Effects of Gd3+ Substitution on the Fabrication of Transparent (Y1−xGdx)3Al5O12 Ceramics

Abstract

Gadolinium has been frequently used in scintillators to enhance the X‐ray stopping power and in phosphors to improve the luminescent properties. In this paper, the fabrication of Gd3+‐substituted transparent (Y1−xGdx)3Al5O12 (x=0.01, 0.5, 0.75, and 1) ceramics via solid reactive sintering has been investigated. The effects of Gd3+ substitution on the phase evolution of the powder mixture, sintering behavior of the powder compact, and properties of the resultant ceramics were mainly demonstrated. It is shown that Gd3+ substitution favors the formation of kinetically stable intermediate compounds, particularly REAlO3 (RE=Y+Gd), and thus retards the crystallization of an RE3Al5O12 garnet. The samples of x=1 composition cracked upon vacuum sintering at temperatures above 1600°C, mainly due to the volumetric expansion induced by garnet formation. The transparent Y1.48Gd1.5Ce0.02Al5O12 ceramic (inline transmittance: ∼65% at 800 nm) vacuum sintered at 1700°C shows an emission band peaked at ∼570 nm upon UV excitation at 340 nm, exhibiting a red‐shift by ∼40 nm in comparison with the regular emission from YAG:Ce.