Optical Study of Neodymium Doped Lanthanum ...

Optical Study of Neodymium Doped Lanthanum Calcium Borate Glasses of La2O 3-8CaO-3B2O 3 System S. R. Dagdale and G. G. Muley* Department of Physics, Sant Gadge Baba Amravati University, Amravati, Maharashtra, India-444602. * Corresponding author. Tel.: + 91-721-2662279, ext-269; fax: + 91-721-2660949, 2662135. E-mail address: gajananggmyahoo.co.in Abstract— The glasses of xNd2O3-(1-x)La2O3-8CaO-3B2O3 system with x = 0 and 0.05 have been synthesized by melt quench technique. The amorphous nature of the glass samples has been confirmed using powder X-ray diffraction study. The ultraviolet-visible-near infrared spectroscopy has been performed to analyze transmission and absorption, and to identify various transition states of the doped glasses. The energy band gap of the grown glasses has also been reported. The samples were also characterized by Fourier transform infrared spectroscopy and reveal the structure of the prepared samples is mainly based on the BO3 and BO4 units. K eywords— Powder X-ray diffraction; Ultraviolet-visible-near infrared Spectroscopy; Fourier transforms infrared spectroscopy.

INTRODUCTION

I

N 1961, E. Snitzer has first reported an optical maser action in Nd3+ doped barium crown glass [1]. Since then, intense work has been carried out on Nd3+ doped glasses for the laser action. The optical and spectroscopic properties of several rare earth ions doped in different glasses such as silicate, glass fibers, borate, phosphate glasses and tellurite etc have been investigated [2-6]. Recently, many rare earth ions-doped glasses found important in the area of solid-state lasers, fiber laser, waveguide laser, laser amplifier in optical communication, optical data storage and amplifier in integrated optical components [7-10]. The host material strongly affects the optical and spectroscopic properties of rare earth ions. High refractive index, high transparency, good chemical and thermal stability along with low melting temperature are key parameter of host glass material for rare earth ions [6, 11, 12]. In the literature, the reports have been seen on studies of optical properties of rare-earth ion- Nd3+ doped lead borate, bismuth borate, cadmium borate [2-4, 6], sodium bismuth/lead borate [7], sodium-lead-borate [13], and bismuth zinc borate [14] glasses. Recently, Yoshimura et al. [15] reported optical and luminescent properties of neodymium doped yttrium aluminoborate and yttrium calcium borate glasses. In this paper, we present synthesis of borate glasses from a xNd2O3-(1-x)La2O3-8CaO-3B2O3 system (with x=0 and 0.05) by the melt quenching method and their optical properties. The prpepared glasses were characterized by powder X-ray diffraction (XRD) and ultraviolet-visible-near infrared (UV-vis-NIR) transmission spectroscopy. The optical energy band gaps of the materials have been determined by using transmission spectra.

was purchased from sd Fine chemicals, Mumbai. All these chemicals were of analytical reagent grade. An alkali borate glasses from system xNd2O3-(1-x)La2O38CaO-3B2O3 with x = 0 (LaCOB) and 0.05 (Nd:LaCOB) were prepared by the melt-quenching method. The chemicals La 2O3, CaCO3, Nd2O3 and H3BO3 with 99.99% purity were used as the starting raw material. Appropriate amounts of the raw materials were crushed in a mortar with the help of pestle to make the homogeneous mixture. Mixtures were heated at 500 oC for 480 min to remove moisture. The materials then removed from the crucible and once again crushed and given heat treatement at 920 o C for 600 min. The polycrystalline powder of LaCOB and Nd:LaCOB compound were synthesized. Then powder sample was melted in a platinum crucible in an electric furnace at 1050 o C. The obtained melts were quenched by pouring on a stainless steel plate and pressed with another stainless steel plate to form amorphous solids plates. The obtained glasses were cut into rectangular slabs of dimensions 6x4x2 mm3 and polished to use for further characterization. XRD patterns of powder glass samples were recorded on a Rigaku MiniFlex-II X-ray diffractometer using Cu-Kα (λ =1.504 Å) radiation to check the amorphous state of the prepared glass samples at the scanning rate of 8 deg/min and 2θ varied from 10–80o. UV-vis-NIR transmission and optical band gap study have been performed using BlackCSR-50 StellarNet UV-vis Spectrophotometer. The FT-IR spectroscopy was performed at a room temperature on Bruker α-ATR instrument in the frequency range 500–4000 cm-1.

EXPERIMENTAL

R ESULTS AND DISCUSSIONS 1 XRD analysis

Lanthanum oxide (La2O3) was purchased from Central Drug House (CDH) (P) Ltd, India. Calcium carbonate (CaCO 3) was purchased from Fisher Scientific, neodymium oxide (Nd2O3) was purchased from LOBA Chemie, India and boric acid (H3BO3)

Figure 1 shows recorded XRD patterns of glass samples LaCOB and Nd:LaCOB. The patterns exhibit a few very broad peaks rather than sharp peaks that reflects amorphous nature of the material.

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perature. It can be observed that the absorption peak at 583 nm attributed to 4I9/2 → 4G5/2, 4G7/2 transition. Moreover, the inhomogeneous bands shown in the figure are assigned to the transitions from the 4I9/2 ground state to the excited state of the Nd 3+ ion. These absorption spectrum show peaks at 525, 583, 743, 802 and 876 nm due to the related transition from ground state 4 I9/2 to the excited states (4G7/2 , 2K13/2 , 4G9/2), (4G5/2 , 2G7/2), (4F7/2 , 4S3/2), (4F5/2) and (4F3/2), respectively of Nd3+ 4f3 electronic configuration [3, 4, 6, 13, 14, 16-18].

80

Fig. 1. Powder XRD patterns of LaCOB and Nd:LaCOB glasses.

2 UV-vis-NIR study Fig 2 shows the optical transmission spectra recorded in the wavelength region 190-1083 nm and band gap of LaCOB and Nd:LaCOB glasses. It can be observed that, the UV absorption edge for the grown glasses have lower cutoff wavelength around 288 nm. Both the glasses have shown the optical transperancies nearly 80 and 70 % in the UV and visible regions rspetively. It has also been verified by recording absorption spectrum for Nd:LaCOB as shown in fig. 3. The optical absorption coefficient (α) of LaCOB and Nd:LaCOB glasses in the wavelength range 190-1083 nm was determined using the relation (1); α = (2.303/d)log(1/T) (1) Where, T is the transmittance and d is the thickness of the glass. The direct band gap of the glass can be determined by using relation (2); (αhν)2=A(Eg - hν) (2) Where, A is a constant. Plotting a graph between (αhν)2 and photon energy (hν), as shown the Figure 2 b), and drawing tanget to straight portion interceting enegy axis gives energy band gap and it was found to be nearly 4.12 eV for both glasses.

2.0

5 FT-IR spectroscopy Fig. 4 a) and b) show the FT-IR spectra of LaCOB and Nd:LaCOB glasses in the frequency range 500 to 4000 cm−1. It was recorded to specify and compare the coordination of boron. In this, the peaks lying in wavenumber range 1600-3700 cm–1 may be attributed to the presence of water molecules in the prepared samples [19-22]. The absorption peaks at 1240 cm-1 represents the asymmetric stretching and symmetric stretching vibrations of BO3 groups [23-24]. The peaks present at 884 and 1085 cm-1 may deserve to the asymmetric and symmetric stretching of B-O in BO4, respectively [25]. The deformation vibration at 716 cm-1 can be assigned as the bending of BO3 groups [19-27] a) LaCOB b) Nd:LaCOB

1.0 0.5

1

2

3 4 hQeV)

1000

Fig.3. Optical absorption spectrum of Nd:LaCOB glass.

b)

1.5

0.0

300 600 900 1200 Wavelength (nm)

600 800 Wavelength (nm)

5

1716

0

400

LaCOB Nd:LaCOB

20

0.2

2370 2085 1942

40

DhQ x10 8 (eV 2/cm 2)

60

743nm 802nm 876nm

a) 525nm 583nm

% Transmittance

80

2.5

0.4

0.0

Transmission (%)

100

0.6

Nd:LaCOB

4I → 4F 9/2 3/2

70

Fig. 2. a) UV-Vis transmission spectra and b) A plot of variation of (αhν)2 versus hν (eV) for LaCOB and Nd:LaCOB glasses. .

4000

3200 2400 1600 Wavenumber (cm-1)

1240 1085 884 716

40 50 60 2 T (Degree)

2965

30

3431

20

Absorption (a. u.)

10

4I → 4G , 2K 4 9/2 7/2 13/2, G 9/2 4I → 4G , 2G 9/2 5/2 7/2

0.8

4I → 4F , 4S 9/2 7/2 3/2 4I →4F 9/2 5/2

Intensity (a. u.)

LaCOB Nd:LaCOB

800

Fig. 1. FTIR spectra of LaCOB and Nd:LaCOB glasses.

4 Absorption spectra The absorption spectra of Nd:LaCOB glass is as shown in figure 3. It was measured in the range of 320-1083 nm at a room tem266

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C ONCLUSION

Absorption and Fluorescence Spectral Analysis of Nd3+ DopedBismuth Boro-Silicate Glasses” International Journal of Modern Engineering Research, vol. 2, no. 5, pp. 3829–3834, SepOct. 2012, ISSN: 2249-6645. [11]Nascimento, M. L. F. Dantas and N. Oliveira, “Assessment of glass-forming ability and the effect of La2O3 on crystallization mechanism of barium–lead–zinc phosphate glasses” Materials Letters, vol. 61, pp. 912–916, Jan 2007, doi:10.1016/j.matlet.2006.06.012. [12] S. Mohan, K. S. Thind, G. Sharma and L. Gerward, “Spectroscopic investigations of Nd3+ doped flouro- and chloro-borate glasses” Spectrochimica Acta Part A, vol. 70, pp. 1173–1179, 2008, doi:10.1016/j.saa.2007.10.038. [13] S. Mohan, K. S. Thind and G. Sharma, “Effect of Nd3+ Concentration on the Physical and Absorption Properties of Sodium-LeadBorate Glasses” Brazilian Journal of Physics, vol. 37, no. 4, pp. 1306-1313, Dec 2007, doi.org/10.1590/S010397332007000800019. [14] B. Shanmugavelu, V. Venkatramu and V. V. Ravi Kanth Kumar, “Optical properties of Nd3+ doped bismuth zinc borate glasses” Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, vol. 122, pp. 422–427, Mar 2014, doi.org/10.1016/j.saa.2013.11.051. [15] E. M. Yoshimura, C. N. Santos, A. Ibanez and A. C. Hernandes, “Thermoluminescent and optical absorption properties of neodymium doped yttrium aluminoborate and yttrium calcium borate glasses” Optical Materials, vol. 31, pp. 795–799, 2009, doi:10.1016/j.optmat.2008.08.004. [16] L. R. P. Kassab, R. D. Mansano, Lu´ıs da S. Zambom, and V. D. Del Cacho, “Semiconductor Characteristics of Nd 3+ Doped PbOBi2O3-Ga2O3 Films” Brazilian journal of physics, vol. 36, no. 2A, pp. 451-454, June 2006, doi.org/10.1590/S010397332006000300059. [17] M. S. Marques, L. de S. Menezes, W. Lozano B., L. R. P. Kassab, and C. B. de Araujo, “Giant enhancement of phonon-assisted onephoton excited frequency upconversion in a Nd3+-doped tellurite glass” Journal of applied physics, vol. 113, pp. 053102-1-4, 2013, doi.org/10.1063/1.4789965. [18] K. Azman, W. A. W. Razali, H. Azhan, M. R. Sahar, “Luminescence spectra of TeO2-PbO-Li2O doped Nd2O3 glass” Advanced materials research, vol. 501, pp. 121-125, 2012, doi:10.4028/www.scientific.net/AMR.501.121. [19] G. El- Deen Abd El-Raheem Yahya, “Studies on Some LithiumBorate Glasses Containing Iron and Copper” Turk. J. Phys., vol. 27, pp. 255-262, 2003. [20] H. A. Silim, Egypt. J. Solids, 29 (2006), pp. 293 [21] G. P. Singh, P. Kaur, S. Kaur, D. P. Singh, “Role of WO3 in structural and optical properties of WO3–Al2O3–PbO–B2O3 glasses” Physica B, vol. 406, pp. 4652–4656, 2011, doi:10.1016/j.physb.2011.09.052. [22] F. M. Ernsbjer, Glastech Ber Glass Science Technology, Vol. 32, No. 3, 1959, p. 81. [23] G. P. Singh, P. Kaur, S. Kaur, D.P. Singh, “Role of V2O5 In structural properties of V2O5-MnO2-PbO-B2O3 glasses” Materials physics and mechanics, vol. 12, pp. 58-63, 2011. [24] M. Sathish, B. and Eraiah, Synthesis,” Characterization and optical properties of niobium doped silver-lead-borate glasses” international journal of engineering research and applications, vol. 2, no. 6, pp. 1264-1270, Nev-Dec 2012, ISSN: 2248-9622.

In the present report, a novel LaCOB and Nd:LaCOB glasses were successfully grown. A simple melt quenching technique was used to prepare glasses of large size with good optical transparency. The XRD patterns confirm the amorphous nature of the glass. The optical transparencies of the LaCOB and Nd:LaCOB glasses are nearly 80 and 70 % in the UV and visible regions respectively. The prepared glasses show lower cut-off wavelength at around 288 nm. The energy band gap of the grown glasses was found to be 4.12 eV. The absorption study confirms presence of transition peaks corresponding to the Nd3+ ions in doped glass. FT-IR study shows the glass structure is based on

BO3 and BO4 groups.

A CK NOWLEDGMENT Authors acknowledge the financial support by Science and Engineering Research Council (SERB), New Delhi under Fast Track Program (SR/FTP/PS-065/2010).

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