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Co-doping of Yb3+ with Mn2+ is a promising way to realize broadband up-conversion (UC) luminescence. The tunable broadband emission has been widely demonstrated in crystal materials, but the research on Yb3+/Mn2+ co-doped transparent optical glass has been scare, especially in fluoride-based transparent glass ceramics (GC) that can realize the uniform ions incorporation and efficient UC emission. Herein, a series of Yb3+/Mn2+ activated transparent fluorosilicate GCs containing perovskite KMgF3 nanocrystals were successfully prepared, and the effect of heat-treatment process and/or Mn2+ ion content on the UC luminescence modulation has been investigated. Our results show that the spontaneous crystallized precursor sample exhibits only a green emission at ~538 nm, while additional orange-emitting band centered at ~613 nm is noticeable in the GCs with the gradual precipitation of KMgF3 nanocrystals after heat-treatment. The controllable luminescence can be assigned to the formation of Yb3+-Mn2+ dimers that are located in multiple coordination environments provided by the glass matrix and crystalized nanocrystals. In addition, the prepared GC samples exhibit excellent reversible emission characteristics during heating and cooling cycles. This research not only provides a new option to design desirable coordination environment for Yb3+-Mn2+ dimers, also helps to recognize the UC process in the transparent matrix in detail.

Ca2YZr2Al3O12:Bi3+,Eu3+ phosphors were elaborated by a traditional solid-state reaction method. The luminescence of Ca2YZr2Al3O12:Bi3+ samples, energy transfer from Bi3+ to Eu3+, and the temperature sensing properties of Ca2YZr2Al3O12:Bi3+,Eu3+ samples have been systematically researched. Under the excitation of ultraviolet light, Bi3+ single doped phosphors give 313 and 392 nm emission bands, which origin from the substitutions of Bi3+ instead of Ca2+ and Y3+ sites, respectively. And the color-adjustable emission from blue to red were observed by increasing Eu3+ content in Ca2YZr2Al3O12:Bi3+,Eu3+ samples. Relying on different temperature dependent variation tendency, the fluorescence intensity ratio (FIR) values present outstanding temperature sensing properties. The absolute and relative sensitivity can be up to 0.826 %K-1 and 0.664 %K-1, respectively. All above results suggest that Ca2YZr2Al3O12:Bi3+,Eu3+ phosphor is a potential alternative for optical thermometer.

In comparison to narrow-band upconversion (UC) luminescence from lanthanide-doped systems, broadband UC emission enables a broad and tailorable emissive color, which is desirable for tunable lasers and multicolor display applications. Herein, dual continuous broadband UC emission covering the visible spectral region at 480–720 nm has been achieved for the first time in Yb3+/Mn2+ co-doped glass ceramics (GCs) functionalized with the precipitation of dual-phase γ-Ga2O3/β-YF3 nanocrystals. A tunable UC emissive color from yellowish to orange could be obtained under 980 nm excitation by varying the Mn2+ doping content and heat treatment temperature of GCs. We ascribe this phenomenon to the typical transition of exchange-coupled Yb3+-Mn2+ dimers in tetrahedral and octahedral ligand environments. The Stokes and power-dependent UC luminescence properties, fluorescence lifetimes, site occupation and the involved UC mechanism are discussed in detail. This research contributes to a better understanding of the UC process between Yb3+ and Mn2+ in transparent hosts and provides a novel perspective for designing broadband-emitting UC materials.

GaSbS–AgI–Ag2S glass system was successfully prepared through the traditional method of vacuum melt quenching. The network structure and physical properties of the system response to the substitution of AgI with Ag2S were investigated by differential scanning calorimeter (DSC), Raman, and electrochemical impedance spectroscopic techniques. The glass transition temperature (Tg), density and hardness of the glass system improved as Ag2S content was increased. The ionic conductivity (room temperature) of the glass system was maintained at the order of ~10−4 S/cm when a high concentration of Ag+ was introduced in the glass matrix. The variation in conductivity originated from structural changes in ionic channels. The optimal glass composition for improving the mechanical and thermal stability and conductivity of solid-state electrolyte materials was inferred from analytical results.

A new glass system of (100-x) (0.2Ga2S3-0.8Sb2S3)-xNaI (x = 5–30 mol%) was investigated through a melt-quenching method for solid-state electrolyte application. Na+ was added into the glass matrix as a conductive ion to study its effect on the properties of glass samples. XRD result indicated that the glasses retained their amorphous state until the NaI content exceeded 30 mol%. With increased NaI component, the density and hardness of glasses slightly decreased. DSC measurement showed that the glass-transition temperature of samples decreased, whereas the glass thermal stability improved. We speculated that the incorporation of NaI may have caused the destruction of [S3Ga–GaS3] ethane-like units and formation of [GaS4−xIx] structure, thereby decreasing the connectivity of the glass network. The conductivity of glass samples was further determined using the AC impedance method.

Crystalline phase evolution through merely adjusting composition was achieved in silicate glass ceramics containing Lu n O n-1 F n+2 (n = 5–10) nanocrystals. Orthorhombic or cubic phase nanocrystals were precipitated in the aluminosilicate glass matrix after thermal treatment together with varying the Na 2 O/NaF ratio. Oxyfluoride nanocrystals with quasi-spherical shape show homogenous and dense distribution in glass matrix by transmission electron microscopy measurement. Intense upconversion and mid-infrared emissions were realized in these glass ceramics compared to the precursor glass, and the emission spectral shapes, relative emission intensity and fluorescence decay curves of Er 3+ in cubic LuOF embedded samples exhibit remarkable differences due to the crystal phase dependent effect in glass ceramics. These results indicate that the crystallization and luminescence properties of oxyfluoride glass ceramics could be modified through the alteration of glass composition, which could be used for the development of novel glass ceramics and design of luminescent properties.

Intense 2.7 μm emission was achieved in transparent glass ceramics containing NaYF 4 :Er 3+ nanocrystals. The effect of adjusting Na 2 O/NaF ratio in glass composition on the crystallizing and luminescence behavior in the glass ceramics was investigated. The controllable crystallization property of NaYF 4 nanocrystals was remained after modifying the glass composition and the crystallization temperature was largely reduced for the samples with high Na 2 O content. The X-ray diffraction and transmission electron microscopy analysis evidenced the shrink of lattice parameter with increasing Na 2 O content. High transparency was kept for these glass ceramic samples, and intense upconversion, near- and mid-infrared emissions were obtained in Er 3+ -doped glass ceramics with an increase of red/green ratio and prominent Stark splits in the sample with high Na 2 O content, indicating the change of crystal field around Er 3+ in the host matrix. Our results indicate that the crystallization and luminescence properties of glass ceramics could be modified through adjusting the glass composition, and it is an effective route to develop glass ceramics with favorable properties.

GeS 2.5 chalcogenide glass was selected for studying effects of Ga addition on physical and structural properties. Glassy and partially crystallized samples of (100− x )GeS 2.5 − x Ga (5 mol% ≤ x ≤ 40 mol%) were prepared, and their thermal and optical properties were characterized. With increasing Ga content ( x ), values of T g and optical band gap of glasses initially increased and then decreased, showing a maximal value at x = 25 mol%, that is, with stoichiometric composition of 85.7GeS 2 ·14.3Ga 2 S 3 . These changes were discussed and correlated to evolution of network structure, which was investigated by Raman spectra recorded in glassy matrices of (100− x )GeS 2.5 − x Ga (5 mol% ≤ x ≤ 40 mol%). This work contributes to understanding of composition–structure–property relationship of chalcogenide glasses.

International audience; The design of optical materials with efficient white-light emission performance is still of great interest in the fields of visible lighting and communication. In this paper, Yb3+/Mn2+/Tm3+ tri-doped upconversion (UC) white-emitting transparent glass ceramics have been successfully fabricated by a melt-quenching technique. The structure and luminescent properties of the resultant samples were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), optical transmission spectra, and photoemission spectra. Owing to the co-precipitation of dual-phase γ-Ga2O3/β-YF3 nanocrystals in the matrix, the Yb3+/Mn2+ co-doped glass ceramics exhibited tunable dual-to single-broadband UC emission with the content of Mn2+ varying from 0.75 to 4 mol%. After Tm3+ ions were introduced into the co-doped GC sample, a UC white-light luminescence was realized by combining the yellowish emission (510–630 nm) of Yb3+-Mn2+ pair and blue emission (476 nm) of Tm3+. Importantly, the white-emitting glass ceramic sample showed excellent thermal recoverability during a heating and cooling cycle within the temperature range of 303–573 K. Our results indicated the designed Yb3+/Mn2+/Tm3+ tri-doped glass ceramics may be a promising candidate for the white-light lasers source. © 2020 Elsevier B.V.

Novel dual valence Eu-doped phospho-alumino-silicate glass-ceramics containing orthorhombic Ba3AlO3PO4 nanocrystals were first fabricated by a traditional melt-quenching method and subsequent heat-treatment in an air atmosphere. Their structural and luminescent properties were systemically investigated by XRD, TEM analysis, and spectroscopic and fluorescence lifetime measurements. The incorporation of Eu3+ into Ba3AlO3PO4 crystallites and the reduction mechanism of Eu3+ to Eu2+ were also discussed based on the optical analyses. Simultaneously, perfect white light emission was obtained under 325 nm excitation. An improved anti-thermal quenching property was achieved resulting from the successful enrichment of Eu3+ and Eu2+ into Ba3AlO3PO4 crystallites, which was evidenced by active energy calculation. Our results indicate that these dual valence Eu-doped transparent Ba3AlO3PO4 glass-ceramics may have potential applications in W-LEDs.

Transparent oxyfluoride glass ceramics containing NaYF 4 :Er 3+ nanocrystals have been prepared by melt quenching and subsequent thermal treatment. X-ray diffraction and high-resolution transmission electron microscopy analysis confirmed the precipitation of NaYF 4 nanocrystals in glass. Energy dispersive spectrometer results evidenced the preferential concentration of Er 3+ ions in nanocrystals. Mid-infrared, upconversion, and near-infrared emissions were measured upon excitation with 980 nm laser diode and the luminescence mechanisms were discussed. Intense 2.7 μm emission originating from the Er 3+ : 4 I 11/2 → 4 I 13/2 transition was achieved due to the incorporation of Er 3+ ions into the precipitated low phonon energy fluoride nanocrystals. The results indicate that oxyfluoride glass ceramic containing NaYF 4 :Er 3+ nanocrystals is a promising candidate material for 2.7 μm laser.

International audience; The glass‐ceramics of AgI‐based electroconductive chalcogenide system was realized using an appropriate heat treatment at a fairly high temperature (Tg + 40°C) and different times ranging from 4 to 20 hours. The crystallization behavior and electroconductive properties of the heat‐treated samples were studied in detail. Transmission study was performed, and the results show that the cut‐off edge of the short wavelength is red‐shifted at prolonged annealing time but remains an excellent transmittance in the mid‐infrared (IR) region. XRD and scanning electron microscopy results indicated that the precipitated crystalline phases are mainly β‐/γ‐AgI. Moreover, a small amount of α‐AgI, which rarely existed at room temperature, is precipitated in the AgI‐rich chalcogenide glass‐ceramics. The ionic conductivity of all glass‐ceramics was enhanced by heat treatment in contrast to that of base glass. Raman analysis exhibited the structure variation in the glass sample after heat treatments. This study provided an observation of crystallization in chalcogenide glass containing large amounts of AgI and be of good guidance to fabricate novel AgI‐based chalcogenide glass‐ceramics that can be candidates in infrared optics and solid electrolyte applications.

International audience; AgI-based Ge-Sb-S, Ga-Sb-S, and Ge-Ga-Sb-S chalcogenide glasses were designed and prepared by melt-quenching, thereafter their thermal properties and conductive performance were comparatively investigated on the basis of their composition-induced network structures. Glass transition in each sample was examined by DSC measurements. Results showed that the samples containing Ge had a higher thermal stability than the Ga-Sb-S-AgI sample, and the Ge-Sb-S-AgI sample obtained had the highest conductivity ion. Raman spectrum analysis was performed, and the results indicated that the [GeS4-xIx] structural units and [SbS3-xIx] pyramids in the matrix produced effective ion transport channel for dissolved conductive Ag+ ions. In the matrix containing Ga, the [Ga(Ge)S4-xIx] structure was consumed by part of [S3Ga-GaS3] ethane-like units, which had no contribution to the ion transition framework. The study provided the directions for composition and structure configuration control in effective conductive chalcogenide glasses.

The structure, spin configuration, magnetocrystalline anisotropy compensation, magnetic properties, and magnetostriction of TbxDy0.9-xNd0.1(Fe0.8Co0.2)(1.93) (0.20 axis (x >= 0.25) to the axis (x >= 0.30) with increasing Tb content, subjected to the anisotropy compensation between Tb3+ and Dy3+ ions. The analysis of X-ray diffraction, EMD and magnetostriction show that TbxDy0.9-xNd0.1(Fe0.8Co0.2)(1.93) is an anisotropy compensation system and the compensation point is realized around x = 0.30. The Laves phase compound Tb0.4Dy0.5Nd0.1(Fe0.8Co0.2)(1.93) has a large spontaneous magnetostriction, the coefficient lambda(111) up to about 1640 ppm. The epoxy bonded 0-3 and pseudo-1-3 composites were fabricated by curing without and with a magnetic field. A high magnetostriction, longitudinal lambda(||) and linear anisotropic lambda(a)(=lambda(||)-lambda(perpendicular to)) up to around 390 and 650 ppm at 6 kOe, respectively, is obtained for the grain -oriented pseudo-1-3 epoxy/Tb0.4Dy0.5Nd0.1(Fe0.8Co0.2)(1.93) composite with 20 vol% alloy particles. (C) 2013 Elsevier B.V. All rights reserved.

Yb3 +/Tm3 + co-doped fluorogermanate glasses have been prepared by the melt-quenching method. Their luminescent properties were investigated by absorption spectra, excitation and emission spectra, and dynamic luminescence decay curves. The energy transfer parameters were analyzed by the phonon sideband theory and the energy transfer mechanism between Yb3 + and Tm3 + was proposed. An efficient 1.8 μm luminescence with reduced up-conversion emission is achieved under excitation of 980 nm laser diode. It is found that the emission at 800 nm is the main path of energy loss in the up-conversion process and it can be lowered at a higher Tm3 + doping level. In addition, the forward energy transfer parameter from Yb3 + to Tm3 + is approximately two orders of magnitude greater than the backward one, supporting efficient 1.8 μm emission.

The structure, magnetocrystalline anisotropy compensation, magnetic properties, and magnetostriction of TbxHo0.8-xPr0.2(Fe0.8Co0.2)(1.93) (0 axis (x axis (x >= 0.15), accompanied by a rhombohedral distortion with large spontaneous magnetostriction coefficients lambda(m). The analysis of XRD, [MD and magnetostriction shows that TbxHo0.8-xPr0.2(Fe0.8Co0.2)(1.93) is an anisotropy compensation system, and the critical compensation point is realized around x=0.15, which shifts to the Tb-poor side compared with the Pr-free counterpart. An optimized effect on magnetostriction especially at a relatively low field (lambda(S)similar to 445 ppm, lambda(a)similar to 510 ppm/3 kOe) was obtained in Tb0.15Ho0.65Pr0.2(Fe0.8Co0.2)(1.93) compound, which is much larger than that of the Pr-free counterpart Tb0.15Ho0.85(Fe0.8Co0.2)(1.93) (lambda(S)similar to 300 ppm) and the Tb0.15Ho0.85Fe2 (lambda(S)similar to 325 ppm), due to the 20 at% Pr introduction. Low content of heavy rare earth Tb, low anisotropy, high saturation magnetostriction and large low-field magnetostriction are obtained in Tb0.15Ho0.65Pr0.2(Fe0.8Co0.2)(1.93) compound, which may make it a promising magnetostrictive material. (C) 2015 Elsevier B.V. All rights reserved.

Structure, magnetization and magnetostriction of Tb 0.3 Dy 0.6 Nd 0.1 (Fe 1-x Co x ) 1.93 (0 ≤ x ≤ 0.40) compounds have been investigated. X-ray diffraction (XRD) analysis shows the presence of single Laves phase with a cubic MgCu 2 -type structure. The easy magnetization direction (EMD) is observed to be direction when x ≤ 0.10, and deviates away with further increasing Co contents. The Co contributes an opposite role in the resultant magnetocrystalline-anisotropy compared to Tb. A small amount of Co substitution for Fe can enhance the Curie temperature for x ≤ 0.25. The magnetocrystalline-anisotropy compensation can be achieved in this system. A minimum in anisotropy is obtained for the Tb 0.3 Dy 0.6 Nd 0.1 (Fe 0.8 Co 0.2 ) 1.93 compound, which has good magneto-elastic properties, e.g., the large saturation magnetostriction λ S (∼930 ppm) and the high low-field magnetostriction λ a (∼670 ppm/3 kOe), and may make it technological interest in the field of magnetostrictive materials.

Novel glasses in a Ga2S3-Sb2S3-AgI system were prepared with a melt-quenching method, and their glass-forming region was identified. The maximum dissolvable AgI in glasses was 65 mol%. The thermal, optical, and structural properties of glasses were investigated as a function of AgI and Ga2S3 contents. The Ga2S3-Sb2S3-AgI glasses possess a wide region of transmission window (0.65−14 μm). An ionic conductivity of approximately 1.01 × 10−3 S/cm can be obtained for a 40 (0.8Sb2S3-0.2Ga2S3)-60AgI glass at an ambient temperature, and the ionic conductivity increased as temperature increased. The relative activation energy of Ag+ conduction was also calculated. These novel glasses show potential for the combined application of infrared optics and solid electrolytes.

To introduce ordered nano-structures inside a transparent amorphous matrix with superior optical and mechanical properties bears scientific and technological importance, yet limited success has been achieved. Here, via simple melting-quenching and subsequent thermal activation, we report the successful preparation of transparent nano-structured glass-ceramics embedded in Sr2LuF7 nano-crystals (∼26 nm), as evidenced by X-ray diffraction, transmission electron microscopy (TEM), and high resolution TEM. The successful incorporation of dopants into formed Sr2LuF7 nano-crystals with low phonon energy results in highly tunable blue–green photoemission, which depends on excitation wavelength, dopant type, and temperature. We found that Eu3+ and Eu2+ ions co-exist in this hybrid optical material, accompanied by the broadband blue emission of Eu2+ and sharp red emissions of Eu3+. A series of optical characterizations are summoned, including emission/excitation spectrum and decay curve measurement, to reveal the reduction mechanism of Eu3+ to Eu2+. Furthermore, near green–white photoemission is achieved via the enrichment of Tb3+/Eu3+ into crystallized Sr2LuF7 nano-crystals. The temperature-dependent visible photoemission reveals thermal activation energy increases with the precipitation of Sr2LuF7 nano-crystals in a glass matrix, suggesting better thermal stability of glass-ceramics than precursor glasses. These results could not only deepen the understanding of glass-ceramics but also indicate the promising potential of Eu3+/Tb3+-ions-doped Sr2LuF7 glass-ceramics for UV pumped white light emitting diodes (WLEDs) with good thermal stability.

Unique Er 3+ doped transparent BaLuF 5 based glass–ceramics were triumphantly elaborated for the first time by melt-quenching technique and subsequent thermal treatment. The structural and luminescent properties were systemically investigated by XRD, TEM, absorption, excitation, down-shift and up-conversion spectra. All samples exhibit intense characteristic emissions of Er 3+ ( 2 H 11/2 , 4 S 3/2 , 4 F 9/2 → 4 I 15/2 ) excited by 980 nm laser. The dramatically enhanced up-conversion (6500 times) and longer lifetime in glass–ceramics confirm that most Er 3+ ions have preferentially entered into BaLuF 5 nanocrystals with lower phonon energy after crystallization. Our results indicate BaLuF 5 based transparent glass–ceramics may be excellent hosts for rare earth ions doping.

A chalcogenide glass system of (80–x)GeS2–17Ga2S3–3La2S3–xAgI (x = 0, 1, 5, 10, 15, 20 mol%) was prepared using the traditional melt-quenching technique. The effects of AgI introduction on the physical, thermal, structural, and infrared properties were studied. Results showed that with the increase in AgI content, density and microhardness also increased, which indicated that the mechanical capacity was improved. A slight redshift was observed at the visible absorbing cut-off edge. Raman spectra analysis indicated that AgI destroyed the [S3Ge–GeS3] structure and resulted in [GeS4−nIn] structure formation, thus decreasing the network connectivity and glass transition temperature. Nevertheless, the remarkable thermal stability of the glasses was likely maintained as demonstrated by differential scanning calorimetry analysis.

Utilizing a facile sol-gel reaction route, we dealt with the fabrication and luminescent properties of Sm3+-activated Y2Mo4O15 red-emitting microparticles. At the excitation of 405 nm, the resultant microparticles showed visible red emission with color purity of 76.7%. According to the detected decay time, the theoretical internal quantum efficiencies of the compounds were analyzed. In addition, temperature-dependent emission spectra were performed to verify the thermal resistance performances of the microparticles. As proof of the suitability of the prepared compounds for solid-state illumination, a white light-emitting diode (WLED) device was packaged using the obtained microparticles, BaMgAl10O17:Eu2+ blue phosphors, (Ba,Sr)2SiO4:Eu2+ green phosphors and near-ultraviolet (NUV) chip. The designed WLED lamp enabled emit bright white light with a good chromaticity coordinate of (0.302, 0.394), satisfied color rendering index (78.3) as well as proper correlated color temperature (6552 K).

The effect of CsCl addition on the nanocrystallization and phase separation behaviors of (100 − x)(0.5GeS2–0.5Sb2S3)–xCsCl (x = 0, 5, 10, 15, 20, 25, 35 and 40 mol%) samples was investigated systematically by various characterization techniques. Transparent chalcogenide glass-ceramic sample embedded CsCl nanocrystals of ~50 nm was obtained successfully through one-step melt-quenching method in a glass with elaborated composition of 37.5GeS2·37.5Sb2S3·25CsCl, which is around the critical solubility of CsCl in GeS2–Sb2S3 based glasses. With the further addition of CsCl (x > 25 mol%), phase separation with different droplet and interpenetrating structures were observed for the first time in chalcogenide glasses. The recognition of these phenomena would be of guiding significance for the future design and fabrication of chalcogenide glass-ceramics with specific microstructures and optical functionalities.

M+/Eu3+ (M = Li, Na, K) co-doped CaB2Si2O8 phosphors have been synthesized by a solid-state reaction approach. XRD measurements confirm that the phase purity of the CaB2Si2O8 host is maintained after the introduction of alkali metal ions and Eu3+ ions. The emission intensity of Eu3+ ions is enhanced by a factor of 1.75 and 1.55 with the incorporation of Li+ and Na+ ions, respectively, originating from the charge compensation and improved asymmetry in the crystal field, while the addition of K+ ions to the composition results in a decreased luminescence intensity due to the structural-defect-related quenching. Temperature dependent measurement reveals that the prepared phosphor exhibits excellent thermal stability with 81% at 423 K of the integrated emission intensity at 298 K. A white light-emitting diode (W-LED) device is fabricated based on the synthesized Eu3+ doped CaB2Si2O8 red phosphor modified by Li ions. All these results indicate that the synthesized phosphor is a promising red-emitting material for W-LEDs application.

Novel chalcogenide glasses and glass-ceramics of (100-x)(0.5GeS 2 –0.5Sb 2 S 3 )–xPbCl 2 (x = 0, 3, 5, 8, 10, 15, 20, and 25) were prepared by single-step melt-quenching technique, and their transmission spectra and thermo-mechanical properties are characterized. The solubility and spontaneous crystallization behavior of PbCl 2 are investigated by employing various techniques of XRD, SEM, and Raman spectra. Two-stage crystal growth was found in these samples with the increase of PbCl 2 content (x). The crystallization behavior of oversaturation and recrystallization of PbCl 2 in glasses is totally different from the typical nucleation and crystal growth initiated by thermal treatment. Especially, transparent chalcogenide glass-ceramic embedded PbCl 2 nanoparticles (~20 nm) was successfully fabricated when x reaches 10 mol%. This study is of guidance significance for future design and elaboration of optically functionalized chalcogenide glass-ceramics.

Novel Tb3+–Yb3+ co-doped transparent glass–ceramics containing NaLuF4 nanocrystals were successfully fabricated by melt-quenching technique for the first time. The structural and luminescent properties were investigated by XRD, TEM, absorption and upconversion spectra systemically. All samples exhibit intense characteristic emissions of Tb3+ (5D4 → 7FJ (J = 3–5) and 5D3 → 7FJ (J = 4–6)) and cooperative luminescence of Yb3+ ion pairs (476 nm) excited by 980 nm laser. The dramatically enhanced upconversion in glass–ceramics suggests that most rare earth ions have preferentially entered into NaLuF4 nanocrystals with lower phonon energy after crystallization. Our results indicate NaLuF4 based transparent glass–ceramics may be excellent hosts for rare earth ions doping.

Novel Ho3+ doped highly transparent NaYbF4 glass-ceramics were successfully fabricated by melt-quenching technique. Their structural and luminescent properties were systemically investigated by XRD, TEM, absorption spectra, upconversion spectra, and lifetime measurements. Excited by 980-nm laser, samples exhibit characteristic emissions of Ho3+. Impressively, the luminescent color can be tuned easily from red for precursor glass to green for glass-ceramics. Such novel phenomenon was elaborately investigated and is owing to the reduced multiphonon nonradiative relaxation and enhanced cross-relaxation of Ho3+ in NaYbF4 nanocrystals after crystallization. Our results indicate that NaYbF4 transparent glass-ceramics is an excellent host for upconversion.

A good Ag-based SERS substrate has been prepared by one-pot reaction using methyl cellulose as a template. Effects of methyl cellulose concentration, silver ammonia chloride solution concentration, reaction duration, and reducing agent on silver nanoparticles were discussed in this paper. The performance of the obtained Ag nanoparticles was characterized by UV-visible spectroscopy, transmission electron microscopy, and surface-enhanced Raman spectroscopy. Results show that the reducing agent plays a crucial role in the performance of silver nanoparticles. Optimum preparation conditions of synthesis of SERS substrates were as follows: 10 mM silver ammonia chloride and 0.2% MC at 75°C, reducing in 0.2% reducing agent at 120 min. TEM studies reveal that particles are mostly spherical and rod in shape with an average size of 80 nm. Silver nanoparticles prepared with MC as a template have been shown to provide strong SERS enhancement signals of R6G, which can be used as a good Ag-based SERS substrate in the analytical environment for routine measurements.

The structure, magnetization and magnetostriction of Tb1−xNdx(Fe0.8Co0.2)1.93 (0 ≤ x ≤ 1.0) alloys have been investigated by means of X-ray diffraction, a vibrating sample magnetometer and a standard strain technique. X-ray diffraction (XRD) analysis shows that the alloys possess predominantly the cubic Laves phase with a MgCu2-type structure for x ≤ 0.6. The lattice parameter of the Laves phase increases with increasing Nd content and obeys the linear Vegard's law. The easy direction of magnetization (EMD) is observed toward when 0 ≤ x ≤ 0.6, accompanied by a rhombohedral distortion with large spontaneous magnetostriction coefficients λ111. The saturation magnetization MS at room temperature (RT) decreases with increasing Nd content when 0 ≤ x ≤ 0.5, then increases with further increasing x for x ≥ 0.6. The linear anisotropic magnetostriction λa (= λ||– λ⊥) at RT decreases initially with increasing x when 0 ≤ x ≤ 0.4, then increases with a further increasing x and exhibits a peak in the range of 0.4

Pseudobinary high Pr-content Tb1−xPrx(Fe0.4Co0.6)1.93 (0.70≤x≤1.00) magnetostrictive alloys have been fabricated by a melt-spinning method. The effects of the composition, spinning, and annealing processes on the structure, thermal stability, and magnetic properties are investigated. At a wheel speed of v≤30 m/s, the as-spun ribbons consist of a mixture of (Tb,Pr)(Fe,Co)2 cubic Laves phase and some non-cubic phases. A single (Tb,Pr)(Fe,Co)2 phase with MgCu2-type structure is formed with the process for the speed of v≥35 m/s and subsequent annealing at 500 °C for 30 min. The lattice parameter of the Tb1−xPrx(Fe0.4Co0.6)1.93 Laves phase increases from 0.7354 nm for x=0.70 to 0.7384 nm for x=1.00 and approximately follows the linear Vegard's law. The Curie temperature decreases, while the saturation magnetization increases as increasing Pr content. The Pr-rich alloys possess the relatively lower coercivity and the faster saturation of magnetostriction as compared with the Tb-rich alloys, which can be understood by their lower magnetic anisotropy.

Dual valence Eu-doped transparent glass-ceramics containing LuPO4 nanocrystals were fabricated by melt-quenching technique in air atmosphere. Their luminescent properties were systematically investigated by excitation, emission spectra, and decay lifetime measurements. The prominent Stark splitting, low forced electric-dipole 5D0–7F2 transition and long decay lifetimes of Eu3+ emission for glass-ceramics reveal the incorporation of Eu3+ into LuPO4 nanocrystals. The enhanced Eu2+ emission and reduction mechanism of Eu3+ to Eu2+ after crystallization are discussed briefly. Our results indicate that transparent LuPO4 glass-ceramics may find applications in photonics.

Novel Eu3+-doped transparent oxyfluoride glass-ceramics containing BaLuF5 nanocrystals were successfully fabricated by melt-quenching technique for the first time. Analyses of XRD patterns prove that the new precipitated glass-ceramics are crystallized in cubic BaLuF5 based on isostructural BaGdF5. Intense red emissions observed in glass ceramics are attributed to the enrichment of Eu3+ ions into BaLuF5 nanocrystals. Besides, obvious stark splitting emissions, low forced electric dipole 5D0→7F2 transition, and long decay lifetimes of Eu3+ ions also evidence the partition of Eu3+ ions into BaLuF5 nanocrystals with low phonon energy. Such transparent material may find applications in photonics.

Intense 2.7 μm emission of Er3+ was achieved in transparent glass ceramics containing orthorhombic Vernier phase lutetium oxyfluoride nanocrystals, which was prepared through conventional melt-quenching and a subsequent thermal treatment method. X-ray diffraction and transmission electron microscopy analysis confirmed the precipitation of orthorhombic Vernier phase lutetium oxyfluoride nanocrystals in glass ceramics. The preferential incorporation of Er3+ ions into nanocrystals was evidenced by TEM element mapping, stark-split absorption band, and prolongation of luminescence lifetimes. Upon 980 nm laser excitation, enhanced 2.7 μm emission originating from Er3+:4I11/2 → 4I13∕2 transition was obtained in glass ceramics via increasing the heat treatment temperature, which resulted from the inhibited non-radiative relaxation from 4I11/2 level and favored energy transfer upconversion process between the localized Er3+ ions. Our results indicate that lutetium oxyfluoride nanocrystal embedded glass ceramic is a promising candidate for 2.7 μm laser.

Luminescent properties of Sb(3+)/Mn(2+) co-doped borosilicate glasses containing no rare earth ions were systematically investigated through absorption, excitation, emission spectra, and decay curves. Upon 250-340 nm light excitation, the glasses exhibit broad blue emission at 400 nm (Sb(3+)) and red emission at 615 nm (Mn(2+)). The varied emitted color from blue through white and eventually to red can be obtained by properly tuning the content of Mn(2+) ions due to energy transfer from Sb(3+) to Mn(2+). Our investigation shows that Sb(3+)/Mn(2+) co-doped glasses may provide a new platform to design and fabricate luminescent materials for UV LED chips in the future.

Luminescent properties of (Cu+)2, Eu3+ single-doped and codoped sodium silicate glasses were systematically investigated by excitation spectra, emission spectra, and decay curves. Due to the efficient energy transfer from (Cu+)2 pairs to Eu3+, varied hues from green to yellowish white and eventually to orange were generated by tuning the content of Eu3+. A perfect white-light emission with CIE coordinates (X=0.336,Y=0.346) was realized in (Cu+)2, Eu3+ and Ce3+ codoped samples. Our research indicates the potential application of (Cu+)2, Eu3+ codoped sodium silicate glasses for converting phosphors for UV LED chips to generate white LEDs.

Oxyfluoride glasses containing Ag species and rare earth (RE) ions (Dy(3+), Sm(3+), Tb(3+)) were prepared by melt-quenching technique. The type of luminescent species of novel excitation band (230-300 nm peaked at 255 nm) and emission band (300-600 nm peaked at 350 nm) were investigated by absorption, excitation, emission spectra, as well as decay lifetime measurements and can be ascribed to isolated Ag(+) ions. Owing to energy transfer from Ag(+) to RE ions, significant enhancements of RE ions emission (76 times for Sm(3+), 41 times for Dy(3+)) were observed for non-resonant UV excitation (255 nm). Our research may extend the understanding of interactions between RE ions and Ag species.

An epoxy-resin bonding route was used to produce composite rods of the highly magnetostrictive alloys Tb 1-x Nd x( Fe 0.8 Co 0.2)1.93 (0.20 ≤ x ≤ 0.75). The structure, spin configuration, magnetostriction and particle size are investigated by means of X-ray diffraction (XRD), a standard strain technique and scanning electron microscope (SEM). The epoxy-bonded 0–3 type and pseudo 1–3 type composites are successfully fabricated, respectively. XRD analysis shows that the easy magnetization direction (EMD) for the alloy of x = 0.20 lies along 〈111〉 axis. The magnetic curing field makes the particles align as a particulate chain and also causes the particles rotating along its EMD direction. The pseudo 1–3 type epoxy-bonded composite has a larger magnetostriction than that of the 0–3 type composite, which can be attributed to the larger magnetostriction coefficient λ111, EMD lying along 〈111〉 direction, the 〈111〉-textured orientation and the chain structure. A large saturation magnetostriction (λ0S ~ 570 ppm) is achieved for the 1–3 type epoxy/ Tb 0.35 Nd 0.65( Fe 0.8 Co 0.2)1.93 composite (about 150–250 μm, 10 kOe), which approaches 70% of its monolithic alloy. Furthermore, it only contains 27 vol.% alloy particles in the insulating epoxy matrix and performs a low magnetic anisotropy, which could make it technologically interesting for the field of Nd -containing magnetostrictive materials.