Kutsch, Bernd

Mennig, Martin

Schmidt, Helmut K.

Schmitt, Mike

Scientific documents from the Saarland University,

FOURTH SAAR-LOR.LUX MEETING
on Funct ional  Advanced Mater ia ls
ßrß'EoErE'
Ccntrc Lorrain d'Optiquc et Elcctrc,tiquc dcs Solidcs
PFROCEEEDTI\TGI.S
at
TECHNOPÖLE DE METZ
CLOES
UI\IVERSITE DE M ET7,-SUPE LEC
FRANCE
NOVEiltBER 2-t-25 1994
Luxembourg
Saarbrücken
IVIetz
Nancy
INTENSIVE COURSES
supported by
the European Community COMETT
via Euro Materiaux
Sm 1994 / Zs
rt
I  \ / lt_*__--t
[Jniversi tö de Metz
( - \  z l)L lDCtcc
l.
Campus de Mctz
t t r
a t
a - t
a t  t
ä
Pöle [Jn iversita i re
Europ6en Nancy-N,Ietz
The meet ing is hclc l  on thc Carnpus of Supclec-N{etz and is incl t rded in the events of  i ts Cerrtenary.
Sol-Gel-Synthesis of Ag-colloid contain ing Lead-Sil ica-Coati ngs and
Investigation of their optical Properties
M. Mennig, M. Schmitt ,  B. Kutsch and H. Schmidt
Inst i tut für Neue Material ien gem. GmbH, lm Stadtwald, D-66123 Saarbrücken
Abstract
1.  Introduct ion
Metal colloids can be used to produce coloured coatings on glass due to their high molar
extinction coefficients. With non-spherical colloids interesting optical effects can be
achieved because colour and polanzation of the transmitted light can be tuned in a wide
range via the eccentricity of the particles. One way to prepare spheroidal colloids is to
establish spherical colloids in glass by melting or ion-exchange and following thermal
treatment. Afterwards this glass is reheated above Tn and deformed by an uniaxial tension
as shown in the case of Ag- and Au-colloids[,2]. In order to investigate whether this
method can be applied to colloids in sol-gel derived glasslike coatings on glass it is
necessary to develop coatings with thermo-mechanical properties adapted to the glass
substrate. For a f irst approach a synthesis route to Ag-colloids in a lead-sil ica-coating was
developed, leading to a glass with 45 vllo/o f PbO and a Tn of about 480"C.
2. Experimental
AgNOg and Pb(CH3COO)r were dissolved in methanol and afterwards complexes with
NH2(CH2)2NH(CHz)sSi(OR)s (DIAMO) in a molar rat io of  1:1 were formed. A transparent
solution is obtained, which also can be mixed with a prehydrolised SiOz-sol containing y-
glycidoxy propyl tr imethoxy silane and tetra ethoxy silane without any Ag or Pb compound
precipitated. This method allows to achieve crackfree coatings after thermal treatment at
150'C -  700'C with a thickness from 0,5 to 1,2 ytm on fused si l ica sl ides.
3.  Results
Fig. 1 shows the result of the UV-Vlsspectroscopy. In the Ag free but Pb and DIAMO
containing reference coat ing (7R) a band at a wavelength of  about 250 nm (7R) can be
observed which is typical  for Pb- ions. From ESCA analysis i t  can be concluded that the
electronic structure of  the Pb is pure ionic in the whole range of densi f icat ion temperatures.
A refract ive index of about 1.6 was measured after densi f icat ion at  500"C, which also
indicates ionic lead in a si l ica network.
The Ag containing lead-silica-coatings densified at 150"C show a distinct absorption peak at
about 350 nm which can be attributed to atomic silver. A weak shoulder at about 440 nm
might be an effect of small Ag-colloids already formed. The slightly yellow coatings densi-
fied at 200"C and 300"C clearly show a plasmon band typical for Ag-colloids. The peak
position is at relatively long wavelengths (440 nm) which may be attributed to the increased
refractive index caused by silver- and lead-ions and to the very small size of the colloids of
about 4 nm, as determined by WAXS and TEM. The intensive absorption band of the yellow
coloured coating densified at 400"C is shifted to shorter wavelengths. This trend is
continued in the case of the yellow brown coloured coating densified at 500"C and 600'C.
At 700'C the coatings show a sharp absorption peak attributed to the typical absorption
band of si lver col loids.
.ä zo
.n
c
€ 1 6
E
ä \ 2
o
0,8
1 - 6 0 c
2  - - -  -  m c
3 - - -  r u c
4 - - - 4 @ C
7  5  . - -  ' - - - smt r
6 m c
- 7 m c
- 7 R m c
ffi* / 1 3I
4
I
I
II
i
0,4
0,0 r-
m
wawlengrh [nm]
Fig.  1:Absorpt ion spectra of  Ag free (7R) and Ag containing Pbo-Sio2-coat ings on fused
sil ica for different emperatures of densif ication, reference air
From WAXS and TEM investigations it is concluded that Ag crystall i tes are growing in the
range between 300"C and 700"C from 4 nm to 28 nm. This should lead to a remarkable
narrowing and a very slight shift of about only a few nm to shorter wavelengths, as it is
concluded from theoretical investigations[3].
But the absorbance spectra for 400'C, 500"C and 600'C are absolutely untypical for Ag
col lo ids.  For their  explanat ion inf luences from part ia l ly burnt organic residuals have to be
taken into account as wel l  as interact ions between Ag and Pb compounds (Pb, PbO, PbOz).
I t  has also be taken into considerat ion that phase seperat ion processes could take place
and seperated inhomogeneit ies could also be dissolved by thermal t reatment at  about
700'C that is much higher than the Tn of the coat ing mater ial .  For the invest igat ion of  these
interest ing quest ions microstructural  invest igat ions by HTEM and XPS wi l l  be carr ied out in
the future.
2
The authors thank the Deutsche Forschungsgemeinschaft and he State of the Saarland for
financial support.
t l lM.Mennig, K.-J.  Berg: Mater ials Science and Engeneering, 89 (1991 ) 421-!24
[Zj U Mennig, M. Schmftt, H. Schmidt, K.-J. Berg, J. Porstendorfer: Proc. 2. ESG-
Konferenz, Venedig 1 993
[3] B. Dusemund, Diplomarbeit, Saarbrucken 1991
3


Sol-gel synthesis of Ag-colloid containing lead-silica-coatings and investigation of their optical properties

Acronym

FOURTH SAAR-LOR.LUX MEETINGon Funct ional  Advanced Mater ia lsßrß'EoErE'Ccntrc Lorrain d'Optiquc et Elcctrc,tiquc dcs SolidcsPFROCEEEDTI\TGI.SatTECHNOPÖLE DE METZCLOESUI\IVERSITE DE M ET7,-SUPE LECFRANCENOVEiltBER 2-t-25 1994LuxembourgSaarbrückenIVIetzNancyINTENSIVE COURSESsupported bythe European Community COMETTvia Euro MateriauxSm 1994 / ZsrtI  \ / lt_*__--t[Jniversi tö de Metz( - \  z l)L lDCtccl.Campus de Mctzt t ra ta - ta t  täPöle [Jn iversita i reEurop6en Nancy-N,IetzThe meet ing is hclc l  on thc Carnpus of Supclec-N{etz and is incl t rded in the events of  i ts Cerrtenary.Sol-Gel-Synthesis of Ag-colloid contain ing Lead-Sil ica-Coati ngs andInvestigation of their optical PropertiesM. Mennig, M. Schmitt ,  B. Kutsch and H. SchmidtInst i tut für Neue Material ien gem. GmbH, lm Stadtwald, D-66123 SaarbrückenAbstract1.  Introduct ionMetal colloids can be used to produce coloured coatings on glass due to their high molarextinction coefficients. With non-spherical colloids interesting optical effects can beachieved because colour and polanzation of the transmitted light can be tuned in a widerange via the eccentricity of the particles. One way to prepare spheroidal colloids is toestablish spherical colloids in glass by melting or ion-exchange and following thermaltreatment. Afterwards this glass is reheated above Tn and deformed by an uniaxial tensionas shown in the case of Ag- and Au-colloids[,2]. In order to investigate whether thismethod can be applied to colloids in sol-gel derived glasslike coatings on glass it isnecessary to develop coatings with thermo-mechanical properties adapted to the glasssubstrate. For a f irst approach a synthesis route to Ag-colloids in a lead-sil ica-coating wasdeveloped, leading to a glass with 45 vllo/o f PbO and a Tn of about 480"C.2. ExperimentalAgNOg and Pb(CH3COO)r were dissolved in methanol and afterwards complexes withNH2(CH2)2NH(CHz)sSi(OR)s (DIAMO) in a molar rat io of  1:1 were formed. A transparentsolution is obtained, which also can be mixed with a prehydrolised SiOz-sol containing y-glycidoxy propyl tr imethoxy silane and tetra ethoxy silane without any Ag or Pb compoundprecipitated. This method allows to achieve crackfree coatings after thermal treatment at150'C -  700'C with a thickness from 0,5 to 1,2 ytm on fused si l ica sl ides.3.  ResultsFig. 1 shows the result of the UV-Vlsspectroscopy. In the Ag free but Pb and DIAMOcontaining reference coat ing (7R) a band at a wavelength of  about 250 nm (7R) can beobserved which is typical  for Pb- ions. From ESCA analysis i t  can be concluded that theelectronic structure of  the Pb is pure ionic in the whole range of densi f icat ion temperatures.A refract ive index of about 1.6 was measured after densi f icat ion at  500"C, which alsoindicates ionic lead in a si l ica network.The Ag containing lead-silica-coatings densified at 150"C show a distinct absorption peak atabout 350 nm which can be attributed to atomic silver. A weak shoulder at about 440 nmmight be an effect of small Ag-colloids already formed. The slightly yellow coatings densi-fied at 200"C and 300"C clearly show a plasmon band typical for Ag-colloids. The peakposition is at relatively long wavelengths (440 nm) which may be attributed to the increasedrefractive index caused by silver- and lead-ions and to the very small size of the colloids ofabout 4 nm, as determined by WAXS and TEM. The intensive absorption band of the yellowcoloured coating densified at 400"C is shifted to shorter wavelengths. This trend iscontinued in the case of the yellow brown coloured coating densified at 500"C and 600'C.At 700'C the coatings show a sharp absorption peak attributed to the typical absorptionband of si lver col loids..ä zo.nc€ 1 6Eä \ 2o0,81 - 6 0 c2  - - -  -  m c3 - - -  r u c4 - - - 4 @ C7  5  . - -  ' - - - smt r6 m c- 7 m c- 7 R m cffi* / 1 3I4IIIIi0,40,0 r-mwawlengrh [nm]Fig.  1:Absorpt ion spectra of  Ag free (7R) and Ag containing Pbo-Sio2-coat ings on fusedsil ica for different emperatures of densif ication, reference airFrom WAXS and TEM investigations it is concluded that Ag crystall i tes are growing in therange between 300"C and 700"C from 4 nm to 28 nm. This should lead to a remarkablenarrowing and a very slight shift of about only a few nm to shorter wavelengths, as it isconcluded from theoretical investigations[3].But the absorbance spectra for 400'C, 500"C and 600'C are absolutely untypical for Agcol lo ids.  For their  explanat ion inf luences from part ia l ly burnt organic residuals have to betaken into account as wel l  as interact ions between Ag and Pb compounds (Pb, PbO, PbOz).I t  has also be taken into considerat ion that phase seperat ion processes could take placeand seperated inhomogeneit ies could also be dissolved by thermal t reatment at  about700'C that is much higher than the Tn of the coat ing mater ial .  For the invest igat ion of  theseinterest ing quest ions microstructural  invest igat ions by HTEM and XPS wi l l  be carr ied out inthe future.2The authors thank the Deutsche Forschungsgemeinschaft and he State of the Saarland forfinancial support.t l lM.Mennig, K.-J.  Berg: Mater ials Science and Engeneering, 89 (1991 ) 421-!24[Zj U Mennig, M. Schmftt, H. Schmidt, K.-J. Berg, J. Porstendorfer: Proc. 2. ESG-Konferenz, Venedig 1 993[3] B. Dusemund, Diplomarbeit, Saarbrucken 19913

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Sol-gel synthesis of Ag-colloid containing lead-silica-coatings and investigation of their optical properties

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