TEMPERATURE DEPENDENCE OF MULTIPHONON ABSORPTION IN HIGHLY TRANSPARENT CUBIC ZIRCONIA

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TEMPERATURE DEPENDENCE OF

MULTIPHONON ABSORPTION IN HIGHLY TRANSPARENT CUBIC ZIRCONIA

B. Bendow, H. Lipson, R. Brown, R. Marshall, D. Billard, Subhabrata Mitra

To cite this version:

B. Bendow, H. Lipson, R. Brown, R. Marshall, D. Billard, et al.. TEMPERATURE DEPENDENCE

OF MULTIPHONON ABSORPTION IN HIGHLY TRANSPARENT CUBIC ZIRCONIA. Journal de

Physique Colloques, 1981, 42 (C6), pp.C6-140-C6-142. �10.1051/jphyscol:1981642�. �jpa-00221578�

JOURNAL DE PHYSIQUE

Colloque 66, suppZ6ment au nOl 2, Tome 42, de'cembre 1981 page C6-140

TEMPERATURE DEPENDENCE OF MULTlPHONON ABSORPTION I N HIGHLY TRANSPARENT CUBIC ZIRCONIA

B .

Bendow"),

Lipson, R.N. Brown, R.C. Marshall,

~ i l l a r d * and S.S.

~ i t r a * * ( ~ )

Solid State Sciences Division, Rome A i r Development Center, Hanscom AFB, MA 01731, U.S.A.

"Centre de Recherche sur l a Physique des Hautes Tempgratures,

N. R. S., 45045 Orle'ans Cedex, France

Y* Dept. of Electrical Engineering, University of Rhode Island, Kingston, R I 02881, U. S. A.

A b s t r a c t - We i n v e s t i g a t e multiphonon absorption i n t h e t h r e e t o f i v e phonon regime o f y t t r i a - s t a b i l i z e d c u b i c z i r c o n i a , over an extended range o f temperatures. The absorption vs. frequency curves a t f i x e d temperature a r e found t o d i s p l a y a n e a r l y exponential decrease t y p i c a l o f multiphonon a b s o r p t i o n i n o t h e r i o n i c c r y s t a l s . A t h e o r e t i c a l model f o r multiphonon absorption i s u t i l i z e d t o f i t t h e data over t h e f u l l range o f frequency and temperature i n v e s t i g a t e d , and good agreement i s obtained between theory and experiment. A s t r o n g suppression o f t h e temperature v a r i a t i o n o f a b s o r p t i o n i s observed a t h i g h frequency, which we a t t r i b u t e t o t h e temperature dependence o f t h e phonon spectrum i t s e l f . 1. I n t r o d u c t i o n - Cubic z i r c o n i a i s an o p t i c a l m a t e r i a l o f considerable i n t e r - e s t because o f i t s unique p r o p e r t i e s : namely, i t i s very hard, has a very h i g h m e l t i n g temperature, r e s i s t s chemical a t t a c k and i s an e x c e l l e n t i n s u l a t o r . It i s r e a d i l y doped w i t h various r a r e - e a r t h and t r a n s i t i o n - m e t a l i o n s t o p r o v i d e a wide range o f p o t e n t i a l laser-host m a t e r i a l s . The c r y s t a l s u t i l i z e d f o r t h i s study were produced a t RADC employing a r e l a t i v e l y new process c a l l e d " s k u l l m e l t i n g " , i n which t h e m e l t i s contained w i t h i n a s o l i d " s k u l l " o f i d e n t i c a l compositionl. This procedure minimizes d i f f i c u l t i e s w i t h r e a c t i o n and contamination encountered i n conventional c r u c i b l e - t y p e growth. Heating i s accomplished by c o u p l i n g RF energy t o zirconium metal placed i n t o t h e charge.

C r y s t a l s a r e f i n a l l y obtained by p r e f e r e n t i a l f r e e z i n g of t h e m e l t when t h e c r u c i b l e i s s l o w l y lowered through t h e c o i l . The y t t r i a - s t a b i l i e d c r y s t a l s o b t a i n e d i n t h i s way possess hardness - 1370 Knoop, d e n s i t y - ^{5.9 gm/cm3,}

thermal c o n d u c t i v i t y - .018 W/cm/OC and v i s i b l e r e f r a c t i v e index - 2.15-2.18.

The y t t r i a c o n c e n t r a t i o n t y p i c a l l y v a r i e s from around twelve t o t w e n t y - f i v e weight percent; t h e sample u t i l i z e d f o r t h e present study contained twenty weight percent y t t r i a .

2. Experimental - The a b s o r p t i o n c o e f f i c i e n t

i n t h e v i c i n i t y o f t h e I R edge was deduced from transmission data, obtained w i t h a Fourier spectrophotometer which was a p p r o p r i a t e l y m o d i f i e d f o r b o t h low temperature2 and h i g h temperature3

( 1 ) ~ r e s e n t address: The BDM Corp, 1801 Randolph Rd, S.E., Albuquerque, NM 87106.

( 2 )

Research supported by Rome A i r Dev.Center(AFSC) under c o n t r a c t no.Fl9628-77-C-0109.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1981642

measurements. Results f o r

vs frequency a t several temperatures between 80 and 1320K a r e displayed i n Fig. 1. Note t h a t t h e absorption vs. frequency curves a t f i x e d temperature d i s p l a y a n e a r l y exponential decrease t y p i c a l o f multiphonon a b s o r p t i o n i n o t h e r i o n i c c r y s t a l s 4 . Moreover, t h e spectra reveal o n l y weak

Fig. 1. I R edge absorption c o e f f i c i e n t

o f cubic z i r o n i a vs frequency

a t several temperatures (OK).

s t r u c t u r a l features, which p r o g r e s s i v e l y disappear w i t h i n c r e a s i n g temperature.

3. Discussion - For i o n i c m a t e r i a l s , one may model t h e temperature dependence o f t h e I R edge a b s o r p t i o n as4

where n i s t h e Bose-Einstein f u n c t i o n and a, i s a temperature dependent average o p t i - c a l phonon frequency. For t h e present purposes we only account f o r l i n e a r v a r i a - t i o n s o f

vs T, i.e., we t a k e

- ^yT). V a r i a t i o n o f parameters t o o b t a i n a best f i t t o t h e data over t h e f u l l range o f a v a i l a b l e temperatures and f r e - quencies leads t o t h e r e s u l t s i n d i c a t e d i n Fig. 2, corresponding t o t h e choices

a, =

1.38x105,

550 cm-l, A=3.85,

= 2 . 0 ~ 1 0 ' ~ / 0 ~ The good agreement obtained between t h e o r y and experiment corroborates t h e i n t e r p r e t a t i o n o f t h e observed spectra as multiphonon absorption. The d e r i v e d average frequency

550cm-I i s c o n s i s t e n t w i t h fundamental I R and Raman data, and i m p l i e s t h a t t h e present a b s o r p t i o n measurements span t h e t h r e e t o f i v e phonon regime.

A noteworthy f e a t u r e o f t h e above r e s u l t s i s t h e r e l a t i v e l y s t r o n g suppression

o f t h e T-dependence o f a b s o r p t i o n a t h i g h temperatures. This e f f e c t , which i s

w e l l known from previous measurements on a1 k a l i - h a l i d e s , i s a t t r i b u t a b l e t o t h e

s t r o n g T-dependence o f t h e fundamental phonon spectrum i t s e l f i n i o n i c c r y s t a l s .

Further confidence i n t h i s i n t e r p r e t a t i o n i s provided by t h e close p r o x i m i t y of

t h e value deduced here f o r

t o those i m p l i e d by Raman s c a t t e r i n g s t u d i e s 5

o f t h e T-dependence o f phonons i n monoclinic Zr02.

JOURNAL

DE PHYSIQUE

t l l ~ l l ~ i l l i r r "

0 288 499 1 1288 1-

TEMPERATURE 1 K )

Fig, 2. bsor t l o n c e f f i i e n s t * e r a t u r e o r r r e e n t t i e l r e q u g n i l e s ?cm- 1. SoYld TlEes a r e tfeorefYca7 cafcuYations and t r i a n g l e s a r e experimental values.

Acknowledgement-The assistance o f F. Gervais o f CNRS w i t h t h e present s t u d i e s i s g r a t e f u l l y acknowledged.

References

See, e.g., D. Michel e t a l , J. Cryst. Growth 43, 546 (1978).

B. Bendow e t a l , i n "Basic O p t i c a l Props o f M a t e r i a l s n , NBS Spec.

Pub #574 (USGPO, Wash., DC, 1980).

D. B i l l a r d e t a l , Revue de Physique Applique (1981, i n press).

B. Bendow, S o l i d S t a t e Phys. 33, 249 (1978).

M. Ishigame and T. Sakurai, JTAmer. Cer. Soc. 60, 367 (1977).