Lanthana-Doped Yttria: A New Infrared Window Material

Abstract

Lanthana -doped yttria has a number of favorable intrinsic properties for infrared window applications. La2O3 is a sintering aid which makes possible pore -free transparent polycrystalline near-net -shape domes and windows by a unique transient second solid -phase sintering technique. This same second phase can be retained by special anneals to impart mechanical toughening by a second -phase crack -deflection mechanism. Transmission electron microscopy has been utilized to characterize crack deflection and the complex second phase nucleation and growth process. Reduced absorption coefficients have been achieved through improved processing, 011-removal, and stoichiometry adjustments. The trade -off between mechanical and optical properties has been quantified, and a region of promising compromise identified.

Sintering Behavior and Optical Properties of Yttria

“…P OLYCRYSTALLINE, fully dense, pure and lanthana-doped yttria-based materials were developed in the 1980-1990s for optical applications like missile infrared-domes. [1][2][3][4][5] Very high values of in-line transmittance (IT) have been measured for electromagnetic radiations with wavelength in the range 0.2-10 mm. 1,3,4 In spite of excellent optical properties, no extensive implementation of such polycrystalline yttria materials has become effective.…”

Mid-infrared laser operation of (Er0.07La0.10Y0.83)2O3 sesquioxide ceramic

“…However, the photodarkening of such media makes it almost impossible to use them in lasers [14]. Lanthana (La 2 O 3 ) is another efficient sintering additive [15]. The 10 mol% La:Y 2 O 3 solid solution is consolidated into laser-quality ceramics only by free vacuum sintering (without subsequent HIPing), as demonstrated previously for (Yb x La 0.10 Y 0.9-x ) 2 O 3 ceramics [16][17][18].…”

BaHfO3:Ce sintered ceramic scintillators

“…However, a significant fraction of particles consists of small, truly nanosized, though agglomerated crystallites. Such a morphology is not very suitable for sintering, unfortunately (Rhodes et al, 1986;Wei et al, 1988;Ikesue et al, 1995). Indeed, the sintered ceramic pellet obtained from this powder in vacuum practically lacks transparency.…”