| 摘要 |
A translucent ceramic principally contains a composition represented by the formula Ba{Ti<SUB>x1</SUB>M<SUB>x2</SUB>(Mg<SUB>1-t</SUB>Zn<SUB>t</SUB>)<SUB>y</SUB>(Ta<SUB>1-u</SUB>Nb<SUB>u</SUB>)<SUB>z</SUB>}<SUB>v</SUB>O<SUB>w</SUB>, wherein M is at least one selected from the group consisting of Sn, Zr, and Hf; w is a positive number for maintaining the electrical neutrality; x 1 +x 2 +y+z=1; 0.015<=x 1 +x 2 <=0.90; 0<x 1 <=0.90; 0<=x 2 <=0.60; 1.60<=z/y<=2.40; 1.00<=v<=1.05; 0<t<1; and 0<=u<=1. The translucent ceramic has high linear transmittance over a wide wavelength range and a large refractive index, is controllable in refractive index and Abbe number in a wide range, and is not birefringent. Therefore, lenses ( 2 ) made of the translucent ceramic are suitable for optical pickups ( 9 ) and other devices that must be small-sized and thin.
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