Optical properties of glasses in the ZnO-CdO-SiO_2 ternary system

Optical properties of glasses in the ZnO-CdO-SiO

2

ternary system

Ma. E. Zayas, E. Rivera, and J. Ma. Rinc6n

The optical properties of new glasses in the ZnO-CdO-SiO2 system containing high CdO levels (50-90 wt. %) has been determined. The refractive-index variation versus CdO and ZnO composition has been considered. Likewise, the refractive index and spectral transmittance in the 20 0-2600-nm range for these glasses has been carried out. From these optical measurements it can be stated that glasses in the ZnO-CdO-SiO2 system would be adequate for infrared windows or as laser matrices.

Introduction

In recent years infrared transmission glasses have become important for different technological applications, mainly in laser technology. Table 1 lists a summary of oxide, halogenide, and chalcogenide glasses that are useful for infrared transmission.' Table 1 includes the data of CdO glasses that were recently investigated by Rincon et al. 2 and by Rivera et al. 3 The optical properties of cadmium silicate glasses has not been studied much in the past.4 5 However, there is a linear relation between the refractive-index variation and the CdO content in some glassy composition systems.6 The aim of this paper is to demonstrate the optical property determinations carried out on new glasses that were recently investigated on the ZnO-CdOSiO2 system7 and to list the possible applications of these types of glass. Materials and Methods

According to the transparent glass zone in the glassformation area of the ZnO-CdO-SiO 2 system, more representative and better optical quality (homogeneity) glasses have been selected for optical measurements. These are glasses 11, 24, and 50, whose compositions are listed in Table 2. Ma. E. Zayas is with the Departamento

de Optica, Centro de

Investigacion de Ensenada Superior de Ensenada, Ensenada, Baja California, Mexico; E. Rivera is with Calipo, S. A., Ensenada, Baja California, Mexico; J. Ma. Rinc6n is with the Instituto de Cerdmica

y Vidrio, Consejo Superior de Investigaciones Cientificas, Arganda del Rey, Madrid, Spain. Received 9 May 1991.

0003-6935/92/347309-04$05.00/o. o 1992 Optical Society of America.

The starting raw materials were reactive-grade high-purity

oxides:

ZnO, proanalysis

Merck; CdO,

Atlas Products, and SiO2 from Mexican Silica, Baja California (99.04 wt. %) with low iron content. The mixture was melted in Pt crucibles in a Superkanthal electric furnace at 1450'C. The mixture was stirred for 2 hr and we used the cooling rate cycle shown in Fig. 1.

The melts were poured into brass molds with different shapes to correspond with the different optical measurements. The final glasses were submitted to machining and optical grinding. The refractive index was determined by two procedures: (a) the prism method was used for an index higher than 1.7, and (b) Abbe refractometry was used for a refractive index lower than 1.7. In the first method, the sample had a prism shape with /20 flatness ( = 0.546 m, Hg green, is the wavelength of the light source that is necessary for surface planimetry). This method is based on the measurement of two angles, namely, minimum deviation angle (D) and the angle that is formed between the superior vertex and the intersecting prism planes (A).8 In the second method, a Bausch & Lomb Abbe refractometer with +0.0001 precision was used. In this instrument the measurement system was a high refractive-index prism in which the sample (20 mm x 20 mm x 4 mm) was located within the polished basal plane (/4). The spectral transmission was measured in the 2 0 0-2600-nm range by using a PerkinElmer 330 spectrometer with a 4-mm-thick plate. The plate was embedded into Canada Balm and glued to a glass holder. The sample was polished on both planes to /2 flattening, as is useful for these kinds of measurements. 1 December 1992 / Vol. 31, No. 34 / APPLIED OPTICS

7309

of ZnO-CdO-SiO Table2. TheoreticalComposition 2 GlassSubmitted to OpticalPropertyDetermination

OpticalGlass' Table1. InfraredTransmission

Glass Composition

Thickness (mm)

Oxide glass GeO 2 -PbO

Ga20 3 -SnO-PbO W0 3-MoO3 -BaO TeO 2-Bi 2O3

GeO2 -Bi 2 0 3 -Tl 2 0 AS2 0 3 -PbO-Bi 203 Bi 2O3 -PbO-BaO Li2 O-CdO-SiO2 Na 2 O-CdO-SiO2 CdO-Bi 2O3 -SiO2

Absorption Edge (i.um)

2.1

5.5 6

2 1 0.5 2 1 1 1 1

5 6.3 6.5 5.7 7.5 5.0 5.0 5.0

Refractive Index

ZrF 4 -BaF 2 -YbF3

ZrF 4 -ThF4 -LaF3 ZrF 4 -BaF2-LaF 3 ThF 4 -BaF2 -LiF ThF4 -BaF2 -YbF3-ZnF2 ThF 4 -BaF 2 -YF3-AIF3 HfF 4 -BaF 2 -Laf 3

HfF4 -BaF2 -ThF4 A1F3 -BaF 2-CaF 2 -YF3 AIF3 -BaF 2 -CaF 2

GaF 3 -NaF-PbF2 GaF 3 -NaF-PbF 2 FeF 3 CrF 3

7 3.6 2 2 4 4 2.4 4 3 0.85 2.2

7.5 8

7.5

7.5 7.5

9 7.2 8.5 8 5.2 8

2 1 1

8.5 12

2 3

13 7.5

(wt. %)

ZnO

CdO

Sio 2

11 24 50

10 30 5

70 30 90

20 40 5

1.91 1.17-1.82

_ 2.1 2.5 2.1 1.96 1.98

Halogenide glass

ZrF4 -BaF2 -ThF4 ZrF4 -BaF2 -GdF3

Composition

l.53(nd) 1.52(0.63 .m) 1.52(0.63 .m) 1.55(nd) 1.52(nd) 1.49(nd)

_ 49

l.

l.

44

(nd)

_ (nd)

The values we obtained depict a refractive-index variation in the 1.5315-2.0324 range according to the different CdO content. The refractive-index variation with wavelength is shown in Fig. 3. A small decrease in the dispersion can be seen when the refractive index is increased. It is worthwhile to point out that the glass has low dispersion with respect to other Cd and lead silicate glasses previously studied.3 The Abbe number or reciprocal relative dispersion was used for comparing the dispersion variation with the chemical composition of glasses. Figure 4 shows that the Abbe number varies strongly with the CdO content and increases when this component is higher; that is, a lowering of dispersion exists, giving rise to high refractive-index glasses (1.5315-2.0324 range) with Abbe numbers in the 12.78-46.50 range. This

_ 7 1.6 (nd)

aI

InF 3 -BaF 2 -YF3 -PbF2 GaF3 -MnF 2 -PbF2

63

1.58-1. (nd)

w

FeF 3

LnF3 -BaF2 -MnF2 ZnF 2 SeF 3 -YF 3-BaF 2 CdF 2 -BaF 2 -ZnF2 ZnCl 2 BiCl 3 -KCl

ThCl4 -NaCl-KCl CdCl 2 -BaCl2-KCl ZnBr 2

CdI2 -CsI-TlI CdF2 -CdCl 2 -BCl 2 Chalcogenide glass As2 S3 GeAsS GeS3 GeSe As2 Se3 GeBiSe GeSbSe GeAsSe ZnSe LaGaGeSe GeAsTe

0.4

9.5

2.2 0.4

8 8.5 12 15 14 25 23 28.3 12

1.2 1.1 0.4 0.5 1.2 1.3

x

W

Q

uD

Q--

1.5(nd) 1.7 (nd) 1.9 1(nd)

6

10

Fig. 1. Heating and cooling rate cycle used to obtain ZnO-CdOSiO 2 glass.

2.1-

5 2 2 15 15 9 8 6.6 5 0.4 2

12 12 11 12 13 17 15 16 20 18 16

2

.11(nd) 2.40 at 10 pm 2.78 at 10 .m 2.61 at 10 pm 2.62 at6 .m

2.0C

X 1.9.

0

uLJ

Z

2.5-2.8 at 10 pm

1.8 1.7

U Wd 1.6

3.8 at 6 .m 1.5-

Results and Discussion

The experimental results of the refractive index that were carried out on the Abbe refractometer and by the minimum deviation method8 are shown in Fig. 2. APPLIED OPTICS / Vol. 31, No. 34 / 1 December 1992

.

t

10

7310

8

TIME (hours)

so

a0

.

,

70

90

WEIGHT /0

Fig. 2. Refractive-index variation versus CdO content for the ZnO-CdO-SiO2 system: 0, experimental results for CdO glass, 0, theoretical results for CdO glass, O. PbO glass from Ref. 6.

(,a)

2.1a

2.0

x,~

03__

_

1 A

C

I

A -

--

0

0z

1.9

0z

uJ

24 Pt 50 Pt

a

I-

1.8-

U0

0

z 1.7

w

I

o 11 Pt 50 Pt

IL

00

A

1.6

O

500

520

540

560

580

PbO (6)

620

600

640

w

660

0z

WAVELENGTH nm)

Fig. 3. Dispersion curves for the ZnO-CdO-SiO2 glass considered here.

o Na2 O-CdO-SiO 2 o PbO A ZnO - CdO- SiO2

oy 52 5.) 44 36

00

28 20

12

WEIGHT a/l Abbe number

ZnO-CdO-SiO2 glass.

variation versus the CdO content for

2.00 CROWN

FLNT'' GLASSESGLSE

1.901.80-

a

0 L.F

1.70-

35SK

1.60-

90

80

9UTIF K az F

P

70

60

50

TIF

40

30

20

VD Fig. 5.

diagram.

Location

(b)

0.07

I-J

z

w

I-

z

0.03 0.008 200

1000 1800 2600

WAVELENGTH(nm)

Fig. 6. (a) Spectral transmission T on ZnO-CdO-SiO 2 glass, (b) internal transmission of a 50 Pt sample on ZnO-CdO-SiO2 glass.

visible and 80% in the near infrared for a 4-mm-thick specimen. The glasses that contain higher ZnO or SiO2 concentrations have spectral transmissions of 92%, but they have a lower refractive index. With respect to Fig. 6(b) the internal transmission for 50 glass melted in a Pt crucible shows an internal transmission of approximately 78-80% between 300 and 1000-nm wavelength and an internal transmission of approximately 80-90% between 1000 and 2200-nm wavelength for a 4-mm-thick specimen.

of ZnO-CdO-SiO

2

The optical properties of the new family of ZnO-CdOSiO2 glasses vary linearly with the CdO content with a refractive index from 1.5315 to 2.0324 ( = 550 nm) and a reciprocal relative dispersion (Abbe number) between 12.78 and 46.50. Otherwise, the spectral transmission of these glasses can reach 92% in the near infrared for higher ZnO and SiO2 content. Therefore, the glasses in the ZnO-CdO-SiO 2 system could be candidates for infrared window applications with the additional advantages that they can transmit in the near infrared with high refractive index and low optical dispersion, and they are cheaper and more chemically stable than those indicated in Table 1.

SKC

P5K

1.50

0.6

Conclusion

16.

Fig. 4.

1.0

0.2-

z reversed behavior with respect to other CdO-SiO2 glasses3 can be due to ZnO and other II, III, and IV periodic table elements that reduce the average dispersion but do not affect the refractive-index values.9 The optical properties determined here allow us to locate this new family of optical glasses in the nD-V diagram, as is shown in Fig. 5. Consequently, these ZnO-CdO-SiO 2 glasses can be considered as a new family of flint glass. The spectral transmittance is shown in Fig. 6(a), where transmissions can be seen of 76% in the

Z

1000 1500 2000 2500

WAVELENGTH (nm)

glass in the optical glass

This work has been possible because of the financial assistance of research project C 193/90 (Comunidad Aut6noma de Madrid) and Cooperation Programme, Cons6jo Nacional de Ciencia y Tecnologia (M6xico) and Consejo Superior de Investigaciones Cien-

tificas (Spain). We thank J. Davalos, Optical Workshop Centro de Investigacion de Ensenada Superior 1 December 1992 / Vol. 31, No. 34 / APPLIED OPTICS

7311

References

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APPLIED OPTICS / Vol. 31, No. 34 / 1 December 1992

and

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