Synthetic gemstone based on solid soln. of lead titanate and zirconate - in which lead is partially replaced by lanthanum and pref. also by rare earth metal

摘要

Synthetic gemstone is made by pressing and sintering the starting materials and then forming cut facets on the surface taking into account the refractive index and the angle of total reflection. Pref. the Pb in addn. to being partially replaced by La, can also be partially replaced by a rare earth element. The Ti and/or Zr may also be partially replaced by Sn. The gemstones may be produced by grinding the starting materials in the form of carbonates or oxides in a ball mill, then pre-sintering at 700-900 degrees C. The product is then ground again and isostatically pressed at room temp. at a pressure of 3.6x108N/m2, then sintered at 1200-1300 degrees C. The prod. is useful as a substitute for diamonds, rutile zircon, sphalerite, or haematite gemstones.