Effect of Sm3+ doping on ferroelectric,energy storage and photoluminescence properties of BaTiO3 ceramics

Rare earth doped ferroelectric ceramics have attracted much attention due to their great potential application for novel multifunctional optical-electro devices. Herein, the x% mol Sm³⁺ doped BaTiO₃ (BTO:xSm³⁺) ceramics were fabricated by the conventional solid-state reaction method. The Sm³⁺ ions composition dependent phase structure, ferroelectric, energy storage and photoluminescence properties were systematically investigated. With the increase of Sm³⁺ ions composition, the remanent polarization decreases dramatically from 15.705 μC/cm² (BTO) to 7.132 μC/cm² (BTO:3.0%Sm³⁺), but the energy storage density and efficiency increase greatly with a relative change of 79.76% and 31.13%, respectively. Furthermore, Sm³⁺ doping causes the transformation from the tetragonal to pseudo-cubic phase for BTO ceramics at room temperature, resulting in a broader temperature transition range from the ferroelectric to paraelectric phase and a lower Curie temperature. Particularly, the pure BTO and BTO:xSm³⁺ ceramics show great thermal stability for energy storage properties. In addition, under the excitation of 408 nm near-ultraviolet light, the BTO:xSm³⁺ ceramics exhibit the strongest orange-red emission peak around 596 nm with a large relative tunability of intensity by 88.97%. The results suggest that the BTO:xSm³⁺ ceramics are suitable for the design of optoelectronic devices.     

Highly-doped YAG:Sm3+ transparent ceramics: Effect of Sm3+ ions concentration

YAG:Sm³⁺ (3–15 at.%) transparent ceramics, a promising cladding material for suppressors of parasitic oscillations at 1064 nm of YAG:Nd³⁺ lasers, have been prepared by solid-state reactive sintering at 1725 °C. The effect of samarium ions concentration on the microstructure and optical properties of YAG:Sm³⁺ sintered ceramics was studied for the first time. The solubility limit of samarium ions in the garnet matrix was found to lie within the range of 9–11 at.%. The spectroscopic characterization of YAG:Sm³⁺ (3–15 at.%) ceramic samples showed that the absorption coefficients corresponding to Sm³⁺ ions transitions increased linearly with increasing Sm³⁺ doping. Also, the increase in the concentration of Sm³⁺ ions contributes to the increase in the intensities of the satellites, leading to the broadening of the main spectral lines and implicitly to the increase of the absorption coefficient around 1064 nm. It was shown that YAG:Sm³⁺ ceramics doped with 9 at.% Sm³⁺ ions possess optical losses of 0.07 cm^?1 at 808 nm and an optical absorption coefficient of 4.45 cm^?1 at 1064 nm. The concentration dependence of the ⁴G_5/2 level decay confirmed that the luminescence extinction is due to the energy transfer between the Sm³⁺ ions through cross-relaxation processes. All these results show that highly-doped YAG:Sm³⁺ (9 at.%) ceramics could be the best candidate for parasitic oscillation suppression in high-power YAG:Nd³⁺ lasers at 1064 nm.     

Photoluminescence properties of rare-earth ion-doped Na5YSi4O12-based glass ceramics

We developed herein photoluminescent glass ceramics based on rare-earth ion-doped Na₅YSi₄O₁₂-type materials according to the Na_3+3xY_1?x?yR_ySi₃O₉ (R: Sm³⁺, Eu³⁺, Dy³⁺, Tb³⁺) composition. Glass ceramics generally have the advantages of excellent chemical durability, heat resistance, and moldability over sintered ceramics. Upon irradiation with near-ultraviolet light, Sm³⁺-, Eu³⁺-, Dy³⁺-, and Tb³⁺-doped glass ceramics emit purplish orange, reddish orange, yellow, and green lights, respectively. The photoluminescent emission intensity of glass ceramics is higher than that of the original glasses, and the emission intensity depends on the crystalline phase. The highest emission intensity of various rare-earth ion-doped glass ceramics is obtained when the parameter y is equal to 0.03, 0.16, and 0.02 for the Sm³⁺-, Eu³⁺-, and Dy³⁺-doped glass ceramic samples, respectively. The internal quantum efficiency is 3%, 37%, 7% and 23% for the Sm³⁺-, Eu³⁺-, Dy³⁺-, and Tb³⁺-doped samples, respectively. Thus the Na superionic conducting Na₅YSi₄O₁₂-type glass-ceramics were proved to have potentiality as novel phosphors.     

Ultra-narrow deep-red emitting AlN:Sm2+phosphor with nano-branched construct for wide color gamut backlight display and high-pressure sensing applications

Rare-earth (RE) doped AlN are excellent candidate materials for electroluminescent devices, full color displays and white lighting technology. In this paper, a deep red Sm²⁺ doped AlN (AlN:Sm²⁺) phosphor was synthesized for the first time by a one-step direct nitridation method. Detailed XRD and EDS studies show the presence of samarium (Sm) ions the AlN, and XPS measurements indicate Sm ions are divalent. SEM and TEM studies show that the AlN:Sm²⁺ have a branched nanostructure, consisting of a primary stem and secondary short nano-branches. AlN:Sm²⁺ phosphor has a broad and strong excitation bands in the range of 300–600 nm, ultra-narrow deep red emission at 686 nm, near unity color purity, and good thermal stability (78.2% at 413 K). A blue-pumped warm white light emitting diode with high color rendering index (Ra∼87.5) and low correlated color temperature (CCT∼4875 K) was fabricated. Moreover, a super-wide color gamut (117.6% of the NTSC) can be achieved by using AlN:Sm²⁺ as the red component. Furthermore, photoluminescence (PL) and Raman spectra of AlN:Sm²⁺ were studied under hydrostatic pressure up to 25 GPa. The shift of the ⁵D₀→⁷F₀ emission band (dλ/dP≈0.13 nm/GPa) and the decrease of PL intensity ratio (⁵D₀→⁷F₀/⁵D₀→⁷F₁, dI_R(0/1)/dP≈−5.6%/GPa) with applied pressure can be used for optical pressure sensor. Raman spectroscopy revealed a phase transition of AlN:Sm²⁺ from wurtzite to rocksalt phase at 19.9 GPa. The large doping of Sm²⁺ ions and unique intrinsic geometry in branched nanostructure co-affect its compressibility and structural stability under high pressure. The results indicate that AlN:Sm²⁺ phosphor has promising applications in backlight displays and optical pressure sensors due to their excellent luminescent properties.     

Thermophysical performances of Sm2O3-doped Gd3TaO7 oxides for thermal barrier coatings

To investigate the effect of Sm₃O₃ addition on the thermophysical performances of Gd₃TaO₇, (Gd_1−xSm_x)₃TaO₇ oxides were synthesised using sol-gel and sintering with high-temperature technologies, and their thermophysical properties were researched. The investigations exhibit that the obtained powders comprise well-distributed particles, and the bulk specimens have densified microstructures. The obtained ceramics have single pyrochlore-lattice. Owing to varied scattering strength coefficient of phonon caused by the differences in ionic radius and mass between the substituting and substituted elements, the value of thermal conductivity of (Gd_1−xSm_x)₃TaO₇ decreases firstly and further increases with the increase fraction of Sm₂O₃. The coefficient of thermal expansion of (Gd_1−xSm_x)₃TaO₇ is ameliorated owing to the higher ionic radius of Sm³⁺ than Gd³⁺. Except for Sm₃TaO₇, the synthesised ceramics display outstanding lattice steadiness up to 1400 °C.     

Structure,Judd-Ofelt analysis and spectra studies of Sm3+-doped MO-ZnO-B2O3–P2O5 (M = Mg,Ca, Sr,Ba) glasses for reddish-orange light application

In the present work, a series of Sm³⁺-doped MO-ZnO-B₂O₃–P₂O₅ (M = Mg, Ca, Sr, Ba) glasses were prepared. The glass structure and luminescence properties were investigated by XRD, DSC, IR, absorption spectroscopy, Judd-Ofelt theory and photoluminescence spectra. The J-O parameters of Sm³⁺-doped glasses follow the trend of Ω₄＞Ω₆＞Ω₂. Under the excitation of 401 nm Xenon lamp, Sm³⁺-doped glasses exhibited four emissions from the transitions of ⁴G_5/2→⁶H_J/2 (J = 5, 7, 9, 11) in the visible spectra. The luminous intensity of Sm³⁺ increases with the asymmetry in local environments and decreases with the increasing radius of the alkaline-earth cation. Among the as-prepared glass, the Sm³⁺-doped glass containing magnesium oxide exhibits higher values of stimulated emission cross-section (2.18 × 10⁻²¹ cm²), gain bandwidth (1.40 × 10⁻²⁷ cm³), and optical gain (3.83 × 10⁻²⁴ cm²). All the Sm³⁺-doped glasses show intense orange light in the CIE 1931 chromaticity diagram with a high color purity exceeding 99%. In addition, the time-resolved emission spectra reveal the decay process of the Sm³⁺ ions for the transitions ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 in the glass containing magnesium oxide. It suggests that Sm³⁺-doped alkaline-earth zinc borophosphate glasses could be a potential candidate for reddish-orange light-conversion fluorescent materials based on the ultraviolet light-emitting diode.     

Influences of rare-earth oxide additives on the formation and properties of porous Si2N2O ceramic

Here we prepared porous silicon oxynitride (Si₂N₂O) ceramics by reaction sintering of SiO₂ and Si₃N₄ using five different rare-earth oxides (RE₂O₃, RE = Lu, Yb, Y, Sm, and La) as sintering aids. The influences of RE₂O₃ on the formation, densification, microstructure, and mechanical properties of Si₂N₂O ceramics have been investigated in detail. The results have indicated that with the increase in RE ionic radius, the formation temperature of Si₂N₂O decreases, and the densification process could be promoted by RE₂O₃ with larger RE³⁺ ionic radius. In addition, microstructures and mechanical properties are highly dependent on the RE₂O₃ additives. With the increase in RE³⁺ ionic radius, Si₂N₂O changes from platelike crystals to elongated crystals. The samples doped with La₂O₃ and Sm₂O₃ with elongated crystals exhibit higher flexural strength and higher Vickers hardness.     

“Dark hole” cure in Ba4.2Nd9.2Ti18O54 microwave dielectric ceramics

Large size Ba_4.2Nd_9.2Ti₁₈O₅₄ (BNT) ceramics doped with MnCO₃, CuO and CoO were prepared by the conventional solid-state method. Only a single BaNd₂Ti₄O₁₂ phase was formed in all samples. No second phase was found in the XRD patterns. The bulk density increases slightly because of the dopants. The SEM results showed that the grain size of Mn²⁺and Cu²⁺-doped BNT ceramics became larger with the increasing amount of dopants. The permittivity of all samples stays the same. However, the Q×f value of BNT ceramics increases by doping, especially with Mn²⁺ ions. The conductivity of BNT ceramic doped with Mn²⁺(0.5 mol‰) under high temperature is lower than that without doping. There are fewer defects in Mn²⁺-doped BNT ceramics. The XPS results indicated that Ti reduction was suppressed in BNT ceramics doped with 0.5 mol‰ Mn²⁺. BNT ceramics doped with 0.5 mol‰ Mn²⁺ ions sintered at 1320 °C for 2 h exhibited good microwave dielectric properties, with ε_r=88.67, Q×f=7408 GHz and τf = 82.98 ppm/°C.     

Influence of Crystallization on the Conversion of Sm3+→Sm2+ in SrO–Bi2O3–K2O–B2O3 Glass‐Ceramics

Sm³⁺‐doped glass 13SrO–2Bi₂O₃–5K₂O–80B₂O₃ was fabricated by the conventional melt‐quenching technique. The glass‐ceramics were obtained by heating the as‐prepared glasses in air atmosphere at selected temperatures 550°C, 600°C, 615°C, and 650°C, respectively. The luminescence spectra of both Sm³⁺ and Sm²⁺ were detected in the ceramic heated at 650°C where crystalline phase is formed. The as‐prepared glass and the ceramics heated at 550°C, 600°C, and 615°C show only the emission due to Sm³⁺. In the sample heated at 650°C in air atmosphere, however, part of Sm³⁺ ions was converted to Sm²⁺, giving rise to sharp emission lines which are characteristic of Sm²⁺ in crystalline state. It is suggested that Sm²⁺ ions are located at Sr²⁺ site in the ceramic while Sm³⁺ ions are located at Bi³⁺ sites. The Sm²⁺‐doped glass‐ceramic has a high optical stability because the fluorescence intensity decreases by only about 8% of its initial value upon excitation at 488 nm Ar⁺ laser.     

Elimination of pyrochlore phase in high-concentration Sm3+-doped PMN-PT piezoelectric ceramics by excessive MgO

Undesirable pyrochlore phase often appears in Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT)-based ceramics with high rare-earth ion (RE³⁺) doping concentration, which greatly limits their development. In this study, 0–5 mol% Sm³⁺-doped Pb(Mg_1/3Nb_2/3)O₃-29PbTiO₃ (PMN-29PT:0-5Sm) ceramics were first synthesized using traditional precursor method. In the X-ray diffraction spectra and scanning electron microscope images of PMN-29PT:3-5Sm ceramics, the diffraction peaks of pyrochlore phase and pyrochlore grains with octahedral morphology were observed, respectively. The reason for the appearance of the pyrochlore phase is that Sm³⁺ doping causes the Nb-rich regions. To eliminate the pyrochlore phase, PMN-29PT:3-5Sm ceramics were resynthesized by an improved precursor method in which an excess of 4 mol% MgO was added to the reactants before pre-sintering. After adding an excess of 4 mol% MgO, the concentration ratio of Nb⁵⁺ and Mg²⁺ in the pyrochlore grains returned to the value in the perovskite grains, and the pyrochlore phase was transformed into the perovskite phase PMN. The dielectric, ferroelectric, and electromechanical properties were compared before and after eliminating the pyrochlore phase. The results show that the comprehensive performance of the ceramics is improved after eliminating the pyrochlore phase.     

Structural,Raman, and Dielectric Studies on Multiferroic Mn‐doped Bi1−xLaxFeO3 Ceramics

Multiferroic Bi_1?xLa_xFeO₃ [BLFO (x)] ceramics with x = 0.10–0.50 and Mn‐doped BLFO (x = 0.30) ceramics with different doping contents (0.1–1.0 mol%) were prepared by solid‐state reaction method. They were crystallized in a perovskite phase with rhombohedral symmetry. In the BLFO (x) system, a composition (x)‐driven structural transformation (R3c→C222) was observed at x = 0.30. The formation of Bi₂Fe₄O₉ impure phase was effectively suppressed with increasing the x value, and the rhombohedral distortion in the BLFO ceramics was decreased, leading to some Raman active modes disappeared. A significant red frequency shift (~13 cm^?1) of the Raman mode of 232 cm^?1 in the BLFO ceramics was observed, which strongly perceived a significant destabilization in the octahedral oxygen chains, and in turn affected the local FeO₆ octahedral environment. In the Mn‐doped BLFO (x = 0.30) ceramics, the intensity of the Raman mode near 628 cm^?1 was increased with increasing the Mn‐doping content, which was resulted from an enhanced local Jahn–Teller distortions of the (Mn,Fe)O₆ octahedra. Electron microscopy images revealed some changes in the ceramic grain sizes and their morphologies in the Mn‐doped samples at different contents. Wedge‐shaped 71° ferroelectric domains with domain walls lying on the {110} planes were observed in the BLFO (x = 0.30) ceramics, whereas in the 1.0 mol% Mn‐doped BLFO (x = 0.30) samples, 71° ferroelectric domains exhibited a parallel band‐shaped morphology with average domain width of 95 nm. Dielectric studies revealed that high dielectric loss of the BLFO (x = 0.30) ceramics was drastically reduced from 0.8 to 0.01 (measured @ 10⁴ Hz) via 1.0 mol% Mn‐doping. The underlying mechanisms can be understood by a charge disproportion between the Mn⁴⁺ and Fe²⁺ in the Mn‐doped samples, where a reaction of Mn⁴⁺ + Fe²⁺→Mn³⁺ + Fe³⁺ is taken place, resulting in the reduction in the oxygen vacancies and a suppression of the electron hopping from Fe³⁺ to Fe²⁺ ions effectively.     

Novel double-perovskite Mg2InSbO6:Sm3+ phosphor with excellent heat-resistant performance and high color purity used in white LEDs

In this study, Sm³⁺-doped double-perovskite Mg₂InSbO₆ phosphors were synthesized via high-temperature solid-state reaction. Mg₂InSbO₆ belongs to the double-perovskite family with a space group of R (No.148). The photoluminescence (PL) spectrum illustrates that Mg₂InSbO₆:0.05Sm³⁺ phosphor can emit intense orange-red emission light at 607 nm due to the ⁴G_5/2→⁶H_7/2 transition. The optimum concentration of Mg₂InSbO₆:xSm³⁺ is confirmed to 0.05 mol. The asymmetric ratio (⁴G_5/2→⁶H_9/2/⁴G_5/2→⁶H_5/2) of Mg₂InSbO₆:0.05Sm³⁺ phosphor is 2.73. The quenching temperature exceeds 500 K, illustrating that Mg₂InSbO₆:Sm³⁺ sample has excellent heat resistance. The high color purity and correlated color temperature (CCT) of Mg₂InSbO₆:Sm³⁺ phosphors are obtained. Furthermore, a white light-emitting diode (w-LED) is successfully fabricated, possessing CCT of 6769 K and high color rendering index (R_a) of 89. Therefore, the orange-red-emitting Mg₂InSbO₆:Sm³⁺ phosphors exhibit great potential to apply in solid-state lighting fields.     

Impact of the A-site rare-earth ions (Ln3+ – Sm3+, Eu3+, Gd3+) on structure and electrical properties of the high entropy LnCr0.2Mn0.2Fe0.2Co0.2Ni0.2O3 perovskites

High entropy perovskites LnCr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2O₃ ceramics were produced by solid-state reactions from oxides. The B-site chemical composition was fixed (Cr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2) and A-site composition was varied by the rare-earth ions (Ln = Sm³⁺, Eu³⁺ and Gd³⁺). The entropy of B-sublattice mixing was 1.609R J/(mol*K). The dependences of the lattice parameters, microstructure features, and electrical properties were discussed as function of the A-site rare-earth ions. The correlation of the lattice parameters with the nature of the A-site rare earth ions was demonstrated. Impact of the rare-earth ions in A-site on microstructural parameters was observed. Charge conduction mechanisms were discussed in details for a wide range of temperatures.     

Sites occupancy preference of Bi3+ and white light emission through co‐doped Sm3+ in LiGd5P2O8

Bi³⁺, Sm³⁺‐activated LiGd₅P₂O₈ (LGPO) phosphors were prepared through high‐temperature solid‐state method. In LGPO host, there are 5 types of Gd crystallographic sites, named as Gd(1)/Gd(2)/Gd(3)/Gd(4), and Gd(5). Bi³⁺‐activated LGPO phosphors exhibit 1 broad excitation band from 250 to 320 nm centered at 293 nm and a broad asymmetric emission band ranging from 350 to 600 nm with the maximum value approximately at 409 nm. It can be concluded from dual‐emission spectra that Bi³⁺ may occupy 2 Gd sites and an obvious spectral blue‐shift appeared with increasing Bi³⁺ content, which is caused by the intensity of crystal field of Bi³⁺ is decreased. Notably, through the calculation of each Gd‐O chemical parameter, the environmental factor (h_e) value of each Gd site can be obtained and it can be further inferred that 2 emission bands centered at 409/461 nm are ascribed to Bi³⁺ ions which occupies Gd(3) and Gd(4) sites, respectively. Energy transfer from Bi³⁺ to Sm³⁺ ions in Bi³⁺/Sm³⁺ co‐doped LGPO samples occurred and it realizes the color‐tunable emission from cyan to yellow including white‐light emission, through controlling Sm³⁺ content. Moreover, energy transfer mechanism between Bi³⁺ and Sm³⁺ ions is verified to be dipole‐dipole interaction by analyzing the spectroscopic experimental results and the critical distance between them is calculated to be 8.22 Å by concentration quenching method. Finally, it is illustrated that Bi³⁺ and Sm³⁺ co‐doped LGPO phosphors will be a promising candidate for n‐UV chip pumped w‐LEDs.     

B-site-doped BiFeO3-based piezoceramics with enhanced ferro/piezoelectric properties and good temperature stability

Here, B-site doped 0.725BiFe_0.98M_0.02O₃-0.275BaTiO₃ (M = Fe, Sc, Ga, and Al) + 0.8 mol% MnO₂ (abbreviated as BF, BS, BG, and BA) (BFM-BT) ceramics were designed and prepared to modulate octahedral distortions. According to bond-valence calculations based on XRD Rietveld refinement data, B-site doped BFM-BT ceramics tended to have a higher distortion as the radius of the doping ion decreases, and obtained a great improvement of ferroelectric and piezoelectric performances. B-site-doped BFM-BT ceramics significantly inhibited the formation of impurities, leading to better ferroelectric and piezoelectric performances. The BFM-BT ceramics exhibited high Curie temperature of 519-530℃ and good temperature stability for piezoelectric performances. The d₃₃ values of BF, BS, and BA ceramics remained the room temperature value ranging from room temperature to 470℃. Meanwhile the content of impure phases, oxygen vacancies and valence of Fe³⁺ to Fe²⁺ decreased with the decreasing radii of B-site doping ions.     

Effect of rare-earth oxide additives on transparency and fluorescence of α-SiAlON ceramics

Recently, novel transparent and fluorescent materials are in demand for various optical applications such as lasers, scintillators, and solid-state lighting. α-SiAlON, which has excellent thermal and mechanical properties, also exhibits photoluminescence depending on the stabilized doped rare-earth ions. Its transparency and fluorescence depend on the rare-earth oxide added as a raw material, particularly in conventional powder processing. In this study, we fabricated α-SiAlON ceramics by adding various rare-earth oxides to elucidate their effects on the transparency and fluorescence of these ceramics. High-transparency α-SiAlON ceramics were fabricated by adding rare-earth oxides whose rare-earth ions have small ionic radii: Y₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, and Lu₂O₃. Because the fraction of α-SiAlON was high, the relative density was high, and the microstructure was composed of fine grains. In particular, α-SiAlON ceramics prepared by adding Ho₂O₃ showed lower light scattering than the other fabricated α-SiAlON ceramics because of the smaller α-SiAlON grains, resulting in higher in-line transmittance (48% at 600 nm). Furthermore, these transparent α-SiAlON ceramics exhibited fluorescence corresponding to the activated rare-earth ions: Ho³⁺, Er³⁺, Tm³⁺, and Yb³⁺ or Yb²⁺.     

Photoluminescence and optical temperature sensing in Sm3+-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 lead-free ceramics

A series of orange-red emitting Sm³⁺ activated Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ (BCZT: xSm³⁺, x?=?0.001–0.007) are synthesized by a conventional solid-state reaction method. The Sm³⁺ ions composition dependent photoluminescence properties are systematically investigated. Under the excitation of a 407?nm near-ultraviolet light, the ceramics exhibit strong characteristic emission of Sm³⁺ ions with dominant orange-red emission peak at around 595?nm, which is ascribed to the transition of ⁴G_5/2 → ⁶H_7/2. The BCZT: 0.004Sm³⁺ ceramic displays the optimal emission among these Sm³⁺-doped BCZT solid solutions. Moreover, the photoluminescence intensity exhibits extremely sensitive to temperature, suggesting that BCZT: 0.004Sm³⁺ could be applicable for temperature sensing. A maximum relative sensitivity of 1.89%?K^?1 at 453?K is obtained. Furthermore, the existence of ferroelectricity in the BCZT host combined with Sm³⁺ activated photoluminescence properties could be useful for developing optical-electro multifunctional materials and devices.     

Spectroscopic and photoluminescence characteristics of Sm3+ doped calcium aluminozincate phosphor for applications in w-LED

Monophase Calcium Aluminozincate (Ca₃Al₄ZnO₁₀) phosphor doped with Sm³⁺ ions by varying concentrations have been prepared at 1300 °C using conventional solid state reaction technique. The crystal structure and phase analysis of the as-prepared phosphor has been carried out by X-ray Diffraction (XRD) studies. Morphology and functional groups present in the phosphor have been investigated thoroughly by using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FT-IR) spectral measurements, respectively. Under 401 nm excitation, the as-prepared phosphor exhibit intense visible orange emission at 601 nm. It has been observed that 1.0 mol% of Sm³⁺ ions concentration is optimum to give intense visible orange emission. The PL analysis reveals that the dipole-dipole interaction is primarily responsible for the concentration quenching observed beyond 1.0 mol% of Sm³⁺ ions. The TR-PL study reveals a bi-exponential behavior of decay curves with an average lifetime of the order of microseconds. The CIE coordinates (x=0.574 and y=0.424) measured for the optimized phosphor are very close to the intense orange emission coordinates specified by Nichia Corporation developed Amber LED NSPAR 70BS (0.570, 0.420). The spectroscopic, PL and TR-PL studies suggest the potential use of Sm³⁺ doped calcium aluminozincate phosphors for display and white light emitting devices.     

Enhancement of Sm3+ emission by SnO2 nanocrystals in the silica matrix

Silica xerogels containing Sm³⁺ ions and SnO₂ nanocrystals were prepared in a sol–gel process. The image of transmission electron microscopy (TEM) shows that the SnO₂ nanocrystals are dispersed in the silica matrix. The X-ray diffraction (XRD) of the sample confirms the tetragonal phase of SnO₂. The xerogels containing SnO₂ nanocrystals and Sm³⁺ ions display the characteristic emission of Sm³⁺ ions (⁴G_5/2 → ⁶H _J (J = 5/2, 7/2, 9/2)) at the excitation of 335 nm which energy corresponds to the energy gap of the SnO₂ nanocrystals, while no emission of Sm³⁺ ions can be observed for the samples containing Sm³⁺ ions. The enhancement of the Sm³⁺ emission is probably due to the energy transfer from SnO₂ nanocrystals to Sm³⁺ ions.     

Synthesis and photoluminescent properties of Sm3+-doped SnO2 nanoparticles

SnO₂ ceramic nanoparticles homogeneously doped with Sm³⁺ ions were synthesized via a sol-gel method, followed by drying and annealing in air. X-ray diffractometry, FT-IR spectrometry and transmission electron microscopy were used to characterize the nanoparticulate samples. After annealing, both doped and undoped SnO₂ nanopowders were shown to adopt the rutile tetragonal crystal form and to exhibit characteristic Sn–O–Sn vibrations. The average particle size was found to be in the region of 23–28 nm. Photoluminescence analysis at room temperature demonstrated strong enhancement of the visible emission from Sm³⁺, via energy transfer from the SnO₂ host matrix to the dopant. The maximum emission efficiency was observed for a concentration of 1.5 atom% Sm³⁺.