light source development. Mechano-chemical synthesis is considered a green chemistry method avoiding the use of complex and time-consuming reactions, energetic-enabled conditions, expensive precursor sources, and hazardous reagents, catalysts, additives, and surfactants. Mechano-chemical synthesis experiments were performed employing a high energy ball-mill and 5N purity lead halide and cesium halide powders. The prepared HPs were evaluated by optical microscopy, SEM, TEM, XRD, and fluorometric measurements. Under UV optical excitation a Mn doped CsPbCl3 sample exhibited a broad red emission band centers at ~615nm, which was slightly red-shifted compared to the emission from a melt-grown Mn: CsPbCl3 crystals (see Figure 1). Post synthesis optimization strategies for HPs were also explored including thermal treatment, high-pressure studies, and solvent dependency. Comparative studies of the emission properties of undoped and Mn doped CsPb(Br1-xClx)3 prepared by mechano-chemical synthesis, microwave-assisted synthesis, and melt-synthesis will also be presented.AcknowledgmentThis work was supported by the Army Research Office (grant W911NF1810447) and National Science Foundation (grant NSF-DMR 1827820-PREM).

High Throughput Doping Study of Na-Mn-O Cathode Materials

With the large demand for energy consumption, sodium-ion batteries have been considered as an alternative to lithium-ion batteries for energy storage1. Among various cathode materials, the Na-Mn-O system is promising with its high specific capacities and excellent battery life. Herein, we applied our high throughput (HTP) system2,3 to explore Na0.66Mn0.9M0.1O2+δ (M: dopant) chemical compositions to perform fast screening of the doping effect in these materials. Using a systematic approach, we establish the relationships between the doping species, crystal structure, electrochemical performance, and air/moisture stability. In detail, 52 different dopants were utilized and prepared as precursor solutions to achieve the HTP sol-gel synthesis. HTP-XRD is performed after sintering to understand the structural changes occurring in doping. HTP-cyclic voltammetry (CV) is then performed to analyze the electrochemical properties. Additionally, to comprehend the relationship between dopants and air stability, an accelerated ageing process is carried out at various humidity levels for several weeks.In this study, we found a broad range of dopants with 20 distinct elements that can be integrated into the layered Na-Mn-O structures, including several previously unstudied dopants (Si, Sc, Ga, Rb, Rh, Cs, Re, and Tl), confirmed by XRD refinements. It's interesting to note that at 10% composition, the dopant species can significantly alter the crystal structure. For the undoped sample, a P2/P’2 biphasic material is obtained by slow cooling. However, with the presence of Li, Mg, Fe, Co, Ni, Zn, and Ga, pure P2 structures are obtained with smooth CV curves, suggesting fewer phase transitions via doping. Meanwhile, Si, B, and Mo-doped samples can introduce more distorted P’2 structures, giving more high-voltage plateaus to increase the voltage of the batteries. Nevertheless, the Rh-doped sample achieves a pure P3 structure, exhibiting smooth CV and higher voltage, but fair cycling. Tunnel structure is also found by Ti-doped samples, with an increased average discharged voltage of 2.74V (undoped:2.47V) and excellent rate performance. A series of novel cathodes yields excellent battery performance, including a high specific capacity of 200 mAh g-1 for the Rb-doped sample, and good capacity retention of 100% after 10 cycles for the Nb-doped sample (undoped showed 92% retention). Significantly, a number of doped samples exhibit high reversible anion redox which was shown to be strongly correlated with the bond valence mismatch of the M-O bonds, suggesting by tuning the polarity of M-O bonds triggered by dopants can stimulate the anionic redox behaviour. Moreover, air/moisture stability analysis is conducted for co-doped samples and found that as little as 5% Li in co-doped samples can stabilize the layered structure dramatically. Na0.66Mn0.9Li0.05Co0.05O2, for instance, substantially improves the air stability to over 99 % structure retention, compared to 0 % in the undoped P2 NMO after a one-month accelerated aging protocol. Therefore, these new insights into the impacts of doping via high throughput screening can serve as new guidelines for rational battery material design and development. Figure 1: Heat map of specific capacities in the periodic table with various dopants. The inset image demonstrates the workflow of the high throughput system.

RKKY exchange interactions in two-dimensional Mn-doped ZnO dilute magnetic semiconductor

In this paper, we have theoretically studied the RKKY indirect exchange interactions in a two-dimensional model of Zn1-xMnxO dilute magnetic semiconductor. Under the RKKY interaction framework, we have calculated the exchange coupling constants for four different doped samples of host ZnO, which are 5%, 10%, 15%, and 20%. The carrier density for the respective configurations is taken as 0.1, 0.5, 0.75, and 1 hole per dopant, considering long-range interactions controlled by the cutoff scale in the RKKY range function. The variation of magnetic coupling strength with the carrier density is also examined, and the overall magnetic behavior of the proposed 2-D system is estimated.

Preparation and Characterizations of PVA/Vanadium Nanocomposites for Gamma Ray Shielding and Antibacterial Activity Applications

The biological use of nanocomposites (NCs) is highly intriguing and is more acknowledged for its value, particularly in nanomedicine. The key goal of this study is to investigate the influence of vanadium nanoparticles (VNPs) addition on PVA’s morphological, optical, and electrical properties. In this work, the PVA/V nanocomposites (NCs) were fabricated with different VNP contents of (0.02, 0.04, and 0.06) wt.% by the casting solution technique. The optical microscopy (OM) and scanning electron microscope (SEM) have been used to examine the surface morphological features of produced films, which showed that the VNP clusters were well dispersed in the polymer medium. The intermolecular interaction of the PVA/V nanocomposite was studied by FTIR examination. The interaction between PVA and V was confirmed by observing the change in IR absorption intensity. The UV–Vis approach was used to explore the optical characteristics of the UV–Vis region. The experimental data demonstrate that variations in the concentration of VNPs significantly impact the absorption. For the doped samples, the absorbance against wavelength is exponential. There is evidence of interface between polymer and nanoparticles because the optical band gap has shrunk from 4.50 eV to 3.30 eV, with a corresponding narrowing of the gap between the valence and conduction bands. The electrical characteristics of alternating current were investigated in the frequency range of 100–5 MHz. The dielectric constant and loss of NC films reduced as the concentration of VNPs rose, whereas electrical conductivity increased. With rising VNPs, the attenuation coefficient values rose. The inhibition zone diameters of Staphylococcus aureus bacteria increased with the increase of VNP contents. We showed that adding polyvinyl alcohol (PVA) to V composites increases their antimicrobial (ANB) activities. Based on these findings, NC films can be used for gamma-ray protection and antimicrobial (ANB) purposes.

Thermoluminescence behavior of Ce3+ doped lanthanum tri-borate phosphor for dosimetry applications

The combustion method was used to synthesize Ce3+ doped LaB3O6 phosphors in a range of dopant concentrations. Both the un-doped and Ce3+ doped LaB3O6 samples matched the required reference card, according to X-ray diffraction patterns. TL glow curves of Ce3+ doped LaB3O6 samples at various dopant concentrations were examined by employing various optical detection filter combinations to define TL characteristics. LaB3O6:Ce3+ (1%) and IRSL-TL 565 nm were selected as the suitable sample and appropriate detection filter pairing. The TL maximum with a higher intensity was seen during preheating trials (with 2 °Cs−1) at around 270 °C. The experimental results showed feasible linearity (R2 = 0.998 and b = 1.054) between 5 and 1000 Gy for the dose response of LaB3O6:Ce3+ (1%). The short-term fading test was conducted at various time intervals up to a week. The findings showed that the dosimetric peak strength was almost constant for up to 5 days. However, an additional spurious maximum appeared at the higher temperature zone. Each sample showed an abnormal heating rate effect, which can be explained by localized electrons caught in the intermediate excited state, which is capable of radiative transitions via the conduction band. To find the overlapping peak numbers and determine the kinetic parameters of preheated LaB3O6:Ce3+ (1%), various heating rates, TM-Ts, initial rise, and computerized glow curve deconvolution techniques were utilized. The results suggest that LaB3O6:Ce3+ may be an appropriate material for TL dosimetry applications due to its efficient TL characteristics.

Two Noncentrosymmetric Bismuth Phosphates: Rational Design Synthesis and Optical Properties.

Developing strategies to rational design noncentrosymmetric structure still attract much interest for their applications in nonlinear optical and piezoelectric materials. Two noncentrosymmetric (NCS) alkaline earth metal bismuth phosphates have been successfully achieved via partial replacement of Bi3+ with Ca2+ or Sr2+ ions. BiCa(H0.5PO4)2 (designated as CaBiPO) and BiSr(H0.5PO4)2 (designated as SrBiPO), together with their solid solution Bi(Sr1-xCax)(H0.5PO4)2 (0 < x ≤ 0.5), crystallize in the NCS space group C2. Both CaBiPO and SrBiPO exhibit ultraviolet nonlinear optical (NLO) properties, and their second-harmonic generation effects belong to type-II phase matching. Meanwhile, they could also act as photoluminescence hosts in which the Eu3+-doping samples SrBiPO:xEu3+ (x = 0.02-0.2) emit orange light. The effect of different radius ions on the derivative structures and the structure-NLO property relationship has also been discussed in detail.

Blue/NIR-emitting Phosphor Based on Sr2CeO4: Tm3+, Yb3+ Obtained by Combustion Synthesis

In this study, pure Sr2CeO4 (SCO) and codoped Sr2CeO4:Tm3+, Yb3+ (SCO:Tm, Yb) of powder phosphors were synthesized by a combustion technique. The concentration of Tm3+ was fixed at 0.5 mol %, while the Yb3+ doping concentration was varied from 0 to 7.0 mol %. The crystalline structure, morphology and luminescence properties were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectroscopy, respectively. The XRD analysis shows the crystalline orthorhombic phase for all synthesized samples of SCO and SCO: Tm, Yb. The SEM results show that the doped sample with 5.0 mol % Yb3+ has the lowest grain particle size of 1.92 mm. The SCO:Tm, Yb phosphors produce mainly blue and near infrared emission bands centered at 481 nm and 813 nm (under 980 nm, excitation) which corresponds respectively to 1G4→3H6 and 3H4→3H6 transitions of Tm3+. In addition, the international commission on illumination CIE coordinates were calculated for all samples taking the range of 400 – 700 nm obtaining for the 5.0 mol % Tm3+ doped sample the coordinates: (x,y) = (0.0833, 0.1671) which match with pure blue color. Due to the strong blue and near infrared emissions, the SCO:Tm, Yb phosphors could be good candidates for use in biomarkers or lighting applications.