Concentration dependence of intensity parameters and radiative properties of Sm3+ ions doped in BaO–ZnO–B2O3 glasses

Accepted Manuscript Concentration dependence of intensity parameters and radiative properties of Sm ions doped in BaO-ZnO-B2O3 glasses

3+

Kirti Nanda, R.S. Kundu, Inder Pal, R. Punia, N. Kishore PII:

S0925-8388(16)30681-8

DOI:

10.1016/j.jallcom.2016.03.112

Reference:

JALCOM 37000

To appear in:

Journal of Alloys and Compounds

Received Date: 30 November 2015 Revised Date:

22 February 2016

Accepted Date: 16 March 2016

Please cite this article as: K. Nanda, R.S. Kundu, I. Pal, R. Punia, N. Kishore, Concentration 3+ dependence of intensity parameters and radiative properties of Sm ions doped in BaO-ZnO-B2O3 glasses, Journal of Alloys and Compounds (2016), doi: 10.1016/j.jallcom.2016.03.112. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Concentration dependence of intensity parameters and radiative properties of Sm3+ ions doped in BaO-ZnO-B2O3 glasses Kirti Nandaa, R. S. Kundua, Inder Pala, R. Punia*a,b and N. Kishorea a

b

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Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar-125001, India. Department of Physics, Indira Gandhi University, Mirpur, Rewari-123401, India.

*Corresponding author.Tel: +919215701113 E-mail: [email protected]

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Abstract

Glass samples with compositions xSm2O3- (100-x)[0.1BaO-0.4ZnO-0.5B2O3]; x = 0.5, 1.0, 1.5

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and 2.0 have been prepared using melt quench technique. Optical absorption and fluorescence spectra have been recorded for prepared glass samples at room temperature. The spectral intensities of Sm3+ transition observed in absorption spectra have been calculated by using JuddOfelt theory. The intensity parameters (Ω2, Ω4 and Ω6) have been estimated by applying least square fit method on the experimental (fexp) and calculated (fcal) oscillator strengths. The variation of Ω2 observed with the increase in Sm3+ ion concentration, is attributed to decease in

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covalency of rare earth oxygen bond due to change in optical basicity of host glass matrix. From the fluorescence spectra, four emission spectral lines have been observed that correspond to the transition from 4G5/2 ground state to lower lying 6H5/2, 6H7/2, 6H9/2 and 6H11/2 states with an excitation wavelength of 402 nm. The intensity parameters and the emission measurements have

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been used to estimate the various radiative parameters such as transition probabilities (AR), radiative lifetime (τR), branching ratio (βR) and stimulated emission cross-sections (σe) of

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luminescent levels. The value of σe is found to decrease with increase in concentration of Sm3+ ions and it possesses higher value for glass sample with x = 0.5 for transition lying in the visible region indicating its importance for photonic applications. Keywords: Glasses; Absorption; Emission; Judd- Ofelt parameters; Radiative properties. 1. Introduction

Oxide glasses containing rare earth ions have important applications as active and inactive components in optical and photonic devices [1]. Glasses doped with rare earth ions are proved to be good laser materials as they emit intense radiations in visible, infrared and near-infrared regions under suitable excitation [2]. Sm3+ ion is one of the most interesting ions for analyzing 1

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the fluorescence properties as it possesses strong fluorescence intensity in the visible region [3], rich energy levels, large emission cross-section and high quantum efficiency. Oxide glasses doped with Sm3+ ions have important application in optoelectronics, under sea communication, high density optical storage, colour displays and visible solid state lasers [3]. The host glass

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matrix is a very important factor to be considered for the development of rare earth doped optical devices [4]. Since the optical properties of rare earth ions strongly depend on their relative distribution in the host matrix, the ligand field around those ions that influence the optical absorption and quantum efficiency of stimulated emissions [5]. Borate glasses are good host

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matrices as they possess low melting point, high transparency, high thermal stability, different coordination numbers and good solubility of rare earth ions that results in excellent optical and

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spectral performance [6]. Glasses doped with ZnO are attractive materials due to their low cost, non-toxicity, non-hygroscopic nature, intrinsic emitting properties and large excitation binding energy [7]. Introduction of ZnO in the glass matrix reduces the melting point and increases the glass forming ability [8]. Zinc oxide can occupy the both network forming and network modifying positions in the glass network [9]. Barium oxide improves the glass forming ability, stability, and chemical resistance and reduces the phonon frequencies that results in

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improvement of internal quantum efficiency of luminescent material [10]. Borate rich glasses used as host matrix containing ZnO and BaO are promising materials for their potential applications in optical fibers, optical filters, laser host, photonic devices etc [11]. Judd- Ofelt theory is the most important theory in estimating the probability of forced electric dipole

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transitions of rare earth ions in various host matrices [12, 13]. This theory defines the intensity parameters (Ω2, Ω4 and Ω6) which are sensitive to the rare earth ion surroundings in the host

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matrix [14]. These intensity parameters are used to estimate the radiative properties of glasses doped with rare earth ions that are useful to optimize the best host matrix in order to improve the laser efficiency of specific electronic transitions [14]. So, the present manuscript shed light on the spectroscopic properties of Sm3+ doped BaO-ZnO-B2O3 glasses by using Judd- Ofelt analysis and the radiative properties have been estimated to quantify the use of the prepared materials for suitable practical applications. 2. Experimental Details Glass samples having compositions xSm2O3- (100-x) [0.1BaO-0.4ZnO-0.5B2O3] with x =0.5, 1.0, 1.5 and 2.0 (coded as BZBSm0.5, BZBSm1.0, BZBSm1.5 and BZBSm2.0) have been 2

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prepared by melt-quench technique using an analar grade chemicals H3BO3, ZnO, BaCO3 and Sm2O3. The procedure of preparation of glass samples has already been published elsewhere [15]. Optical absorption spectra of the prepared glass samples have been recorded using Varian Carry 5000 double beam UV-visible spectrophotometer at room temperature in the spectral range

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300 - 1800 nm. Luminescence spectra were obtained at room temperature using Shimadzu spectrofluorophotometer having model no. RF5301PC in spectral range 500-750 nm under an excitation wavelength of 402 nm using Xenon lamp having power of 150 W. 3. Results and Discussion

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3.1. Physical Properties

Various physical parameters have been calculated and are listed in Table 1, to get information regarding the structure of the prepared glass matrices. The parameters such as density (ρ), molar

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volume (Vm) and refractive index (n) of Sm3+ doped BaO-ZnO-B2O3 glasses had already been reported elsewhere [15] and the behaviour of density and molar volume suggests that the increase in concentration of Sm3+ ions in the base glass matrix results in loosely packed structure of prepared glass samples. Linear refractive index was also observed to increase with increase in Sm3+ ions content in host glass matrix. Some other physical parameters such as Sm3+ ion

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concentration (N), inter nuclear distance (ri), polaron radius (rp) and field strength (F) have been calculated using the formulas mentioned below [16] and the values are listed in Table 1 for different glass compositions. The concentration of Sm3+ ions in the prepared glass samples is

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calculated using the following expression

N=

ρ × NR M

× NA

(1)

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where ρ is the density, M is the average molecular weight of prepared glass samples, NR is the number of moles of rare earth ions and NA is the Avogadro’s number. The values of inter nuclear distance (ri) and polaron radius (rp) is calculated using the obtained values of N as follows [16] ri = (1/ N )

1/3

(2)

rp = (1/ 2 )( π / 6 N )

1/3

3

(3)

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Perusal of the data presented in Table 1 reveals that the values of ri and rp decreases with the increase in Sm3+ ion concentration in the glass matrix indicates the decrease in inter-nuclear distance between Sm3+- Sm3+ ions.

3.2 Optical Absorption Spectra

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The absorption spectra of the prepared glass samples have been recorded in spectral range 3001800 nm at room temperature and are presented in Fig. 1. Twelve absorption bands are observed in UV-VIS-NIR regions of absorption spectra for different glass compositions. These transitions are due to f-f transitions from ground state 6H5/2 to various excited states: 4D3/2 (359 nm), 6P7/2

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(373 nm), 6P3/2 (402 nm), 4I13/2 (460 nm), 4I11/2 (476 nm), 6F11/2 (944 nm), 6F9/2 (1077 nm), 6F7/2 (1224 nm), 6F5/2 (1369 nm), 6F3/2(1470 nm), 6H15/2 (1522 nm) and 6F1/2 (1584 nm) [7, 17, 18]. The

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intensities of observed absorption bands increase with increase in Sm3+ ions concentration. The majority of observed transitions are due to the induced electric dipole contribution with selection rule (∆J ≤ 6) [7]. The transitions from ground state 6H5/2 to 6H and 6F terms lying in NIR region are spin allowed and are intense and distinctly sharp due to the effective shielding of 4f electrons by the filled 5s and 5p shells [7]. The transition 6H5/2 → 6F1/2 is the hypersensitive transition for the Sm3+ ion, which follows the selection rules |∆S| = 0, |∆L| ≥ 0 and |∆J| ≥ 0 [3].

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The values of optical band gap calculated from Tauc’s plots have already been published [15]. Optical band gap was observed to decrease with the increase in Sm3+ ion concentration which is caused due to increase in number of non-bridging oxygens in glass matrix. The increase in non-bridging oxygens is due to the structural changes has discussed in our earlier

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communication [15].

3.3. Oscillator strengths and Judd-Ofelt intensity parameters

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The intensities of absorption bands can be expressed in terms of measured oscillator strengths (fexp) by the following expression f exp = 4.32 × 10−9 ∫ ε (ν )dν

(8)

where ε(ν) is the molar absorption coefficient of absorption band corresponding to the energy ν (cm-1) and can be obtained using Beer-Lambert’s law. Judd-Ofelt (J-O) theory extensively describes the intensities of crystal field induced electric-dipole transitions of lanthanide ions observed in absorption and emission spectra of Ln3+ doped either solids or solutions as host matrix. The utility of the Judd-Ofelt theory [12, 13] is that it provides a theoretical expression for 4

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calculated oscillator strength (fcal) of the transitions from the initial state ψj to the final state ψ'j' and is given by

∑

t = 2,4,6

Ωt | 〈Ψj || U t || Ψj '〉 |2

(9)

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f cal

8π 2 mcν (n 2 + 2) 2 = 3h(2 J + 1) 9n

where m is the mass of electron, c is the speed of light, h is the Planck’s constant and (2J+1) is the degeneracy of the ground state. The factor (n2+2)2/9n is the Lorentz field correction factor as Sm3+ ions are in a dielectric medium of refractive index n. ||Ut||2 are the doubly reduced squared

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matrix elements of a unit tensor operator of rank t and values available in literature are used in the present calculations [19, 20]. The values of experimental oscillator strength, fexp and

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calculated oscillator strength, fcal, for each observed electronic transition in the absorption spectra are determined by Eq. (8) and Eq. (9) respectively for all the prepared glass samples and are presented in Table 2. The method of least square fitting has been performed between the obtained values of fexp and fcal to estimate J-O intensity parameters Ωt (t = 2, 4, 6). The values of root mean square deviation (δrms) observed for the prepared glass samples are presented in Table 2. The small values of δrms observed for all glass samples show good fitting between the two

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values (fexp and fcal) along with the applicability, validity and accuracy of J-O theory. The values of fexp, fcal and δrms decrease with increase in concentration of Sm3+ ions in BaO-ZnO-B2O3 glass matrix.

The values of J-O intensity parameters (Ω2, Ω4 and Ω6) are listed in Table 3. The intensity

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parameter Ω2 is sensitive to the host matrices and its magnitude specifies the covalence of metal ligand bond, structural change and symmetry of the ligand field around rare earth ions sites [21].

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The parameters Ω4 and Ω6 are long-range parameters that are related to the bulk properties of the glass matrix such as rigidity, viscosity, and basicity of the glass matrix. The parameters Ω4 and Ω6 depend on the dielectric media and are also affected by the vibronic transitions of the rare

earth ions bound to the ligand atoms [22]. The values of Ω2 decrease with the increase in concentration of Sm3+ ions in the host glass matrix that infers the decrease in covalency of Sm-O bond and asymmetry around the Sm3+ ion [2]. The covalency of Ln-O bond is affected by the optical basicity of glass matrix and the glass matrix with higher basicity possess more covalent Ln-O bond [23, 24]. The addition of doping ions in the glass matrix will affect the basicity of that matrix by the two ways. One is to vary the basicity of glass matrix by doping ions 5

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themselves and other is by the change in the structure of the glass network when the doping ions are introduced into the matrix [25]. As already published, the structural change is observed with the addition of Sm3+ ions (doping ions) in the present host glass matrix that results in increase in the number of BO3 structural units with respect to the BO4 units [15]. And the group basicity of

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BO3 structural units is smaller than the BO4 units [25], it suggests that the optical basicity of the glass matrix may also decrease and thus results in decrease of covalent character of samariumoxygen (Sm-O) bond. The values Ω2 for the prepared glasses vary the same way. The values of intensity parameters Ω4 and Ω6 also decrease with the increase in Sm3+ ions concentration in the

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glass matrix. The decrease in magnitude of Ω6 suggests the decrease in rigidity and viscosity of prepared glass matrices [2]. Since the increase in concentration of Sm3+ ions in borate host

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matrix is at expanse of decrease in concentration of B2O3 that provide rigidity to the glass matrix. The value of spectroscopic quality factor χ = Ω4/Ω6 is observed to be less than unity and it decreases with increase in Sm3+ ions concentration [26]. 3.4. Emission Spectra

From the absorption spectra presented in Fig. 1, it is observed that the intensity of transition 6

H5/2→6P3/2 (402 nm) is relatively larger than the other transitions. So, the emission spectrum for

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the prepared glass samples has been recorded at excitation wavelength 402 nm. The emission spectra recorded in spectral range 500-750 nm in region for different glass compositions are presented in Fig. 2. By choosing the excitation wavelength 402 nm, the Sm3+ ions get excited from ground state 6H5/2 to higher energy level 4P3/2. Sm3+ ions in higher excited state decay non-

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radiatively to meta-stable state 4G5/2 state and populate it. The energy level 4G5/2 get depopulate as the unstable Sm3+ ions relax to the nearest lying states 6H5/2, 6H7/2, 6H9/2 and 6H11/2 with the

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emission of fluorescence having wavelengths 565 nm (yellow), 602 nm (orange), 648 nm (orange reddish) and 712 nm (red) respectively [27]. These transitions are useful in colour displays, high density optical storage and medical diagnostics [28]. The emission peaks 6H5/2and7/2 appears to have two components due to Stark splitting of ionic levels. The emission spectrum shown in Fig. 2 for all prepared glass samples indicates that the samples exhibit strong emission at wavelength 602 nm in visible region. The energy level diagram indicating the observed transitions of Sm3+ ions in prepared glass samples have been presented in Fig. 3. Emission spectra observed for prepared glass samples doped with Sm3+ ions are similar to those reported for a number of other glass systems [3, 17]. The emission intensity gradually increases for glass 6

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samples with x = 0.5 to 1.5 and beyond x = 1.5 for glass sample with x = 2.0, the emission intensity get decreased. The increase in emission intensity for glass samples with x upto 1.5 wt% advocates the minor cross relaxation, i.e., the transfer of energy from excited state of Sm- ion by electric multipole interaction to neighbouring Sm-ion lying in the ground state is low [29]. The

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decrease in emission intensity with increase in Sm3+ ions concentration beyond 1.5 wt% is due to concentration quenching in Sm3+ ions occurred because of mutual Sm3+-Sm3+ interaction at higher concentration and increase in non- radiative energy transfer through cross relaxation and resonant energy channels [2].

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3.5. Radiative and Laser Properties

Judd-Ofelt parameters (Ωt=2,4,6) are used to calculate the radiative properties of Sm3+ ions doped in BaO-ZnO-B2O3 glasses corresponding to 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and G5/2 → 6H11/2 transitions [3, 17]. The spontaneous transition probability (AR) for a transition from

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initial state ψj to its lower lying final state ψ'j' can be obtained from the following relation 64π 4 n(n 2 + 2) 2 AR (ψ j,ψ ' j ') = Sed 3hλ 3 (2 J + 1) 9

(10)

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where Sed is the electric dipole line strength and is given by

Sed = e 2

∑

t = 2,4,6

Ωt | 〈ψ j || U t || ψ ' j '〉 |2

(11)

The term (n(n2+2)2/9) is the local field correction for the electric dipole transitions. The total

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radiative transition probability AT (ψj) is obtained by the summation of the AR (ψj, ψ'j') terms

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calculated over all terminal levels and is written as

AT (ψ j ) = ∑ AR (ψ j,ψ ' j ')

(12)

The radiative lifetime, τR (ψj) of an emitting state is given by the reciprocal of the total radiative transition probability AT (ψj) for all transitions from this state and is expressed as

τ R (ψ j ) = 1/ AT (ψ j )

(13)

The fluorescence branching ratio (βR) for different emissions with same initial level can be calculated from the transition probabilities by using following equation

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β R (ψ j ,ψ ' j ') = AR (ψ j ,ψ ' j ') / AT (ψ j )

(14)

The stimulated emission cross-section, σe(ψj, ψ'j'), between the emission levels ψj and ψ'j' having a probability of AR (ψj, ψ'j') is given by

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σ e (ψ j ,ψ ' j ') = (λ p4 / 8π cn 2 ∆λ eff ) AR (ψ j,ψ ' j ')

(15)

where λp is the transition peak wavelength and ∆λeff is the effective line width determined by the dividing the area of the emission band by its average height. The estimated values of radiative

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transition probabilities (AR), branching ratio (βR), stimulated emission cross-sections (σe), total radiative transition probability (AT) and radiative lifetime (τR) are listed in Table 4 for all the prepared glass samples. The values of AT obtained by summing the probabilities of all the four

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individual transitions, are observed to decrease with the increase in Sm3+ concentration in the base glass matrix. The radiative transition probability is controlled by the crystal field parameter, which is related to the asymmetry in the ligand field around the rare earth ions [30]. The higher distortion in the cage surrounding rare earth ions results in lowering the site symmetry that leads to an increase in transition probability [30]. As discussed above that the

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increase in Sm3+ ion concentration in the present base glass matrix decreases the value of Ω2 and increases the symmetry around the rare earth ion sites that leads to decrease in the values of AT. Also the increase in Sm3+ ions concentration is at cost of decrease in BaO, ZnO and B2O3 concentration in the host glass matrix which is responsible for decrease of AT. Since the addition

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of ZnO to the borate glass network results in decrement of its phonon energy [31] that increases radiative transition probability (AT) but the decrease in ZnO concentration may lead to decrease in the values of AT. In addition to this, the glasses containing BaO are expected to show minimal

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non-radiative losses due to coupling of Sm3+ ions with low energy phonon [32]. However, the decrease in BaO concentration with increase in Sm3+ ions content in base glass matrix may results in increase in non-radiative losses with decrease in radiative transition probability (AT). The value of radiative lifetime (τR) of metastable level 4G5/2 listed in Table 4, infers its efficiency to store energy and depends on the transition probability which in turn depends upon the local field strength around the rare earth ions. Perusal of the data presented in Table 4 reveals that the value of τR increases with increase in concentration of Sm3+ ions in the base glass matrix. Besides the dependence of radiative lifetime of metastable level on the transition probabilities, it also 8

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depends upon ion-ion interaction between rare earth ions. The increase in interaction between the Sm3+-Sm3+ ions leads to increase in radiative lifetime [33]. As explained above that the increase in concentration of Sm3+ ions in the present host glass matrix lead to decrease in ion-ion separation and therefore the interaction between Sm3+-Sm3+ ions increases that results in increase

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in the values of radiative lifetime.

The fluorescence branching ratio (βR) obtained from the Eq. (14), is an important optical parameter to evaluate the lasing power of a transition [2]. The values of βR of four emission transitions observed in the emission spectra in wavelength range 500 to 750 nm are listed in

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Table 4 for all prepared glass samples. It is observed that the value of βR is highest for the transition 4G5/2→ 6H7/2 followed by the transition 4G5/2→ 6H9/2. The observed four fluorescence transitions (6H5/2, 6H7/2, 6H9/2, 6H11/2) in the emission spectra account for nearly 92% of the total

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fluorescence from the 4G5/2 level. The value of branching ratio greater than 0.50, makes the prepared glass samples the suitable material for laser emission corresponding to transition4G5/2→ 6

H7/2 lying in visible region. The parameter stimulated emission cross-section (σe) signifies the

rate of energy extraction from the optical material. The material to have low threshold and a high gain for laser application needs to have large stimulated emission cross-section. The value of σe 6

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for the transition 4G5/2 → 6H9/2 is observed to be higher and followed by the transition 4G5/2 → H7/2. The stimulated emission cross-section is found to decrease with increase in Sm3+ ion

concentration in the present host glass matrix and its value is highest for glass sample BZBSm0.5 for transition 4G5/2 → 6H9/2 making it a suitable candidate for developing visible and fibre optics

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amplifiers. The values of σe observed for prepared glass samples have been compared with the values reported in literature for other glass systems [3, 7, 17]. The stimulated emission crosssection is influenced by the intensity parameter Ω2 that explains the local environment around

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rare earth ions. The value of Ω2 decreases with the increase in Sm3+ concentration in the present host glass matrix that leads to diminution of the values of σe [30, 34]. For any optical material to be used in optical amplifiers and lasers, it should have high value of σe. However, the values of σe observed for the present host matrices are observed to vary in opposite direction. Conclusions

Sm3+ ion doped glass samples with compositions xSm2O3- (100-x)[0.1BaO-0.4ZnO-0.5B2O3]; x = 0.5, 1.0, 1.5 and 2.0 are prepared using melt quench technique. Optical absorption and emission spectra have been recorded at room temperature for the prepared glass samples. The 9

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spectroscopic properties of Sm3+ions doped glasses have been analyzed using J-O theory. The observed small value of rms deviation for experimental and calculated oscillator strength indicates the validity of J-O theory and the goodness of fitting procedure. The decrease in intensity parameter Ω2 indicates the decrease in covalent nature of rare earth- oxygen bond in the

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host glass matrix with the increase in concentration of Sm3+ ions. The emission spectra have been analyzed in details to identify the use of the prepared glasses for laser transitions of interest. Intense visible emission is observed for the Sm3+ doped barium zinc borate glasses under the excitation of wavelength 402 nm. Self quenching of Sm3+ ions in the glass matrix starts for glass

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sample with x > 1.5 that leads to decrease in the intensity of observed emission spectral lines. Radiative parameters such as transition probability (AR), radiative lifetime (τR), branching ratio

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(βR) and stimulated emission cross-sections (σe) of luminescent levels observed in emission spectra have been estimated. The stimulated emission cross- section is observed to decrease with increase in concentration of Sm3+ ions. Among the prepared glasses samples doped with Sm3+ ions, the glass sample with x = 0.5 have higher value of stimulated emission cross- section for transition lying in visible region suggests the use of BZBSm0.5 glass sample for photonic applications.

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Acknowledgments

Authors are thankful to UGC (SAP), New Delhi and DST (FIST), New Delhi and DRDO (IRDE) Dehradun for financial assistance in the form of grants. One of the authors (Kirti Nanda) is thankful to UGC for providing BSR Fellowship.

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Figure Captions:-

Fig. 1. Absorption spectra for glass samples xSm2O3- (100-x)[0.1BaO-0.4ZnO-0.5B2O3] with x = 0.5, 1.0, 1.5 and 2.0.

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Fig. 2. Emission spectra of glasses xSm2O3- (100-x)[0.1BaO-0.4ZnO-0.5B2O3]; x = 0.5, 1.0, 1.5 and 2.0.

Fig. 3. Energy level diagram indicating absorption and emission transitions of Sm3+ ions doped

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Tables:-

BZBSm0.5 1.79 17.73 7.14 1.443

BZBSm1.0 3.58 14.08 5.67 1.444

BZBSm1.5 5.36 12.31 4.96 1.524

BZBSm2.0 7.12 11.20 4.51 1.563

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Physical Parameters N (1020 ions cm-3) ri (Å) rp (Å) n[15]

Transitions

359 373 402 460 476 944 1077 1224 1369 1470 1522 1584 δrms

4

D3/2 P7/2 6 P3/2 4 I13/2 4 I11/2 6 F11/2 6 F9/2 6 F7/2 6 F5/2 6 F3/2 6 H15/2 6 F1/2

BZBSm0.5 fexp fcal 10.42 5.64 8.24 8.62 2.58 3.38 0.56 0.52 2.12 0.22 0.60 0.60 0.61 0.59 0.80 0.77 0.51 0.53 0.39 0.38 0.37 0.39 0.17 0.21 ±4.38 × 10-5

Oscillator Strength (10-5) BZBSm1.0 BZBSm1.5 fexp fcal fexp fcal 3.97 4.43 2.59 2.07 3.38 4.20 2.45 2.04 1.19 1.46 1.13 1.24 0.32 0.38 0.36 0.41 1.12 0.98 0.91 0.91 0.29 0.33 0.23 0.30 0.41 0.42 0.37 0.39 0.58 0.60 0.59 0.59 0.36 0.42 0.34 0.34 0.27 0.30 0.26 0.28 0.25 0.32 0.27 0.30 0.10 0.10 0.10 0.09 ±1.37 × 10-5 ±1.19 × 10-5

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λ (nm)

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Table 1. Concentration of Sm3+ ions (N), inter nuclear distance (ri), polaron radius (rp), and linear refractive index (n) of xSm2O3- (100-x) [0.1BaO-0.4ZnO-0.5B2O3] glasses with x = 0.5, 1.0, 1.5 and 2.0.

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BZBSm2.0 fexp fcal 2.70 2.07 1.99 1.02 0.97 1.24 0.17 0.26 0.65 0.66 0.19 0.23 0.33 0.29 0.51 0.49 0.29 0.25 0.23 0.26 0.26 0.21 0.13 0.11 ±0.11 × 10-5

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Table 2. Experimental (fexp) and calculated oscillator strengths (fcal) of Sm3+ doped BaO-ZnOB2O3 glasses.

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J-O Parameters (10-20 cm2)

BZBSm0.5 BZBSm1.0 BZBSm1.5 BZBSm2.0

Ω2

Ω4

Ω6

7.31 2.04 1.49 1.07

3.48 1.50 1.20 1.17

5.91 4.84 4.26 2.98

χ = Ω4/ Ω6

0.59 0.31 0.28 0.39

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Host matrix

Radiative parameters G5/2 →6H5/2 λp AR βR σe

BZBSm0.5 565 5.78 0.034 0.260

BZBSm1.0 565 2.34 0.024 0.102

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G5/2 →6H7/2

λp AR βR σe

602 71.93 0.426 3.310

4

G5/2 →6H9/2

λp AR βR σe

648 75.97 0.450 4.264

4

G5/2 →6H11/2

λp AR βR σe

BZBSm2.0 565 3.31 0.031 0.072

602 54.53 0.559 2.421

602 55.67 0.578 2.113

602 45.36 0.419 1.708

648 30.48 0.312 1.621

648 28.12 0.292 1.323

648 50.72 0.468 1.937

711 15.21 0.090 0.736

711 10.27 0.105 0.532

711 10.33 0.107 0.483

711 8.88 0.082 0.243

AT τR

168.89 5.92

97.62 10.24

96.27 10.39

79.96 12.51

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BZBSm1.5 565 2.15 0.0223 0.514

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Table 3. Judd- Ofelt intensity parameters (Ω2, Ω4, Ω6) for different glass compositions xSm2O3(100-x) [0.1BaO-0.4ZnO-0.5B2O3]; x = 0.5, 1.0, 1.5 and 2.0.

Table 4. Emission band position (λp (nm)), radiative transition probability (AR (s-1)), branching ratio (βR), stimulated emission cross-section (σe× 10-22 (cm2)), total radiative transition probability (AT (s-1)) and radiative lifetime (τR (ms)) as a function of Sm3+ ions concentration in the host glass matrix BaO-ZnO-B2O3.

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Absorbance

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x = 0.5 x = 1.0 x = 1.5 x = 2.0

400

600

800

1000 nm)

1200

1400

1600

1800

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G

500

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4

G

6 5/2

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4

= 402 nm

6

5/2

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Emission intensity

ex

550

H

H

7/2

4

5/2

G

4

600

650 nm)

x = 0.5 x = 1.0 x = 1.5 x = 2.0 6

5/2

G

H

6 5/2

700

9/2

H

11/2

750

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Highlights

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Sm3+ ions doped BaO-ZnO-B2O3 glasses have been prepared by melt-quench technique.
Judd-Ofelt intensity parameters have been obtained from absorption spectra.
Radiative properties have been estimated from Judd-Ofelt theory.