Fabrication and characterizations of holmium oxide based magneto-optical ceramics

A significant improvement in the sintering of Ho2O3 powders obtained by self-propagating high-temperature synthesis as a result of the addition of lanthanum oxide was made. It was found that the addition of 5% lanthanum oxide slightly affects the Verdet constant value (which is ~1.3 times higher than the corresponding value for terbium-gallium garnet, and is similar to the value for terbium-aluminum garnet ceramics), but significantly increases the transparency of ceramics. Samples of 5% La:Ho2O3 magneto-optical ceramics with a transmission of up to 76% at a wavelength of 1 μm at a thickness of 1 mm were obtained. Such La:Ho2O3 ceramics have transparency windows in the ranges of 0.93–1.06, 1.3–1.6 and 2.2–7 μm, what distinguishes them from materials containing Tb3+ ions, that are opaque in these ranges. It is shown that La:Ho2O3 ceramics have relatively high mechanical characteristics (HV = 8.4 GPa, E = 182 GPa, KIC = 0.95 MPa m0.5) which vary slightly depending on the lanthanum oxide concentration.