Spectral analysis of Sm3+ and Dy3+: B2O3–ZnO–PbO glasses

ARTICLE IN PRESS

Physica B 373 (2006) 100–106 www.elsevier.com/locate/physb

Spectral analysis of Sm3+ and Dy3+: B2O3–ZnO–PbO glasses G. Lakshminarayana, S. Buddhudu Department of Physics, Sri Venkateswara University, Tirupati 517 502, India Received 1 October 2005; received in revised form 1 November 2005; accepted 2 November 2005

Abstract This paper reports on the spectral results of Sm3+ or Dy3+ (1.0 mol%) ions-doped B2O3–ZnO–PbO (BZP) glasses. Measurements of X-ray diffraction (XRD), differential scanning calorimeter (DSC) profiles of these rare-earth ion-doped glasses have been carried out. From the DSC thermograms, glass transition (Tg), crystallization (Tc) and melting (Tm) temperatures have been evaluated. Direct and indirect optical band gaps have been calculated based on the glasses UV absorption spectra. These glasses have shown strong absorption bands in the near-infrared (NIR) region and their oscillator strengths have been computed. Emission bands of 4G5/2-6H5/2 (564 nm), 4 G5/2-6H7/2 (602 nm), 4G5/2-6H9/2 (647 nm) and 4G5/2-6H11/2 (710 nm) for the Sm3+: glass, with excitation at 6H5/2-4I9/2 (484 nm) have been recorded. Of them, 4G5/2- 6H7/2 (602 nm) has shown a bright emission. With regard to the Dy3+: glass, a bright fluorescent yellow emission at 576 nm (4F9/2-6H13/2) has been observed, apart from 4F9/2-6H15/2 (484 nm) and 4F9/2-6H11/2 (666 nm) emission transitions with excitation at 450 nm (6H15/2-4I15/2) excitation wavelength. Stimulated emission cross-sections of all the emission bands of Sm3+ and Dy3+: BZP glasses have been computed based on their measured Dl (FWHM) and measured lifetimes (tm). r 2005 Elsevier B.V. All rights reserved. PACS: 61.43.Fs; 78.55.
m; 78.55.
Hx; 78.60.
b Keywords: RE glasses; Optical analysis

1. Introduction Glasses based on heavy metal oxides (HMO) are becoming an important class of materials for optoelectronic applications [1–5]. The large mass, low field strength and high polarizability of lead gives some special significance to glasses that are developed. Lead oxide has the ability to form stable glasses over a wide range of concentrations due to its dual role, as glass modifier and as glass former. In our laboratory, we have recently studied the spectral properties of transition metal ions, such as Cu2+ [6] and Mn2+, Co2+ and Ni2+ [7] ions-doped B2O3–ZnO–PbO (BZP) glasses. In the present work, we have undertaken these BZP glasses with Sm3+ and Dy3+ as the dopant rare-earth ions. Rare-earth ion-doped glasses have received more attention because of their potential applications towards the development of visible and nearCorresponding author. Tel.: +91 877 22616111; fax: +91 877 2249666.

E-mail addresses: [email protected], [email protected] (S. Buddhudu). 0921-4526/$ - see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.physb.2005.11.143

infrared (NIR) optical lasers and amplifiers, sensors and optical switching, etc. [8–20]. Earlier, it is shown that the spectrum of Sm3+ ions in lead borate glasses, the heavy metal lattices, enhance the fluorescence yield of the rare earth due to their low phonon energy and give a chance of observing lasing emission [18]. Because of the fact that these two rare-earth (Sm3+ or Dy3+) ions show line-like and more intense absorption bands in the NIR region and interesting emission trends in the reddish-orange and yellow wavelength regions; these ions have been incorporated into these BZP glasses, to understand the glass composition effects on the optical analysis of Sm3+ and Dy3+ glasses systematically, following the standard procedures. 2. Experimental studies 2.1. Glasses preparation Following are the Sm3+ or Dy3+ ions-doped lead-based zinc borate (BZP) glasses that are developed for the present

ARTICLE IN PRESS G. Lakshminarayana, S. Buddhudu / Physica B 373 (2006) 100–106

work, along with a reference glass: 45B2 O3 25ZnO2ð50
xÞPbO
xSm2 O3 45B2 O3 25ZnO2ð50
xÞPbO
xDy2 O3

101

Table 1 Physical properties of Sm3+ and Dy3+ (1.0 mol%): 45B2O3–5ZnO–49PbO glasses Physical quantities

and

Data Sm3+ (1.0 mol%)

Dy3+ (1.0 mol%)

374.811 5.774 2.1582 0.9278 1.9175 4.7589 0.8159 2.60 2.49 359.3 519.7 829.0 160.4 0.518

375.054 5.775 2.1584 0.9272 1.9179 4.760 0.8155 2.57 2.47 407.3 598.2 865.2 190.9 0.715

45B2 O3 25ZnO250PbO ðreference glassÞ where x ¼ 1.0 mol% in both cases. The starting materials used in the present work were reagent grade of H3BO3, ZnO, Pb3O4, Sm2O3 and Dy2O3. All weighed chemicals were powdered finely and mixed thoroughly before each batch (10 g) was melted in ceramic crucibles in an electrical furnace for an hour, at 950 1C. These melts were quenched in between two brass plates to obtain 2–3 cm diameter optical glass discs of 0.3 cm thickness. These glasses thus obtained were all annealed at 200 1C for an hour, to remove thermal strains in the glasses. Due to high lead content in the composition of host glass, it appeared in transparent yellow colour. Fig. 1 presents the photograph of a reference glass, Sm3+ and Dy3+ (1.0 mol%) ions-doped glasses. 2.2. Measurements Glass densities were measured with toluene as an immersion liquid from the Archimedes’s principle. Abbe refractometer was used to measure the glass refractive index at Na (589.3 nm) lamp wavelength. Powder X-ray diffraction (XRD) spectra were obtained on Shimadzu XD 3A diffractometer with a Ni filter and Cu-Ka (1.5418 A˚) radiation with an applied voltage of 30 KV and 20 mA anode current calibrated with Si at the rate of 21 min
1. Differential scanning calorimeter (DSC) profiles were carried out on Netzsch STA 409C in the temperature range 301–1200 1C, at the rate of 10 1C min
1, under N2-gas atmosphere. The optical absorption spectra (400–2500 nm)

Average molecular weight, M (g) Density, d (g/cm3) Refractive index, nd (589.3 nm) Number Density, N (ions/cm3)1020 Polaron radius, rp (A˚) Interionic distance, ri (A˚) Field strength, F (1016 cm
2) Direct optical band gap (eV) Indirect optical band gap (eV) Glass transition temperature, Tg (1C) Crystallization temperature, Tc (1C) Temperature of melting, Tm (1C) Glass stability factor, S ¼ Tc
Tg (1C) Hruby’s parameter, kgl ¼ ððT c
T g Þ=ðT m
T c ÞÞ

were measured on a Varian-Cary Win spectrometer. The excitation and emission spectra were obtained on a SPEX Fluorolog-2 Fluorimeter (Model II) with Data max software to acquire the data with a Xe-arc lamp (150 W) as the excitation source. A Xe-flash lamp with a phosphorimeter attachment was used to measure the lifetimes of the emission transitions of these glasses. Table 1 presents the physical properties of Sm3+ and Dy3+ ions-doped glasses. From the DSC profile, the values of Tg, Tc and Tm were evaluated and from these the values of glass stability factor (S) and Hruby’s parameter (Kgl) were calculated and the results are given in Table 1. The glass stability factors reveal that these glasses are more stable. Hruby’s parameter gives information on the stability of the glass against devitrification. 3. Results and discussion 3.1. Sm3+ glass

Fig. 1. Photograph of Sm3+ and Dy3+ (1.0 mol%) ions-doped glasses along with reference glass.

The XRD pattern of the glass (1.0 mol% Sm3+: 45B2O3–5ZnO–49PbO) is shown in Fig. 2, which confirms its amorphous nature. The DSC thermogram for the Sm3+: glass is shown in Fig. 3. From this profile, we have identified two crystallization peaks at 519.7 1C (Tc1), 592.8 1C (Tc2). Due to the high lead content in the host matrix, a high thermal stability was noticed with the glass; based on the Tg, Tc and Tm, as presented in Table 1. Both direct and indirect optical band gaps have been calculated from the UV absorption spectrum of Sm3+: glass, following the procedure given earlier [6], and the results are listed out in Table 1. The VIS–NIR absorption spectrum of Sm3+ ion is shown in Fig. 4, with strong absorption bands in the NIR region. The rare-earth ions

ARTICLE IN PRESS G. Lakshminarayana, S. Buddhudu / Physica B 373 (2006) 100–106 200

0.70

175

0.65

150

0.60

6

F7/2 1233 nm

6

F9/2 1080 nm Optical Density (a.u.)

Intensity (a.u)

102

125

100

6

F5/2 1380 nm

4

G5/2 568 nm

6

F3/2 1492 nm

0.55 6

0.50

75

0.45

50

0.40

6

F11/2 950 nm

1535 nm ( H 15/2 ) 6

F1/2 1594 nm

600

800

1000

1200

1400

1600

1800

6

H13/2 1983 nm

2000

2200

Wavelength (nm)

10

20

30

40

50

60

70

80

2θ θ (Degrees)

Fig. 4. VIS–NIR absorption spectrum of Sm3+: 45B2O3–5ZnO–49PbO glass.

Fig. 2. XRD spectrum of Sm3+: 45B2O3–5ZnO–49PbO glass. Table 2 Absorption transition 6 H5/2-

0.0

Tg o 359.3 C

Exo .

-0.5

(mW/mg)

-1.0

Tc1 o 519.7 C T c2

-1.5

O

592.8 C

Sm3+: glass 4 G5/2 6 F11/2 6 F9/2 6 F7/2 6 F5/2 6 F3/2 6 H15/2 6 F1/2 6 H13/2

Tm O

829.0 C

-2.0 -2.5

Absorption transition 6 H15/2-

-3.0 -3.5 0

200

400

600

800

1000

1200

Temperature (°C)

Fig. 3. DSC profile of the Sm3+: 45B2O3–5ZnO–49PbO glass.

are characterized by partially filled 4f shell which is shielded by 5s2 and 5p6 electrons. All transitions in the absorption spectrum of Sm3+ start from the ground state 6 H5/2 to the various excited states. The transitions observed in the absorption spectrum of Sm3+ are intra-configurational (f–f) transitions. The nine observed absorption bands are assigned to 6H5/2-4G5/2, 6F11/2, 6F9/2, 6F7/2, 6 F5/2, 6F3/2, 6H15/2, 6F1/2 and 6H13/2 at 568, 950, 1080, 1233, 1380, 1492, 1535, 1594 and 1983 nm, respectively [21]. The intensities of spectral lines are measured in terms of oscillator strengths using the relation fexp ¼ 4.32  10
9 R e(n)dn where e(n) is the molar extinction coefficient at the given wave number (cm
1). If the absorption band takes a Gaussian shape, the oscillator strength can be calculated by the half-width method when fexp ¼ 4.32  10
9 SDn, where

Dy3+: glass 6 F3/2 6 F5/2 6 F7/2 6 H7/2, 6F9/2 6 F11/2, 6H9/2 6 H11/2

Energy (cm
1)

Exp. osci. strength (fexp)  (10
6)

17605.6 10526.3 9260 8110.3 7246.4 6702.4 6514.6 6273.5 5043

0.10066 0.12834 0.64541 0.73786 0.61776 0.10688 0.01036 0.00426 0.06281

Energy (cm
1)

Exp. osci. strength (fexp) (  10
6)

13298 12563 11086 9124 7837 5949

0.07634 0.24872 0.30952 0.55541 1.5128 0.21237

Dn (cm
1) is the width of the band at half the peak intensity. Quite often, the bands R in glasses do not show a Gaussian shape, in such cases e(n)dn should be evaluated by measuring the area under the curve [22]. The oscillator strengths for measured absorption bands are given in Table 2. Fig. 5 presents (a) excitation and (b) emission spectra of Sm3+ glass. In the visible range, five excitation peaks are identified which are assigned to the electronic transitions of 6H5/2-4F7/2 at 403 nm, 6H5/2-(6p, 4p)5/2 at 418 nm, 6 H5=2 ! 4 G9=2 at 445 nm, 6H5/2-4I9/2 at 484 nm and 6 H5=2 ! 4 F3=2 at 528 nm. Only the prominent excitation at 484 nm has been selected for the measurement of emission spectrum of Sm3+: glass. When the 4I9/2 level (484 nm) of Sm3+ is excited, the initial population relaxes

ARTICLE IN PRESS G. Lakshminarayana, S. Buddhudu / Physica B 373 (2006) 100–106 70000

λemi:=602nm

484nm

60000

λexci:=484nm

103

602nm

60000 50000

Emis.Int. (a.u.)

Exci.Int. (a.u.)

50000

40000 445nm

30000

20000

418nm 403 nm

40000

30000

647 nm 564nm

20000

528nm

10000

10000 710nm

0

0 350

(a)

400

450

500

550

Wavelength (nm)

500

550

(b)

600

650

700

750

Wavelength (nm)

Fig. 5. (a) Excitation, (b) emission spectra of Sm3+: 45B2O3–5ZnO–49PbO glass.

21000

a: =1.581 ms (λemis=602 nm)) b: =1.425 ms (λ emis=647 nm))

17500

c: =1.133 ms ( λemis=564 nm))

a

d: =1.020 ms (λ emis=710 nm))

14000

Photon Counts

finally to the 4G5/2 level. Between 4I9/2 and 4G5/2 levels, there are several levels with smaller energy differences, which encourage their efficient non-radiative relaxation leading to the population of the 4G5/2 state. This state is separated from the next lower-lying 6F11/2 by about 7000 cm
1, which makes the multiphonon relaxation negligible. Thus, it could be stated that radiative transitions and relaxation by non-radiative energy transfer are the two main processes, which could finally depopulate the 4G5/2 state. The emission spectrum has exhibited four emission transitions, which are assigned to 4G5/2-6H5/2 (564 nm), 4 G5/2-6H7/2 (602 nm), 4 G5=2 ! 6 H9=2 (647 nm), 4G5/26 H11/2 (710 nm) transitions. Among these four emission bands, the transition 4 G5=2 ! 6 H7=2 (602 nm), has shown a strong emission. The Sm3+: glass shows a bright orangereddish emission under an UV source also. The transition 4 G5/2-6H7/2 with DJ ¼ 71 is a magnetic dipole (MD) allowed but it is electric dipole (ED) dominated, the other transition 4 G5=2 ! 6 H9=2 is purely an ED one [23]. Generally, the intensity ratio of ED to MD transitions has been used to measure the symmetry of the local environment of the trivalent 4f ions. The greater the intensity of the ED transition, the more the asymmetry nature [24]. In the present work, 4G5/2-6H9/2 (ED) transition of Sm3+ ions is more intense than 4G5/2-6H5/2 (MD) specifying the asymmetric nature of the glass host. We have measured the lifetimes of four emission transitions with the excitation wavelength (484 nm) and Fig. 6 presents the decay curves of these four emission transitions. The emission cross-section (sEp ) is an important parameter and its value signifies the rate of energy extraction from the optical material. By correlating the measured lifetimes (tm), the emission peak wavelength (lp), full-width at halfmaximum (FWHM, Dlp) from the recorded fluorescence spectrum and the refractive index measured at 589.3 nm (nd ¼ 2.1582), and the stimulated emission cross-section

With excitation at 484 nm b

10500

7000

c d

3500

0

1

2

3

4

5

6

7

8

Time (ms)

Fig. 6. Decay curves of the emission transitions of Sm3+: 45B2O3– 5ZnO–49PbO glass.

(sEp cm2 ) for all four emission transitions have been computed from the formula [25] l4p sEp ¼ Q 2 . 8 cnd Dlp tm The results are documented in Table 3. Fig. 7 describes the energy level scheme involved in the emission process with 484 nm as the excitation wavelength. 3.2. Dy3+ glass The XRD of the glass (1.0 mol% Dy3+: 45B2O3– 5ZnO–49PbO) is given in Fig. 8, which confirms the amorphous nature. The DSC thermogram for the Dy3+:

ARTICLE IN PRESS G. Lakshminarayana, S. Buddhudu / Physica B 373 (2006) 100–106

104

Table 3 Emission peak wavelengths (lp), full-widths at half-maximum (FWHM, Dlp), measured lifetimes (tm), stimulated emission cross-sections (sE) of different emission transitions lp (nm)

Dlp (nm)

(i) Sm3+: B2O3–ZnO–PbO glass measured with lexc ¼ 484 nm 4 G5/2-6H5/2 564 16 1.133 0.159 4 G5/2 -6H7/2 602 14 1.581 0.169 4 G5/2-6H9/2 647 18 1.425 0.195 4 G5/2-6H11/2 710 20 1.020 0.355 Orange/Red ratio (O/R) ¼ 2.449 (ii) Dy3+: glass measured with lexci ¼ 450 nm 4 F9/2-6H13/2 576 16 4 F9/2-6H15/2 484 24 Yellow/Blue ratio (Y/B) ¼ 2.170

80

sE (  1020)

tm (ms)

0.518 0.404

Intensity (a.u.)

Emission transitions

100

60

40

20

0.378 0.161

0 10

20

30

40

50

60

70

80

90

2θ θ (Degrees)

Fig. 8. XRD spectrum of Dy3+: 45B2O3–5ZnO–49PbO glass.

4

F7/2 6 4 ( P, P)5/2 4 4 G I9/2 9/2 4 G 4 7/2 F3/2 4 G5/2

710nm

602nm 647nm

56 4nm

Energy (cm -1 )10

3

403nm 418 nm 44 5nm 484 nm

12 6

F11/2,9/2,7/2,5/2,3/2

Exo.

NR

0.0

Tg 407.3 °C

-0.5

(mW/ mg)

25

-1.0

Tc 598.2 °C

Tm 865.2 °C

-1.5

6

H15/2 F 6 1/2 H13/2 6 H11/2 6 H9/2 6 H7/2 6 H5/2 6

568nm 950nm 1080 nm 1233nm 1380nm 1492 nm 1535 nm 1594 nm 1983 nm

0

-2.0

-2.5 0

200

400

600

800

1000

1200

Tempareture (°C)

Fig. 9. DSC profile of the Dy3+: 45B2O3–5ZnO–49PbO glass.

Fig. 7. Absorption, exci., emission energy levels scheme of Sm3+: BZP glass.

glass is shown in Fig. 9. The values of Tg, Tc and Tm have been identified from this profile and presented in Table 1. Both direct and indirect optical band gaps have been evaluated from the UV absorption spectrum of Dy3+: glass, and the values are given in Table 1. Fig. 10 presents the VIS–NIR absorption spectrum of Dy3+ ion with strong absorption bands in the NIR region. The bands are assigned from the ground state, 6H15/2. The transitions from the next excited state 6H13/2 may be ruled out due to thermalization as the energy gap between 6H15/2 and 6H13/2 is around 3000 cm
1. From Fig. 10 the levels of 6F3/2, 6F5/2, 6 F7/2, (6H7/2, 6F9/2), (6F11/2, 6H9/2) and 6H11/2 are well resolved [21]. The position and intensity of certain transitions of rare-earth ions are found to be very sensitive

to the environment around the ion. Such transitions are termed as hypersensitive transitions [26]. All known hypersensitive transitions obey the selection rule |DS| ¼ 0, |DL|p2, |DJ|p2 [26]. In the case of Dy3+ (4f9) ion, the hypersensitive transition (6F11/2, 6H9/2) is found to be more intense than the other transitions. Oscillator strengths have been measured for all these absorption bands and are presented in Table 2. Fig. 11(a) presents excitation, and (b) presents emission spectrum of Dy3+ ions. Excitation spectrum was measured by monitoring intense emission at 576 nm. There are four obvious excitation peaks from the excitation spectrum, and these are assigned to the electronic transitions with the ground level 6H15/2 to higher energy levels of Dy3+, i.e. 6H15/2-(4I13/2, 4F7/2) (388 nm), 6 H15/2-4G11/2 (423 nm), 6H15/2-4I15/2 (450 nm) and

ARTICLE IN PRESS G. Lakshminarayana, S. Buddhudu / Physica B 373 (2006) 100–106 6

H15=2 ! 4 F9=2 (470 nm) based on the energy levels reported earlier [21]. From these excitation transitions, only a prominent transition (450 nm) has been selected for the measurement of emission spectrum of Dy3+: glass. When the 4I15/2 level of Dy3+ is excited with 450 nm wavelength, though this level is within thermal excitation energy at room temperature, we do not get any fluorescence from this level. The next eigen state of Dy3+ is 4F9/2 whose energy from ground state is 20,660 cm
1. This state is separated from the next lower lying level (6F1/2) by about 6000 cm
1, what makes the multiphonon relaxation negligible inspite of high phonon energies of the host (_w1000 cm
1 ). It appears that only radiative transitions and relaxation by non-radiative energy transfer processes could be depopulating the 4F9/2 state [27]. The emission spectrum has shown three emission transitions, which are assigned to 4F9/2-6H15/2 (484 nm), 4F9/2-6H13/2 (576 nm) and 4F9/2-6H11/2 (666 nm) transitions. Among these

105

transitions, the transition 6F9/2-6H13/2 has shown bright yellow emission intensity i.e. a major part of the emission intensity is contained in the 4F9/2-6H13/2 transition. We have measured the lifetimes of yellow (576 nm) and blue (484 nm) emission transitions with the excitation at 450 nm. The lifetime of red (666 nm) emission transition could not be obtained due to its low emission intensity. Fig. 12 presents the decay curves of the emission transitions of the Dy3+: glass and with these measured lifetimes (tm), the emission peak wavelength (lp), full-width at half maximum (FWHM, Dlp) and the refractive index (nd ¼ 2.1584) measured at 589.3 nm, the stimulated emission crosssections (sEp cm2 ) have been calculated and are listed out in Table 3 and Fig. 13 describes the energy level scheme for the emission processes with the 450 nm excitation wavelength.

32000

a: =0.518 ms for λemi=576 nm) 0.60

b: =0.404 ms for λ emi=484 nm) 6

0.50

F3/2 752 nm 6 F5/2 796 nm

24000 Photon Counts (a.u)

Optical Density(a.u.)

0.55

(With excitation at 450 nm)

6

F11/2 , H9/2 1276 nm

6

6

F7/2 902 nm

0.45

6

6

H 7/2 , F9/2 1096 nm

16000

a

8000

0.40

6

H11/2 1681 nm

b

0.35

0 750

900

1050

1200

1350

1500

1650

0.0

1800

0.5

1.0

Fig. 10. VIS–NIR absorption spectrum of Dy3+: 45B2O3–5ZnO–49PbO glass.

28000

λemi:=576nm

λexc i:=450nm

450 nm

576 nm

21000

14000

470 nm

Exci.Int. (a.u)

21000

484 nm 14000

423 nm

7000

7000 388 nm 666 nm

0 300

(a)

350

2.0

2.5

3.0

Fig. 12. Decay curves of the emission transitions of Dy3+: 45B2O3– 5ZnO–49PbO glass.

28000

Exci.Int. (a.u)

1.5 Time (ms)

Wavelength (nm)

400

450

Wavelength (nm)

0

500

490

(b)

560

630

Wavelength (nm)

Fig. 11. (a) Excitation, (b) emission spectra of Dy3+: 45B2O3–5ZnO–49PbO glass.

700

ARTICLE IN PRESS G. Lakshminarayana, S. Buddhudu / Physica B 373 (2006) 100–106

106

26

4

4

I13/2, F7/2

as potential and interesting optical luminescent materials of technological importance.

4

G11/2 I15/2

4

576nm

666nm

F9/2

6

F1/2 F F5/2 6 F 6 7/2 H 6 5/2 6 ( H7/2, F9/2) 6 6 ( H9/2, F11/2) 6 H11/2 6

13

6 3/2

6

H13/2

6

752nm

796nm 902nm 1096nm 1276nm 1681nm

0

References

4

484nm

423nm 450nm 470nm

-1

Energy(cm )10

3

388nm

NR

H15/2

Fig. 13. Absorption, exci., emission energy levels scheme of Dy3+: BZP glass.

4. Conclusion In summary, it is concluded that we have successfully developed transparent, moisture-resistant and more stable (1.0 mol%) Sm3+ and Dy3+: 45B2O3–5ZnO–49PbO glasses for their optical characterization. From XRD, DSC profiles, glass nature and thermal properties have been understood. VIS–NIR absorption spectra of these glasses have been analyzed. Emission spectrum of Sm3+ glass has shown four emission transitions, 4G5/2-6H5/2 (564 nm), 4G5/2-6H7/2 (602 nm), 4G5/2-6H9/2 (647 nm) and 4G5/2-6H11/2 (710 nm) with excitation at 484 nm (6H5/24 I9/2) and Dy3+: glass has shown three emission transitions 4 F9/2-6H15/2 (484 nm), 4F9/2-6H13/2 (576 nm) and 4F9/ 6 6 2- H11/2 (666 nm) upon excitation at 450 nm ( H15/ 4 2- I15/2). Upon exposure to the UV rays, samarium and dysprosium glasses have shown bright reddish-range and yellow emissions, respectively, from their surfaces. We have measured the decay curves and also evaluated stimulated emission cross-sections of these emission bands of Sm3+ and Dy3+ glasses. Based on the results given in Tables 1–3 and different figures (Figs. 1–13), these could be suggested

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