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Dị tật Uhl`s là bệnh lý hiếm gặp đặc trưng bởi mất hoàn toàn hoặc một phần lớp cơ tim phải, chỉ còn lớp nội tâm mạc và thượng tâm mạc. Thường bệnh nhân (BN) khó sống tới tuổi trưởng thành. Chúng tôi thông báo một trường hợp BN nữ 24 tuổi có dị tật Uhl`s được chẩn đoán và phẫu thuật tại trung tâm Tim mạch Bệnh viện E Hà Nội

Giới thiệu một kỹ thuật mới trong phẫu thuật Glenn hai hướng có hai tĩnh mạch chủ trên ở bệnh nhân một tâm thất. Một trong những nguyên nhân thất bại của phẫu thuật Glenn hai hướng ở bệnh nhân có hai tĩnh mạch chủ trên là do hai tĩnh mạch này nhỏ, dòng chảy yếu, khi làm miệng nối với động mạch phổi dễ gây xoắn, tắc, huyết khối miệng nối. Việc góp hai tĩnh mạch chủ trên chuyển thành một hợp lưu tĩnh mạch lớn hơn với miệng nối đủ rộng để nối với động mạch phổi có thể giải quyết vấn đề này. Chúng tôi báo cáo 2 trường hợp đã áp dụng thành công kỹ thuật này tại trung tâm tim mạch Bệnh viện E, cung cấp một lưu lượng máu đều đến hai phổi và mang lại sự tăng trưởng kích thước động mạch phổi cũng như giảm thiểu sự hình thành huyết khối.

Ca2Al2SiO7:x.Sm3+ (x = 0.5, 1.0, 1.5, 2.0, 2.5, and 3.5 mol.%) (CAS:x.Sm3+) phosphors were synthesized by a solid-state reaction technique. The structure, photoluminescence properties and thermal stability of phosphors were investigated in detail. Results of X-ray diffraction show that CAS:x.Sm3+ materials have a single-phased tetragonal structure, and an expansion of the unit cell relates to the increasing of Sm3+ concentration. Photoluminescence study displayed that the CAS:x.Sm3+ phosphors reach the highest emission intensity at 1.5 mol.% Sm3+ and achieved the luminescence quenching phenomenon a higher concentration. The dominant interaction mechanism of the concentration quenching process is determined due to the dipole–dipole interaction, and the critical transfer distance (Rc) is 26.7 A. The temperature dependence of photoluminescence spectra indicates that the Ca2Al2SiO7:Sm3+ (1.5 mol.%) phosphor possess good thermal stability, and that the activation energy is around 0.12 eV (968 cm−1). Several characteristic vibrations in the 200–1000-cm−1 region were observed by Raman spectra, and the color chromaticity coordinates of the samples were also calculated and discussed.

Metal nanoparticles (NPs) are precipitated on the surface or within the glass; such glass has attracted considerable interest because of its potential practical applications in optics, electromagnetics, and biosensing devices. Although such glass has been prepared via the deposition of separately synthesized NPs or via secondary heating of glass doped with metal ions, developing a well-designed NP-doped glass still remains a formidable challenge. Here, we succeeded in precipitating Ni NPs on the surface and within the glass by heating the Ni2+-doped Al2O3–SiO2 glass under hydrogen gas. The Al2O3–SiO2 glass prepared via melt quenching comprised two phases in which the Ni2+ ions were preferentially bound in the Al3+-rich phase. When hydrogen gas was loaded, it diffused in the glass; then, Ni2+ ions were reduced to Ni atoms, concurrently forming Al–OH bonds. The reduction of Ni2+ ions was discussed in relation to the hydrogen diffusion and reaction with the Ni2+ ions. The optical absorption band at ~ 350 nm wavelength could be assigned to the surface plasmon resonance of Ni nanoparticles. The precipitated Ni NPs moved toward the glass surface, which were removed using an acid solution. Thus, Ni-free glass exhibited fast H2 and He gas diffusion rates compared to silica glass.

In this study, the synthesis and luminescence properties (LP) of Al2O3-SiO2 glasses doped with different concentrations of Ce3+, namely, 0.05 mol.%, 0.1 mol.%, and 0.3 mol.% Ce3+, were investigated. The LP of the obtained samples were characterized by ultraviolet–visible absorption (UV–VIS) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and photoluminescence (PL) spectroscopy. The results showed that the valence states of the cerium ions can be controlled by heating the synthesized glasses in hydrogen atmosphere leading to change their LP. The existence of the absorption band at about 295 nm and of a broad band spectrum with a maximum at 250 nm can be attributed to Ce3+ ion and the charge transfer band of Ce4+ ion, respectively. A broad emission at 366 nm observed under excitation of UV light at 310 nm originated from the well-known 4f–5d transition of Ce3+ ion. The role of Al3+ ions is also considered when glass samples were treated under the hydrogen atmosphere. It is revealed that the presence of aluminum ions enabled controlling the valence states of cerium via the formation of OH bonds that can reduce Ce4+ to Ce3+ ions in glass sample treated in reduced atmosphere. The increasing of PL peaks appeared during the treatment under hydrogen atmosphere at high temperature.

Dy3+-doped glasses with compositions of (69-x)B2O3 + 10TeO2 + 10Al2O3 + 10Li2O + xDy2O3 (x = 0.1; 0.5; 1.0 and 2.0 mol%) were prepared by a melt–quenching technique. An in-depth Judd-Ofelt analysis has been carried out to estimate the influence of the hypersensitive transitions (HST) of Dy3+on the validity of the obtained intensity parameters Ωλ (λ = 2, 4, 6). The thermalization effect of the three-levels system of 6H13/2 (level 0), 4F9/2 (level 1) and 4I15/2 (level 2) was taken into account to evaluate its radiative transition probabilities, life times and energy levels. The obtained results were compared with the experimental data to estimate the validity of the Judd-Ofelt analysis. The Inokuti-Hirayama model was used to analyze the luminescence decay curves. The dipole-dipole interaction was shown to be the dominant mechanism in energy transfer process through cross-relaxation between Dy3+ ions. The possibility to produce the light with chromaticity coordinates in the white-light region by mixing intense blue (484 nm, 4F9/2 → 6H15/2) and yellow (575 nm, 4F9/2 → 6H13/2) emissions of the single Dy3+doped alumino-lithium-telluroborate glass was observed and estimated.

KGdF4:Tb3+, KGdF4:Sm3+ and KGdF4:Tb3+,Sm3+ polycrystalline were synthesized under hydrothermal conditions. The XRD and TEM patterns as well as excitation, luminescence spectra and luminescence decay curves of Sm3+, Tb3+ and Gd3+ have been measured at room temperature. For KGdF4:Tb3+(Sm3+), energy transfer processes from Gd3+ ions to Tb3+ (or Sm3+) ions are related to energy migration through Gd3+ ions and energy trapping by Tb3+ (or Sm3+) ions. The energy trapping rate strongly depends on the nature of RE3+ (Tb3+ or Sm3+) ions and it influences to the luminescence efficiency of RE3+ ion. For KGdF4:Tb3+,Sm3+, the characteristic emission bands of Tb3+ ion (blue and green) and Sm3+ ion (orange-red) are obtained simultaneously upon excitation by 375 nm. The chromaticity coordinates and correlated color temperature (CCT) are used to estimate the emission feature of prepared material. The quenching of the luminescence and lifetime of 5D4 (Tb3+) level are relate to the energy transfer process from Tb3+ to Sm3+ ions. It is shown that, by fitting the decay curves of 5D4 (Tb3+) to the Inokuti and Hirayama model, the dominant interaction mechanism between Tb3+ and Sm3+ is dipole-quadrupole interaction. The probability (WET) and the efficiency (ηET) of energy transfer from Tb3+ ions to Sm3+ ions increase with the increase of Sm3+ concentration.

Spectroscopic properties and energy transfer mechanisms for isostructural fluoride K2YF5 and K2GdF5 crystals singly and doubly doped with different concentrations of Tb3+ and Sm3+ ions have been investigated under excitation in the deep ultraviolet (DUV) and vacuum UV (VUV) spectral regions. In these hosts luminescence of Sm3+ ions is enhanced under DUV excitation by doping with Tb3+ ions, namely, the Sm3+ excitation spectra show additional intense excitation in the region of Tb3+ spin-allowed 4f – 5d transitions at 200–220 nm due to energy transfer from Tb3+ to Sm3+. The decay curves of Tb3+ ion luminescence have been measured at room temperature for the series of samples containing different concentration of Sm3+ and have been fitted by the Inokuti-Hirayama model. The results have revealed that the dipole-dipole interaction is the dominant interaction mechanism in the energy transfer process from Tb3+ to Sm3+ ions. The probability (WET) and the efficiency (EET) of energy transfer from Tb3+ to Sm3+ increase depending on the Sm3+ concentration in these crystals.

The change of Eu3+− surrounding in the system SrO−x.B2O3 with various x values (x = 0.33, 0.5, 1) synthesized by combustion method was investigated via photoluminescence (PL) spectra and phonon sideband (PSB) spectra. From the analysis of PSB spectra, it is reasonable to suggest that when increasing B2O3 content the electron−phonon coupling strength increases due to the increase in the number of B O− non−bridging bond. By using Judd−Ofelt (JO) theory for PL spectra of Eu3+ ion, the Ω2 intensity parameter was calculated and it also shows the asymmetry of Eu3+− surrounding increase corresponding to the B2O3 content.

Cu nanoparticles (NPs) have attracted considerable attention as a substitute for noble metals, such as Au and Pt, due to their unique surface plasmon resonance (SPR) properties, natural abundance, and low fabrication cost. We succeeded in one-step preparation of Cu NPs with a uniform size on glass surface by heating Cu2+ ions-containing Na2O–Al2O3–SiO2 glass in hydrogen atmosphere. The formation of Cu NPs was confirmed using scanning and transmission electron microscopies, small-angle X-ray scattering, and visible and infrared absorption spectroscopies. Heat treatment in a hydrogen environment facilitated the diffusion of hydrogen molecules into the glass to form Cu atoms and Al OH bonds. The Cu atoms migrated through gaps formed by Al OH toward the surface, where they combined to form Cu NPs. The optical spectra of showed sharp and intense SPR bands at a peak wavelength of 580 nm, indicating the homogeneous distribution of uniformly sized Cu NPs on the glass surface without aggregation. The obtained samples exhibited good sensing performance due to the strong SPR properties. Further advantage of our method was that Cu nanoparticles can be repeatedly formed by heating under H2 gas after removing the previously formed particles.

K2GdF5 single crystals doped with 5.0 at.% of Nd3+ ions (K2GdF5:Nd3+) have been synthesized by the hydrothermal technique. The identification and control of the phase purity of synthesized crystals were performed using powder X-ray diffraction analysis. The spectroscopic characteristics of Nd3+ ions in K2GdF5 were analyzed through the absorption and luminescence spectra as well as decay curves. Upconversion luminescence spectra of K2GdF5:Nd3+ in the visible region were recorded under excitation by laser radiation with a wavelength of 785 nm. The nature of the Nd3+- ligand bonding and Judd-Ofelt intensity parameters were estimated using the absorption spectrum. The Ω4/Ω6 ratio was used to predict the structure of the emission spectrum of the K2GdF5:Nd3+ crystal. The application capability of the 4F3/2 → 4I9/2 emission band (864 nm) for laser action in K2GdF5:Nd3+ is proposed based on the radiative parameters such as the experimental branching ratio (βexp), integrated emission cross-section (ΣJJ’) and stimulated emission cross-sections (σλp). The nonradiative energy transfer process between Nd3+ ions in K2GdF5:Nd3+ is also discussed in detail using the Inokuti-Hirayama and Yokota-Tamimoto models.

Aluminosilicate (AS) glasses doped with different Dy3+ concentrations were synthesized via sol–gel method. Absorption, photoluminescence spectra and lifetime of this material have been studied. From analytical results of absorption spectra, the Judd–Ofelt (JO) parameters of prepared samples have been determined. These JO parameters combined with photoluminescence spectra have been used to evaluate transition probabilities (AR), branching ratios (β) and the calculated oscillator strengths of AS:Dy3+ glasses. The radiative branching ratio of 4F9/2 → 6H13/2 transition has a minimum value at 62.2% for βR which predicts that this transition in AS:Dy3+ glasses can give rise to lasing action. JO parameters show that the Ω2 increases with the increasing of Dy3+ ion concentration due to the increased polarizability of the average coordination medium and decreased average symmetry.

Controlling valence state of metal ions that are doped in materials has been widely applied for turning optical properties. Even though hydrogen has been proven effective to reduce metal ions because of its strong reducing capability, few comprehensive studies focus on practical applications because of the low diffusion rate of hydrogen in solids and the limited reaction near sample surfaces. Here we investigated the reactions of hydrogen with the Cu2+-doped Na2O-Al2O3-SiO2 glass, and found that a completely different reduction is occurring than results reported so far, which is dominated by the Al/Na concentration ratio. For Al/Na 1, on the other hand, the reduction of Cu2+ ions occurred simultaneously with the formation of OH bonds, while the reduced Cu metal moved outwards and formed a metallic film on glass surface. The NMR and FT-IR results indicated that the Cu2+ ions were surrounded by Al3+ ions that fo...

K2YF5 single crystals doped with Sm3+ ions (K2YF5:Sm3+) have been synthesized by the hydrothermal method at a temperature of 750 K and pressure of 100 MPa. The absorption and luminescence spectra of the K2YF5:Sm3+ samples have been measured at room temperature. Sm3+ luminescence quenching occurs in K2YF5:Sm3+ single crystals at Sm3+ concentrations higher than 2.0 at%. This phenomenon relates to the energy transfer process through cross-relaxation between Sm3+ ions. Dynamics of the energy transfer process has been analyzed by the Inokuti-Hirayama model and the dipole–quadrupole interaction has been found to be a dominant mechanism in this process. Under excitation by 785 nm laser radiation, K2YF5:Sm3+ single crystals show the upconversion luminescence bands in the visible spectral region as well as some sharp and strong emission lines in the near infrared region. The excited state absorption has been defined to be the main mechanism for upconversion luminescence in K2YF5:Sm3+ crystals.

We have recently developed new Eu 2+ -doped Na 2 O–Al 2 O 3 –SiO 2 glasses by heating precursors in H 2 gas, in which Al 3+ ions play an important role in reducing Eu 3+ to Eu 2+ . However, the pathway by which the Eu 3+ ions are reduced was not established. To address this question, the structural changes involving Al 3+ and Eu 3+ ions have been elucidated from Magic-Angle Spinning Nuclear Magnetic Resonance (MAS NMR) in solid state and X-ray absorption fine-structure spectroscopies. In the glasses with Al/Na >1, the Al 3+ ions form AlO 4 units without incorporating Na + ions for charge compensation, and the Eu 3+ ions are coordinated by a network structure comprising AlO 4 and SiO 4 . When heated in H 2 gas, the H 2 gas molecules diffuse and react with the Eu 3+ ions, reducing them to Eu 2+ and forming O–H bonds. The diffusion rate of H 2 molecules was analyzed from the formation process of O–H bonds; 3.37×10 −12 m 2 /sec at 700 °C and 39.5 kJ/mol for diffusion coefficient and activation energy, respectively.

Controlling of valence states of metal ions doped in glasses has attracted considerable interest due to the possibility of looking toward optical applications. In this study, new Na 2 O-Al 2 O 3 -SiO 2 glasses were developed to dope Eu 2+ and Mn 2+ with well controlled valence states by heating in H 2 gas atmosphere, and the changes in the valence state of doped-ions and their fluorescence properties were investigated using visible and infrared optical absorption spectroscopies, X-ray absorption fine structure spectroscopy, and fluorescence spectroscopy. Among Eu 3+ , Mn 3+ and Mn 2+ ions incorporated in the as-prepared glasses, the Eu 3+ and Mn 3+ ions were reduced to Eu 2+ and Mn 2+ ions, respectively, by heating in H 2 gas and OH bonds were concurrently formed. The fluorescence spectra of glasses heated in H 2 exhibited broad emission bands at 450 and 630 nm wavelength, assigned to the Eu 2+ and Mn 2+ , respectively, ions, in which the fluorescence intensity at 450 nm was observed to decrease with increasing Mn 2+ ion content. The increased fluorescence intensities were analyzed as the energy transfer from Eu 2+ to Mn 2+ ions and the energy transfer efficiency was estimated with a concentration of Eu 2+ and Mn 2+ ions.

Optical materials 107, 110049 (2020). doi:10.1016/j.optmat.2020.110049, K$_2$Y$_{0.99}$Ln$_{0.01}$F$_5$ (Ln = Ce, Eu and Sm) single crystals have been synthesized by the hydrothermal technology. The optical properties of Ce$^{3+}$ and Eu$^{3+}$ ions doped into K$_2$YF$_5$ matrix have been studied under excitation in the deep UV and vacuum UV (VUV) region. The obtained data from excitation spectra and Dorenbos models have been used to predict the energies of the f-d and charge transfer transitions as well as the energy levels location of divalent (Ln$^{2+}$) and trivalent (Ln$^{3+}$) lanthanide ions within the band gap of K$_2$YF$_5$. In particular, the f-d and charge-transfer transitions of Sm$^{3+}$ in the luminescence excitation spectrum of K$_2$YF$_5$:Sm$^{3+}$ have been identified. The host referred binding energy (HRBE) and vacuum referred binding energy (VRBE) schemes have been constructed for Ln$^{2+}$ and Ln$^{3+}$ ions doped K$_2$YF$_5$ crystal which were used for the analysis of possible applications of K$_2$YF$_5$ doped with Ln$^{3+}$ ions as thermoluminescence materials., Published by Elsevier Science, Amsterdam [u.a.]

The Raman, absorption, luminescence spectra and lifetimes curves of Sm 3+ -doped K 2 GdF 5 were measured. Based on the Judd-Ofelt analysis, the values of radiative transition probabilities, branching ratios, integrated emission cross-sections and radiative lifetimes of excited states of Sm 3+ in K 2 GdF 5 crystal were calculated. The migration of excitation energy between the Gd 3+ ions and the trapping processes of Gd 3+ excitation energy by Sm 3+ and Tb 3+ ions in K 2 GdF 5 crystal are reported. The role of the overlapping between the broad, allowed absorption bands of the RE 3+ ions and the narrow absorption lines 6 I J and 6 P J of Gd 3+ ions on the trapping rates of the RE 3+ was discussed. The energy transfer between the Sm 3+ ions was studied by the decay measurement, which has been fitted by Inokuti-Hirayama energy transfer model and revealed that electric dipole–quadrupole interaction is responsible for the energy transfer process in Sm 3+ ions doped K 2 GdF 5 crystal.

Dy3+-doped glasses with various compositions (35+x)B2O3+ (45−x)TeO2+9.5ZnO+10Na2O+0.5Dy2O3 (x=0; 10 and 20) were prepared by a melt–quenching technique. The Dy3+ ions are used as an optical probe, of which the Judd–Ofelt parameters, the phonon-side band, and the Raman spectra were quantitatively estimated to search the change of glass structure (the change of the ratio of [BO4] to [BO3] units, formation of the non-bridging oxygens (NBO−), the change of [TeO3] to [TeO4] units) as a function of the B2O3 content. The Ω2 and Ω6 values of Dy3+-doped boro-tellurite samples are larger than that of Dy3+-doped borate or tellurite sample. The CIE chromaticity color coordinates were calculated for the luminescence spectra of Dy3+ ions of the glasses with the different compositions and they were all located in the vicinity of white light center of the color coordination diagram.

The absorption, luminescence, Raman spectra and lifetimes of Sm-doped alkali telluroborate glasses (TB glasses) TB:Sm 3+ have been investigated. The dual energy transfers including energy transfer between Sm 3+ - Sm 3+ pairs and Sm 3+ - non-bridging oxygen (NBO) intrinsic defects were investigated. The concentration quenching of luminescence intensity was explained by the non-radiative energy transfer between the Sm 3+ ions through the cross-relaxation mechanism. The decay curves are single exponentials with low concentrations (lower 0.10 mol%) and become non-exponentials at higher concentrations. The non-exponential decay curves are fitted to the Inokuti and Hirayama model to give the energy transfer parameters between Sm 3+ ions. The dominant interaction mechanism for energy transfer process is dipole–dipole interaction. The energy transfer induced Sm 3+ photoluminescence enhancement in tellurite glass was experimentally studied and confirmed.

Ternary CdSe x S1−x alloy quantum dots (QDs) were synthesized using a wet chemical method. Their morphology, particle size, structural, optical, and vibrational properties were investigated using transmission electron microscopy, x-ray diffraction, UV–Vis, fluorescence and Raman spectroscopy, respectively. The optical and vibrational properties of the QDs can be controlled by adjusting the Se/S molar ratio. The absorption and emission peaks shift to a longer wavelength range when increasing the Se content. The presence of two CdSe-like and CdS-like longitudinal optical phonon modes was observed. The dependencies of the optical and phonon modes on the Se content are discussed in detail.

Tellurite glass doped with different concentrations of Eu3+ ions has been prepared by the conventional melting process. Photoluminescence, Raman spectra, phonon side-band spectra, and Judd–Ofelt analysis were carried out. Some spectroscopic parameters were estimated to predict the luminescence efficiency of the materials. The energy transfer between the rare-earth ions was observed, and a model for its cross-relaxation was proposed and quantitatively estimated. The charged intrinsic defects in the form of nonbridging oxygen (NBO) were determined, and the energy transfer between NBO and rare-earth ions observed. The energy-transfer-induced Eu3+ photoluminescence enhancement in tellurite glass is studied.

In this study, the role of sodium ions (Na+) in the generation of thermoluminescence (TL) peaks in the 77–680 K region of natural quartz are investigated by combining the TL and phototransferred thermoluminescence (PTTL) spectrally-resolved glow curves. The TL spectrum is characterized by four emission bands at 380, 470, 590, and 620 nm, which are related to four TL peaks at 383, 513, 598, and 648 K, respectively. The dynamic parameters of the TL peaks are evaluated using the initial rise method. PTTL is also studied in the temperature range of 77–330 K. In this region, PTTL curves show four main peaks at 160, 190, 250, and 295 K, in which the intensity of the PTTL peak at 250 K is shown to be relative to the Na+ concentration and the double irradiation process. PTTL measurements were further used to estimate the relationship between the TL peak at 598 K and PTTL peak at 383 K.

Energy level position of divalent and trivalent lanthanides in the band gap relative to the valence and conduction bands of Sr3B2O6 host lattice was determined through the f→d transition energy of Ce3+ ion, the thermal quenching of Eu2+ emission and charge transfer energy of Eu3+. The lowest 4f→5d absorption transition of Tb3+ and the charge transfer energy of Sm3+, which predicted from the energy level scheme, are well matched to the observed energies from photoluminescence excitation spectra of Sm3+ and Tb3+ in Sr3B2O6 material. In addition, an anomalous emission of Sr3B2O6:Eu2+ was successfully explained by a combination of the presence of traps in lattice and the proposing energy level scheme.

Tb3+ doped K2YF5 single crystal was synthesized by the hydrothermal technique. Structure of material was analyzed by X-ray diffraction pattern and Raman spectra. The optical properties were studied through absorption, luminescence spectra and decay curves. Absorption spectra were used to calculate the bonding parameter (δ) and Judd-Ofelt intensity parameters (Ω2,4,6). The JO parameters and emission spectra have been used to estimate radiative properties such as transition probability (AR), branching ratios (βcal, βexp), lifetime (τcal) stimulated emission cross-sections (σλp, 10−22 cm2) and optical gain (σλp × τcal, 10−25 cm2 s) for 5D3→7FJ and 5D4→7FJ (J = 0 ÷ 6) transitions. The dominant interaction mechanism and energy transfer parameters between Tb3+ ions have been found by fitting the decay curves of 5D3 level to the Inokuti-Hirayama model. In addition, the quantum cutting process based on energy transfer between Tb3+ ions has also been studied for K2YF5:Tb3+ crystal.

With the advantages of selectivity, spectral resolution and reduction of interference on account of light scattering, synchronous luminescence spectroscopy (SLS) is successfully applied to analyze complex mixtures with overlapped emission and/or excitation spectra. In fact, it is difficult to clearly distinguish the contributions of various luminescence centers to low-energy band of semiconductor nanocrystals (NCs). Herein, we report the application of SLS method to detect luminescence centers in colloidal Cd0.3Zn0.7S NCs. Their conventional luminescence and synchronous luminescence spectra were comparatively investigated. Differently from conventional luminescence spectrum, the emission peaks at 460 and 515 nm were found using SLS method. They are attributed to the emission transitions related to sulfur and zinc/cadmium vacancies. The obtained results are useful to clarify the nature of luminescence centers as well as relaxation mechanism in CdxZn1-xS NCs.

Alkali-alumino-telluroborate glasses with the different network modifier elements were prepared by melt–quenching method. Absorption, excitation, luminescence spectra as well as decay curves of 5D4 level were measured at room temperature. A phonon side band of 7F6 → 5D4 transition has been obtained from the excitation spectra of Tb3+ ion. The role of modifier ion radius in luminescence enhancement from 5D4 level of Tb3+ ion was discussed in detail. In prepared glasses, multiphonon relaxation rate from 5D3 level to 5D4 is enhanced in the host glasses containing modifier ions with large radius. This is main reason leading to the enhancement of luminescence from 5D4 level of Tb3+ ion in alkali-alumino-telluroborate glasses under excitation at 350 nm. Additionally, the Judd-Ofelt theory was used to estimate the features of ligand field and radiative properties of Tb3+ ion. The calculated results have shown that the 5D4→7F5 transition has potential applications for laser action and optical amplifier.

Glasses doped with rare-earth (RE) ions have attracted considerable interest because of their potential applications in photonic devices, such as phosphors, optical amplifiers, lasers, and memory. The design and preparation of host glasses for doping RE ions are very important for achieving the desired performance in different devices. In this study, we successfully prepared nano-sized SnO2 crystal-precipitated glasses activated with Eu3+ ions that exhibited highly intense fluorescence. We elucidated how the crystallization of SnO2 was controlled and how the intensity of the fluorescence from the Eu3+ ions was enhanced by the SnO2 nanocrystals. After heating the 5SnO2·95SiO2 glass in air, the Sn4+ ions were crystallized to form SnO2 and Eu3+ ions were incorporated in the crystals. The external emission yield of the Eu3+ ions under excitation at 337 nm increased to a highest value of 75% under a content of 0.5 wt% Eu2O3. The precipitation of SnO2 crystals was suppressed as the Eu3+ ion content increased and no SnO2 crystals were precipitated in the glasses containing more than 10 wt% Eu2O3. In addition, after heating in a hydrogen gas atmosphere, the Sn4+ ions in the crystals were reduced to Sn2+, which produced blue-colored emission at a wavelength around 400 nm due to the T1 → S0 transition of the parity-allowed 5s2-type emission center, but no Eu3+ ions were reduced.

A bright yellow light from Yb3+ and Er3+ doped Y2SiO5 upconversion materials in particle and fiber form were prepared by a co-precipitation, and electrospinning method. The morphologies of the prepared samples were investigated through FT-IR, FE-SEM, XRD and Raman measurements. The upconversion properties of the samples are carefully studied based on the absorption, fluorescent and decay time measurements. Under 980 nm excitation, the prepared material shows bright yellow emission. By controlling the concentration of Yb3+ or Er3+ and the excitation laser power, the ratio of red to green emission intensity can be varied to adjust the color tuning properties of the phosphor. The upconversion mechanism, and transition probabilities were elucidated owing to Judd–Ofelt theory. The radiative quantum efficiencies for the red (4F9/2) and green (4S3/2) bands were estimated to be 87% and 55%, respectively. The color coordinates of the system were evaluated as a function of the dopant concentrations and plotted on a standard CIE index diagram. The change of band intensity ratio with dopant concentrations gives a promising potential of the current phosphor for lighting application.

The structural and luminescence properties of chalcogenide semiconductor Ca x Ba 1− x Ga 2 S 4 solid solutions ( x =0.1–0.9) doped with 7 at% of Eu 2+ ions were studied at room temperature. It was found, that the crystal structure of Ca x Ba 1− x Ga 2 S 4 solid solutions varies with the amount of Ca 2+ cations and phase transition from cubic to orthorhombic takes place with increase of x value. Ca x Ba 1− x Ga 2 S 4 :Eu 2+ solid solutions exhibit intense photoluminescence in cyan to yellow spectral region depending on x due to 5d→4f electron–dipole transitions in Eu 2+ ions. The peak position of the emission band shifts from 506 nm for x =0.1 to 555 nm for x =0.9 and the full width at half maximum of the emission band varies from 62 nm to 72 nm depending on the symmetry of the crystal lattice. The PL excitation spectrum of Ca x Ba 1− x Ga 2 S 4 :Eu 2+ covers the range at half maximum from 310 nm to 480 nm for x =0.1 and to 520 nm for x =0.9. It was shown that long-wavelength shift is caused by influence of the growing crystal field strength on Eu 2+ ions.

Controlling valence state of metal ions that are doped in materials has been widely applied for turning optical properties. Even though hydrogen has been proven effective to reduce metal ions because of its strong reducing capability, few comprehensive studies focus on practical applications because of the low diffusion rate of hydrogen in solids and the limited reaction near sample surfaces. Here, we investigated the reactions of hydrogen with Cu

In this work, the structural characteristic and photoluminescence properties of Eu\(^{3 + }\) doped B\(_{2}\)O\(_{3}\)-TeO\(_{2}\) -ZnO-Na\(_{2}\)O glasses were investigated. These glasses were prepared by a melting method in air, combined with thermal annealing at 350\(^{\circ}\)C, 450\(^{\circ}\)C and 550\(^{\circ}\)C for different duration times. The structural analysis results of these glasses revealed the formation of micro-crystals in the annealed host glass. The photoluminescence spectra of Eu\(^{3 + }\) doped in these samples were observed. The local vibration mode around Eu\(^{3 + }\) ions was investigated by the phonon side-band (PSB) associated with \(^{7}\!F_{0}-^{5}D_{2}\) transition of Eu\(^{3+}\). Judd-Ofelt parameters were then evaluated based on photoluminescence spectra and the luminescence intensity ratios of \(^{5}D_{0} \to ^{7}\!F_{J}\) (\(J=2, 4\) and 6) to \(^{5}D_{0} \to ^{7}\!F_{1}\) transition were predicted. The obtained results were then used to calculate \(\Omega _{2},\;\Omega _{4},\; \Omega _{6} \) parameters based on Judd-Ofelt theory. These \(\Omega _{2}\), \(\Omega _{4}\), \(\Omega _{6}\) parameters allow to derive radiative properties of Eu\(^{3 + }\) ions in glass material such as transition probabilities, radiative lifetimes and peak stimulated emission cross-section for the \(^{5}D_{0} \to ^{7}\!F_{J}\) transitions.

KABxTyE (xB2O3+yTeO2 +10K2O+10Al2O3 +0.5Eu2O3) glasses with the variation of B2O3/TeO2 ratios (x/y = 30/50, 40/40 and 50/30) and KABTzEu glasses ((50-z)B2O3+30TeO2+10Al2O3+10K2O + zEu2O3, with z = 0.1, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mol%) were prepared by melt–quenching technique. The structure of glasses was analyzed through X-ray diffraction (XRD) patterns, Fourier-transform infrared spectroscopy (FTIR) and phonon-sideband (PSB) spectra. The Judd-Ofelt (JO) theory was used to estimate the properties of ligand and the radiative parameters of prepared glasses such as lifetime (τcal), effective line width (Δλeff), stimulated emission cross-section (σP), gain bandwidth (σP × Δλeff), optical gain (σP × τcal) and quantum efficiency (η). The influence of B2O3/TeO2 ratio and Eu3+ concentration on structure and optical properties of materials was discussed in detail. Energy transfer process between Eu3+ ions was studied by using Inokuti-Hirayama and Yokota-Tamimoto models. The energy transfer channels between Eu3+ ions were also proposed.

The optical properties of Eu[Formula: see text] ions in tellurite glass ceramics with the chemical composition 50TeO2–29B2O3–10ZnO–10Na2O–1Eu2O3-based precursor glasses were presented. These precursor glasses have been prepared by melt quenching method in air, followed by thermal annealing at 550[Formula: see text]C for 12 h, 24 h and 36 h. After thermal annealing process, the micro–crystals appeared in host tellurite glasses. Judd–Ofelt (JO) parameters were calculated from the photoluminescence (PL) spectral measurements. The [Formula: see text], [Formula: see text] and [Formula: see text] parameters have been used to estimate the radiative properties of Eu[Formula: see text] ions in tellurite glass ceramics such as transition probabilities, branching ratio, radiative lifetimes and stimulated emission cross-section. The results of tellurite glass ceramic have been discussed and compared with the similar studies.

Dy3+-doped K2GdF5 single crystals with 10.0 mol% have been prepared by hydrothermal condition. The spectra are analyzed in term of the Judd?Ofelt theory, the intensity parameters (Xk, k = 2, 4, 6) have been evaluated for Dy3+-doped K2GdF5 sample. The electric (Sed), magnetic (Smd) dipole line strength, radiative (A), and total radiative (AT) transition probabilities, lifetime (sR), branching ratios (bR) for the excited levels of Dy3+ doped K2GdF5 crystals were investigated by using the intensity parameters. In addition, the stimulated emission cross-sections (rkp) and integrated emission cross-section (Rif) have been predicted for the transitions from excited level, 4F9/2, to the 6H15/2, 6H13/2 and 6H11/2 levels. The energy transfer occurs from Gd3+ to Dy3+, resulting in the additional intense excitation UV-narrow bands for the luminescence of the Dy3+ ions. Fil: Do, Phan Van. Water Resources University; Vietnam Fil: Tuyen, Vu Phi. Vietnam Academy of Science and Technology. Institute of Materials Science; Vietnam Fil: Quang, Vu Xuan. Duy Tan University; Vietnam Fil: Thanh, Nguyen Trong. Vietnam Academy of Science and Technology. Institute of Materials Science; Vietnam Fil: Thai Ha, Vu Thi. Vietnam Academy of Science and Technology. Institute of Materials Science; Vietnam Fil: Tuyen, Ho Van . Duy Tan University; Vietnam Fil: Khaidukov, Nicholas M.. Kurnakov Institute of General and Inorganic Chemistry; Rusia Fil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fí­sica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; Argentina Fil: Lee, Yong Ill . Changwon National University. Department of Chemistry; Corea del Sur Fil: Huy, Bui The . Changwon National University. Department of Chemistry; Corea del Sur

Judd–Ofelt parameters of Eu 3+ -doped alkali and earth alkali fluoro-aluminoborate glasses are determined from the fluorescence spectra. The dependence of these parameters on the compositional changes of the materials is discussed. The glass containing sulphate component shows the larger values of Ω compared with the fluoro-aluminoborate glasses because of higher Δ CT (Eu 3+ –F − ) values. The difference of ionic radius and electronegativity between Na and Ca lead to higher Ω 2 parameter of CaF 2 –Al 2 O 3 –B 2 O 3 :Eu 3+ glass. Persistent spectral hole burning has been observed in Eu 3+ ions doped alkali-and earth alkali fluoro-aluminoborate glasses with the compositions of 16NaF·73B 2 O 3 ·8Al 2 O 3 ·3Eu 2 O 3 and 16CaF 2 ·73B 2 O 3 ·8Al 2 O 3 ·3Eu 2 O 3 , which have been prepared using conventional melting technique.

K2YF5 crystals doped Sm3+ ions were synthesized under hydrothermal condition. The absorption, luminescence spectra, and lifetimes of K2YF5:Sm3+ were measured at room temperature. The results were analyzed using Judd–Ofelt (JO) theory giving the values of three Ω2, Ω4, and Ω6 intensity parameters. Using these JO parameters as well as from the emission, various radiative parameters such as transition probabilities (AR), radiative lifetime (ιR), calculated branching ratios (βR), measured branching ratios (βmes), and stimulated emission cross-sections (σλp) have been calculated for 4G5/2 excited level.

Optically stimulated luminescence (OSL) properties of K2YF5 crystals singly doped with different concentrations of Tb3+ ions and doubly doped with Tb3+ and Ce3+ or Tb3+ and Dy3+ have been investigated for the first time. Radioluminescence spectra and OSL efficiency for stimulation with different wavelengths of light have been analyzed for each compound. Also, dosimetric characteristics of the most efficient composition, namely K2YF5:1 at.% Tb3+, have been studied. Finally, the OSL signal peculiarities for K2YF5:1 at.% Tb3+ have been compared to those of a commercial Al2O3:C dosimeter.

The structure of the radioluminescent (RL) spectrum of Li 2 B 4 O 7 :Cu crystal is complex, having no normal Gauss peaks. The RL spectrum recorded showed one sharp and strong peak near 365 nm. For the purpose of explaining this phenomenon, we used the self-trapped exciton (STE) model to analyze experimental data of absorption spectrum, emission spectrum, radioluminescence spectrum and decay-time curves. We found a short lifetime component (of the order of ns) from phosphorous signals of Li 2 B 4 O 7 :Cu. We realized that the short lifetime component related to inherent signal of host lattice and the d–p transitions of Cu + . This result is applicable in the detector system with high time resolution.

The thermoluminescence (TL) properties of isostructural fluoride K2YF5 and K2GdF5 crystals doped with Tb3+ of different concentrations have been studied in the temperature range from 30 to 500 °C after α, β and X-ray irradiation. Strongly different structures of TL glow curves following α or β irradiation have been found for Tb3+ doped K2YF5 for all studied concentrations of Tb3+ whereas for K2GdF5 crystals the different TL curves after α or β irradiation are detected only for heavily doped samples. On the other hand, all the studied materials show similar TL glow curves after β or X-ray irradiation. It has been discovered that K2YF5 doped with 1 at.% Tb3+ has TL radiation sensitivity to β irradiation of the same order as that of the well known TLD-100 (LiF:Mg,Ti) phosphor and much higher sensitivity to α irradiation. The TL mechanism in K2YF5 and K2GdF5 doped with Tb3+ is discussed by taking into account the TL emission spectra from irradiated samples, which are identical to the emission spectra of the Tb3+ ions in these hosts under photo-excitation, and the kinetics parameters obtained with the method of various heating rates.

In this work, we have investigated the influence of doping agents on the luminescence properties of multiply doped Li 2 B 4 O 7 and the temperature lag between TSL materials and the heating element. The results of thermoluminescence studies show that the Ag doping leads to the appearance of a new glow curve peak at 165 °C and the increasing sensitivity of Li 2 B 4 O 7 :Cu,Ag,P is correlated with copper and phosphate concentrations. Under the excitation at 245 nm the emission spectra show maxima at 365 and 450 nm in the ceramic, crystal and glass. The low energy shift in the latter system might be related to the local structural distortion in the glass around Cu + ions.

Nearly lattice-matched ZnS x Se 1-x (0 ≤ x < 0.1) grown heteroepitaxially on (001) GaAs substrates was studied by Raman spectroscopy. We observed clearly Raman scattering on the plasmon-longitudinal optical (LO) phonon coupled mode at the GaAs side of the ZnS x Se 1-x -GaAs interfacial region under suitably polarised exciting light, i.e. light with electric field perpendicular to the [110] crystallographic axis. By the systematical study of Raman scattering on the coupled mode as a function of S substitution we found a clear correlation between the plasmon-LO phonon coupling strength and the lattice match. At the well-matched grown epilayer, ZnS 0.06 Se 0.94 , the Raman scattering on the plasmon-LO phonon coupled mode appears to be strongest.

Temperature dependence of the excitonic and biexcitonic emissions in cubic ZnS single crystals has been studied by photoluminescence technique. We observed the very well-resolved excitonic and biexcitonic emissions from cubic ZnS single crystals with very low excitation density, in the tens-of-milliwatts-per-square-centimetre range. The kinetic energy contribution to the shift with temperature of the biexcitonic emission was determined showing a characteristic difference with the normal shift caused by the temperature-narrowed band gap.

At low temperature, ZnSe emits strongly the near-band-edge luminescence consisting of the excitonic emissions and defect-related ones. However, it was observed that these emission lines are strongly fatigued under ultraviolet irradiation. Based on various experiments, we propose a mechanism of photo-induced traps to explain the photoluminescence fatigue phenomenon. These traps are created or enhanced in ZnSe by irradiation of the ultraviolet light with photon energy much above the band gap energy of cubic ZnSe.

Selected ancient Vietnamese (proto)porcelains and celadons (13–16th centuries) from the Ha Lan (Nam Ð inh), Chu Ðâu (Nam Sach, Hai Duong) and Hop Le (Binh Giang, Hai Duong) ceramic kilns were studied by chemical analysis, macro- and micro-Raman spectroscopy, thermal expansion and differential thermal analysis. Raman spectra of quartz, cristobalite, rutile, mullite, anatase, iron oxide, amphibole and glassy phases were analysed and their evolutions are used to discuss the ancient ceramic technology (raw materials used, firing procedures of the glaze and body, etc.). Structural composition data taken from thermal expansion measurements and Raman spectroscopy are in good agreement. Particular attention is given to the analysis of glaze for the feasible discrimination between original artefacts and modern copies. On the basis of experimental results, the samples made at Chu Ð au can be considered as true porcelains, whereas those made at Hop Le and Ha Lan had evolutions towards porcelain and high-temperature-fired fine faience, respectively. Copyright © 2000 John Wiley & Sons, Ltd.