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Luminescence methods for study of phase separation and crystallization in glasses
JoumalofLuminescence24/25(1981)lll—114 North-Holland Publishing Company
Ill
LUMINESCENCE METHODS FOR STUDY OF PHASE SEPARATION AND CRYSTALLIZATION IN GLASSES (*) H. Mack (**) and G. Boulon Physico-Chimie de Matériaux Luminescents, Université Lyon I, 43 Bd. du 11 Novembre 1918, 69622 Villeurbanne, France Renata Reisfeld (***) Department of Inorganic and Analytical Chemistry The Hebrew University of Jerusalem, Israel 4have been Phosphotungstate glasses by varying quantities prepared. Depending on thedoped relative concentration of of the Eu~ component and cooling rate, glassy phase or an ordered structure was obtained. The nature of th~surrounding medium was determined by site selective excitation of Eu3 probe ions. Striking dependence on the nature of the site was observed in a series of spectroscopic phenomena, for example: line shape of the 5D 7F 3 3-.- 1 transition of Eu Seri~sof glasses containing W0 2 , were prepared by melting3,theNa~O, mixtures around cooling either P205, atEu~~ and, 1000°C in someandcases, additional rapidly (during 5—6 seconds) or slowly (more than 15 seconds). The first series UO2 enabled to find the optimum concentration of WO 3 at which either ordered or glassy specimen were obtained, depending only on the conditions of preparation. In the lower concentration range: 50—69 weight per cent W03 , pure glassy material were obtained under all experimental conditions. At concentration higher than 70 s9nlples containing ordered material imbedded in the glassy medium were obtained k’). Based on these results the main optical measurements were performed on glasses based on 70 % W03 between weight per The second series contained 70 % W03, stochiometric3 ratio of 0.5—10 Na20:P2O5 correscent. third series, 1 % of U0 2 was added pondingIn totheNa2HPO4 and varying concentration of Eu to all mentioned above compositions. 2 Table 1 presents the compositions weight per cent of 4 glasses results of which are discussed: Code
3+
W0 3
0-0-1 70-0-1 70—1—1 70-0-7
-
70 70 70
P205 68.73 15.40 14.83 11.69
Na20 30.02 13.44 12.95 10.20
Eu 1 1 1 7
(*) (**)
U0 2 + 2 -
1 -
Oxygen 0.16 0.16 0.22 1.11
Table 1
Partially supported by U.S. Army grant, BAJA - 80 - C - 0188 Present address: Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, Israel. (***) Enrique Berman Professor of Solar Energy.
0 022—2313/81 /0000—0000/$02 .75 © North-Holland
II. allot?. a
112
at / I’lsua
wpowthsn mid csystalllmthuz In gkaws
The first sample (0—0—1) is a pure phosohate glass. The P~0..:Na,0ratio in that case Is corresponding to NaH 3PO... bandwidth cif’ a atRhodamine 4.4 K. (RH 590) The samples were excited3 ‘YAG, in thewith •i~levels of of Eu’’0.1using dye laser, ptmiped by Nd The excitation wavelength varied from 5775 it to 5800 it in intervals of 1 it. Whe crystallization occurred, the excitation maximtai was found to be at 5790 • 0.4 Fig. I presents~D:~F
1 emission of Eu’’ excited at 5790 it. Curve 1 belongs to glass 0—0—1:Eu’ in pure phosphate. This sample pertains the pure glassy state at all experimental conditions and is characterized by the high inhomogenous broadening (2). Curve 2 describes glass 70—0—1:1 Eu~’ in phosphotungstate on fast cooling and curve 3 descrIbes a sample with the same composition on slow cooling. Curve 4 is of glass 70-0—7. The results pictured in curve 4 are obtained independently of the cooling rate. The narrow peaks of curves 3 and 4 are characteristic of the crystalline material, in contrast to the inhomogenously broadening of the glassy material. Elsewhere it is proven by crystallographic methods that the composition of all crystallites were corresponding to EuPO4. 3 +containing) 1 ~ U0 Fig. 2 presents the emission spectra of a sample L Eu only: 70—0-1 (curve 1) and 70-1-1 (curve 2) - 1 Z Eu 1’ . Both samples were prepared on fist cooling. As can be seen from the sharpness and height of curve 2, U022 assists the crystallization of EuP0~ in the glassy state.
I
/
I h ‘ML~L-ET1 w
_____
S000
aro
•
MOO
5M0
Fig. 1: Emission spectra3 gf in phosphate and phosphotungsta~e 03~’F1transition of Eu glasses. Excitation at 5790 A 4.4K 1) 0—0—1; 2) 70—0—1 fast cooling; 3) 70—0-1 slow cooling; 4) 70—0-7.
550
500
MaO
7F in glasses.of Eu~’ + Fig.phosghotungstate 2: ‘Dr 1 transition I t Eu3 and I •‘~ ~u3 + I ~ U0 3’ . Excitation at 5790 A. 4.4K. 1) 70—0—1; 2) 70—1—1.
II. Mae/c ci at
/
Phase separation and erestalltzaoo,t in glasses
113
It should be noted that in all cases when the crystallites were formed, they were imbedded in the glassy material as can be seen from the background broadening in Figs. 1 and 2. In order to distinguish between the two phases, a site selective excitation was performed by changing the wavelength of the excitation light. The results of these measurements are presented in Fig. 3, where we see that only the excitation at 5790 ~ gives the sharp 3emission of the in the spectrum glassy state. crystallites, while other wavelengths excite the Eu A compatible picture was obtained by studying dynamical properties. The decay curves of the ~ state of Eu3 , when excited at 5790 ~, exhibits a simple exponential , typical to the crystallites, with a lifetime of 3.20 rn second. Other excitatioo~ result in a non-exponential behaviour of the decay curves, typical of the Lu3 in the glassy state, with shorter sean lifetimes. The results of the lifetimes obtained frors the straight initial portions of the decay curves are presented in Hg. 4.
6022
5952
5300
5850
5785
e.G
7F 5-’- 5 emission spectra on excitation 2 in Glass phosphotungstate. wavelength. 70-1-1; Eu~~ 4.4K. wa~elength: and UD2Exsitation 1) 5775 ~ 2) 5785 ~ 3) 5789 ~ 4) 5790 ~ 5) 5800
5790
5795
5855
0,5
Fig. 3: Dependence of 5D
Hg. 4: Dependence of decay time of ~D level of Eu3+ on excitation U0 4 in phosphotungstate. 4.4K.and wavelength. Glass 70-1-1, Eu~~ The22 value given is 2.3 (= ln 10) times the mean life-time.
In conclusion it was shown that by selective excitation of Eu~ into the 5D 0 state it is possible to distinguish whether the ion is situated in a crystallized or in an alternative glassy medium. REFERENCES (1) (2)
R. Reisfeld, H. Mack, A. Eisenberg and Y. Eckstein, 3. Electrochem. Soc. i22, 273, 1975. R. Reisfeld and C.K. Jhrgenson, Lasers and Excited States of Rare Earths. Springer, Berlin, 1977.
Ill
LUMINESCENCE METHODS FOR STUDY OF PHASE SEPARATION AND CRYSTALLIZATION IN GLASSES (*) H. Mack (**) and G. Boulon Physico-Chimie de Matériaux Luminescents, Université Lyon I, 43 Bd. du 11 Novembre 1918, 69622 Villeurbanne, France Renata Reisfeld (***) Department of Inorganic and Analytical Chemistry The Hebrew University of Jerusalem, Israel 4have been Phosphotungstate glasses by varying quantities prepared. Depending on thedoped relative concentration of of the Eu~ component and cooling rate, glassy phase or an ordered structure was obtained. The nature of th~surrounding medium was determined by site selective excitation of Eu3 probe ions. Striking dependence on the nature of the site was observed in a series of spectroscopic phenomena, for example: line shape of the 5D 7F 3 3-.- 1 transition of Eu Seri~sof glasses containing W0 2 , were prepared by melting3,theNa~O, mixtures around cooling either P205, atEu~~ and, 1000°C in someandcases, additional rapidly (during 5—6 seconds) or slowly (more than 15 seconds). The first series UO2 enabled to find the optimum concentration of WO 3 at which either ordered or glassy specimen were obtained, depending only on the conditions of preparation. In the lower concentration range: 50—69 weight per cent W03 , pure glassy material were obtained under all experimental conditions. At concentration higher than 70 s9nlples containing ordered material imbedded in the glassy medium were obtained k’). Based on these results the main optical measurements were performed on glasses based on 70 % W03 between weight per The second series contained 70 % W03, stochiometric3 ratio of 0.5—10 Na20:P2O5 correscent. third series, 1 % of U0 2 was added pondingIn totheNa2HPO4 and varying concentration of Eu to all mentioned above compositions. 2 Table 1 presents the compositions weight per cent of 4 glasses results of which are discussed: Code
3+
W0 3
0-0-1 70-0-1 70—1—1 70-0-7
-
70 70 70
P205 68.73 15.40 14.83 11.69
Na20 30.02 13.44 12.95 10.20
Eu 1 1 1 7
(*) (**)
U0 2 + 2 -
1 -
Oxygen 0.16 0.16 0.22 1.11
Table 1
Partially supported by U.S. Army grant, BAJA - 80 - C - 0188 Present address: Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, Israel. (***) Enrique Berman Professor of Solar Energy.
0 022—2313/81 /0000—0000/$02 .75 © North-Holland
II. allot?. a
112
at / I’lsua
wpowthsn mid csystalllmthuz In gkaws
The first sample (0—0—1) is a pure phosohate glass. The P~0..:Na,0ratio in that case Is corresponding to NaH 3PO... bandwidth cif’ a atRhodamine 4.4 K. (RH 590) The samples were excited3 ‘YAG, in thewith •i~levels of of Eu’’0.1using dye laser, ptmiped by Nd The excitation wavelength varied from 5775 it to 5800 it in intervals of 1 it. Whe crystallization occurred, the excitation maximtai was found to be at 5790 • 0.4 Fig. I presents~D:~F
1 emission of Eu’’ excited at 5790 it. Curve 1 belongs to glass 0—0—1:Eu’ in pure phosphate. This sample pertains the pure glassy state at all experimental conditions and is characterized by the high inhomogenous broadening (2). Curve 2 describes glass 70—0—1:1 Eu~’ in phosphotungstate on fast cooling and curve 3 descrIbes a sample with the same composition on slow cooling. Curve 4 is of glass 70-0—7. The results pictured in curve 4 are obtained independently of the cooling rate. The narrow peaks of curves 3 and 4 are characteristic of the crystalline material, in contrast to the inhomogenously broadening of the glassy material. Elsewhere it is proven by crystallographic methods that the composition of all crystallites were corresponding to EuPO4. 3 +containing) 1 ~ U0 Fig. 2 presents the emission spectra of a sample L Eu only: 70—0-1 (curve 1) and 70-1-1 (curve 2) - 1 Z Eu 1’ . Both samples were prepared on fist cooling. As can be seen from the sharpness and height of curve 2, U022 assists the crystallization of EuP0~ in the glassy state.
I
/
I h ‘ML~L-ET1 w
_____
S000
aro
•
MOO
5M0
Fig. 1: Emission spectra3 gf in phosphate and phosphotungsta~e 03~’F1transition of Eu glasses. Excitation at 5790 A 4.4K 1) 0—0—1; 2) 70—0—1 fast cooling; 3) 70—0-1 slow cooling; 4) 70—0-7.
550
500
MaO
7F in glasses.of Eu~’ + Fig.phosghotungstate 2: ‘Dr 1 transition I t Eu3 and I •‘~ ~u3 + I ~ U0 3’ . Excitation at 5790 A. 4.4K. 1) 70—0—1; 2) 70—1—1.
II. Mae/c ci at
/
Phase separation and erestalltzaoo,t in glasses
113
It should be noted that in all cases when the crystallites were formed, they were imbedded in the glassy material as can be seen from the background broadening in Figs. 1 and 2. In order to distinguish between the two phases, a site selective excitation was performed by changing the wavelength of the excitation light. The results of these measurements are presented in Fig. 3, where we see that only the excitation at 5790 ~ gives the sharp 3emission of the in the spectrum glassy state. crystallites, while other wavelengths excite the Eu A compatible picture was obtained by studying dynamical properties. The decay curves of the ~ state of Eu3 , when excited at 5790 ~, exhibits a simple exponential , typical to the crystallites, with a lifetime of 3.20 rn second. Other excitatioo~ result in a non-exponential behaviour of the decay curves, typical of the Lu3 in the glassy state, with shorter sean lifetimes. The results of the lifetimes obtained frors the straight initial portions of the decay curves are presented in Hg. 4.
6022
5952
5300
5850
5785
e.G
7F 5-’- 5 emission spectra on excitation 2 in Glass phosphotungstate. wavelength. 70-1-1; Eu~~ 4.4K. wa~elength: and UD2Exsitation 1) 5775 ~ 2) 5785 ~ 3) 5789 ~ 4) 5790 ~ 5) 5800
5790
5795
5855
0,5
Fig. 3: Dependence of 5D
Hg. 4: Dependence of decay time of ~D level of Eu3+ on excitation U0 4 in phosphotungstate. 4.4K.and wavelength. Glass 70-1-1, Eu~~ The22 value given is 2.3 (= ln 10) times the mean life-time.
In conclusion it was shown that by selective excitation of Eu~ into the 5D 0 state it is possible to distinguish whether the ion is situated in a crystallized or in an alternative glassy medium. REFERENCES (1) (2)
R. Reisfeld, H. Mack, A. Eisenberg and Y. Eckstein, 3. Electrochem. Soc. i22, 273, 1975. R. Reisfeld and C.K. Jhrgenson, Lasers and Excited States of Rare Earths. Springer, Berlin, 1977.