Excimer laser deposition of apatite at room temperature on titanium

JOURNAL DE PHYSIQUE 1V Colloque C4, suppltment a u Journal de Physique 111, Volume 4, avril 1994

Excimer laser deposition of apatite at room temperature on titanium substrates E.N. ANTONOV, VN. BAGRATASHVILI, E.N. SOBOL, R. SMITW* and S.M. HOWDLE*"

Sci. Res. Centerfor Technol. Lasers, Troitsk 142092, Russia * IRC in Biomedical Materials, E14NS, London, U K. ** Chem, Departm. Nottingham Univ., NG7 2RD, Nottingham, U.K.

ABSTRACT. H i g h l y a d h e s i v e a p a t i t e f i l m s w e r e d e p o s i t e d b y p u l s e l a s e r s p u t t e r i n g o f a p a t i t e t a r q e t o n T i s u b s t r a t e s a t room of multit e m p e r a t u r e . The model o f l a s e r a h l a ? i o n / d e p o s i i i u n component s o l i d s was d i s c u s s e d t o e x p l a i n t h e o b s e r v e d d i f f e r e n c e s i n t h e p r o p e r t i e s o f films o b t a i n e d f r o m a p a t i ? e ~ n i n e r a l , s i n t e r e d h ~ d r o k m p a t i t e , a n d bone t i s s u e t a r g e t s .

INTRODUCTION H y d r o x y a p a t i t e (HA) i s t h e m i n e r a l b a s e o f b o n e t i s s u e a n d i s u s e d a s a $ L a l o g i c a l l y c o m o a t l b l e c o a t i n g f o r m e d i c a l a n d d e n t a l i m p l a n t s C11. P l a s m a s p r a y i n g is commonly u s e d f o r HA d e p o s i t i o n , b u t

recently

f i l m d e p o s i t i o n t e c h n i q u e s have heen used s u c c e s s f u l l y '

laser

assisted

Crystalline

CZ-42.

f i l m s c f HA h a v e b e e n o b t a i n e d by m a n i p u l a t i o n o f t h e l a s e r f l u e n c e a n d t h e a t m o s p h e r i c c o n d i t i o n s and u s e o f h i g h s u b s t r a t e t e m p e r a t u r e s ,

>400'~

C21.

I n o u r e x p e r i ~ e r t t s , n a t u r z l a p a t i t e [ N A l s a m p l e s were s u c c e s s f u l l y u s e d f o r film

deposition

of

high

quality

coatings

on

Ti

substrates

at

room

f b r e e t v p e s o f s a m o l e s HA. NA a n d b o n e t i s s u e w e r e u s e d a s t a r g e t s a p a t i t e f i l m d e p o s i t i o n b y KrF-ewcimer Physik),

In

our

experiments

the

(ERG-203,

l a s e r , h=248 nm

focused

pe-Lodically a c r o s s the t a r g e t i n order t o

laser

UV

avoid

the

c r a t e r s i n t h e t a r g e t . The l a s e r p u l s e r e p e t i t i o n

beam

Lambda

was

scanned

formation

rate

was

5

for

of

deep pulse

Hz,

e n e r g y u p t o 3 0 0 m J ( c o n t r o l l e d by a t t e n u a t o r ) , a n d l a s e r p u l s e f l u e n r e

on

t h e t a r g e t was 0.7-11

cm

37d a T i

f311

2/c:n2.

T h e t a r g e t t o s u b s t r a t e d i s t a f i c e s w e r e 3.5

t a r g e t ( 0 . 0 5 mm t h i c k n e s s ) w a s used a s s u b s t r a t e f o r

d e p o s i t i o n . The f i l m t h i c k n e s s was v a r i e d from

in

the

vacuum

cell

-2

Efm

and

Residual

air

pressure

to

-0.1

5 e p o s i t i o r r a t e was i n t h e -ange 0.02 - 5 W/pulse.

apatite the

was maintained a t 3-10-= Torr.

The d e p o s i t e d a p a t i t e f i l m :

were

examined

by

SEM,

FT-IR

and-Raman

r p e c t r c s c n p y . The f i l m a d h e s i o n w a s d e t e r m i n e d b y a s c r a t c h test; a

unique

q u a n t i t a t i v e m e t h o d f o r v e r y t h i n f i l m s C53. T h e s c r a t c h i n g w a s made c o r u n d u m p o i n t w i t h a 57 ni!,/

radius.

The a d h e s i v e f o r c e was

determined

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jp4:1994441

Sv

a by

JOURNAL DE PHYSIQUE IV

C4-184

the maximum vertical load which could be

applied

to

the

point,

without

stripping the film from the substrate CS].

RESULTS Most of Our investigations were

made

with

titanium

substrates; an

important implant material. The films deposited from H A and N A samples were mirror-like and scanning electron microqraphs showed smooth

surfaces with

round shaped particles of 1-10 /Lm in size. Both the suantity and the of

particles

controlled

by

increasing

the

laser

fluence.

size

The films

deposited from bone tissue were much more spongy and round shaped particles appeared only at the fluences more than -5

J/cm2.

The adhesion of films on Ti substrates vs fluence is shown With a substrate temperature of 40o0c, bath H A and adhesion with a maximum fluence near 2-4 J/cm

L

in

fiq.1.

N A films have excellent

. This is in accordance

the results of C21. Conversely, the adhesion of

films obtained

at

with room

temperature from H A and bone was quite low. The most striking results were

In

obtained with films prepared from NA at room temperature.

the

fluence

range 2-4 J/cm2 those films have practically the same adhesion level as the films deposited at 4 0 0 ~ ~ . The films were investigaied by F T - i R spectroscopy. The vibration of the phosphate ions (P'?:-)

of

1000-1100 cm-' respectively 16;. the initial spectra of

HA

HA

appear in the

range

550-610

The film spectra, obtained

and N A

Fiq.1. The adhesion of films obiairisd i i sm a;fferar:r Corgets

are

qiven

in

from

bands -1 cm and

NA,

and

fiq. 2.

Fjq.2. FT-IR spectra of NA-il), H ~ l ( 2 )and NÀ films: at 2C i., L,.Î/cr?i2-: 31 7 3 I . y 2 -;4j;qt

~QQ Z JF ;CV . ~ ~ ( ~ ! , j/;Jjc!&{B)

N o t e t h e c l a s o s i m i l a r i t i c s b e t u e e n t h e s p e c t r a o f HA a n d R a m n s p e c t r a o f trk laser

fluencos

increasod,

NA f i l m s a r o a l s o

~r-:$

and

szbstratp

almost

temperatures.

identical the

As

t h e maximum c f t h e m a i n a b s o r p t i o n p e a k

a?

the

FT-

the

laser

in

The

NA.

same

is

fiuence

FT-IR

soectra

c h i f t s t.o l o u e r f r e q ~ i e o c i e s . A p a r t i c ü l a r l y z t r i k l ~ gi e a t u - - e c f t h e spectre 0

o b t a i n e d a t 400 C is t h e s t r o n g f e a t u r e n e a r 1110 cm T h e s e u a t a shovr spectral features

that and

thers

the

t a r g e t s and s u b s t r a t e Zemperatures,

dfrec?

ne

1s

adhesion

corroi.ation

proserties. ue

have

-1.

shown

o r o p e r t i e s o f t h e f i l m s may b e c h a r a c t e r i z e d by

hotween

H~wever for that

the

spectral

the

different mechanicai

methuds

without

d e s t r u c t à o n of t h e m a t e r i a i s . DISCliSSXDN The f i l m a d h e ç i a n a t a c i v e n s u b s t r a t s t e m p e ~ a t u r ed e p e n d s nn t h e

!d) and v - l z c i t y

(v) of p a r t i c l e s emiited fron t h e

values a r e determined f i r s t l y

a b l a t i o ! ~ and

by

taryct.

and

d

T3i

secondly

size

p r o c e s s e s a n d ai.het- p s r a m ~ t e t - s . L a s e r i r r a d i a t i o n n f t h e t a r g e t s r e s u l t emissior. o f i c n s , atoms and

i*

cniliâional

by

in

p a r t i c l e s û f : i a r i r , u s s i z e s . Tbese s p e c i o s 5 r e a c i i t h e s u b s t r a t e w l t h v e l c r i t i e s i--iG -.!c' C(TI/SE.C. [Y!, 2r3b f n r m 3 d e n s e

f i l m . Th-

,nitro

p a r t i c i e s w i t h d>?O jhn h a v e v * : l c~i f~/ s e c .

producinq

hence

wrire

spongy f i l m s w i t h püor acihesicn. Ue h a v e d e v e i o p e d m o d e l s f o r a n a l y s i s o f l a s e r i n d u c f d d e c o r p c s i t i a n o f csulti-componeni

s . d f e t - i a ? s ii.-IO>. Sic:-

s t r i k e s t n e tarqe-i,

the:-& is

ii

f r o n t c i t h e c h e n i c a l !-eaitii.:.

cauced

3v

fiuencz

reyici!:

?ha?.

Hfnco

.the

tkc

t h e c h e s i c a i a n d ; i ! ? y ~ i c a l ;?oce-,sei e f & b : a t i o n ,

ili

particles.

reaches

mecRariicai d e s t a - i i i i i s n of

The n a r t i c l e s i z e s

~3t-t.

'!iis

the

dstee!-aineci by

::il?

&-absorption

tempera?ut-e rtre45:ive

02s

of

dezi;spiisltion the

II!

f!O,

i

eaissisn

i a r g > ? t and

lasir

alio f l i i c t t i a t e s .

c:-:riabl!itr

s c a l e o f r e a c c i a n f i - o a t d i s t a n c e a n d d o n c t e.czee:;

the

when

whir%

ifi

ijt'ies w i t t : ? i m e .

The Fressure a a i ~ ! i - t + ~ d r q u i i k l y

resul tinq

? , i ~ d e i ~ .sticbj

vaide

cazroo.,

the :.*hot-e

1/&,

rnol'f i c i e n t .

F o r H A a n d 1\14, v a p c r i r a t i a i - i i c t h e %;airi o t - a c e c s o f H o w e v e r , v a p o r i i a t i o n ma,

msrste~ia!

.3!3iation.

be a c c o n p a n i e d by @ a l e ~ ; ~ i adf e : 3 m p o s i t i n n .

This

p r o c e s s i s a h i g h t e n ; p f r a t ~ : r e anG m a s t c i v e t h e p a r t i c l c i , w i t h

t ! ; ~ trace-,

of m e l t i a c , .

351-400

F c r bc>ne a b l a t i o n t h e d e c c m p o i i t i 3 n o f c o l l a g e n a t

l e a d s t o d e s t r u c t i o n b e i o r e v a p o r i r a t i o n and t h e

particles

"C

oust

graducfd

s h o w a n i r r e c j u i a r f-crm.

the ore tic^? a n a l y s i s ClCl sRcw t h a t t b e r e i s a n o ~ t i ~ f~l ua e la c e a t w h i c h d is m i n i n a l

and

ti?l;,

adheei;l;i

is

m,ieirnal.

Out-

reçion

~v:ict-iilierthl

t - e s b i t s a r e i r : i i j r e e m e n t w i t h t h i s iriodei, F a r a g t : a n t i t a t i v ~ r n m p a r i s s r i . m o r e p r e c i s ~de-?i ~ i t i o no f c p t i c a !

i h e r m a l ?:nd

mechanical

p,!-ane+.eeus

3

is

JOURNAL DE PHYSIQUE IV

C4-186 nceded. room

T h e d i f f e r e n t a d h e s i o n p r o p e r t i e s c f i-!A ar;d NA

temperatures

may

be

caused

Dy

the

films

differences

coefTicients o r i n mechanical p r o p e r t i e s of ine t a r g e t hiyh substrate temuerztures,

in

a?

absorption

materlals.

roce esses

crystallisation

the

prepared

At

the

beccme

more

i m p o r t a n t C21. N o t e , we e s t i m a t e t h a t t h e i n c r e z s e o f s u b s t r a t e t e m p e r a t u r e

it

To a m e i i 3 r a t e t h e f i l m q u a l i t y

possible

is

to

introduce

absorbinq impurities i n t o t h e i n i t i a ? w2terials.

T h ü s incre,?.-inc

a b s o r b e d b y t h e t ü r g e t s o r , o n e m?,y

wavelen?th

laser

I L S P 3.

le!!.

? : ~ iss l?ss t h a n

d u s t o t h e k i n e t i c energy of evaporateci p.zrtic!es

at

hiqhlï

the ecergy which

the

a b s o r p t i ~ no f t h e t a r q e t q a t e r i a l i t s e l f is h i q h c r . SUflPIARY

W e ",ne deve!oped

I a z e r s p u t t e r i n g ?erk?iqce-, which a l i o w d e p o s i t i o n o f

3 i g h q u a l i t y a p a t i t e f i l * i s on t o s u h s t r a t ~ sa t r r o m t e m g e r a t s r e ;

time s u c h iow t m g e r a t ~ i ? e c ,have h e i n ~ i q e c i s u c c e s s f i i l l y . Wo fllms

30

to

titani:iim

scihstrates

arrdtthss

es hoc^

haw

thc

degosifr-Y

eu celle:^+

c h a r a c t e r i s t i c s . A t h e o r e t i c a l mode1 o f l a s e r a b l a t i o n a*

first

adhosior!