Doped Zinc Borate Research Articles

The effect of zinc substitution on the optical properties of Sm3+ doped zinc borate glasses

Zinc borate glasses are a relatively well known glass type that can be produced at comparably low temperatures. Variations in both the type and concentration of network modifier atoms induce structural alterations within the glass matrix. If doped with optically active dopants, e.g. rare earth ions, compositional changes also affect the local surrounding of the dopants and consequently their optical properties such as emission peak shape and peak ratio. To investigate the effect of different low field strength network modifier ions in zinc borate glasses two glass series were prepared using the melt quench technique; Sm3+ was used as dopant ion: 50B2O3, xK2O, (49-x)ZnO, 1Sm2O3 (x = 5,10,15, …, 30 mol%) and 50B2O3, 30MO, 19ZnO, 1Sm2O3 (M = Ca, Sr and Ba). It is found that the substitution of ZnO for K2O notably enhances the intensity of the red Sm3+emission. Based on the literature this effect is attributed to a change in symmetry at the rare earth position. Additionally, the effect of network modifier concentrations and the different network modifier types on the Sm3+ absorption spectra is examined, discussed and compared to literature data. Furthermore, the glasses are characterized according to their density, refractive index, molar volume, and oxygen packing density.

Optical Properties of Gd2O3 with Silver doped Zinc Borate Glasses

Glasses with chemical composition ZnO-B2O3-Gd2O3-Ag2O were prepared using melt quenching method. The synthesized glass was characterized using X-ray diffraction method. The densities of these glasses were measured using the Archimedes method, and the corresponding molar volumes were calculated using the corresponding formula. Absorption spectra were recorded using a UV-visible spectrometer. The energy bandgap was investigated using the Tauc’s diagram. The variation of band gap energy in relation to Gd2O3 concentration has been discussed. Study the structure and functional groups of the prepared samples were studied using FTIR spectra. Emission and excitation spectra were recorded using a luminescence spectrometer. Photoluminescence spectra provides stable blue light emission in rich in Gd2+ ions glass, Color coordination has also been decided using CIE chromaticity diagram and showing that blue emission was observed in all samples with slightly different positions.

Network Structure and Luminescent Properties of ZnO-B2O3-Bi2O3-WO3:Eu3+ Glasses.

In this study, we investigated the influence of Bi2O3 and WO3 on both structure and optical properties of 50ZnO:(49 - x)B2O3:1Bi2O3:xWO3; x = 1, 5, 10 glasses doped with 0.5 mol% Eu2O3. IR spectroscopy revealed the presence of trigonal BØ3 units connecting superstructural groups, [BØ2O]- metaborate groups, tetrahedral BØ4- units in superstructural groupings (Ø = bridging oxygen atom), borate triangles with nonbridging oxygen atoms, [WO4]2- tetrahedral, and octahedral WO6 species. Neutron diffraction experimental data were simulated by reverse Monte Carlo modeling. The atomic distances and coordination numbers were established, confirming the short-range order found by IR spectra. The synthesized glasses were characterized by red emission at 612 nm. All findings suggest that Eu3+ doped zinc borate glasses containing both WO3 and Bi2O3 have the potential to serve as a substitute for red phosphor with high color purity.

Spectroscopic features of Tb3+ doped strontium zinc borate glasses for green laser applications

These days green laser is preferred as a flexible tool for welding direct bonded copper plates used in power electronics to improve electrification of automotive industry. As terbium is known for green emission, Tb3+ doped strontium zinc borate glasses are melt quenched. The broad hump in x-ray diffraction spectra revealed the amorphous nature. Structural modifications and stability of glasses was shown from fourier transform infrared spectra and differential thermal analysis traces. The Judd-Ofelt intensity parameters are calculated to realize the ligand environment among Tb3+ ions in host glass. The Tb3+ concentration dependent fluorescence properties in visible region and the non-radiative decay rates of 5D4→7F5 transition due to resonant energy transfer apart from intensity quenching of 5D3→7F5 transition in green region was studied. A strong peak registered at 542 nm for the transition 5D4→7F5 in the green region of emission spectra under the excitation of 378 nm. The radiative properties for the prominent luminescent transitions 4D5→7FJ (J=6,5,4,3) of Tb3+ ions are measured using Judd-Ofelt parameters. The values σe, βR,η (%), life- time decay and CIE co-ordinates for the transition 5D4→7F5 confirms that this transition is appropriate for potential green laser.

Ionic Conductivity and Dielectric Relaxations in Li+ Ions Doped Zinc Borate Glass System

The main objective of this work is to study the role of Li+ ions in the ionic conduction of the zinc borate glass system. In this paper, ionic conduction and dielectric relaxations of (30-x) Li2O-xLi2SO4−50B2O3−20ZnO (where x = 0, 2.5, 5, 7.5 mole%) glass system, coded as LLBZ1, LLBZ2, LLBZ3, and LLBZ4, have been discussed. We have performed ionic conductivity measurements in the frequency and temperature range of 40 Hz to 10 MHz and 443 K–500 K, respectively. Increase in conductivity is mainly due to the rise in the temperature, which leads to thermal activation and helps the mobile modifier ions to migrate easily by crossing the barrier. Further, studied dielectric relaxation using the scaling behavior in terms of stretched exponent (β). Dielectric loss tangent (tan δ) shows inverse behavior with increasing frequency rates.

Gamma, neutron, and heavy charged ion shielding properties of Er3+-doped and Sm3+-doped zinc borate glasses

AbstractThis study aimed to investigate the nuclear radiation shielding properties of erbium (Er)-reinforced and samarium (Sm)-reinforced borate glasses. In the 0.015–15 MeV photon energy range, attenuation coefficients, as well as half-value layer tenth-value layers, and the mean-free path have been calculated. Additionally, effective, and equivalent atomic numbers, effective atomic weight, electron density, and exposure and energy absorption build-up factors were also calculated. To evaluate the overall nuclear radiation attenuation competencies of Er-rich and Sm-rich glasses, effective removal cross-section values for fast neutrons and projected range/mass stopping power values for alpha and proton particles were also determined. The glass sample BZBEr2.0 had the highest linear and mass attenuation coefficients (µandµm), effective conductivity (Ceff), the effective number of electrons (Neff), and effective atomic number (Zeff) values as well as the lowest half-value layer (T1/2), tenth value layers (T1/10), mean free path (λ), exposure build-up factor, and energy absorption build-up factor values.µmvalues were reported as 2.337, 2.556, 2.770, 2.976, 2.108, 2.266, 2.421, 2.569, and 2.714 for BZBEr0.5, BZBEr1.0, BZBEr1.5, BZBEr2.0, BZBSm0.0, BZBSm0.5, BZBSm1.0, BZBSm1.5, and BZBSm2.0 glass samples at 0.06 MeV, respectively. The results showed that Er has a greater effect than Sm regarding the gamma-ray shielding properties of borate glasses. The results of this investigation could be used in further investigations and added to older investigations with the same aim, to aid the scientific community in determining the most appropriate rare-earth additive, to provide adequate shielding properties based on the requirement.

Design, synthesis and mechanism of green afterglow phosphors Zn4B6O13:Mn2+ doped with Ln3+ (Ln = Sm, Yb, Eu) guided by VRBE

In this work, the construction of host referred binding energy (HRBE) diagram and vacuum referred binding energy (VRBE) diagram is described in detail. The energy gap of Zn4B6O13 is calculated by diffuse reflectance spectroscopy and the energy level positions of Eu3+ in VRBE are determined by the charge transfer (CT) band of Zn4B6O13 doped Eu3+ to construct a complete lanthanide ions VRBE diagram. According to the constructed VRBE of Zn4B6O13 system, novel long-afterglow phosphors Zn4B6O13:Mn2+ co-doped with Ln3+ (Ln = Sm, Yb, Eu) is designed and synthesized successfully. The influence of B2O3 contents on the crystal structure and luminescence of the Mn2+ doped zinc borate phosphors were analyzed by XRD and emission spectra. Photoluminescence excitation and emission spectra, persistent luminescence spectra and afterglow decay curve indicate that the doping of lanthanide ions Sm3+ and Yb3+ prolonged the afterglow duration of green emission of Mn2+ effectively. The fitting results of persistent luminescence spectra is consistent with the fast decay process of afterglow decay curve. The energy level depths of Sm3+ and Yb3+ traps obtained by thermoluminescence analysis are 0.49 eV and 1.12 eV respectively, which are in good agreement with the results calculated by VRBE. The energy level position of Sm3+ and Yb3+ below the conduction band (CB) are suitable trap depth, which can store and release electrons continuously. However, that of Eu3+ is too deep to enhance the afterglow. According to the VRBE theory, the mechanism of the electron trap is satisfactorily explained, which is important to the subsequent research of system design and mechanism explanation of lanthanide ions doped long afterglow materials.

Effect of chirp on supercontinuum generation from Barium Zinc Borate glasses

Supercontinuum generation from undoped and rare-earth doped Barium Zinc Borate glass with variation in input chirp of a fs pulse is investigated. With varying chirp, the most intense peak of the supercontinuum (SC) spectrum is observed. The peak shift for rare-earth-doped samples with the negatively chirped pulses was not significant compared to that observed with positively chirped pulses. Comparing the evolution of SCG with varying input pulse chirp suggested a material dependency of supercontinuum generation under chirping.

Carbon dots optimize the luminescence and morphological of Tm3+ doped zinc borate composites for NUV-WLEDs

Rare earth (RE)-doped luminescent materials have shown tremendous potential applications in the optical field. However, it is still a challenge to improve its luminescence properties further. In this study, the Tm3+-doped zinc borate (4ZnO·B2O3·H2O, ZBH) with a flaky-like morphology was successfully prepared by a facile hydrothermal reaction. The photoluminescence (PL) performance of ZBH:Tm3+ is improved through incorporating yellow N-doped carbon dots (yNCDs). Simultaneously, by changing the content of yNCDs in ZBH:Tm3+ host, the morphological evolution from flaky-like to flower-like of the ZBH:Tm3+/yNCDs composite are realized. The ZBH:Tm3+/yNCDs composite with flower-like exhibits the strongest white light emission and splendid thermal stability under 360 nm excitation wavelength, matching the current mainstream near-ultraviolet (NUV) LED chip. Thus, ZBH:Tm3+/yNCDs composite might be a promising luminescent material in the NUV white lighting and display fields. The findings of this study developed a novel idea for improving the luminescent properties of RE-doped materials. Besides, it also solves fluorescence quenching problems of carbon dots in the solid-state illumination field.

In-Silico Monte Carlo Simulation Trials for Investigation of V2O5 Reinforcement Effect on Ternary Zinc Borate Glasses: Nuclear Radiation Shielding Dynamics.

In the current study, promising glass composites based on vanadium pentoxide (V2O5)-doped zinc borate (ZnB) were investigated in terms of their nuclear-radiation-shielding dynamics. The mass and linear attenuation coefficient, half-value layer, mean free path, tenth-value layer, effective atomic number, exposure-buildup factor, and energy-absorption-buildup factor were deeply simulated by using MCNPX code, Phy-X PSD code, and WinXcom to study the validation of ZBV1, ZBV2, ZBV3, and ZBV4 based on (100−x)(0.6ZnO-0.4B2O3)(x)(V2O5) (x = 1, 2, 3, 4 mol%) samples against ionizing radiation. The results showed that attenuation competencies of the studied glasses slightly changed while increasing the V2O5 content from 1 mol% to 4 mol%. The domination of ZnO concentration in the composition compared to B2O3 makes ZnO substitution with V2O5 more dominant, leading to a decrease in density. Since density has a significant role in the attenuation of gamma rays, a negative effect was observed. It can be concluded that the aforementioned substitution can negatively affect the shielding competencies of studied glasses.

Microstructure and microwave dielectric properties of Ni doped zinc borate ceramics for LTCC applications

Abstract A detailed study was performed using the density function theory to research the mechanism of the improvement of the sintering and dielectric properties of Ni2+ substituted Zn3B2O6 ceramic. The mechanism involved bond properties, electron density and formation energy. The synthesis process is based on the solid-state reaction method and characterized via scanning electron microscopy, X-ray energy-dispersive spectroscopy, Raman spectrometry, network analysis, differential thermal analysis and thermo-mechanical analysis. The Zn1 site was the priority to be substituted by Ni2+, and the substitution happened in all the Zn tetrahedrons. The activation energy and densification window decreased slightly, and the sintering property was modified. The bond property and electron distribution around the tetrahedron with Ni2+ changed, and densification level and dielectric performance of the ZBO ceramic improved (er = 6.9, Q×f = 91,000 GHz at 15 GHz, τf = −55.6 ppm/°C with high relative density (97.1%) at 900 °C).

Influence of Ag nano particles on spectroscopic and luminescence properties of Dy3+ doped borate glasses

Dy3+ doped lithium zinc borate glasses with silver (Ag) nanoparticles (NPs) were synthesized by the conventional melt quenching method. Impact of silver NPs on the luminescence properties of 59B2O3: 20ZnO: 10Na2O: 10Li2O: 0.5SnO: 0.5Dy2O3 glasses doped with Dy3+ions were investigated. Ag+ ions have been reduced and nucleated to AgNPs by thermochemical redox method. Amorphous characteristics of the glasses were confirmed by XRD measurements. Raman and Fourier transform infrared spectra were used to estimate structural and vibrational bands of the glass samples. Localized surface plasmon resonance (LSPR) band is observed at 419 nm for 0.3 mol% of Ag along with three absorption bands of dysprosium were observed. Luminescence studies were performed on these glasses and found that three emission bands at 484, 575, and 665 nm when excited with wavelength of 349 nm, which corresponds to 4F9/2 to 6H15/2, 4F9/2 to 6H13/2, and 4F9/2 to 6H11/2 transitions of Dy3+ ions.

Structural, physical and radiation attenuation properties of tungsten doped zinc borate glasses

For the x WO3 (40 – x) ZnO 50B2O3 10K2O, (0 ≤ x ≤ 20 wt%) glass system. optical, structure, gamma and neutron radiation shielding aspects were examined comprehensively. The mass attenuation coefficients of gamma-rays, the mean free photon path (MFP), and the effective atomic number (Zeff) have been determined experimentally at photon energies 238, 662,911, 1173, 1332 and 2614 keV. The results obtained were compared with the corresponding theoretical data, which were found to be dependent on glass components and energy. Moreover, the calculated ƩR shows that increasing the removal cross section increases with increasing the WO3 concentration. The molar volume of the glasses has been derived from density measurements and studied as a function of composition. FTIR spectral results revealed that the glass network matrix is sequentially formed by BO3, BO4, ZnO4, WO4 and WO6 structural groups. The optical transmission was done on these glasses and the absorbance was increased as WO3 increased. Moreover, the peak shifted to a longer wavelength as WO3 increased and a decreasing behavior of the bandgap. The obtained results have been analyzed in the light of various oxidation states of tungsten ions in the glass matrix. All results pointed out that these glasses have potential applications in radiation shielding.

Physical, Mechanical and Structural Properties of Yttrium Oxide Doped Zinc Borate Glasses

In this project, the nominal glass composition with the form of (55-x) H3BO3-45ZnO-xY2O3 (x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) are synthesized by melt quenching techniques. The effect of Y2O3 on physical, mechanical and structural properties of glasses have been investigated using different characterization techniques. The parameters like density, molar volume and oxygen packing density have been calculated. Based on the micro hardness study, it has showed the decreasing trend from 518.80 N.mm-2 to 453.13 N.mm-2 with an increasing of Y2O3 content from 0.0 mol% to 2.5 mol%. The structural features of the yttrium oxide doped zinc borate glass were studied via X-Ray Diffraction (XRD) to confirm the amorphous nature of glass and Fourier Transforms Infrared Spectroscopy (FTIR) has been done to obtain the band positions and functional groups. FTIR spectral studies were recorded in the 400-4000 cm-1 wavenumber range at room temperature.

Synthesis and Optical, Thermal, Structural Investigation of Zinc-Borate Glasses Containing V2O5

Vanadium pentaoxide (V 2 O 5 ) doped zinc borate (ZnB) oxide glasses that could be used in fiber optic cable cores in optoelectronics, in laser crystals in solar energy systems have been synthesized successfully. Structural characters of synthesized glasses were determined with differential scanning calorimeter (DSC) and Fourier-Transform infrared spectroscopy (FTIR). Glass transition (T g ), crystallization (T c ) and melting temperatures (T m ), and thermal stabilities ($\Delta$T) of the glasses were determined and also their association with the change in V 2 O 5 was explained. Structural units of boron and zinc that form the structure were determined according to FTIR data. As a result, it was determined that boron formed the glass matrix with BO 3 , BO 4 and boroxol ring structural units; on the other hand, zinc contributed to the glass matrix with tetrahedral ZnO 4 and octahedral ZnO 6 structural units, and vanadium usually had modifier role in the structure with its VO 4 and VO 5 structural units. V 2 O 5 ’s presence in the structure with increasing amount changes thermal, structural and physical properties. Among the properties that significantly change, the most important one is optical properties. Indirect optical band gaps, Urbach energies, refractive index values of these synthesized samples were determined, and quite clear shifts towards red region were observed in the transmittance and absorption spectra. Optical band gap decreased to 1.24 eV from 2.55 eV with increasing amount of V 2 O 5 ; on the other hand, Urbach energy was determined to increase to 0.630 eV from 0.246 eV. Densities, molar volumes of these synthesized glasses were also examined and commented on.

Optoelektronik Uygulamalar için Nb+5 Katkılı Çinko Borat Camların Sentezi ve Optik, Termal ve Yapısal Özelliklerinin Belirlenmesi

Bu çalışmada niyobyum pentaoksit (Nb2O5) katkılı yüksek oranda çinko oksit (ZnO) içeren çinko borat (ZnB) oksit camlar yüksek sıcaklıkta eritme tavlama yöntemi ile başarıyla sentezlenmiştir. Sentezlenen camlara ait yapısal karakterler diferansiyel taramalı kalorimetre (DSC) ve Fourier dönüşümlü kızılötesi spektroskopisi (FTIR) ile belirlenmiştir. DSC verilerine göre camsı geçiş (Tg), kristallenme (Tc), erime (Tm) sıcaklıkları ve termal kararlılıklar (T) belirlenerek Nb2O5 değişimiyle ilgisi açıklanmıştır. DSC verilerine göre Tg, Nb2O5 konsantrasyonunun artışıyla 560oC’den 555oC’ye; Tc, 681oC’den 657oC’ye düşmüştür. Sentezlenen cam numunelerin termal kararlılığı ise Nb2O5 artışıyla 121oC’den 102oC’ye düşmüştür. FTIR verilerine göre borun ve çinkonun yapısal birimleri açıklanmıştır. Borun cam matrisini BO3, BO4 ve borok-sol halka yapısal birimleriyle oluşturduğu, çinkonun ise cam matrisine tetrahedral ZnO4 ve oktahedral ZnO6 yapısal birimleri ile katkıda bulunduğu, niobyumun yapıda düzenleyici görev üstlendiği belirlenmiş-tir. Verilerin değerlendirilmesi sonucunda niyobyumun cam ağında oktahedral NbO6 biriminde bulunduğu gözlenmiştir. Nb2O5’in en belirgin biçimde değiştirdiği özelliklerin başında optik özellikler gelmektedir. Direkt ve indirekt optik bant aralığı, Urbach enerjisi, kırılma indisi üzerinde çalışılmış, geçirgenlik spekt-rumda çok net olmayan kaymalar gözlenmiştir. Optik bant aralığı Nb2O5 artışıyla azaldığı, Urbach enerjisi-nin arttığı belirlenmiştir. Sentezlenen numunelere ait yoğunluk, molar hacim ayrıca incelenmiş ve Nb2O5 konsantrasyonundaki artışın yoğunluk ve molar hacim değerlerini belirgin bir biçimde arttırdığı görülmüştür.

Electrical conductivity studies on LiCl doped zinc borate glasses

Abstract Lithium ion conducting ternary glass system xLiCl-(100-x)[0.68B2O3:0.32ZnO] with 25≥x≥5 mol% is prepared by microwave heating method. The ion conductivity is analysed using single power law proposed by Almond-West. The electrical conductivity is studied in the temperature range of 300-400 K and over a frequency range of 100 Hz-10MHz. Cole-Cole plots of these glasses showed and semicircle with spur indicating that single transport mechanism is operating. DC conductivities follow Arrhenius law and increases with increasing LiCl content. While the DC activation barrier calculated from linear least square fit show a step-wise decrement with increasing LiCl content. The observed increase in σdc and decrease in Edc with LiCl mol% is attributed to the enhanced Li+ ion content and opening of network structure caused due to the occupation Cl- ions around Li+ ions. A.C. activation barrier and frequency independent d.c. conductivity are comparable with those obtained in temperature dependent conductivities. Concentration of Li+ ions and structural degradation play a pivotal role in the ion transport in disordered systems

Cathodoluminescence and thermoluminescence of ZnB2O4:Eu3+ phosphors prepared via wet-chemical synthesis

In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements (XRD) and they were well consistent with PDF card No. 39-1126, indicating the formation of pure phase. The thermoluminescence (TL) behaviors of Eu activated ZnB2O4 host lattice are studied for various beta doses ranging from 0.1 to 10 Gy. The high-temperature peak of Eu activated sample located at 192 °C exhibited a linear dose response in the range of 0.1–10 Gy. Initial rise (IR) and peak shape (PS) methods were used to determine the activation energies of the trapping centres. The effects of the variable heating rate on TL behaviour of Eu activated ZnB2O4 were also studied. When excited using an electron beam induced light emission (i.e cathodoluminescence, CL) at room temperature (RT), the as-prepared phosphors generate reddish-orange color due to predominant emission peaks of Eu3+ ions located at 576–710 nm assigned to the 5D0→7FJ (J=1,2,3, and 4) transitions. The maximum CL intensity for Eu3+ ions at 614 nm with transition 5D0→7F2 was reached Eu3+ concentration of 5 mol%; quenching occurred at higher concentrations. Strong emission peak for Eu3+ ions at 614 nm with transition 5D0→7F2 is observed. The CL experimental data indicate that ZnB2O4:Eu3+ phosphor as an orange-red emitting phosphor may be promising luminescence materials for the optoelectronic applications.

Thermoluminescence dose and heating rate dependence and kinetic analysis of ZnB 2 O 4 :0.05Dy 3+ phosphor

Abstract The intention of this study is to explore the thermoluminescence (TL) behavior of beta irradiated 5% Dy3+ doped zinc borate (Zn(BO2)2:0.05Dy3+) phosphor prepared using the nitric acid method. The TL glow curve corresponding from 1 Gy to 80 Gy beta irradiation (preheated at 140 °C) shows a maxima at c.a. 180 °C. The dependence of heating rate was tested and found out that thermal quenching effect was dominating on TL glow curves as the heating rate increases. The dose response of the phosphor material exposed to beta radiation was investigated. Deconvolution was applied using the peak fit method on the glow curve for optimized conditions. Also peak shape (PS), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) methods were used to evaluate the trapping level parameters, namely trap depth (E), frequency factor (s) and order of kinetics (b) associated with the main glow curve in Zn(BO2)2:0.05Dy3+ phosphor after beta irradiation of 20 Gy. The values of trap depth corresponding with the TL glow peak at 180 °C were found to be 0.93 eV, 0.92 ± 0.05 and 1.05 ± 0.02 respectively. Furthermore W and c parameters characterizing thermal quenching based on the Mott-Seitz theory were determined as 0.31 ± 0.04 eV and 162.55. The TL mechanism appears more likely to get second order kinetics, suggesting the probability of re-trapping of charge carriers by emptied traps.

Investigation of Er doped zinc borate glasses by low-temperature photoluminescence

Er3+ doped (95-x)B2O3-xZnO-5TiO2 (x = 45, 50 and 55mol%) bulk glasses were prepared by conventional melt quenching method and investigated by transmission and photoluminescence (PL) spectroscopy. Transmission spectra exhibit sharp absorption bands at 364, 377, 406, 441, 448, 488, 521, 541, 651, 792, 974, and 1530nm, that correspond to absorption on Er3+ ions and they are attributed to the optical transitions from the ground state 4I15/2 to the excited states 4G9/2, 4G11/2,4F9/2, 4F3/2, 4F5/2, 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2, 4I11/2 and 4I13/2, respectively. The optical gap has been estimated around 3.5eV with a tendency to increase with increasing ZnO content. Low-temperature PL properties of the Er3+ doped glasses and of the host glass itself were investigated. To achieve this goal, two different wavelengths (325 and 514.5nm) were used for PL excitation. PL spectra excited by He-Cd laser at 325nm were dominated by the host glass broad-band luminescence centred at around 570nm. Simultaneously we observed narrow emission and absorption features due to 4f-4f electronic transitions in Er3+ ions superposed on the broad band host glass luminescence. We argue that these superposed narrow absorption dips represent a direct evidence of the energy transfer from the electronic structure of the host to 4f states of Er3+ ions. Fine structure of Er3+ emission bands at 980 and 1530nm, corresponding to radiative transitions from the two lowest excited states of Er3+ ions to the ground state manifold have been investigated at room temperature and at 4K, and a schematic energy diagram of Stark levels of 4I11/2, 4I13/2 and 4I15/2 manifolds has been deduced.