Method of producing translucent ceramic

A method of producing a translucent ceramic having a refractive index of equal to or more than 1.9 and being paraelectric and comprising a polycrystalline oxide perovskite crystal phase, the method comprising the steps of:

• molding a ceramic material powder and a binder into a predetermined shape to thereby yield a translucent ceramic green compact comprising a perovskite crystal phase represented by the formula ABO3 wherein A is an A-site element comprising Ba in the perovskite crystal phase;
• and B is a B-site element and is two of Mg, Ta, Nb, Zn and Ta in the perovskite crystal phase,
• bringing the ceramic green compact into contact with a ceramic powder having substantially the same composition with the ceramic material powder, and
• firing the ceramic green compact in contact with the ceramic powder to thereby yield said translucent ceramic,
• wherein the perovskite crystal phase is a member of the group consisting of
• (a) Formula I:
• Ba{(SnuZr1-u)xMgyTaz}vOw in which x+y+z=1, 0≦u≦1.00, 1.00≦v≦1.05;
• w is arbitrary;
• and x, y, and z lie within the range enclosed by Point A (x=0.40, y=0.23, z=0.37), Point B (x=0, y=0.39, z=0.61), Point C (x=0, y=0.27, z=0.73), and Point D (x=0.40, y=0.11, z=0.49), excluding the line between Point A and Point B,
• (b) Formula II:
• Ba(ZrxZnyTaz)vOw in which x+y+z=1, 1.00≦v≦1.050;
• w is arbitrary;
• and x, y, and z in Formula I lie within the range enclosed by Point A (x=0.01, y=0.29, z=0.70), Point B (x=0.06, y=0.29, z=0.65), Point C (x=0.06, y=0.36, z=0.58), and Point D (x=0.01, y=0.36, z=0.63), and
• (c) Formula III:
• Ba{(SnuZr1-u)x(ZntMg1-t)yNbz}vOw in which x+y+z=1, 0≦t≦1.00, 0≦u≦1.00, 1.00≦v≦1.450;
• w is arbitrary;
• and x, y, and z lie within the range enclosed by Point A (x=0.25, y=0.35, z=0.40), Point B (x=0, y=0.35, z=0.65), Point C (x=0, y=0.20, z=0.80), Point D (x=0.10, y=0.10, z=0.80), Point E (x=0.55, y=0.10, z=0.35), Point F (x=0.35, y=0.30, z=0.35), and Point G (x=0.30, y=0.30, z=0.40).