Transparent complex oxide sintered body, manufacturing method thereof, and magneto-optical device

A method for manufacturing a transparent complex oxide sintered body comprising the steps of:

• providing a source powder comprising a rare earth oxide represented by the compositional formula:
• (TbxY1-x)2O3 wherein x is a number from 0.4 to 0.6, and a sintering aid comprising an oxide of at least one element selected from Group 2 elements and Group 4 elements, the source powder being prepared by:
• furnishing an aqueous solution containing (a) terbium ions, (b) yttrium ions, and (c) ions of at least one element of the sintering aid, letting components (a), (b) and (c) co-precipitate from the solution, filtering and oxidizing the co-precipitate, and
• heat treating the oxidized co-precipitate or an oxide thereof by heating in an oxygen-containing atmosphere at a temperature of from 800° C. to less than 1,200° C. and then cooling in an inert atmosphere, vacuum or reducing atmosphere down to 350° C. or below, and
• molding a compact from the source powder;
• wherein a powder sample taken from the compact or a compact prepared under the same condition as the compact, when heated in air from room temperature at a heating rate of 15° C./min, exhibits a weight gain of at least y % due to oxidative reaction starting from a temperature of at least 250° C., y being determined by the formula (I):
• y=2x+0.3 (I), and
• wherein x is the number from 0.4 to 0.6,
• sintering the molded compact in an inert atmosphere or vacuum;
• hot isostatic pressing (HIP) the sintered compact to form a transparent complex oxide sintered body,
• wherein when excited with excitation light of wavelength 380 nm, the transparent complex oxide sintered bod emits light including a component of wavelength 545 nm which has a luminescent lifetime of at least 0.3 ms, and a specimen of 11 mm long made from the sintered body has an overall light transmittance of at least 81.0% at a wavelength of 1,064 nm.