Preparation and characterization of transparent magneto‐optical Ho 2 O 3 ceramics

Transparent magneto‐optical Ho 2 O 3 ceramics were successfully prepared with an in‐line transmittance of ~73% at the wavelength of 1000 nm (~90% of the theoretical transmittance of Ho 2 O 3 single crystal) and an average grain size of ~28 μm. The ceramics were fabricated using sulfate‐exchanged nitrate‐type layered rare‐earth hydroxide as the precipitation precursor at a relatively low sintering temperature of 1700°C. The layered compound exhibited nanosheet morphology and fully collapsed into a round oxide powder with an average particle size of ~48 nm by pyrolysis. Calcination temperature for Ho 2 O 3 powder significantly affected the optical quality of the sintered body and the optimum calcination temperature was found to be 1050°C. The transparent magneto‐optical Ho 2 O 3 ceramics displayed wavelength‐dependent Verdet constants of −180, −46, and −20 rad/Tm at 632, 1064, and 1550 nm, respectively. Thus, the Ho 2 O 3 ceramics show good potential for applications in high‐power laser systems.