OPTICAL PROPERTIES OF Cr3+ ION IN LaMgAl11O19 and La1-x Ndx MgAl11O19

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HAL Id: jpa-00226938

https://hal.archives-ouvertes.fr/jpa-00226938

Submitted on 1 Jan 1987

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

OPTICAL PROPERTIES OF Cr3+ ION IN LaMgAl11O19 and La1-x Ndx MgAl11O19

B. Viana, V. Poncon, C. Garapon, A. Lejus, D. Vivien, G. Boulon

To cite this version:

B. Viana, V. Poncon, C. Garapon, A. Lejus, D. Vivien, et al.. OPTICAL PROPERTIES OF Cr3+

ION IN LaMgAl11O19 and La1-x Ndx MgAl11O19. Journal de Physique Colloques, 1987, 48 (C7),

pp.C7-505-C7-507. �10.1051/jphyscol:19877120�. �jpa-00226938�

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JOURNAL DE PHYSIQUE

C o l l o q u e C7, s u p p l 6 m e n t a u n 0 1 2 , Tome 4 8 , d k c e m b r e 1 9 8 7

OPTICAL PROPERTIES OF

cr3

⁺ ION IN LaMgAl, 0, and La, - Ndx MgAl,

,

^0,

,

B. VIANA, V. PONCON*, C. GARAPON*, A.M. LEJUS, D. VIVIEN a n d G. BOULON*

Chimie Apppliquee de 1'Etat Solide, ENSCP, 11, Rue Pierre et Marie Curie, UA 302, F-75231 Paris Cedex 0 5 , France

* p h y s i c o - ~ h i m i e des Materiaux Luminescents, Universite claude Bernard, Lyon I , UA-442, 4 3 , Bd du 11 novembre 1918,

F-69622 Villeurbanne Cedex, France

Abstract

Lanthanum-magnesium hexaaluminate LaMgAl Olg w i t h magnetoplumbite-like s t r u c t u r e i s a remarkable good laser h o s t f o r Ndsi i o n s (LNA). I n t h i s s t u d y

cr3+

i o n s are introduced as an a c t i v a t o r (LaMsA111-&rfi19) o r as a s e n s i t i z e r

( L a l - ~ ~ l 1 0 1 9 ) i n t h i s matrix. ESR and o p t i c a l s p e c t r a o f L a M @ ~ l ~ ~ _ f i r g ~ ~ c r y s t a l s r e v e a l 3 k i n d s o f s i t e s for

cr3+

: ( 4 f ^{), (}2 a ) and ⁽1 2 k ) . The presence o f

Br2 -

^?Ti2 broad band fluorescence makes t h i s m a t e r i a l a p o s s i b l e candidate f o r a r e d o r IR e m i t t i n g v i b r o n i c laser. O p t i c a l p r o p e r t i e s o f L a l - ~ g A l l l - y C r y O 1 9 r e v e a l t h a t both r a d i a t i v e and non-radiative cr3+

-

^~ ^denergy t r a n s f e r s o c c u r ^~ ⁺ i n t h i s material. T h i s allows t o i n c r e a s e t h e l a s e r emission r a t i o compared w i t h s i n g l e doped LNA.

I n t r o d u c t i o n

Lanthanum-magnesium hexaaluminate LaMgAlllOlg w i t h magnetoplumbite like s t r u c t u r e ( 1 ) is a remarkable good h o s t f o r laser m a t e r i a l s . Doped with ~ d i t ~ + forms t h e INA (Lal-&#@ll1Ol9) a new performant IR l a s e r m a t e r i a l (2 ). T h i s p a p e r d e a l s w i t h t h e o p t i c a l p r o p e r t i e s of LaMgAlllOlg doped w i t h cr3+ a c t i n g

-

e i t h e r as a n a c t i v a t o r i n LaMgAll1_firfilg

-

o r a s a s e n s i t i z e r i n Lal-#d+qAll1-+rfll9.

Iarge rod-shaped s i n g l e c r y s t a l s of t h e s e 2 k i n d s of m a t e r i a l s are obtained by t h e flame fusion method. T h e i r s t r u c t u r e is hexagonal with space group P63/~mc (magnetoplumbite t y p e ) . They e x h i b i t a cleavage along ( 0 0 1 ) p l a n e s . O p t i c a l measurements a r e performed on cleavage p l a t e l e t s .

*

ESR s t u d i e s a r e c a r r i e d o u t i n t h e 120-300 K range. Angular v a r i a t i o n o f t h e s p e c t r a r e v e a l s t h a t cr3+ i o n s are mainly l o c a l i z e d i n t o t h e ( 4 f ) a n t i p r i s m s , a few o f them being s i t u a t e d i n (12 k ) octahedra. S m a l l s a t e l l i t e s f l a n k i n g t h e c e n t r a l ESR l i n e a r e due t o Cr-Cr p a i r s i n ( 4 f ) - ( 4 f ) s i t e s . T h e i r i n t e n s i t y i n c r e a s e s with chromium c o n c e n t r a t i o n .

*

_TheDq parameter obtained from a b s o r p t i o n s p e c t r a is lower t h a n f o r ruby, h i g h e r t h a n f o r GSGG and almost i d e n t i c a l t o that o f a l e x a n d r i t e (BeA1204:Cr).

T h i s may a l l o w t o observe t h e f l u o r e s c e n t t r a n s i t i o n s both from 2~ and 4 ~ 2 l e v e l s

( 4 ) .

*

Fluorescent s p e c t r a ( e x c i t a t i o n A = 532 tun) were performed between 4K and 295K ( s e e f i g . 1 ) . They e x h i b i t , on t h e s h o r t wavelengths s i d e 2~

- ^4R2

narrow l i n e s r e v e a l i n g t h e e x i s t e n c e , from t h e i r r e s p e c t i v e wavelength 695.3 nm, 688.6 nm and 691.5 nm, of 3 k i n d s o f sites f o r

cr3+:

( 4 f ) t r i g o n a l a n t i p r i s m (main s i t e ) b u t a l s o ( 2.3) r e g u l a r and ( 12 k ) d i s t o r t e d octahedra, both with low occupancy r a t i o .

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19877120

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J O U R N A L DE PHYSIQUE

Figure 1

FlUOreSCenCe spectrum o f cr3+ i n LaMgA111-,@+19

One observes a l s o t h e 4 ~ 2

-

^{4 ~ 2}broad band emission r e s p o n s i b l e o f t h e long t a i l o f t h e fluorescence spectrum toward t h e long wavelengths. S a t e l l i t e l i n e s around 720 nm a r e due both t o v i b r o n i c s i d e bands and Cr-Cr pairs t r a n s i t i o n s .

*

Chromium fluorescence decays were followed u s i n g a t i m e scale corresponding t o t h e 2~

-

^{4 ~ 2}t r a n s i t i o n ( a few ms). The fluorescence decays are e x p o n e n t i a l a t 4.4 K for low cr3+ c o n c e n t r a t i o n b u t n o t when t h e c o n c e n t r a t i o n i n c r e a s e s . From t h e s e r e s u l t s it t u r n s that t h e presence of a broad band luminescence extending towards t h e long wavelengths i n LaMgklll-&rfllg makes t h i s m a t e r i a l a p o s s i b l e c a n d i d a t e f o r red o r n e a r I R e m i t t i n g v i b r o n i c l a s e r .

I n s i n g l e doped neodymium l a s e r materials, the continuous emission spectrum of pumping lamp and t h e narrow a b s o r p t i o n bands o f Nd3+ a r e not w e l l matched. The i n t r o d u c t i o n i n t h e ~ ddoped m a t r i x o f a second i o n e x h m i t i n g ~ +

large a b s o r p t i o n bands i n t h e v i s i b l e range ( l i k e cr3+ i o n s ) allows t o s e n s i t i z e t h e fluorescence of Nd3+ ( I n G S G G : N ~ ~ + t h e codoping by cr3+ l e a d s t o a y i e l d o f 4.5 % compared t o t h e s i n g l e doped YAG:Nd c r y s t a l (about 1 , 5 %) ( 5 ) ). cr3+

-

^Nd3$

t r a n s f e r s are demonstrated i n t h e hexaaluminate from Nd3+ fluorescence e x c i t a t i o n spectrum and o p t i c a l p r o p e r t i e s o f chromium ( i n t e n s i t i e s measurements and

fluorescence i n t e n s i t y decay on s i n g l e doped and ccdoped Samples).

x

z

0 1.22 m s F i g u r e 2

Fluorescence decays and 0.01 1.37 m s lifetimes of Cr3+ in

*-#d$@l~. 8sCr0. 11°19

0.1 0.58ms 0.15 0.65 m s 0.2 O.48ms

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T r a n s f e r occurs by radiative m o d e because the dips i n t h e cr3+ e m i s s i o n broad band c o r r e s p o n d t o t h e Nd3+ absorption l i n e s .

T r a n s f e r occurs too by non radiative mode, the integrated fluorescence of

cr3+

i o n is d e c r e a s i n g i n codoped samples. The cr3+ fluorescence decays are non

e x p o n e n t i a l a n d get faster as ~ d concentration increases ~ + ( s e e F i g . 2 ) .

Mean p a r a m e t e r s are used t o characterize the transfer : t h e transfer efficiency is high ( 7 3 % for L a g ~ $ J d o ~ 1 M g A 1 1 0 ~ 8 9 C r ~ : 0 . ~ ~ 0 1 g ) b u t the t i m e transfer reachs a h i g h value ^{( 2 1 0}PS for L % . $ J d 0 . 1 M ~ A 1 ~ ~ . ~ 9 C r ~ . ~ ~ 0 ~ ~ ) .

F r o m these r e s u l t s i t t u r n s t h a t cr3+ s e n s i t i z e s the Nd3+ fluorescence i n t h e LaM+llOlg matrix h o w e v e r the transfer is e f f i c i e n t b u t very s l o w . The

consequence is that the coactivation w i l l be much m o r e e f f i c i e n t i n CW operation than i n Q-switched o n e .

R e f e r e n c e s

(1) A. KAHN, A.M. LEJUS, M. MADSAC, J. THERY, D. VIVIEN, J . C . BERNIER J. Appl. P h y s .

52

11 ( 1 9 8 1 ) .

M. GASPERIN, M.C. SAINE, A. KAHN, F. LAVILIE, A.M. LEJUS J. Solid. State Chem. 6 1 ( 1 9 8 4 ) .

( 2 ) M. LEDLC, L.D. SCHEARER, D. VIVIEN, A.M. LEJUS, J. THERY I . E . E . E . J. Q u a n t u m E l e c t r o n , 713 ( 1 9 8 6 ) .

( 3 ) B. VIANA, A.M. LEJUS, D. VIVIEN, V. PONCON, G. BOULON J. Solid State Chem. ( i n press ⁾

.

( 4 ) J . C . WALLING, O.G. PETEFSON, H.P. JENSSEN, R.C. MOIUUS, E.W.O'DELL I . E . E . E . J. QuantWIl E l e c t r o n

eE-16

1 3 0 2 ( 1 9 8 0 ) .

( 5 ) M.I. DEXCHOUK, A.K. GILEV, A.M. ZABAZNOV, V.P. MIKHAILOV, A.A. STAVROV, A.P. SHKADAREWICH

O p t i c s Conon.

55

2 0 7 ( 1 9 8 5 ) .

OPTICAL PROPERTIES OF Cr3+ ION IN LaMgAl11O19 and La1-x Ndx MgAl11O19

HAL Id: jpa-00226938

https://hal.archives-ouvertes.fr/jpa-00226938

Submitted on 1 Jan 1987

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.