Synthesis and characterization of lithium niobium borate glasses containing neodymium

A series of(90–x)Li_2B_4O_7-10Nb_2O_5-xNd_2O_3 glass samples(x=0, 5 mol.%, 10 mol.%, 15 mol.%, 20 mol.% and 25 mol.%) were synthesized using melt quenching technique. X-ray diffraction(XRD), differential thermal analyzer(DTA), Fourier transformed infrared(FTIR), ultraviolet-visible-near-infrared(UV-Vis-NIR) spectrometer and photoluminescence(PL) spectroscopic characterizations were made to examine the influence of Nd3+ concentration on the physical, structural and optical properties. Various physical properties such as glasses density, molar volume, thermal stability, ion concentration, polar on radius, inter-nuclear distance, field strength, cut-off wavelength, energy band gap and Urbach energy were calculated. The samples were amorphous in nature and confirmed from XRD pattern. The FTIR spectra revealed the presence of BO_3 and BO_4 functional groups. UV-Vis-NIR spectra exhibited nine prominent bands centered at 353, 430, 475, 524, 583, 681, 745, 803, 875 nm corresponding to the transitions from the ground state to ~4D_(3/2), ~2P_(1/2), ~2G_(9/2), ~4G_(7/2), ~4G_(5/2), ~4F_(9/2), ~4F_(7/2), ~4F_(5/2), ~4F_(3/2) excited states, respectively. Moreover, the emission spectra at 355 nm excitation displayed three peaks centered at 903 nm(~4F_(3/2)→~4I_(9/2)), 1059 nm(~4F_(3/2)→~4I_(11/2)) and 1333 nm(~4F_(3/2)→~4I_(13/2)), respectively. Fluorescence lifetime was recorded between 53.69 to 28.43 μs. It was found that varying concentration of Nd~(3+) ions strongly affected the physical, structural and optical properties of the glass samples.     

Electrochemical response of Nd~(3+) ions containing lithium borate glasses

The present investigation was to understand the electrical properties of 27.5 Li_2O-(72.5–x) B_2O_(3-x)Nd_2O_3 with x=0.5, 1, 1.5 and 2 glasses. We analyzed the impedance data for a wide frequency range to get inside the conduction phenomenon. The conductivity of the glasses decreased due to the decrease in the mobility of mobile Li~+ ions. This decrease was due to polymerization of glass network caused by the Nd~(3+) ions. Modulus formalism confirmed that the Li~+ ions overcame the same barrier no matter whether it took part in the conduction process or relaxation process. Scaling of the electrochemical data showed that conduction process in the ion conducting glasses was composition dependent and not the temperature dependent.     

Effect of Nd~(3+) on spectroscopic properties of lithium borate glasses

The spectroscopic properties of lithium borate glasses as a function of Nd3＋ ions concentration were reported.Optical absorption spectra of these glasses showed a number of absorption bands in ultra violet and visible region.Optical absorption edge was found to shift towards the longer wavelength（red shift） with increase in Nd2O3.Luminescence spectra revealed three major bands at 902, 1063 and 1334 nm which was due to 4F3/2→4I9/2, 11/2 ＆13/2 transitions of Nd3＋ ions.Luminescence intensity was maximum for 1 mol.% Nd2O3 and further increase in Nd2O3 resulted in luminescence quenching.The luminescence quenching behavior at higher concentration of Nd2O3 was attributed to the Nd3＋-Nd3＋ interaction in the glass matrix.An absorption and emission property of these glasses suggested that these glasses could be useful for 1.06 μm infrared laser applications.     

Electrical and optical properties of lithium borate glasses doped with Nd2O3

Glass series with general formula 25Li2O-(75-x)B2O3-xNd2O3 was prepared by conventional melt quench technique. Electrical and optical characterizations of these glasses were carried out. It was observed that conductivity of glasses decreased and activation energy increased with the addition of Nd2O3. The density and refractive index of the glasses increased while optical band gap and radiation length decreased due to structural changes.     

Electrochemical behavior of Ca-based bulk metallic glasses

Since 2002, numerous Ca-based bulk metallic glass (BMG) alloys have been discovered. These BMG alloys are of interest because of their low densities and costs; however, few studies have examined the properties of these novel materials. In this study, the thermophysical and electrochemical behavior of three Ca-based BMGs was examined and compared to a crystalline, Mg-based alloy. Cyclic-anodic polarization tests were conducted in a 0.05 M Na₂SO₄ electrolyte, and posttest analyses by scanning electron microscopy were conducted to assess the damage to the exposed surfaces.     

Physical,structural and optical studies on magnesium borate glasses doped with dysprosium ion

Intense visible emissions from dysprosium(Dy3+) ions doped glasses became prospective for diverse technological applications. In this paper, physical, optical and structural properties of magnesium borate glasses doped with varied concentrations of Dy_2 O_3 were examined. Such glasses were synthesised by melt quenching method and characterized at room temperature using several analytical techniques.Luminescence and absorption spectra(in the visible region) of as-quenched samples were used to evaluate the physical and optical properties. XRD pattern confims the amorphous state of as-quenched samples. The Fourier transform infrared(FTIR) spectra of glasses reveal various bonding vibrations assigned to different functional groups. UV-vis-NIR spectra disclose eight absorption bands accompanied by a band for hypersensitive transition positioned at 1260 nm(~6 H_(15/2)→~6 F_(11/2)). The values of direct and indirect optical energy band gap of the studied glasses are decreased with the increase of Dy~(3+) ion contents. The photoluminescence spectra of all glasses under the excitation of 380 nm display two prominent emission bands centred at 497 nm(~4 F_(9/2)→~6 H_(15/2), blue) and 587 nm(~4 F_(9/2) →~6 H_(13/2), green).The achieved intense luminescence from the proposed glass composition may be beneficial for solidstate laser applications.     

Optical properties of Eu2+-doped strontium borate glasses containing F- and Li+ ions

In this experiment, strontium borate glasses were prepared using the conventional quenching method in air atmosphere. Optical absorption, photoluminescence excitation and emission spectra, X-ray excited luminescence (XEL), and luminescence decay curve of the as-prepared glasses were investigated at room temperature. The as-prepared glasses had two kinds of Eu ions, i.e., Eu2 and Eu3 . Compared with the reported results of strontium borate glasses, Eu2 luminescence was enhanced in the studied strontium borate glasses coprepared with F- and Li ions. The coexisting of Li or F- in the borate glasses could create more negative defect VSr″ and stabilize Eu2 ions, which might act as donor of electrons;For the F- doping, the new center of B(O, F)4 (or BO3F) and BO2F2 units could be considered to be the distorted (BO4), which were needed as a rigid framework to stabilize the divalent rare earth ions.