Glass formation and crystallization in the ZrO2Al2O3P2O5 system

Journal of Non-CrystallineSolids80 (1986) 509-517 North-Holland, Amsterdam

509

Section IV. New glasses and preparation techniques GLASS FORMATION A N D CRYSTALLIZATION IN THE ZrOz-AizO3-P205 SYSTEM ZHENG Guopei, BAI Xueling and SUN Yongshi Shanghai Colored Optical Glass Works, Shanghai, PRC

The glass formation of the ZrO2-A1203-P205 system in the high phosphate region is determined. The crystallizationprocess and the crystal types formed during heat treatment have been studied. The structure of these glasses is discussed. 1. Introduction Investigations of the formation, properties, and structure of phosphate glasses are few in comparison with those of silicate and borate glasses. Studies of the crystallization process and crystal types of phosphate glasses are sparse. Moriya Taro has studied the crystallization process of AI(PO3)3 glass. Gan Fuxi and Deng Peizhen [2] have investigated the properties and structure of crystalline and non-crystalline metaphosphate glasses in detail. Kanazawa Kobun [3,4] has discussed the crystallization process of CaOMgO-P205 and magnesium metaphosphate glass. Quachenbuch et al. [5,6] have investigated the glass formation and properties in the A1203-BzO3P:O5 system. Mcdowell et al. [7] have discussed the A1203-P2Os-B205 glass-ceramics articles and methods of formation in their patent. Gonzales et al. [8] and Stone [9] have investigated the ternary system MgO-A1203P205 and CaO-AI203-P2Os. But the investigation of glass formation, the process of crystallization, and the crystal types in this glass-ceramic system have rarely been reported. In this paper, various experimental methods such as differential thermal analysis, X-ray diffraction analysis, infrared and Raman spectroscopy are used to study the crystallization process and the crystal types for different heat treatment periods. The structural units in these glasses are discussed. 2. Experiment and results

2.1. The glass formation of the ZrOe-AI203-P2Qs The investigated glass compositions are shown in table 1. Batch materials used in glass melting were: aluminium metaphosphate AI(PO3)3,

Zheng Guopei et al. / Glass formation and crystallization in ZrO2-A1203-P205

510

Table 1 The glass compositions Sample No.

mol.%

wt%

ZrO2 PA25 FAzo PAZ2 PAZ 4 PAZ6 PAZ8 PAZlo PAZI2 PAZ14 PAZ1~ PAZ25 PAZ1, PAZel PAZ22 PAZ27

2.6 3.9 6.5 7.8 9.7 12.8 13.8 14.5 5.6 11.0 21.4 22.4 27.0

A1203

P205

25.0 30.0 24.7 23.7 24.7 24.7 22.6 23.1 21.5 22.6 6.9 13.2 13.3

75.0 70.0 72.7 72.4 68.8 67.5 67.7 64.1 64.7 62.9 87.5 75.8 65.3 77.6 66.2

6.8

Results

ZrO2

2.0 3.8 6.0 7.9 9.1 11.8 13.0 13.8 5.0 10.0 20.0 20.0 20.0

A1203

P205

19.3 23.5 18.9 18.6 19.3 18.9 17.6 18.2 16.8 17.7 5.0 10.0 10.0

0.7 76.5 79.1 77.6 74.7 73.2 73.3 70.0 70.2 68.5 90.0 80.0 70.0 80.0 70.0

10.0

glass glass glass glass glass opaque opaque opaque opaque opaque not glass not glass not glass not glass not glass

hydrated alumina AI(OH)3 and titanium oxide TiO2. The batch materials were accurately weighted, thoroughly mixed, charged into a 1000 ml silica crucible and heated in a furnace. The melting temperature could range from 1400 to 1650°C, depending upon the glass composition. After melting, the glass was poured onto a cast-iron plate and then it was annealed in the range from 500 to 700°C. Fig. 1 shows regions of glass formation of the ZrO2-AI203-P20~ system. A1203 5O

4O

'2vvvv P205

90

/vvv 80

70

,\ 60

50

Fig. 1. Regions of glass formation of the ZrO2-A1203P205 system in the high Z r 02 phosphate region.

\

Zheng Guopei et al. / Glass formation and crystallization in ZrO2-AI203-P205

No,

1200

1100

1000

, 0C

900

,

511

PA 25 PAZ

~///'//..d 2

PAZ 4

~/"/.-//'I

PAZ 6

/,.G/,.-',.-'/A

PAZ 8

~ / / / . A ~

:.:::.:ii~!:...:, !;!. i~: i i;: i~i~::.:.;:.~i:::.

V/'/A crystallized

crystallized on s u r f a c e

opalesented

Fig. 2. T h e t e m p e r a t u r e r e g i o n o f c r y s t a l l i z a t i o n .

2.2. The temperature region of crystallization All glass samples were maintained in a gradient-furnace for 3 h. The temperature regions of crystallization are shown in fig. 2.

2.3. Differential thermal analysis of glasses T h e D T A curves of the 7 glasses were determined at a temperature increment of 5°C per min. The results are shown in fig. 3. 045°C

1050 PAZ I 0 •PAZ 8 1010°C

PAZ6 I

O00°C PAZ 4

945°C

PAZ

2

PA

Fig. 3. D T A curves of the glasses. 25

512

Zheng Guopei et al. I Glass formation and crystallization in ZrOe-AIzO3-P20~

PA25

PAZ2

PAZ 4

Fig. 4. X-ray diffraction patterns.

Zheng Guopei et al. / Glass formation and crystallization in ZrO2-AI203-P~O~

PAZ6

PAZ B

PAZIo

Fig. 4. (Continued)

,

i

513

514

Zheng Guopei et al. / Glass formation and crystallization in ZrO2-A1203-P205

2.4. X-ray diffraction analysis Various glass samples were maintained at different heat-treatment schedules. The schedules are shown in table 2. Their X-ray diffraction patterns were measured and compared with the standard patterns in order to identify the crystallization products. The devitrified initial glasses also were measured. Fig. 4 shows X-ray diffraction curves of glass samples. The crystallization products of these glass samples are shown in table 3. Table 2 Heat-treatment schedules No.

A B C D

Maintained time (h)

1000°C

1100°C

1150°C

1200°C

5 5 5 5

0 15 15 15

0 0 5 5

0 0 0 20

Table 3 Crystallization products of the glass samples Heat treatment

Initial

A

B

C

D

PA25

Al(PO3)3 A1PO4

AIPO4 AI(PO3)3

ALP04 AI(PO3)3

A1PO4 Al(PO3)3

PAZ2

Al(PO3)3 A1PO4 ZrP207

AIPO4 AI(PO3)3 ZrP207

AlPO4 ZrP207

A1PO4 ZrP207

PAZ4

AI(PO3)3 ZrP207

AIPO4 AI(PO3)a ZrP207

AIPO4 AI(PO3)3 ZrP207

AIPO4 ZrP207

AIPO4 AI(PO3)3

AIPO4

AIPO4

AI(PO3)3

ZrP207

PAZ6

ZrP207 PAZ8

ZrP207

AI(PO3)3 ZrP207

AI(PO3) 3 ZrP207

AIPO4 AI(PO3)3 ZrP207

AIPO. ZrP207

PAZ10

ZrP207

ZrP207

AI(PO3)3 ZrP207

AI(PO3)3 ZxP207

AIPO4 ZrP207

PAZ14

ZrP207

ZrP207

AI(PO3)3 ZrP207

AIPO4 AI(PO3)3 ZrP207

AIPOa ZrP207

Zheng Guopei et al. / Glassformation and crystallization in ZrO2-AI20~-P:05

515

Table 4 The properties of the glasses Glass number

Density (g/cm3)

Refractive index No

Expansion coefficient x 10--7/°C (20-500°C)

PA25 PAZ: PAZ4 PAZ6 PAZ8

2.609 2.622 2.63 l 2.67l 2.680

1.5234 1.5269 1.5322 1.5381

55.1 53.0 54.6 64.0 57.2

2.5. The measurement of physical properties of the glasses The density, expansion coefficient, and refractive index were determined. The results are shown in table 4.

2.6. Infrared spectroscopy The I R spectra of the glasses before heat treatment were determined. The samples were prepared in KBr pellets. The IR spectra of the glass samples are shown in fig. 5.

2.7. Raman spectroscopy The R a m a n spectra of the glasses were determined. The Raman spectra are shown in fig. 6. 3. Discussion

3. I. The glass formation of the ZrO2-AbO3-P20s system Gan Fuxi et al. [10] have discussed the glass formation of the ternary

\

2200 3800

\\ /

800 1400

~00

Fig. 5. IR spectra of the glasses.

516

Zheng Guopei et al. / Glass formation and crystallization in ZrO2-A120~-P205 -PA Z 6 PAZ 4

J

PAZ2

J

?

~.~"

PAZ14

A25

J

Y k

1500

I

I

I

1000 500200

Fig. 6. Raman spectra of the glasses.

1500

i

1000

I

5o0 20o

system phosphates and found that the regions of glass formation in the R,nO,,-AI2Oa-P205 system are in narrow regions between the metaphosphate RmO,'P205 and AIEOa'3P2Os. Glass formation is possible, but not for the ZrO2"P205 system. It is expected that clear glass is only obtained in the regions near AIEOa'3P205 (fig. 1). In the A12Oa'3P205 base glass, ZrO2 is added. When the amount of ZrO2 is less than 7 mol.%, homogeneous and clear glass is obtained. When the amount of ZrO2 is higher than 7 tool.%, zirconium pyrophosphate crystallizes and the glass is opaque. When the glass compositions depart from the narrow region, glass formation is impossible (table 1). 3.2. O n the structure of Z r O 2 - A 1 2 0 3 - P 2 0 5 glass

Gan Fuxi et al. [2,10] investigated the structure of metaphosphate glasses and considered that metaphosphate glass has a structure of long chains constructed by (PO4) tetrahedra; the network modifiers are located in the interspaces between those chains. Jin Yifeng et al. [11] have investigated the Raman spectra of N a 2 0 AlEO3-P205 glass and considered that when the Na20/P205 is smaller than 1 and AlEOa/P205 is smaller than 0.3, Al 3+ can form (A106) hexahedra. Bobovich [12] studied the influence of cations on the bonding in the phosphate skeleton in binary glasses containing various cations at the metaphosphate stoichiometry using Raman spectroscopy. The band at 700 cm -1 was assigned to the symmetrical vibration of the - P - O - P group (bond o r d e r = 1) and the bands at 1155-1230cm -1 to symmetrical and anti-symmetrical vibrations of the -PO2 group (bond order = 1.5). The Raman spectra ot LrU2-AI2Oa-P205 glasses (fig. 6) show several characteristic bands at 720cm -1 and 1225-1235 cm -~. These structural bands were assigned to the symmetrical vibration of the - P - O - P group and symmetrical and antisymmetrical vibrations of the -PO2 group [12]. The shift of band peaks is due to the influence of Zr 4+ cations on the bonding in the phosphate skeleton.

Zheng Guopei et al. / Glass formation and crystallization in ZrO:-AIeO;-P20~

517

T h e I R spectra of these glasses (fig. 5) show that their absorption peaks correspond to the stretching and deformation vibrations caused by the chain structure of the m e t a p h o s p h a t e group. Accordingly, the Z r O 2 AlzO3-P205 system in the high phosphate region has the structure of long (PO4) chains. AI 3+ and Z r 4+ are in 6-fold coordination and act as glass network modifying ions which fill the interstices between chains.

3.3. The crystallization process of the ZrO2-Al203-P20s glasses in the high phosphate region On the basis of the results .of X - r a y diffraction analysis, we know the glasses of the ZrO2-A1203-P205 system crystallize during heat treatment. T h e crystallization products are mainly aluminium metaphosphate [Al(PO3)3], aluminium phosphate (AIPO4), and zirconium pyrophosphate (ZrP2OT). In the glass PA25 without ZrO2, the majority product is AI(PO3)3 at 1000°C. T h e r e is a smaller proportion of AIPO4. When the t e m p e r a t u r e is raised, AIPO4 crystallizes gradually. At 1150°C and 1200°C the majority product is A1PO4. T h e r e is a smaller amount of AI(PO3)3 (fig. 4, table 3). When the content ZrO2 is low ( 2 - 4 % ) , the crystallization products are mainly Al(PO3)3 and ZrP207 at 1000°C. When the t e m p e r a t u r e rises AI(PO3)3 and AIPO4 crystallize gradually. At 1150°C and 1200°C the majority product is AIPO4. T h e r e are smaller amounts of Zr2P207 and AI(PO3)3. When the glasses of the Z r O 2 - A I 2 0 3 - P 2 0 5 system in the high phosphate region are heat-treated for crystallizing the crystal phases are mainly AIPO4, ZrP207 and AI(PO3)3. T h e s e crystals have high t e m p e r a t u r e resistance, so that glass ceramics of high-phosphate which can withstand high temperatures are obtained.

Reterences [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]

Moriya Taro, J. Ceram. Soc. Japan 68 (6) (1960) 145. Deng Peizheng and Gan Fuxi, J. Chinese Silicate Society 4 (2) (1965) 90. Kanazawa Kobun, J. Ceram. Soc. Japan 79 (5) (1971) 179. Kanazawa Kobun, J. Ceram. Soc. Japan 81 (4) (1973) 127. C.L. Quackenbush and A.G. Kolbeck, Ceram. Bull. 56 (9) (1977) 789. R.M. Klein, A.Q. Kolbeck and C.L. Quackenbush, Ceram. Bull. 57 (2) (1978) 198. J.F. Macdowell and L.E. Wilson, US Patent 3 519 445. F.J. Gonzales and J.W. Halloran, J. Am Ceram. Soc. (63) (9-10) (1980) 598. P.E. Stone, E.P. Egan and J.R. Lahr, J. Am. Ceram. Soc. 39 (3) (1956) 89. Gan Fuxi et al., Optical Glass, 2nd ed. (Science Press, 1982). Jin Yifen et al., Research on Raman Spectra of Glass in Na20-AI203-P205 System, Thesis Annual Meeting Committee of Glass Speciality (1983). [12] Y.S. Bobovich, Opt. Spectra 13 (1962) 274. [13] Gan Fuxi et al., J. Chinese Silicate Soc. 9 (4) (1981) 365.