Method of producing optically transparent ceramics

Claim 3

A method as claimed in claim 1, wherein the starting material contains PbO in an amount of 3 - 20 mol % in excess of that calculated for producing said optically transparent ceramic.

Claim 4

A method as claimed in claim 1, wherein the hot-pressing is effected under a pressure of 70 - 400 kg/cm 2 at a temperature of 1300 - 1450° C for 5 - 200 hours.

Claim 5

A method as claimed in claim 1, wherein the ceramic has the composition defined by the portion surrounded by the broken lines, the abscissa and the ordinate of FIG. 5, said portion including said lines.

Claim 6

A method as claimed in claim 2, wherein the ceramic has the composition defined by the portion surrounded by the broken lines, the abscissa and the ordinate of FIG. 5, said portion including said lines.

Claim 7

A method as claimed in claim 1, wherein the ceramic has the composition defined by the portion surrounded by the broken lines and the ordinate of FIG. 7, said portion including said lines.

Claim 8

A method as claimed in claim 2, wherein the ceramic has the composition defined by the portion surrounded by the broken lines and the ordinate of FIG. 7, said portion including said lines.

Claim 9

A method as claimed in claim 1, wherein the ceramic has the composition represented by the general formula of (Pb 1 -x .sbsb.1 -x .sbsb.2, Ba x .sbsb.1, Sr x .sbsb.2)(Zr y , Ti 1 -y )O 3 , wherein 0.05 ≦ x 1 + x 2 ≦ 0.5 and 0.6 > y ≦ 0.91.

Claim 10

A method as claimed in claim 2, wherein the ceramic has the composition represented by the general formula of (Pb 1 -x .sbsb.1 -x .sbsb.2, Ba x .sbsb.1, Sr x .sbsb.2)(Zr y , Ti 1 -y )O 3 , wherein 0.05 ≦ 1 1+ x 2 ≦ 0.5 and 0.6 ≦ y ≦ 0.91.

Claim 11

A method as claimed in claim 8, wherein 0.05 ≦ x 1 + x 2 ≦ 0.3.

Claim 12

A method as claimed in claim 9, wherein 0.05 ≦ x 1 + x 2 ≦ 0.3.

Claim 15

The process of claim 12, wherein said powdery mixture is so compounded that said transparent ceramic has a formula (Pb 1 -x .sbsb.1 -x .sbsb.2, Ba x .sbsb.1, Sr x .sbsb.2)(Zr y , Ti 1 -y )O 3 wherein 0.05 ≦ x 1 + x 2 ≦ 0.5 and 0.6 ≦ y ≦ 0.91.

Claim 16

The method of claim 13, wherein said powdery mixture is so compounded that 0.05 ≦ x 1 + x 2 ≦ 0.3 and 0.6 ≦ y ≦ 0.91.

Claim 19

The method of claim 15, wherein said powdery mixture is so compounded that said transparent ceramic has a formula (Pb 1 -x .sbsb.1 -x .sbsb.2, Ba x .sbsb.1, Sr x .sbsb.2)(Zr y , Ti 1 -y )O 3 wherein 0.05 ≦ x 1 + x 2 ≦ 0.5 and 0.6 ≦ y ≦ 0.91.

Claim 20

The method of claim 16, wherein said powdery mixture is so compounded that 0.05 ≦ x 1 + x 2 ≦ 0.3 and 0.6 ≦ y ≦ 0.91.

Claim 21

The product of the process of claim 12.

Claim 22

The product of the process of claim 15.

Claim 23

The process of claim 1, wherein said solid solution is selected from the group consisting of BaTiO 3 , BaZrO 3 , Ba(Ti,Zr)O 3 , SrTiO 3 , SrZrO 3 , Sr(Ti,Zr)O 3 , (Ba,Sr)TiO 3 , (Ba,Sr)ZrO 3 , and (Ba,Sr)(Ti,Zr)O 3 .

Claim 24

A process for producing an optically transparent ceramic having a perovskite-type crystal structure and represented by the general formula ABO 3 , wherein component A includes Pb and at least one element selected from the group consisting of Ba and Sr and component B includes Zr or both Zr and Ti, said method comprising: forming an aqueous solution of compounds containing the elements of component A, uniformly dispersing in said solution oxides of the elements constituting the component B to form a dispersion, the amount of said oxides added to said solution being such that the ratio of the component A elements to the component B elements in said dispersion corresponds to the ratio of component A elements to component B elements in said ABO 3 , forming a uniform precipitate of the oxide or oxides of component B and the oxalate of component A by adding to said dispersion oxalic acid in an amount of about 1.05 to 1.1 times the amount of component A in said dispersion on an equivalent basis and an alcohol selected from the group consisting of methanol, ethanol and propanol, drying said precipitate, calcining the dried precipitate to form a complex oxide therefrom, moulding said complex oxide under pressure to form a green compact, and hot-pressing said green compact under a pressure of greater than 70 kg/cm 2 in an atmosphere of oxygen at a temperature from 1,200° to 1,500° C for more than two hours.

Claim 25

A process for producing an optically transparent ceramic having a perovskite-type crystal structure and represented by the general formula ABO 3 , wherein component A includes Pb and at least one element selected from the group consisting of Ba and Sr and component B includes Zr or both Zr and Ti, said method comprising: forming an aqueous solution of compounds containing the elements of component A, uniformly dispersing in said solution oxides of the elements constituting the component B to form a dispersion, the amount of said oxides added to said solution being such that the ratio of the component A elements to the component B elements in said dispersion corresponds to the ratio of component A elements to component B elements in said ABO 3 , forming a uniform precipitate of the oxide or oxides of component B and the oxalate of component A by adding to said dispersion oxalic acid in an amount of about 1.05 to 1.1 times the amount of component A in said dispersion on an equivalent basis and an alcohol selected from the group consisting of methanol, ethanol and propanol, drying said precipitate, calcining the dried precipitate to form a complex oxide therefrom, moulding said complex oxide under pressure to form a green compact, and hot-pressing said green compact under a pressure of greater than 70 kg/cm 2 in an atmosphere of oxygen at a temperature from 1,200° to 1,500° C for more than two hours.