Doped Sodium Borate Research Articles

Photochromic 3D Optical Storage: Laser‐Induced Regulation of Localized Optical Basicity of Glass

Abstract3D optical storage, spatially expanding storage capacity, is regarded as an effective and economical way to break the diffraction limit of the conventional 2D optical storage. In this study, a new kind of 3D optical storage medium, i.e., vanadium ions (V5+) doped sodium borate glass, is developed, showing intriguing spatially‐selected photochromism (PC) upon laser driven excitation. Significantly, a brand‐new PC mechanism of V5+‐aggregation regulated by localized optical basicity (OB) of glass is proposed and demonstrated. The developed PC glass is responsive to a low‐price desktop‐level mini‐laser to encode optical information, yields unique twofold decoding modes in bright‐ and dark‐fields, and shows good data erasibility. 3D volumetric optical storage with a memory density of ≈480 Mbit cm−3 is realized with the aid of an advanced femtosecond laser micro‐machining system. The findings suggest a novel design approach to fabricate 3D PC glass in terms of manipulating the scale of optical basicity in glass, hopefully stimulating the development of new multi‐dimensional PC optical storage media.

Silver nanoparticles improved infrared photoluminescence of Nd3+ doped sodium borate glasses

Method of melting and quenching was used to prepare the alkali borate–based glasses embedded with Nd3+ ions and silver nanoparticles (Ag NPs). In the as–prepared glass, silver NPs were formed by loading the thermal reducing agent such as antimony trioxide in the composition. The optical absorption and microscopic outcomes confirmed the growth of silver NPs in the prepared glass system. The prepared glass was annealed at 450 °C for 0, 5, 10, 15, and 25 hrs to tune the spectroscopic and photoluminescence features of Nd3+ ions loaded in the glass. The photoluminescence intensity and related features were enhanced continuously with heat treatment schedule. However, subsequently the features were reduced at longer schedule. The variation of these features was ascribed to the local field–generated silver NPs. The results revealed that the entitled glass could be utilized for photonic and optoelectronic applications when activated with Nd3+ ions and routed with Ag NPs.

Effect of Gamma Irradiation on Structural and Optical Properties of Zirconium Incorporated Sodium Borate Glasses

ABSTRACT The effects of gamma irradiation in the dose rate of 25 kGy on the structural and optical properties of ZrO2 doped sodium borate glasses were studied. Glassy nature confirmed by XRD and all the physical parameters were calculated. IR spectra revealed the characteristic vibrational and stretching bands due to trigonal and tetrahedral borate network. Slight changes were caused by gamma irradiation in the intensities of the characteristic infrared borate bands and zirconium bands. Irradiated samples developed a noticeable absorption band similar to the F-band familiar in alkali halide crystals which clearly indicated that successive irradiation produced defects in the glass material. Substitution of ZrO2 to the glass matrix suppressed the formation of visible absorption band formed by irradiation whereas no extra peak was observed in the spectral regions. A nonlinear trend was ascribed in the energy band gap values due to the creation of more number of non-bridging oxygen atoms. Emission spectra showed five emission bands corresponding to the zirconium ions which decreased to a very low intensity with a red shift after irradiation. Matching the colour co-ordinates bright blue emission was found for 5 mol% ZrO2 in both irradiated and non irradiated sample.

Formation of samarium(II) in synthetic sborgite prepared in air at low temperature

A mixture of boric acid combined with trivalent samarium doped sodium borate was fired in air at 450 °C. The addition of water to the hot residue resulted in the generation of a product in which the incorporated samarium has been reduced from the trivalent form to the divalent state as identified by emission spectroscopy. This product has been identified as a synthetic form of the mineral sborgite. The divalent samarium emission appears to result from the samarium ion occupying a boron site in the material.

Spectroscopic Inquiry of the Fe2O3-role in Binary Sodium Borate, Sodium Silicate and Sodium Phosphate Glasses and Effects of Gamma Irradiation

Optical absorption spectral investigations have been carried out on Fe3+ ions doped sodium borate, sodium silicate and sodium phosphate glasses before and after gamma irradiation. The UV-visible absorption spectrum exhibits bands characteristic of Fe3+ ions coordination in each system. Interesting aspects of FT-IR spectra were found, and this gives information about the structure changes in the constituent units of these glass systems as a function of Fe2O3 concentration. All glasses reveal characteristic absorption bands due to the addition of different ratios of iron which explain the state of iron in each system in terms of its valence and coordination number. Results indicate that iron favors a higher oxidation state (tetrahedral coordination) in the case of sodium silicate glasses. The doping with progressive Fe2O3 additions (0.5−7.5 %) has some effect on the number and position of the characteristic bands due to formation of FeO4 groups. The IR absorption spectra after irradiation reveal limited changes in the intensity which can be correlated with minor changes in bond angles and /or bond lengths within the structural units by irradiation.

Structural and optical properties of lithium sodium borate glasses doped with Sm3+ ions

Absorption and emission spectra of Sm 3+ doped lithium sodium borate (LNB) have been reported. The samples were prepared by the melt-quenching technique and characterized by X-ray diffraction (XRD), diffraction thermal analysis (DTA), Fourier transforms infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). From the thermo-grams spectrum, glass transition (Tg), crystallization (Tc) and melting temperatures (Tm) have been evaluated. Direct and indirect optical band gaps have been calculated based on the glasses UV absorption spectra. These glasses have shown strong nine absorption bands with hypersensitive transition at 1221 nm (6 H 5/2→4 H 3/2) and five emission bands for the transition at 4 I 7/2→6 H 13/2 (green color), 4 I 7/2→6 H 7/2 (orange color), 4 I 7/2→6 H 9/2 (orange color), 4 I 7/2→6 H 11/2 (red color) and 4 I 7/2→6 H 13/2 (red color) with performing an excitation of 400 nm. The oscillator strengths, refractive index, ions concentration, polaron radius and other parameters have been calculated for each dopant.

Contribution of Eu ions on the precipitation of silver nanoparticles in Ag-Eu co-doped borate glasses

Ag+ doped sodium borate glasses with different Eu ions concentration were prepared by the melt-quenching method. The absorption at about 410nm which was caused by the surface plasmon resonance (SPR) of Ag nanoparticles (NPs) is promoted with increasing of Eu ions concentration. Meanwhile, the luminescent spectra showed that the emission intensity of Ag+ decreased while that of the Ag aggregates increased simultaneously. The results indicated that the Ag ions intend to form the high-polymeric state such as Ag aggregates and nanoparticles with increasing of europium ions. Owing to the self-reduction of Eu3+ to Eu2+ in our glass system, it revealed that Ag+ has been reduced by the neighboring Eu2+ which leads to the formation of Ag aggregates and the precipitation of Ag NPs in the matrix. In addition, energy transfer (ET) process from Ag+/Ag aggregates to the Eu3+ was investigated for the enhancement of Eu3+ luminescence.

Optical Characterization of Erbium Doped Sodium Borate Glass

Borate glass has been identified as one of the potential host for optical application. In this work, a serie of borate glass of the system (80-x) B203 –10Na2O- 10ZnO- x Er2O3 (x= 0.5 -1.5 mol %) has been prepared by melt quenched technique. Their optical properties by mean of the UV-VIS-IR and photoluminescence have been identified. From the result, there are 5 significant absorption peaks that corresponds to 487 nm, 750 nm, 820 nm,894 nm and 979 nm wavelength have been observed. Meanwhile there are six significant emission peaks have been observed which corresponds to 401 nm, 434 nm, 481.5 nm, 526 nm, 556 nm and 700 nm wavelength. Thus, from the photoluminescence results, the green, yellow and red spectrum can be expected. Some other results will be analysed and discussed.

Synthesis and Optical Characterization of Silver Doped Sodium Borate Glasses

Silver doped sodium borate glasses prepared by melt-quenching technique were checked by XRD technique for their amorphous nature. It is observed that the molar volume increases with increasing Ag2O content leading to open struc- ture. Fourier Transform Infrared spectroscopy (FTIR) reveals the formation of BO3 and BO4 groups upon addition of silver oxide as modifier. From the Ultraviolet-Visible (UV-VIS) absorption spectra it is seen that the optical band gap increases with the increase of Ag2O content. Urbach energy is observed between 0.55 - 0.77 eV. The results obtained from molar volume, Fourier Transform Infrared spectroscopy and band gap energy measurements are in agreement with each other and nearly give the similar information about the studied glasses.

Structural, optical absorption and luminescence properties of Nd3+ ions in NaO-NaF borate glasses

Abstract Structural and spectroscopic properties of neodymium doped sodium borate and fluoroborate glasses of composition (in mol%) (99 − X) B2O3 + XNa2O + 1Nd2O3, X = 49.5, 39.5 and 29.5 and 49.5B2O3 + XNa2O + (49.5 − X) NaF + 1Nd2O3, X = 0 and 24.75 have been investigated using XRD, FTIR, absorption and emission spectra and decay curve. The XRD of the glasses confirm their glassy nature and the FTIR spectra reveal the presence of BO3 and BO4 units along with the strong OH− groups in the glasses. The UV–vis-NIR absorption spectra were used to calculate the bonding parameters ( β ¯ and δ), to identify the ionic/covalent nature of the glasses. The spectral intensities have been calculated by using Judd–Ofelt analysis and inturn used to estimate radiative properties such as radiative transition probabilities, radiative lifetimes, branching ratios, peak stimulated emission cross-sections. Branching ratios and stimulated emission cross-sections show that the 4F3/2 → 4I11/2 transition of the glasses under investigation has the strong emission around 1060 nm. The decay from the 4F3/2 level of Nd3+ ions is found to be single exponential. Multiphonon relaxation and quenching due to OH− groups play a governing role in the luminescence quenching of 4F3/2 level of Nd3+ ions in the titled glasses. The results obtained are compared with reports on similar glasses.

Composition dependent structural and optical properties of Sm 3+-doped sodium borate and sodium fluoroborate glasses

Sodium borate and fluoroborate glasses doped with trivalent samarium (Sm 3+) were prepared and their detailed spectroscopic analysis was carried out. The FTIR spectra reveal that, the glasses contain BO 3, BO 4, non-bridging oxygen and strong OH − bonds. From the optical absorption spectra, Judd–Ofelt intensity parameters ( Ω λ , λ=2, 4 and 6) have been evaluated and are in turn used to predict radiative properties such as radiative transition probability ( A), stimulated emission cross section ( σ P E ) and branching ratios ( β R) for the excited levels of Sm 3+ ions in sodium borate and sodium fluoroborate glasses. The dependence of the spectral characteristics of Sm 3+ ions due to compositional changes have been examined and reported. The value is found to decrease with the decrease in the sodium content in the glass. The decay from the 4G 5/2 level is found to be non-exponential indicating a cross-relaxation among the Sm 3+ ions.

Optical properties and ultrafast optical nonlinearity of Yb3+ doped sodium borate and bismuthate glasses

In this paper, we report the optical and ultrafast nonlinear optical properties of Yb3+ doped sodium borate and bismuthate glasses. The glasses have been prepared through the melt quench technique. Optical absorption measurements show compositional dependent absorption spectrum of Yb3+, which is due to the higher crystal field induced by Bi3+ ions. Local structure of the glasses has been identified by using Fourier transform infrared and Raman studies. From open aperture z-scan measurements done by using 100 fs laser pulses, the ultrafast optical nonlinearity in these materials is calculated at the nonresonant excitation wavelength of 800 nm. The measured three-photon absorption originates from the glass host, with contributions from the nonbridging oxygens and the nonlinear electronic polarization of the Bi3+ ions.

Spectral diffusion broadening by soft local modes in Sm 2+-doped sodium borate glass

An explanation for the anomalous temperature broadening of zero-phonon transition corresponding to 7F 0↔ 5D 0 electronic transition in Sm 2+–doped sodium borate glasses is given. The main broadening mechanism is spectral diffusion induced by thermal fluctuation of long-living soft localized modes over the whole studied temperature region 5–293 K.

Temperature and pressure dependence of the homogeneous width of 7F 0– 5D 0 electronic transition in Sm 2+-doped sodium borate glass

The homogeneous width Γ h of 7F 0↔ 5D 0 transition in Sm 2+ ions doped into sodium borate glass was determined at T=5–293 K under P=1 bar and at T=5, 80 and 120 K under various P up to 8 kbar. The line width Γ h was obtained from spectral hole burning (SHB) and time-resolved resonant fluorescence line narrowing (FLN) experiments. It was found that at P=1 bar the T-dependence of Γ h changes from Γ h( T)∝ T 2 (quadratic) for T<20 K to Γ h( T)∝ T (linear) for T>20 K. Under pressure, Γ h grows slightly at all three T values studied (at 80 K by 1.2%/kbar and at 120 K by 1.6%/kbar in the range 0–8 kbar). Possible mechanisms to explain the observed T- and P-dependences of Γ h are briefly discussed.

Optical hole burning studies in europium doped oxide glasses

Europium doped sodium borate, silicate, borosilicate, germanate and tellurite glasses have been prepared by melt quenching technique. Optical spectroscopy techniques were used to characterize the divalent and trivalent ions. Optical hole burning technique was used to characterize rare-earth ion doped glasses for optical data storage. The hole burning mechanisms, which depend on the glass composition and the preparation methods used, are discussed.

포토폴리머와 희토류이온이 첨가된 유리에서의 이광자흡수를 이용한 광정보저장

We studied feasibility of three-dimensional optical memory by utilizing femtosecond laser-induced changes of transmission in photopolymers and photoluminescence in Eu and Sm ion doped sodium borate glasses. We produced transmission change by two photon absorption and obtained sub-Um size spots in photopolymers using 780 nm modelocked Ti-sapphire laser pulses. We also changed valence state of Eu and Sm ions by multi-photon absorption and achieved sized spot formation in Sm-doped glasses.

Optical absorption and fluorescence properties of Er3+ in sodium borate glass

Spectroscopic properties of Er3+ ions in sodium borate glass have been studied. The indirect and direct optical band gaps (Eopt) and energy level parameters (RacahE 1, E2 and E3), spin-orbit (ξ4f) and configurational interaction (α)) are evaluated. Spectral intensities for various absorption bands of Er3+ doped sodium borate glass are calculated. Using Judd-Ofelt intensity parametersΩ 2, Ω4, Ω6, radiative transition probabilities (A), branching ratios (β) and integrated absorption cross sections (Σ) are reported for certain transitions. The radiative lifetimes (τR) for different excited states are estimated. From the fluorescence spectra, the emission cross section (σP) for the transition,4I13/2 → 4I15/2 is reported.

Effect of TiO 2 on electron paramagnetic resonance, optical transmission and dc conductivity of vanadyl doped sodium borate glasses

Glass systems with composition xTiO 2·(30− x)Na 2O·70B 2O 3 (series I) and xTiO 2·(70− x)B 2O 3·30Na 2O (series II) containing 2 mol% V 2O 5 have been prepared (0≤ x≤7, mol%) by normal melt-quenching. The electron paramagnetic resonance (EPR) spectra of VO 2+ ions have been recorded in the X-band (∼9.13 GHz) at room temperature. Spin Hamiltonian parameters, g ||, g ⊥, A ||, A ⊥, the dipolar hyperfine coupling parameter ( P) and the Fermi contact interaction parameter ( K) have been calculated. The increase in Δ g ||/Δ g ⊥ with increase in TiO 2 content in series I shows that the octahedral symmetry of V 4+O 6 complex is reduced, whereas in series II the octahedral symmetry is improved with increase in x. The decrease in P, in both the series, indicates that the 3d xy orbit expands with increase in mol% of TiO 2. The molecular orbital coefficients, α 2 and γ 2 have been calculated by recording the optical transmission spectra in the range 500–850 nm. α 2 and γ 2 increase with increase in x in both the series, which indicates that, the covalency of the vanadium oxygen bonds decreases. The dc conductivity σ, decreases and activation energy, W increases with increase in TiO 2:Na 2O ratio whereas with increase in TiO 2:B 2O 3 ratio the variation in σ and W is within experimental error.

Effect of the addition Y2O3 on persistent spectral hole burning in europium doped sodium borate glass

Persistent hole burning is observed in a europium doped sodium borate glass from 10 to 100 K. Hole burning efficiency increased 18× when 5% yttrium oxide was added to the glass mixture. Hole burning was observed up to 300 K in Eu3+, Y3+ Co-doped glass.

Photochemical reactions of samarium ions in sodium borate glasses irradiated with near-infrared femtosecond laser pulses

Photoinduced processes of Sm 3+-doped sodium borate glasses under high-power, 800 nm femtosecond laser irradiation have been studied. Both the photoreduction of Sm 3+ to Sm 2+ and the formation of intrinsic defects are observed at an irradiance well below the threshold for laser-induced damage. We propose that these photoinduced processes arise from the linear and two-photon absorption of the short-wavelength component of the supercontinuum and the subsequent ionization of the glass matrix. Photochemical hole burning (PHB) has been observed for 5 D 0– 7 F 0 transition of Sm 2+ in the sodium borate glasses irradiated with near-infrared femtosecond laser pulses. The efficiency of hole burning at 77 K was about 5 times higher in the irradiated glasses than in thermally reduced glasses. We consider that both the metastable Sm 2+ and the intrinsic defects were responsible for the highly efficient PHB phenomenon.