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Article

Spectroscopic Properties of Pr3+, Tm3+, and Ho3+ in Germanate-Based Glass Systems Modified by TiO2

by
Marta Kuwik
*,
Karolina Kowalska
,
Joanna Pisarska
* and
Wojciech A. Pisarski
Institute of Chemistry, University of Silesia, Szkolna 9, 40-007 Katowice, Poland
*
Authors to whom correspondence should be addressed.
Materials 2023, 16(1), 61; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010061
Submission received: 10 November 2022 / Revised: 10 December 2022 / Accepted: 16 December 2022 / Published: 21 December 2022
(This article belongs to the Special Issue Recent Advances of Luminescent Materials and Devices in Optics and Photonics)
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Abstract

:
In this paper, the effect of the GeO2:TiO2 molar ratio in glass composition on the spectroscopic properties of germanate glasses was systematically investigated. The visible luminescence bands associated with characteristic 1D2 → 3H4 (red), 5S2, 5F4 → 5I8 (green), and 1D2 → 3F4 (blue) transitions of Pr3+, Ho3+, and Tm3+ ions in systems modified by TiO2 were well observed, respectively. It was found that the luminescence intensity of glasses containing Pr3+ and Ho3+ ions increases, whereas, for Tm3+-doped systems, luminescence quenching with increasing content of TiO2 was observed. Based on Commission Internationale de I’Eclairage (CIE) chromaticity coordinates (x, y) analysis, it was demonstrated that the value of chromaticity coordinates for all glasses depends on the GeO2:TiO2 molar ratio. The addition of TiO2 to system compositions doped with Tm3+ ions shifts the (x, y) to the center of the CIE diagram. However, chromaticity coordinates evaluated for glasses containing Pr3+ ions move to a purer red color. Our results confirm that the spectroscopic properties of the studied glasses strongly depend on TiO2 content. Moreover, it can be stated that germanate-based glass systems modified by TiO2 can be used for optoelectronics in RGB technology as red (Pr3+), green (Ho3+), and blue (Tm3+) emitters.

1. Introduction

Over the past years, the progress in the capacity of modern optoelectronic and photonic technologies has contributed to the increasing interest in luminescence materials, particularly glasses, glass ceramics, and ceramics [1,2,3,4,5,6]. Inorganic systems doped with trivalent lanthanide (Ln3+) ions have been paid attention due to their spectroscopic properties in visible and near-infrared spectral range and possible applications as luminescent solar converters [7], solid-state lighting [8], generators of white light [9], optical thermometers [10,11], laser and broadband fiber amplifiers [12,13]. One of the more interesting uses of glasses doped with Ln3+ ions is the production of emitters for RGB technology [14]. In particular, systems containing rare earth ions such as praseodymium ions (Pr3+) are promising red-emitting materials [15,16]. Sun et al. [17] reported that Pr3+-doped aluminosilicate glasses may be a potential candidate for efficient visible fiber lasers operated at 610 and 640 nm wavelengths. Moreover, glasses doped with holmium ions (Ho3+) are being extensively studied due to possible green luminescence [18,19]. As Rani et al. [20] suggested, relatively higher values of stimulated emission cross-section and quantum efficiency observed for 5S2 → 5I8 transition allow us to contemplate that Ho3+-doped borate glass systems can be used for fabricating green lasers. On the other hand, materials containing thulium ions (Tm3+) due to characteristic luminescence properties are analyzed in the visible blue region [21,22,23].
It is worth noting that the luminescence properties of Ln3+ ions are sensitive to the chemical composition of the host matrix. The presence of modifier oxides has an equally significant influence on the structural, thermal, and spectroscopic properties of materials doped with Ln3+ ions. Particularly noteworthy are metal oxides such as titanium (IV) oxide (TiO2), which is a useful component of the glass and glass ceramics systems [24,25,26,27]. The addition of TiO2 to the glass matrix becomes very interesting for developing new optical materials due to good physical, chemical, electrical, and optical properties and high transparency in the visible and near-infrared (NIR) regions [28]. Furthermore, modifier oxide TiO2 increases the linear and non-linear refractive indices, increasing the radiative transition probabilities and improving the non-linear optical properties [29]. Thermal studies indicate that glasses with low titanium (IV) oxide content exhibit high stability against crystallization [30]. The presence of small quantities of TiO2 in glass matrices is observed to enhance the glass-forming ability and chemical durability of the glasses [31]. However, the previously published results indicated that the oxide modifier TiO2 added to some host matrices effectively promotes glass crystallization, and it is quite difficult to synthesize thermally stable and fully amorphous systems with a high TiO2 concentration [32,33,34]. To the best of our knowledge, the spectroscopic properties of rare earth ions in germanate-based glass matrices are not frequently examined in the function of high concentrations of titanium (IV) oxide.
Keeping in mind the above considerations, in this paper, spectroscopic properties of Pr3+, Ho3+, and Tm3+ have been investigated in GeO2/TiO2-based glass systems. Spectroscopic properties of selected rare earth ions were analyzed as a function of the molar ratio GeO2:TiO2 (from 5:1 to 1:5) in the glass composition. The excitation and visible emission spectra for germanate glass systems were registered and discussed. Based on measurements, the Commission Internationale de I’Eclairage (CIE) chromaticity coordinates (x, y) for all glasses depending on the content of GeO2 and TiO2 were defined.

2. Materials and Methods

A series of multicomponent oxide glasses containing various molar ratio GeO2:TiO2 and singly doped with praseodymium (Pr3+), thulium (Tm3+), and holmium (Ho3+) ions were synthesized by a conventional melt-quenching method. The following nominal chemical composition (60-x)GeO2-xTiO2-30BaO-(10-y)Ga2O3-yLn2O3 (Ln = Pr, Tm, Ho; x = 10, 20, 30, 40, 45, 50; y = 0.1) of systems are given in molar%. In the present study, the appropriate metal oxides of high purity (99.99%, Aldrich Chemical Co. St. Louis, MO, USA) were weighted and mixed in an agate mortar. After homogenization, each batch of 5g was melted in a non-covered corundum crucible (Łukasiewicz Research Network, Institute of Ceramics and Building Materials, Cracow, Poland) in a high-temperature electrical furnace (FCF 4/170M produced by Czylok, Jastrzębie Zdrój, Poland) at 1250 °C in ambient air. The glass samples were kept at this temperature for 60 min before slowly being cooled down to room temperature. Finally, glass samples were shaped and polished to meet the requirements for photoluminescence spectral measurements.
Optical spectroscopy was used to examine the influence of the GeO2:TiO2 molar ratio on the luminescence properties of the studied glass systems. The excitation and emission spectra were recorded using a Photon Technology International (PTI) Quanta-Master 40 (QM40) UV/VIS Steady State Spectrofluorometer (Photon Technology International, Birmingham, NJ, USA) coupled with a tunable pulsed optical parametric oscillator, pumped by the third harmonic of a Nd:YAG laser (Opotek Opolette 355 LD, OPOTEK, Carlsband, CA, USA). The laser system was equipped with a double 200 mm monochromator, a xenon lamp (75W) (USHIO Inc. Japan) as a light source, and a multimode UVVIS PMT (R928) (PTI Model 914) detector (Photon Technology International, Birmingham, NJ, USA). All measurements were carried out at room temperature.

3. Results and Discussion

3.1. Characterization of Germanate-Based Glass Systems Modified by TiO2

For the germanate-based glasses to be employed for useful application in RGB technology, their structural and thermal characterization is essential. Therefore, in the first step of characterization of properties of germanate-based glass systems, the phase analysis was conducted using X-ray diffraction (XRD). Independently of TiO2 concentration, it was found that the X-ray diffraction patterns show two broad peaks characteristic of an amorphous state. Hence, it has been confirmed that the obtained germanate glasses are fully amorphous. It is interesting to notice that the glass-forming region for the studied compositions is relatively broad. Our previous results indicate that the type of rare earth ions does not affect the crystallization of the local structure of germanate systems modified by TiO2 [35].
Moreover, the glass transition phenomenon and, hence, the amorphous phase can be studied from the analysis of glass transition temperature (Tg). This parameter is one of the most fundamental material factors, and it has a critical impact on the suitability of a system for optoelectronic applications. There are a variety of thermal and mechanical analytical techniques that can be used to measure this crucial parameter. In our study, we used Differential Scanning Calorimetry (DSC) to characterize the thermal properties of germanate-based glasses. Details are given in Ref. [36]. The obtained results show that the value of Tg increases in the presence of TiO2 in the glass host. When the glass transition of a system is situated as a function of the composition, the change in Tg values indicates definite changes in the glass network. Based on the thermal characterization, the studied systems suggested less open glass structure for germanate samples modified by TiO2. Additionally, it was found that the thermal stability parameter (ΔT) is reduced for the glass systems, where the concentration of TiO2 increases. However, this important factor is still above 100 °C, exhibiting the good thermal stability of germanate-based glasses.
Another critical parameter is the phonon energy of the glass host (hν), which can be determined based on excitation spectra [37]. The value of phonon energy reveals essential information regarding the modification of glass structure with a change in the composition. Our studies indicate that the phonon energy of the glass host is reduced for systems modified by TiO2 [36]. Previously published results demonstrate that germanate glasses are perspective materials as oxide glass host matrices for rare earth ions thanks to their favorable properties, such as smaller multiphonon relaxation probabilities due to relatively low phonon energy [38,39,40]. It can be assumed that the presence of TiO2 in glass composition causes the reduction in matrix phonons and improves the efficiency of the visible luminescence of praseodymium, holmium, and thulium ions in germanate-based glass systems. For that reason, the visible luminescence of Pr3+, Ho3+, and Tm3+ ions in the obtained glass samples are presented and discussed in detail in the next sections.

3.2. Spectroscopic Properties of Ln3+-Doped Germanate-Based Glass Systems

The influence of chemical composition on the spectroscopic properties of glass systems singly doped with trivalent praseodymium, holmium, and thulium ions is a key issue, confirmed by previous investigations [41,42,43,44]. Therefore, in our study, the excitation and emission spectra in the visible range for the studied glasses were registered in the function of the GeO2:TiO2 molar ratio.
Firstly, the excitation spectra of TiO2-modified germanate glass systems doped with praseodymium ions were monitored at λem = 645 nm. All registered spectra show four bands assigned to transition originating from the 3H4 ground state to higher-lying 3P2, 3P1, 3P0, and 1D2 states (Figure 1). The most intense bands centered at 450 nm (3H4 → 3P2), 471 nm (3H4 → 3P1), and 486 nm (3H4 → 3P0) overlap, giving a characteristic profile. The energy gaps between excited states 3P2, 3P1, 3P0 are very small, and the excitation energy transfers very fast from the 3P2 state via 3P1 to the 3P0 state by non-radiative relaxation. Next, the 3P0 excited state is depopulated, giving several radiative transitions to the lower-lying states of Pr3+ ions. The band corresponding to the transition from the 3H4 ground state to the excited state 1D2 was also observed. It is worth noting that the maximum of this band is shifted to a longer wavelength region, and intensity increases with the change of GeO2:TiO2 molar ratio (Inset of Figure 1).
Figure 2 presents spectra (monitored at λem = 547 nm) of TiO2-modified germanate glass systems with five excitation bands corresponding to the transition from the 5I8 ground state of Ho3+. The observed bands of relatively low intensity located in the ultraviolet range (363 nm and 389 nm) can be attributed to 5I8 → 3H5, 3H6 and 5I8 → 5G4 transitions. However, the most intense excitation bands were measured in the wavelength range of visible radiation and centered at 450 nm (5I8 → 5G6, 5F1). It should be stated that the intensities of all excitation bands depend on GeO2:TiO2 molar ratios. Moreover, the intensities of bands located at 389, 420, 450, and 488 increased with a change of glass composition, whereas the decrease in intensity was observed well for the excitation band associated with the 5I8 → 3H5, 3H6 transition of Ho3+ ions.
The excitation spectra for germanate-based glass systems were registered and monitored at 455 nm and 650 nm, the wavelengths corresponding to blue (1D2 → 3F4) and red (1G4 → 3F4) emissions of thulium ions (Figure 3). Independently on the GeO2:TiO2 molar ratio in the glass composition, only two bands corresponding to the transition from the 3H6 ground state to the excited states 1D2 (λem = 455 nm) and 1G4 (λem = 650 nm) were observed. It is interesting that the intensity of excitation bands strongly depends on the concentration of glass formers. The intensity of band originating from the 3H6 → 1G4 transition (λem = 650 nm) significantly decreases with the change in the GeO2:TiO2 molar ratio. On the other hand, the increase in the intensity of the second excitation band 3H6 → 1D2 (λem = 455 nm) was observed.
Figure 4 shows the luminescence spectra of glasses containing Pr3+ ions recorded under direct excitation by the 450 nm line (3P2 state). Independently of the GeO2:TiO2 molar ratio, several luminescence bands were observed, and it should be noticed that the studied systems exhibit blue, green, and intense orange-red emissions. The registered blue and green emission bands at around 484 nm and 526 nm, 540 nm correspond to 3P0 → 3H4 and 3P1 → 3H5, 3P0 → 3H5 transitions, respectively. The spectral range between 570 nm and 760 nm consists of two broad unresolved luminescence groups of bands as a result of overlapping bands originating with the 1D2 → 3H4, 3P0 → 3H6, 3P0 → 3F2, and 3P1 → 3F3, 3P1 → 3F4, 3P0 → 3F4 transitions of Pr3+ ions. Among visible luminescence bands, the most intense are due to the 1D2 → 3H4, 3P0 → 3H6 (608 nm), 3P0 → 3F2 (645 nm), and 3P0 → 3H4 (484 nm) transitions of praseodymium ions. Furthermore, the intensity of orange-red luminescence increases with the change in the GeO2:TiO2 molar ratio (Figure 5a) and the reduction in the phonon energy of the glass host. On the other hand, it was stated that the intensity of the emission band due to 3P0 → 3F2 decreased in comparison to the band associated with the 1D2 → 3H4 transition of Pr3+ ions. In accordance with Mallur and Babu [45], who studied the spectroscopic properties of borate glasses, multiphonon relaxation rates can be negligible between the 3P0 and 1D2 states of praseodymium ions. As a result of a possible cross-relaxation (CR) process, the excited state 1D2 level is more populating.
Moreover, Flizikowski et al. [46] reported that emissions attributed to transitions from the 1D2 state are more sensitive to the changes in glass composition than the 3P0 emissions. Our experimental results determined that due to the non-radiative transition among CR channel 3P0:3H4 → 1D2:3H6, the red emission corresponding to the 1D2 → 3H4 transition of Pr3+ increases. In contrast, emission originating with the transition from the 3P0 state decreases for glass systems with higher content of TiO2. Therefore, it could be stated that the presence of titanium (IV) oxide in the germanate host raises the cross-relaxation processes between Pr3+ ions. According to Naresh and Ham [47], the relation between the intensity of orange (1D2 → 3H4) and blue (3P0 → 3H4) emission, referred to as the orange-to-blue ratio (O/B), depends on glass composition and Pr3+ ion concentration. Taking into account the ratio value between the intensity emission at 608 nm and 484 nm, the results demonstrate that the change of glass modifier concentration (TiO2) also causes an increase in orange intensity and a decrease in blue emission (Figure 5a). Figure 5b presents the energy level diagram with all visible transitions under the excitation of Pr3+ ions in TiO2-modified germanate glasses at 450 nm.
Based on recorded excitation spectra for systems doped with Ho3+ ions, the 450 nm wavelength was chosen in order to register the registration of luminescence spectra in the function of the GeO2:TiO2 molar ratio for the studied glass systems (Figure 6). Independently of the chemical composition, the glass systems exhibit green and red emissions, and bands with maxima at around 547, 660, and 752 nm were noticed on the spectra. Furthermore, the most intense band, among emission bands, corresponds to 5S2, 5F4 → 5I8 (green emission) transitions of holmium ions. In agreement with studies for phosphate glasses doped with Ho3+ ions [48] and antimony–germanate optical glass fiber co-doped with Yb3+/Ho3+ [49], the crucial spectroscopic parameter determined based on emission spectra is the R/G ratio. This factor is a relation between the intensity of red (5F5 → 5I8) and green (5S2, 5F4 → 5I8) luminescence of holmium ions. Contrary to the spectroscopic properties of studied glasses doped with Pr3+ ions, our results for glass systems doped with Ho3+ show that the red-to-green ratio is independent of the GeO2:TiO2 molar ratio (Figure 7a). However, the intensity of both the green (547 nm) and red (660 and 752 nm) emission increase with a change in the TiO2-modified germanate glass composition. From this point of view, it can be stated the spectroscopic consequence of the reduction in phonon energy due to a higher TiO2 concentration is the achievement of the efficient green luminescence of Ho3+ ions. Figure 7b shows the energy level diagram of holmium ions in the studied glass systems.
Next, the emission spectra of Tm3+-doped TiO2-modified germanate glasses were registered under direct excitation of the 1D2 state (λexc = 359 nm) and 1G4 state (λexc = 470 nm) (Figure 8). It is worth noting that the studied systems emit blue and red radiations regardless of the GeO2:TiO2 molar ratio. The luminescence bands due to the transition from the excited states 1D2, 1G4, 3F2, 3F3, and 3H4 to lower-lying states of thulium ions were observed for all the studied glass systems. Additionally, it should be noticed that the blue emission band with a maximum at 454 nm is the most intense in comparison with other bands registered under excitation at λexc = 359 nm (Figure 9a). However, the relatively strong red emission due to the 1G4 → 3F4 transition of Tm3+ ions was observed when the glass samples were excited by 470 nm. The influence of excitation wavelengths on the intensities of emission corresponding to transitions from the excited states of Tm3+ ions is well known and investigated, among other things, by Piramidowicz et al. for fluorozirconate glasses [50]. Analysis of our results indicates that the shape of the emission band (1G4 → 3F4) changed with excitation wavelengths and proves the overlapping of two luminescence bands corresponding to the 1D2 → 3H4 and 1G4 → 3F4 transition of thulium ions. The change of luminescence intensity looks similar to the one observed on the excitation spectra. Nevertheless, a different relationship was shown in the case of a band with a maximum at 702 nm (Figure 8). This emission band was also registered for Yb3+/Tm3+/Gd3+-doped NaYF4 [51] and SrYbF5 co-doped with Er3+/Tm3+ ions [52]. Based on the energy level scheme, the observed band can be assigned to 3F2, 3F3 → 3H6 transitions of Tm3+ ions. It should be pointed out that a population of the lower-lying states 3F2 and 3F3 is due to the cross-relaxation process accompanied by direct pumping of the excited state 1G4 [53]. Figure 9b presents the energy level diagram with excitation and emission transitions for Tm3+ ions in TiO2-modified germanate glasses.

3.3. CIE Chromaticity Coordinates (x, y) Analysis

Germanate-based glasses singly doped with praseodymium, holmium, and thulium ions can be promising matrices for optoelectronics in RGB technology due to visible emissions. Generally, these rare earth ions are incorporated into glass host matrices to produce systems emitting three primary colors of light: red (Pr3+), green (Ho3+), and blue (Tm3+). The concentration of glass components is a crucial factor of intensity and color emission associated with characteristic transitions of rare earth ions. In order to evaluate the influence of glass composition on color visible luminescence, a CIE diagram and chromaticity coordinates (x, y) are usually employed. These important spectroscopic parameters are regulated by the Commission Internationale de l’Éclairage, defined in 1931, and they express all colors by using the three primary colors of X, Y, and Z. Therefore, the chromaticity coordinates for the studied germanate-based glass systems modified by TiO2 were calculated from luminescence spectra and analyzed in detail.
Figure 10 shows the CIE diagram with marked coordinates (x, y) for systems doped with Pr3+, Ho3+, and Tm3+ ions. The presented results indicate that luminescence color depends on the GeO2:TiO2 molar ratio in the glass composition. The studied germanate-based glass systems containing Pr3+ ions emit red luminescence and chromaticity coordinates evaluated for these glasses shifts to a purer red color when the content of TiO2 is changed from 10 mol% to 50 mol%. On the other hand, the x and y coordinates of the glasses doped with Ho3+ ions are similar and, regardless of TiO2 concentration, point to the green region of the CIE chromaticity diagram. Previously systematic spectroscopic studies confirm that systems containing Ho3+ ions are promising candidates for green light emitters [54,55]. Based on the CIE diagram, it was found that all studied glasses doped with Tm3+ ions exhibit blue emission, similar to borotellurite, borosilicate [56], as well as phosphate [57] glass systems. Analysis of the CIE chromaticity coordinates calculated for systems doped with Tm3+ ions in the function of GeO2:TiO2 molar ratio demonstrates the opposite tendency in comparison with results obtained for glasses doped with Pr3+ ions. The values of coordinates shift to the perfect white light (x = 0.333, y = 0.333) when the concentration of glass component TiO2 increases.
Considering the above results for all studied glasses, it can be concluded that TiO2 as a glass modifier significantly influences the spectroscopic properties of rare earth ions in germanate glass systems. Therefore, a suitable titanium dioxide concentration allows for receiving optical materials with improved luminescence properties. Titanium dioxide is an important modifier of the germanate matrix, which, depending on the concentration, type of optically active dopant, and excitation wavelength, contributes significantly to the improvement of critical spectroscopic parameters of systems such as emission intensity or CIE chromaticity coordinates. We suggest that the results for TiO2-modified germanate glasses doped with Pr3+, Ho3+, and Tm3+ ions are attractive for visible emission, giving an essential contribution to the development of luminescent glasses and celebrating the year 2022 as the International Year of Glass, IYOG [58].

4. Conclusions

In summary, the influence of the oxide glass modifier TiO2 on the spectroscopic properties of germanate-based systems singly doped with rare earth ions (Pr3+, Ho3+, and Tm3+) was investigated. Independently of the GeO2:TiO2 molar ratio, intense red (608 nm), green (547 nm), and blue (454 nm) emissions were observed for glasses doped with Pr3+, Ho3+, and Tm3+ ions, respectively. It was demonstrated that the concentration of titanium oxide significantly increases the emission intensity of glass systems containing Pr3+ and Ho3+ ions. However, blue emission decreases with increasing content of TiO2 in germanate-based glasses doped with Tm3+ ions. Additionally, it can be concluded that the visible radiative transitions of Pr3+, Ho3+, and Tm3+ ions are greatly dependent on the reduction in the phonon energy of the glass host modified by TiO2. Based on CIE chromaticity coordinates (x, y) analysis, it has been proven that the change of GeO2:TiO2 molar ratio causes significant and opposite color modification for the studied systems doped with Pr3+ and Tm3+ ions. The addition of TiO2 to system compositions doped with Tm3+ ions shifts the (x, y) to the center of the CIE diagram. In contrast, chromaticity coordinates evaluated for glasses containing Pr3+ ions move to a purer red color. It was confirmed that the spectroscopic properties of germanate-based glasses strongly depend on TiO2 content. Our results suggest the applicability of TiO2-modified germanate glasses as novel visible photoluminescent materials in RGB technology and photonic devices.

Author Contributions

Conceptualization, M.K., J.P. and W.A.P.; methodology, M.K. and K.K; formal analysis, M.K. and W.A.P.; investigation, M.K. and K.K.; writing—original draft preparation, M.K.; writing—review and editing, W.A.P. and J.P.; visualization, M.K.; supervision, W.A.P. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Science Centre (Poland), grant number 2018/31/B/ST8/00166.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Liao, X.; Jiang, X.; Yang, Q.; Wang, L.; Chen, D. Spectral Properties of Er3+/Tm3+ Co-Doped ZBLAN Glasses and Fibers. Materials 2017, 10, 486. [Google Scholar] [CrossRef] [Green Version]
  2. Zhang, M.; Wen, H.; Pan, X.; Yu, J.; Shao, H.; Ai, F.; Yu, H.; Tang, M.; Gai, L. Study on Upconversion and Thermal Properties of Tm3+/Yb3+ Co-Doped La2O3-Nb2O5-Ta2O5 Glasses. Materials 2018, 11, 1352. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  3. Ye, Y.; Wang, S.; An, H. White-light emission and chromaticity characterization of Dy3+ doped fluoride glass for standard white light source. J. Non-Cryst. Solids 2019, 526, 119697. [Google Scholar] [CrossRef]
  4. Xing, J.; Shang, F.; Chen, G. Upconversion luminescence of Yb3+/Er3+ co-doped NaSrPO4 glass ceramic for optical thermometry. Ceram. Int. 2021, 47, 8330–8337. [Google Scholar] [CrossRef]
  5. Tang, Z.; Han, W.; Huang, Z.; Qi, J.; Zhang, Y.; Yi, J.; Yuan, J.; Lu, T. Near-infrared luminescent properties of Ln:LaGdZr2O7 (Ln = Nd, Yb). Ceram. Int. 2020, 46, 22270–22275. [Google Scholar] [CrossRef]
  6. Ermakova, L.V.; Leonidov, I.I. Towards a new group of olive-type afterglow phosphors: The case of Ca2GeO4:Dy3+. Mater. Lett. 2018, 233, 39–41. [Google Scholar] [CrossRef]
  7. Aouaini, F.; Maaoui, A.; Mohamed, N.B.H.; Alanazi, M.M.; Maati, L.A.E. Visible to infrared down conversion of Er3+ doped tellurite glass for luminescent solar converters. J. Alloys Compd. 2022, 894, 162506. [Google Scholar] [CrossRef]
  8. Khan, I.; Khattak, S.; Shoaib, M.; Kaewkhao, J.; Ullah, I.; Rooh, G. Spectral investigation of lithium-telluride based glasses doped with Sm3+-ions lighting application. J. Alloys Compd. 2021, 875, 160095. [Google Scholar] [CrossRef]
  9. Divina, R.; Evangelin Teresa, P.; Marimuthu, K. Dy3+ ion as optical probe to study the luminescence behavior of Alkali lead bismuth borate glasses for w-LED application. J. Alloys Compd. 2021, 883, 160845. [Google Scholar] [CrossRef]
  10. Kumar, A.; Couto, H.; Esteves da Silva, J.C.G. Upconversion Emission Studied in Er3+/Yb3+ Doped/Co-Doped NaGdF4 Phosphor Particles for Intense Cathodoluminescence and Wide Temperature-Sensing Applications. Materials 2022, 15, 6563. [Google Scholar] [CrossRef]
  11. Faria, W.J.; Gonçalves, T.S.; de Camargo, A.S.S. Near infrared optical thermometry in fluorophosphates glasses doped with Nd3+ and Nd3+/Yb3+. J. Alloys Compd. 2021, 883, 160849. [Google Scholar] [CrossRef]
  12. Pisarski, W.A.; Pisarska, J.; Lisiecki, R.; Ryba-Romanowski, W. Broadband Near-Infrared Luminescence in Lead Germanate Glass Triply Doped with Yb3+/Er3+/Tm3+. Materials 2021, 14, 2901. [Google Scholar] [CrossRef] [PubMed]
  13. Charfi, B.; Damak, K.; Maâlej, R.; Alqahtani, M.S.; Hussein, K.I.; Alshehri, A.M.; Hussain, A.M.; Burtan-Gwizdala, B.; Reben, M.; Yousef, E.S. Enhancement of Optical Telecommunication Bands: Pr3+-Doped Halide Phosphate Glasses Display Broadband NIR Photoluminescence Emission. Materials 2022, 15, 6518. [Google Scholar] [CrossRef] [PubMed]
  14. Erol, E.; Vahedigharehchopogh, N.; Kibrili, O.; Ersundu, M.C.; Ersundu, A.E. Recent progress in lanthanide-doped luminescent glasses for solid-state lighting applications—A review. J. Phys. Condens. Matter 2021, 33, 483001. [Google Scholar] [CrossRef] [PubMed]
  15. Kumar, M.; Vijayalakshmi, R.P.; Ratnakaram, Y.C. Investigation of structural and optical properties of Pr3+ doped and Pr3+/Dy3+ co-doped multicomponent bismuth phosphate glasses for visible light applications. J. Mol. Struct. 2022, 1265, 133333. [Google Scholar] [CrossRef]
  16. Tanaka, H.; Kalusniak, S.; Badtke, M.; Demesh, M.; Kuleshov, V.N.; Kannari, F.; Krankel, C. Visible solid-state lasers based on Pr3+ and Tb3+. Prog. Quantum Electron. 2022, 84, 100411. [Google Scholar] [CrossRef]
  17. Sun, Y.; Yu, F.; Liao, M.; Wang, X.; Li, Y.; Hu, L.; Knight, J. Emission properties of Pr3+-doped aluminosilicate glasses at visible wavelengths. J. Lumin. 2020, 220, 117013. [Google Scholar] [CrossRef]
  18. Mariselvam, K.; Liu, J. Green emission and laser properties of Ho3+ doped titano lead borate (TLB) glasses for colour display applications. J. Solid State Chem. 2021, 293, 121793. [Google Scholar] [CrossRef]
  19. Alqarni, A.S.; Hussin, R.; Ghoshal, S.K.; Alamri, S.N.; Yamusa, Y.A.; Jupri, S.A. Intense red and green luminescence from holmium activated zinc-sulfo-boro-phosphate glass: Judd-Ofelt evaluation. J. Alloys Compd. 2019, 808, 151706. [Google Scholar] [CrossRef]
  20. Rani, P.R.; Venkateswarlu, M.; Swapna, K.; Mahamuda, S.K.; Srinivas Prasad, M.V.V.K.; Rao, A.S. Spectroscopic and luminescence properties of Ho3+ ions doped Barium Lead Alumino Fluoro Borate glasses for green laser applications. Solid State Sci. 2020, 102, 106175. [Google Scholar] [CrossRef]
  21. Jiménez, J.A.; Ibarra, V. Tm3+ Ion Blue Emission Quenching by Pd2+ Ions in Barium Phosphate Glasses: Fundamental Analysis toward Sensing Applications. J. Phys. Chem. B 2022, 126, 8579–8587. [Google Scholar] [CrossRef]
  22. Mariselvam, K.; Juncheng, L. Concentration effect of Tm3+ ions doped B2O3-Li2CO3-BaCO3-CaF2-ZnO glasses: Blue laser and radiation shielding investigations. Opt. Laser Technol. 2022, 154, 108262. [Google Scholar] [CrossRef]
  23. Rao, A.S. Color tunable photoluminescence in KZABS: Tm3+ glasses under different sources of excitation for photonic applications. J. Non-Cryst. Solids 2022, 585, 121532. [Google Scholar]
  24. Alajerami, Y.S.M.; Suhairul, H.; Hashim, S.; Hassan, W.M.S.W.; Ramli, A.T. The effect of titanium oxide on the optical properties of lithium potassium borate glass. J. Mol. Struct. 2012, 1026, 159–167. [Google Scholar] [CrossRef]
  25. Zhu, W.; Jiang, H.; Zhang, H.; Jia, S.; Liu, Y. Effect of TiO2 and CaF2 on the crystallization behavior of Y2O3-Al2O3-SiO2 glass ceramics. Ceram. Int. 2018, 44, 6653–6658. [Google Scholar] [CrossRef]
  26. Herrera, A.; Londoño, F.; Balzaretti, N.M. Structural and optical properties of Nd3+ doped GeO2-PbO glass modified by TiO2 for applications in laser and fiber amplifier. Opt. Mater. 2021, 113, 110884. [Google Scholar] [CrossRef]
  27. Haily, E.; Bih, L.; Jerroudi, M.; Azrour, M.; El Bouari, A.; Manoun, B. Structural investigation of SrO-BaO-TiO2-B2O3-P2O5 glass ceramics. Mater. Today Proc. 2021, 37, 3798–3802. [Google Scholar] [CrossRef]
  28. De, M.; Jana, S. Optical characterization of Eu3+ doped titanium barium lead phosphate glass. Optik 2020, 215, 164718. [Google Scholar] [CrossRef]
  29. De, M.; Jana, S.; Mitra, S. Structural and spectroscopic characteristic of Eu3+ embedded titanium lead phosphate glasses for red luminescence. Solid State Sci. 2021, 114, 106560. [Google Scholar] [CrossRef]
  30. Burtan-Gwizdala, B.; Reben, M.; Cisowski, J.; Szpil, S.; Yousef, E.S.; Lisiecki, R.; Grelowska, I. Thermal and spectroscopic properties of Er3+-doped fluorotellurite glasses modified with TiO2 and BaO. Opt. Mater. 2020, 107, 109968. [Google Scholar] [CrossRef]
  31. Balaji Rao, R.; Krishna Rao, D.; Veeraiah, N. The role of titanium ions on structural, dielectric and optical properties of Li2O-MgO-B2O3 glass system. Mater. Chem. Phys. 2004, 87, 357–369. [Google Scholar] [CrossRef]
  32. Duan, R.-G.; Liang, K.-M.; Gu, S.-R. Effect of Changing TiO2 Content on Structura and Crystallization of CaO-Al2O3-SiO2 System Glasses. J. Eur. Ceram. 1998, 18, 1729–1735. [Google Scholar] [CrossRef]
  33. Krimi, S.; El Jazouli, A.; Rabardel, L.; Couzi, M.; Mansouri, I.; Le Flem, G. Glass Formation in the Na2O-TiO2-P2O5 System. J. Solid State Chem. 1993, 102, 400–407. [Google Scholar] [CrossRef]
  34. Kleebusch, E.; Patzig, C.; Höche, T.; Rüssel, C. Effect of the concentrations of nucleating agents ZrO2 and TiO2 on the crystallization of Li2O-Al2O3-SiO2 glass: An X-ray diffraction and TEM investigation. J. Mater. Sci. 2016, 51, 10127–10138. [Google Scholar] [CrossRef]
  35. Pisarski, W.A.; Kowalska, K.; Kuwik, M.; Pisarska, J.; Dorosz, J.; Kochanowicz, M.; Zmojda, J.; Dorosz, D. New multicomponent titanate-germanate glasses and their luminescence properties. Proc. SPIE 2020, 11456, 1145603. [Google Scholar]
  36. Pisarski, W.A.; Kowalska, K.; Kuwik, M.; Polak, J.; Pietrasik, E.; Pisarska, J. Novel Multicomponent Titanate-Germanate Glasses: Synthesis, Structure, Properties, Transition Metal, and Rare Earth Doping. Materials 2020, 13, 4422. [Google Scholar] [CrossRef]
  37. Pisarska, J.; Pisarski, W.A.; Lisiecki, R.; Ryba-Romanowski, W. Phohon Sideband Analisysi and Near-Infrared Emission in Heavy Metal Oxide Glasses. Materials 2021, 14, 121. [Google Scholar] [CrossRef]
  38. Szal, R.; Zmojda, J.; Kochanowicz, M.; Miluski, P.; Dorosz, J.; Lesniak, M.; Jeleń, P.; Starzyk, B.; Sitarz, M.; Kuwik, M.; et al. Spectroscopic properties of antimony modified germanate glass doped with Eu3+ ions. Ceram. Int. 2019, 45, 24811–24817. [Google Scholar] [CrossRef]
  39. Kuwik, M.; Górny, A.; Zur, L.; Ferrari, M.; Righini, G.C.; Pisarski, W.A.; Pisarska, J. Influence of rare earth ions concentration on luminescence properties of barium gallo-germanate glasses for white lighting. J. Lumin. 2019, 211, 375–381. [Google Scholar] [CrossRef]
  40. Zmojda, J.; Kochanowicz, M.; Miluski, P.; Golonko, P.; Baranowska, A.; Ragiń, T.; Dorosz, J.; Kuwik, M.; Pisarski, W.A.; Pisarska, J.; et al. Luminescent Studies on Germanate Glasses Doped with Europium Ions for Photonic Applications. Materials 2020, 13, 2817. [Google Scholar] [CrossRef]
  41. Morassuti, C.Y.; Andrade, L.H.C.; Silva, J.R.; Baesso, M.L.; Guimaraes, F.B.; Rohling, J.H.; Nunes, L.A.O.; Boulon, G.; Guyot, Y.; Lima, S.M. Spectroscopic investigation and interest of Pr3+-doped calcium aluminosilicate glass. J. Lumin. 2019, 210, 376–382. [Google Scholar] [CrossRef]
  42. Pisarska, J.; Kuwik, M.; Górny, A.; Dorosz, J.; Kochanowicz, M.; Zmojda, J.; Sitarz, M.; Dorosz, D.; Pisarski, W.A. Influence of transition metal ion concentration on near-infrared emission of Ho3+ in barium gallo-germanate glasses. J. Alloys Compd. 2019, 793, 107–114. [Google Scholar] [CrossRef]
  43. Monisha, M.; Prabhu, N.S.; D’Souza, A.N.; Bharadwaj, S.; Chowdary, R.J.; Sayyed, M.I.; Alhuthali, A.M.S.; Al-Hadeethi, Y.; Kamath, D.S. Structural, dielectric, optical and photoluminescence studies of Tm3+ doped B2O3-BaO-MgO-Li2O-Na2O-LiF glasses featuring strong blue emission. J. Non-Cryst. Solids 2021, 560, 120733. [Google Scholar] [CrossRef]
  44. Kowalska, K.; Kuwik, M.; Pisarska, J.; Pisarski, W.A. Near-IR Luminescence of Rare-Earth Ions (Er3+, Pr3+, Ho3+, Tm3+) in Titanate-Germanate Glasses under Excitation of Yb3+. Materials 2022, 15, 3660. [Google Scholar] [CrossRef]
  45. Mallur, S.B.; Babu, P.K. Optical properties of Praseodymium (Pr3+) doped bismuth boro-tellurite glasses containing CdSe nanoparticles. Mater. Res. Bull. 2022, 147, 111651. [Google Scholar] [CrossRef]
  46. Flizikowski, G.A.S.; Zanuto, V.S.; Novatski, A.; Nunes, L.A.O.; Malacarne, L.C.; Baesso, M.L.; Astrath, N.G.C. Upconversion luminescence and hypersensitive transitions of Pr3+-doped calcium aluminosilicate glasses. J. Lumin. 2018, 202, 27–31. [Google Scholar] [CrossRef]
  47. Naresh, V.; Ham, B.S. Influence of multiphonon and cross relaxation on 3P0 and 1D2 emission levels of Pr3+ doped borosilicate glasses for broad band signal amplification. J. Alloys Compd. 2016, 664, 321–330. [Google Scholar] [CrossRef]
  48. Jupri, S.A.; Ghoshal, S.K.; Omar, M.F.; Hamzah, K.; Yusof, N.N.; Yaacob, S.N.S.; Zain, S.K.M.; Danmallam, I.M. Enhanced spectroscopic properties of holmium doped phosphate glass: Role of Ag/TiO2 nanoparticles embedment. J. Lumin. 2022, 252, 119380. [Google Scholar] [CrossRef]
  49. Kochanowicz, M.; Zmojda, J.; Miluski, P.; Pisarska, J.; Pisarski, W.A.; Dorosz, D. NIR to visible upconversion in double-clad optical fiber co-doped with Yb3+/Ho3+. Opt. Mater. Express 2015, 5, 1505–1510. [Google Scholar] [CrossRef]
  50. Piramidowicz, R.; Bok, A.; Klimczak, M.; Malinowski, M. UV emission properties of thulium-doped fluorozirconate glasses. J. Lumin. 2009, 129, 1874–1877. [Google Scholar] [CrossRef]
  51. Vidyakina, A.A.; Kolesnikov, I.E.; Bogachev, N.A.; Skripkin, M.Y.; Tumkin, I.I.; Lähderanta, E.; Mereshchenko, A.S. Gd3+-Doping Effect on Upconversion Emission of NaYF4: Yb3+, Er3+/Tm3+ Microparticles. Materials 2020, 13, 3397. [Google Scholar] [CrossRef]
  52. Liu, Q.; Yan, X.; Chen, Y.; Wang, X. Upconversion emission of SrYbF5:Er3+ nanosheets modified by Tm3+ ions. J. Rare Earths 2013, 11, 1053–1058. [Google Scholar] [CrossRef]
  53. Zhang, H.; Jia, T.; Shang, X.; Zhang, S.; Sun, Z.; Qiu, J. Mechanisms of the blue emission of NaYF4:Tm3+ nanoparticles excited by an 800 nm continuous wave laser. Phys. Chem. Chem. Phys. 2016, 18, 25905–25914. [Google Scholar] [CrossRef]
  54. Prakash, M.R.; Neelima, G.; Kummara, V.K.; Ravi, N.; Viswanath, C.S.D.; Rao, T.S.; Jilani, S.M. Holmium doped bismuth-germanate glasses for green lighting applications: A spectroscopic study. Opt. Mater. 2019, 94, 436–443. [Google Scholar] [CrossRef]
  55. Venkateswarlu, M.; Mahamuda, S.K.; Swapna, K.; Prasad, M.V.V.K.S.; Srinivasa, A.R.; Shakya, S.; Babu, A.M.; Prakash, G.V. Holmium doped Lead Tungsten Tellurite glasses for green lighting applications: A spectroscopic study. Opt. Mater. 2015, 163, 64–71. [Google Scholar]
  56. Lakshminarayana, G.; Caldiño, U.; Meza-Rocha, A.N.; Lira, A.; Venkateswara Rao, P.; Singh, V.; Dahshan, A.; Kityk, I.V.; Lee, D.-E.; Yoon, J.; et al. Fluorescence features of Tm3+-doped multicomponent borosilicate and borotellurite glasses for blue laser and S-band optical amplifier applications. Opt. Mater. 2019, 96, 109354. [Google Scholar] [CrossRef]
  57. Meza-Rocha, A.N.; Speghini, A.; Lozada-Morales, R.; Caldiño, U. Blue and white light emission in Tm3+ and Tm3+/Dy3+ doped zinc phosphate glasses upon UV light excitation. Opt. Mater. 2016, 58, 183–187. [Google Scholar] [CrossRef]
  58. Parker, J.M.; Duran, A. Glass, optics and IYOG: Opinion. Opt. Mater. Express 2022, 12, 2938–2941. [Google Scholar] [CrossRef]
Materials 16 00061 g001 550
Figure 1. Excitation spectra for Pr3+ ions in TiO2-modified germanate glasses. The inset presents a shift of the maximum of excitation band due to 3H4 → 1D2 transition.
Figure 1. Excitation spectra for Pr3+ ions in TiO2-modified germanate glasses. The inset presents a shift of the maximum of excitation band due to 3H4 → 1D2 transition.
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Figure 2. Excitation spectra for Ho3+ in TiO2-modified germanate glasses.
Figure 2. Excitation spectra for Ho3+ in TiO2-modified germanate glasses.
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Figure 3. Excitation spectra for Tm3+ in TiO2-modified germanate glasses.
Figure 3. Excitation spectra for Tm3+ in TiO2-modified germanate glasses.
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Figure 4. Luminescence spectra for Pr3+ ions in TiO2-modified germanate glasses.
Figure 4. Luminescence spectra for Pr3+ ions in TiO2-modified germanate glasses.
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Figure 5. (a) The integrated luminescence intensities of orange and blue lines due to main 1D2 → 3H4 and 3P0 → 3H4 transitions and (b) energy level scheme for Pr3+ in TiO2-modified germanate glasses.
Figure 5. (a) The integrated luminescence intensities of orange and blue lines due to main 1D2 → 3H4 and 3P0 → 3H4 transitions and (b) energy level scheme for Pr3+ in TiO2-modified germanate glasses.
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Figure 6. Luminescence spectra for Ho3+ ions in TiO2-modified germanate glasses.
Figure 6. Luminescence spectra for Ho3+ ions in TiO2-modified germanate glasses.
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Figure 7. (a) The integrated emission intensities of red and green lines due to main 5F5 → 5I8 and 5S2, 5F4 → 5I8 transitions and (b) energy level scheme for Ho3+ in TiO2-modified germanate glasses.
Figure 7. (a) The integrated emission intensities of red and green lines due to main 5F5 → 5I8 and 5S2, 5F4 → 5I8 transitions and (b) energy level scheme for Ho3+ in TiO2-modified germanate glasses.
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Figure 8. Luminescence spectra for Tm3+ in TiO2-modified germanate glasses. The inset presents luminescence bands registered in spectral range between 620 and 680 nm.
Figure 8. Luminescence spectra for Tm3+ in TiO2-modified germanate glasses. The inset presents luminescence bands registered in spectral range between 620 and 680 nm.
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Figure 9. (a) The luminescence intensities of blue and red lines due to main 1D2 → 3F4 and 1G4 → 3F4 transitions and (b) energy level scheme for Tm3+ ions in TiO2-modified germanate glasses.
Figure 9. (a) The luminescence intensities of blue and red lines due to main 1D2 → 3F4 and 1G4 → 3F4 transitions and (b) energy level scheme for Tm3+ ions in TiO2-modified germanate glasses.
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Figure 10. The influence of GeO2:TiO2 molar ratio on CIE chromaticity coordinates for glasses doped with praseodymium, holmium, and thulium ions.
Figure 10. The influence of GeO2:TiO2 molar ratio on CIE chromaticity coordinates for glasses doped with praseodymium, holmium, and thulium ions.
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Kuwik, M.; Kowalska, K.; Pisarska, J.; Pisarski, W.A. Spectroscopic Properties of Pr3+, Tm3+, and Ho3+ in Germanate-Based Glass Systems Modified by TiO2. Materials 2023, 16, 61. https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010061

AMA Style

Kuwik M, Kowalska K, Pisarska J, Pisarski WA. Spectroscopic Properties of Pr3+, Tm3+, and Ho3+ in Germanate-Based Glass Systems Modified by TiO2. Materials. 2023; 16(1):61. https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010061

Chicago/Turabian Style

Kuwik, Marta, Karolina Kowalska, Joanna Pisarska, and Wojciech A. Pisarski. 2023. "Spectroscopic Properties of Pr3+, Tm3+, and Ho3+ in Germanate-Based Glass Systems Modified by TiO2" Materials 16, no. 1: 61. https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010061

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