Optical absorption and photoluminescence properties of Dy3+ doped heavy metal borate glasses – Effect of modifier oxides

Dy3+ ions infused modifier reliant boro-phosphate glasses: A promising host for W-LED demand

An exclusive set of Dy3+ ions incorporated Boro-phosphate glasses with different modifier ions like Sr, Mg, Ba, Li and Zn have been manufactured by quenching the melts. The optical behavior of the present glasses was explored through absorption, luminescence & lifetime studies. Physical parameters such as refractive index (RI) and density have been calculated and utilized to evaluate other parameters. The JO parameters exhibited the style Ω2 > Ω4 > Ω6, and the luminescence spectra exhibited three strong transitions; 4F9/2→6H15/2 (magnetic dipole), 4F9/2→6H13/2 (electric dipole) and 4F9/2→6H11/2 (magnetic dipole). Lasing action characteristics such as emission cross-section, transition probability and branching ratio were projected from the JO parameters and oscillator strength values. The color chromaticity coordinates were determined using the CIE color chromaticity diagram. Lifetime analyses have been performed to comprehend the decay performance of the BPNfDy:X glasses.

Noncytotoxic Dy3+ -activated glass emits cool white light for near ultraviolet-based white light-emitting diodes, visible lasers, and biomedical applications

Using the melt quenching technique, a lithium zinc borate glass (LZB) system with trivalent dysprosium ions (Dy3+ ) was synthesized, and the luminescence and lasing properties of these materials were examined for the generation of white light. Structural investigation through X-ray diffraction revealed that the prepared glass had an amorphous nature. The optimized glass containing 0.5 Dy3+ had a direct optical band gap of 2.782 eV and an indirect optical band gap of 3.110 eV. A strong excitation band at 386 nm (6 H15/2 →4 I13/2 ) was recognized in the ultraviolet (UV) light region of its excitation spectrum. Emission bands could be seen in the photoluminescence spectrum at 659, 573, and 480 nm under the 386 nm excitation. These transitions of emission resembled electronic transitions such as (4 F9/2 →6 H11/2 ), (4 F9/2 →6 H13/2 ), and (4 F9/2 →6 H15/2 ). In a pristine glass matrix, the higher intensity ratio of yellow to blue can result in the production of white light. The optimized Dy3+ ion concentration was observed to be 0.5 mol%. In addition, an analysis of lifetime decay was conducted for all synthesized glasses, and their decay trends were systematically investigated. Noticeably, we assessed the photometric parameters and found that they were close to the white light standard. Furthermore, a cytotoxicity study was carried out using lung fibroblast (WI-38) cell lines for the optimized 0.5Dy3+ -doped LZB glass and it appeared to be noncytotoxic. It is clear from the results that the noncytotoxic LZB glass doped with 0.5 Dy3+ ions could be a suggestive choice for the manufacture of white light-emitting diodes and lasers using near-UVs.

Recent progress in lanthanide-doped luminescent glasses for solid-state lighting applications-a review

Nowadays, solid-state white light-emitting diodes (wLEDs) have attracted remarkable attention for applications in general lighting, displays and numerous electronical devices due to their eminent efficiency, longer lifetime and higher mechanical durability compared to traditional incandescent and fluorescent lights. In current commercial wLEDs, a combination of Y₃Al₅O₁₂:Ce³⁺yellow phosphor with blue LED chip and epoxy resin is generally used to generate white light. However, there are some considerable frailties mostly originated from phosphor and resin such as, degradation upon heat, and moisture, inhomogeneous spectral distribution, and poor color rendering capability. Therefore, phosphor embedded glass-ceramics have been developed as a promising way to obtain durable solid-state lighting devices. However, in these methods, there is a greater risk of reactions between the phosphor material and the glass host. At this point, lanthanide-doped luminescent glasses have drawn great attention as a new generation phosphor and/or epoxy free white-light-emitting source owing to their favorable properties including high thermal and chemical stability, high transparency, and easy manufacturing process. This review article aims to comprehensively summarize the recent progress in singly (i.e., Dy³⁺, Eu²⁺), doubly (i.e., Dy³⁺/Eu³⁺, Dy³⁺/Tm³⁺, Dy³⁺/Ce³⁺, Ce³⁺/Sm³⁺, Ce³⁺/Tb³⁺) and triply (i.e., Ce³⁺/Tb³⁺/Mn²⁺, Eu³⁺/Tb³⁺/Tm³⁺, Ce³⁺/Tb³⁺/Eu³⁺, Tm³⁺/Tb³⁺/Sm³⁺, Ce³⁺/Dy³⁺/Eu³⁺, Ho³⁺/Tm³⁺/Yb³⁺, Er³⁺/Tm³⁺/Yb³⁺) lanthanide-doped glasses for solid-state lighting applications through down-shifting and up-conversion emissions. Theoretical background including energy transfer mechanisms, glass synthesis methods, radiative and colorimetric properties are given in details. Finally, various effective strategies are highlighted that minimize the critical challenges associated with lanthanides-such as providing energy transfer from quantum dots or nanoparticles to lanthanides, and doping lanthanides in low phonon energy glass-to improve the white light emission of luminescent glasses and broaden their application areas.

Influence of Dy3+ co-doping on the luminescence properties of bluish-green Ba1−0.5ySr1−0.5yAl2SiO7:yEu2+ phosphors

The emission intensity of Ba_0.985Sr_0.985Al₂SiO₇:0.03Eu²⁺ is enhanced due to the incorporation of Dy³⁺. The emission intensity of Ba_0.975Sr_0.975Al₂SiO₇:0.03Eu²⁺, 0.02Dy³⁺ was about 350% that of the Ba_0.985Sr_0.985Al₂SiO₇:0.03Eu²⁺ phosphor.

Investigations on the spectroscopic properties of Dy3+ ions doped Zinc calcium tellurofluoroborate glasses

A new series of Dy³⁺ doped (30-x)B₂O₃+30TeO₂+20CaCO₃+10ZnO+10ZnF₂+xDy₂O₃ (x=0.01, 0.1, 0.5, 1, 2 and 3 in wt%) Zinc calcium tellurofluoroborate glasses were prepared and their structural, luminescence and excited state dynamics have been studied and reported. The structural properties have been characterized through XRD and FTIR studies to confirm the amorphous nature and to explore the presence of fundamental stretching vibrations. The bonding parameters (δ and β), optical band gap, Urbach's energy, oscillator strengths and Judd-Ofelt (JO) intensity parameters were calculated from the absorption spectra. The JO intensity parameters and the Y/B intensity ratio values have been used to explore the nature of the bonding and asymmetry around the Dy-ligand field environment. The luminescence properties of the present Dy³⁺ doped glasses have been analyzed through luminescence excited state dynamics and radiative properties such as transition probability (A), stimulated emission cross-section (σ_P^E) branching ratio (β) and radiative lifetime (τ_R) values. The combination of dominant blue (⁴F_9/2→⁶H_15/2) and yellow (⁴F_9/2→⁶H_13/2) emissions generates white light emission in the CIE chromaticity diagram thus suggests that the present Dy³⁺ doped glasses are suitable for white light applications. The lifetime of the ⁴F_9/2 excited state is found to decrease with the increase in Dy³⁺ ion content and the concentration quenching of the Dy³⁺ ions emission could be ascribed due to the resonant energy transfer and cross-relaxation processes. The non-exponential behavior of the decay curves has been analyzed with Inokuti-Hirayama model and the interaction between the Dy³⁺ ions is of electric dipole-dipole in nature.

Spectroscopic and energy transfer behavior of Dy(3+) ions in B2O3TeO2PbOPbF2Bi2O3CdO glasses for laser and WLED applications

A new series of white light emitting Dy(3+) doped Lead tellurofluoroborate glasses have been prepared and their spectroscopic and energy transfer behavior were explored through analyzing XRD, FTIR, Raman, SEM, EDAX, optical absorption, photoluminescence and lifetime measurements. The fundamental stretching of the various borate and tellurite networks were identified using FTIR and Raman spectral analysis. The bonding parameter studies reveal the ionic nature of the DyO bond in the present glasses. The Judd-Ofelt (JO) intensity parameters determined from the absorption spectra have been used to investigate the nature of bonding and symmetry orientation of the Dy-ligand field environment. The luminescence intensity increases with increasing Dy(3+) ion concentration up to 0.5wt%, beyond that luminescence quenching is observed. The JO parameters have been used to determine the transition probability (A), stimulated emission cross-section (σP(E)), radiative lifetime (τR) and branching ratios (βR) for the different emission transitions from the (4)F9/2 excited level. The higher σP(E) and βR values of the (4)F9/2→(6)H15/2 and (4)F9/2→(6)H13/2 transitions suggest the possible laser action in the visible region. The Y/B ratio, CIE chromaticity color coordinates (x, y) and Color correlated temperature (CCT) were also estimated from the luminescence spectra for different concentration as well as pumping wavelengths. The x, y chromaticity color coordinates fall within the white light region and the white light can be tuned by varying the excitation wavelengths. The lifetime of the (4)F9/2 excited state were measured and is found to decrease with increasing Dy(3+) ion content. The non-exponential behavior is predominant in higher Dy(3+) ion content glasses and is due to the efficient energy transfer between Dy(3+)Dy(3+) ions. The decay curves were fitted to the Inokuti-Hirayama (IH) model to understand the nature of energy transfer. Among the prepared glasses, 0.5DPTFB glass possesses higher A,βR,σP(E),η values and is suggested for lasers and WLED applications.