Influence of Lanthanum Concentration on Microstructure of (Ho_1–xLa_x)₂O₃ Magneto‐Optical Ceramics

Abstract

Transparent cubic‐phase solid solution (Ho1–xLax)2O3 (where x = 0, 0.03, 0.05, 0.07, and 0.1) ceramics are sintered in a vacuum at 1780 °C for 3 h from nanopowders made by self‐propagating high‐temperature synthesis. The lanthana is proved to significantly influence the microstructure of the ceramics. The average crystallite sizes of the (Ho1–xLax)2O3 ceramics decrease with an increase in the concentration of lanthana. After vacuum sintering and low‐temperature annealing in air, the ceramics have second‐phase grains at the crystallite boundaries and the triple points. The volume fraction of the second phase is found to be in direct proportion to the lanthana content in the ceramics. This second phase is believed to be (Ho1–xLax)2O3 solid solutions with a higher lanthanum content in comparison with the surrounding crystallites. Annealing of the ceramics at 1500 °C for 2 h leads to the elimination of the second phase.

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

“…As a rule, due to the mixing of components at the molecular level during the SHS synthesis of the precursor, solid-solution rare-earth sesquioxide powders are expected to be of single-phase nature. However, after sintering and / or subsequent annealing in air, in some cases, secondary phases enriched in lanthanum may be formed at the grain boundaries of ceramics [22]. The studied (Er 0.07 La 0.10 Y 0.83 ) 2 O 3 ceramic was of single-phase nature (cubic, bixbyite-type structure, sp.…”

Thermo-Optical Studies of Laser Ceramics

“…The sinterability of the individual oxides is usually insufficient for producing laser-quality ceramics without hot isostatic pressing and is a nontrivial task, even with its application. Therefore, at free vacuum sintering, a sintering additive La 2 O 3 [ 45 , 58 , 61 ] and in some cases Y 2 O 3 is used, when the solubility of lanthanum oxide is insufficient for a single-phase ceramics to be formed (for example, in Dy 2 O 3 [ 42 , 56 ]). These additives are isovalent to REE oxides and, except for some decrease in thermal conductivity, have do not negatively affect the characteristics of ceramics.…”

Selective Laser Spectroscopy of the Bixbyite-Type Yttrium Scandate Doped by Rare-Earth Ions

“…They could serve as a viable alternative to the well-established YAG crystals. RE 3+ -doped sesquioxide materials show strong potential for a variety of applications, including solidstate light-emitting devices [9][10][11], high-efficiency luminescent materials [12,13], rare-earth magnets [14,15], magneto-optical recording materials [16,17], and so on.…”