Influence of Ball Milling Speed on Microstructure and Optical Transparency of Nd:YAG Ceramics

doi:10.15541/jim20140621

Abstract

Abstract:

Transparent 1.0at%Nd:YAG ceramics were fabricated by the solid-state reaction and vacuum sintering method using Y₂O₃, α-Al₂O₃ and Nd₂O₃ as starting powders. These powders were mixed in ethanol with MgO and TEOS as sintering aids and ball milled at different speeds for 10 h. Effects of ball milling speed on the particle size of powder mixtures as well as the densification process, the microstructure and the optical transparency of Nd:YAG ceramics were mainly investigated. It is showed that coarse powders can be ground into fine particles with increase of the ball milling speed up to 130 r/min. Porosities of the sintered Nd:YAG ceramics decrease with the increase of ball milling speed. Al-rich secondary phase can be observed in the microstructure of Nd:YAG ceramics when the ball milling speed is over-high, and it will cause a decrease in the optical transmittance. For the sample sintered at 1760℃ for 50 h from the powder mixture ball milled at 130 r/min, the in-line transmittance reaches 83% at 1064 nm and there are almost no pores at the grain boundaries and inner grains.

Key words: Nd:YAG laser ceramics, ball milling speed, microstructure, optical transmittance

CLC Number:

TQ129

LIU Jing, LIU Jun, LI Jiang, LIN Li, PAN Yu-Bai, CHENG Xiao-Nong, GUO Jing-Kun. Influence of Ball Milling Speed on Microstructure and Optical Transparency of Nd:YAG Ceramics[J]. Journal of Inorganic Materials, 2015, 30(6): 581-587.

Figures/Tables 11

Fig. 1 FESEM micrographs of the raw powders (a) Y2O3; (b) Y2O3 (at high magnification); (c) α-Al2O3 and (d) Nd2O3

Fig. 2 FESEM micrographs of the powder mixtures ball milled at different speeds for 10 h (a) 70 r/min; (b) 90 r/min; (c) 130 r/min; (d) 170 r/min

Table 1 Specific surface areas (SBET) of powder mixtures ball milled at different speeds for 10 h

Ball milling speed/(r·min^-1)	70	90	110	130	150	170
S_BET /(m²·g^-1)	5.833	6.275	6.985	7.295	7.370	7.412

Fig. 3 Photographs of Nd:YAG ceramics sintered at 1760℃ for 50 h from the powder mixtures ball milled at different speeds

Fig. 4 In-line transmittances of Nd:YAG ceramics sintered at 1760℃ for 50 h from powder mixtures ball milled at different speeds (a) 190-1100 nm; (b) 1064 and 400 nm

Fig. 5 Relative density versus sintering time at 1550 ℃ for Nd:YAG ceramics from powder mixtures ball milled at different speeds

Fig. 6 Relative density versus sintering temperature for Nd: YAG ceramics from powder mixtures ball milled at different speeds for 2 h

Fig. 7 SEM micrographs of ceramics sintered at 1600℃ for 2 h from powder mixtures ball milled at different speeds for 10 h (a) 70 r/min; (b) 90 r/min; (c) 110 r/min; (d) 130 r/min; (e) 150 r/min; (f) 170 r/min

Fig. 8 Sintering trajectory for Nd:YAG ceramics sintered between 1500℃ and 1750℃ from powder mixtures ball milled at different speeds

Fig. 9 SEM micrographs of ceramics sintered at 1550℃ for different time from powder mixtures ball milled at different speeds

Fig. 10 EPMA micrographs of ceramics sintered at 1760℃ for 50 h from powder mixtures ball milled at different speeds (a) 70 r/min; (b) 90 r/min; (c) 130 r/min; (d) 170 r/min

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