Glasses are the most advanced material in terms of technology and are utilized in a wide range of applications. They are notable for being optically transparent and brittle. Due to their wide range of prospective uses and applications in the design and development of photonic devices, the rare-earth (RE) doped glass materials have attracted a lot of attention
Due to their high transparency, low melting point, great thermal stability, and potent solubilities in rare earth ions, borate-based glass hosts have been demonstrated to be capable of lasing in the NIR range. A particularly good optical medium are borate glasses
Optical material activated by Nd3+ ions are very interesting for emitting devices. Especially Nd3+ ions are very attractive active media for powerful solid-state laser working in the NIR spectral region
Kashif. et. al (2020) had studied Nd3+ ion doped lithium borate glasses their result shows their prepared glasses are the potential for application of “photovoltaics”
In our work we focus on the optical properties of Nd3+ ions doped in Calcium -Aluminum-Borate-Barium-Sodium glass matrix. The direct and indirect band gaps Nd3+ concentration dependent was evaluated. The optical properties of CaO-Al2O3-BaO-B2O3-Na-Nd2O3 (where x=0.1,0.3, and 0.5 mol%) host glass were optimized for Nd3+ concentration and understand the feasibility of using it for NIR emitting solid state device applications.
The glass system of 23CaO-10Al2O3-(51-X) B2O3-6BaO-10Na2O-XNd2O3 where X=0.1,0.3, and 0.5, (coded as CaAlBBaNaNd0.1, CaAlBBaNaNd0.3, CaAlBBaNaNd0.5 mol%) where prepared by conventional melt quenching technique. The high purity chemicals CaCO3, Al2O3, H3BO3, BaCO3, Na2CO3, and Nd2O3 were mixed and grinded by using agate, mortar to make fine powder and the total amount of each batch of glass formula was thoroughly mixed till it obtained a homogeneous mixture and weighed to 15 gm. a porcelain crucible with well grinded oxides was used to place the uniform mixture in electrical muffle furnace. Density (ρ) measurements on glass samples were performed using the Archimedes technique using toluene as the immersion solvent. The prepared mixture was then heated at 11500 C for 3hours, the homogeneous oxides melt remained and then swiftly dispensed into stainless steel block that had been pre - heated, and it was quenched to create uniform thick glass samples. To reduce thermal stress, the glass underwent an entire day of annealing at 5500C before being allowed to cool gradually to ambient temperature. The powdered approach was utilized to capture the X-ray diffraction pattern of glass samples. CuKα with a wavelength of 1.54 nm, was employed as a source in the Diffractometer. The FTIR spectra were recorded at room temperature using Perkin Elmer Lambda PRONTIER (MIV-FTIR) The acquired glass sample were shaped for characterization. Using Perkin Elmer lambda 950 UV/VIS/NIR spectrophotometer, the optical absorption spectra of present glass were measured in UV/VIS/NIR region of 250-2500nm. The photoluminescence spectra were recorded using near-infrared spectrophotometers (Quanta Master (QM)-300, PTI-Horiba) using Xenon as a source.
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(N1) CaAlBBaNaNd0.1 |
23CaO-10Al2O3-50.9B2O3-6BaO-10Na2O--0.1Nd2O3 |
(N2) CaAlBBaNaNd0.3 |
23CaO-10Al2O3-50.7B2O3-6BaO-10Na2O--0.3Nd2O3 |
(N3) CaAlBBaNaNd0.5 |
23CaO-10Al2O3-50.5B2O3-6BaO-10Na2O--0.5Nd2O3 |
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Density(g/cm3) |
2.55 |
1.92 |
2.57 |
Molar volume(cm3/mol) |
29.54 |
38.96 |
29.34 |
Refractive index (n) |
1.57 |
1.57 |
1.57 |
Dielectric constant(ℇ) |
2.46 |
2.46 |
2.46 |
Nd3+ionconcentration (x1021ions/cm3) |
20.45 |
15.39 |
20.63 |
Polaron radius (Aº) |
5.57 |
4.25 |
3.26 |
Interionic distance ri(Aº) |
7.61 |
5.81 |
4.46 |
Field Strength (Fx1020)cm-2 |
9.64 |
1.65 |
2.80 |
Average boron-boron separation (dB-B)(Aº) |
2.25 |
2.48 |
2.25 |
Molar refraction (R)(cm3/mol) |
9.55 |
12.78 |
9.62 |
Molar cation polarizability (αcat) |
3.79 |
5.07 |
3.82 |
No. of oxides in chemical formula (NO2-) |
2.22 |
2.22 |
2.22 |
Electronic oxide polarizability (αo2-n) |
1.60 |
2.17 |
1.61 |
Optical basicity(Λ) |
0.62 |
0.90 |
0.63 |
Metallization Criteria(M) |
0.86 |
0.86 |
0.86 |
Theoretical Basicity(Λtheo) |
0.69 |
0.69 |
0.69 |
With the addition of Nd2O3, the samples' average molecular weight rises. Since (Nd2O3), which has a greater molecular weight (336.4782), substitutes (B2O3), which has a lower molecular weight (69.6202), this is evident. In relation to the geometrical configuration, cross-link density, interstitial space sizes, coordination number, and refractive index, changes in the density of the glass can have an impact on the optical band gaps of the glass system. The density values in the current glass are 2.55, 1.92, and 2.57; following the first value, the second value decreased to 1.92; the first value increases as a result of the substitution of Nd2O3 with B2O3, which has a greater molecular weight. While the creation of non-bridging oxygen (NBO) atoms in the glass matrix may be responsible for the drop-in density in the second sample. The nature of the glass density and the modifying impact of neodymium ions by producing interstitial gaps with NBO in the glass matrix are credited with the trend of the molar volume of its values. Due to the excessive dopant concentration in the glass, the polaron radius and interionic distance shrank as the concentration of neodymium ions rose.
The
The analysis of IR spectra can reveal information on the rotation and vibration of different molecules within a glass matrix. The features of a molecule's vibrations are related to frequency; these vibrations are distinct from those of other groups of molecules in the matrix and each has a unique characteristic of vibrational frequency. The above figure show the CaAlBBaNaNd glasses' recorded Fourier transform infrared spectra at room temperature. The spectrum shows eight conventional bands coming from different elements in the current glasses doped with Nd3+ ions and it reflects the functional groups of the glass matrix. The significant changes in the band positions are observed from
The intensities of these bands differ from one composition to another. The band observed at 400-500cm is due to Ca2+ cation vibrations. The second band observed at 769-1200 cm-1 due to presence of B-O bond stretching in BO4- structural unit from a diborate group. The band observed at 1200-1569 due to the stretching vibrations of NBOs of trigonal units of BO3. The existence of symmetric hydrogen bond (OH) group vibrations in the referred glasses is what causes the final strong broad band at 3389 cm-1. Alkali and alkali earth elements, which have functional fundamental properties vibrational wave number for the pertinent element groups present in the glass network, are present in the glass network during the formation of the glass network, which results in the bands seen in the spectrum
The absorbance studies of 23CaO–10Al2O3–(51-x)B2O3-6BaO-xNd2O3-10Na2O- glass doped with various concentrations of Nd2O3 are calculated in UV–VIS-NIR recorded at room temperature in the wavelength range of 300-1000nm is shown in
The optical band gap energy as illustrated in
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01 |
(N1) CaAlBBaNaNd0.1 |
3.54 |
3.24 |
Present work |
02 |
(N2) CaAlBBaNaNd0.3 |
3.65 |
3.41 |
Present work |
03 |
(N3) CaAlBBaNaNd0.5 |
3.62 |
3.38 |
Present work |
04 |
M1 (borate :ca+al+na) |
3.835 |
3.363 |
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05 |
Nd 0.5 |
3.51 |
3.14 |
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06 |
BBaAzNd |
3.40 |
3.15 |
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The NIR emission spectra of Nd3+ ions doped CaAlBBaNaNd glasses under 582 nm excitation wavelength were recorded and shown in the
The glasses were prepared using melt quenching technique. With the addition of Nd2O3, the samples' show average molecular weight increases. The absorbance studies of 23CaO–10Al2O3–(51-x) B2O3-6BaO-10Na2O glass doped with various concentrations of Nd2O3 are evaluated using UV–VIS-NIR. Amorphous nature of the glass was confirmed by X-ray diffraction study. Signature bands of borate network was observed especially BO3 and BO4 vibrational units were observed using Fourier transform infra-red spectra. Excitation of 582 nm was used as source to excite the Nd3+ ions in CaAlBBaNaNd glass from 4I9/2 ground state to 4F3/2 excited state the peaks corresponding to 4F3/2 to 4I9/2 and 4F3/2 to 4F13/2 are absorbed at 1074 and 1341nm respectively among two bands a transitions corresponds to 4F3/2→4I11/2 (1074nm) is a potential laser transition having high intensity than the remaining transitions for all the as prepared glasses. These glasses are potential candidates for NIR emitting solid state device applications.
Basavaraj Gurav would like to thank Dr. Harish C Barshilia, Chief Scientist, Head of Surface Engineering Division, National Aeronautical Laboratory (SED- NAL), and Bangalore for supporting to carry out characterizations. Also, thanks to Dr. R. Rajaramakrishna and National Education Society (N.E.S) of Karnataka, Bangalore for their kind support to carry out the research in the Department of Post Graduate Studies and Research in Physics.