Abstract: A member of supporting magnetic disc substrates is provided, comprising a ceramic sinter containing a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt, and chromium, wherein the ceramic sinter has conductive aggregates on its peripheral surface. In the member, the ceramic component may be forsterite and the conductive component is iron oxide, wherein the ceramic sinter comprises a main phase of 2MgO.SiO2 and a secondary phase of at least one of MgFe2O4, Fe3O4, and Fe2O3.

Abstract: A member of supporting magnetic disc substrates is provided, comprising a ceramic sinter containing a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt, and chromium, wherein the ceramic sinter has conductive aggregates on its peripheral surface. In the member, the ceramic component may be forsterite and the conductive component is iron oxide, wherein the ceramic sinter comprises a main phase of 2MgO.SiO2and a secondary phase of at least one of MgFe2O4Fe3O4and Fe2O3.

Abstract: A member of supporting magnetic disc substrates is provided, comprising a ceramic sinter containing a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt, and chromium, wherein the ceramic sinter has conductive aggregates on its peripheral surface. In the member, the ceramic component may be forsterite and the conductive component is iron oxide, wherein the ceramic sinter comprises a main phase of 2MgO.SiO2 and a secondary phase of at least one of MgFe2O4, Fe3O4 and Fe2O3.

Abstract: A member used within a plasma processing apparatus and exposed to a plasma of a halogen gas such as BCl3 or Cl2 is formed from a sintered body of metals of Group IIIa of Periodic Table such as Y, La, Ce, Nd and Dy, and Al and/or Si, for example, 3Y2O3.5Al2O3, 2Y2O3.Al2O3, Y2O3.Al2O3 or disilicate or monosilicate, and in particular, in this sintered body, the content of impurity metals of Group IIa of Periodic Table contained in the sintered body is controlled to be 0.15 wt % or more in total. Specifically, for this member, an yttrium-aluminum-garnet sintered body having a porosity of 3% or less and also having a surface roughness of 1 ?m or less in center line average roughness Ra is utilized.

Abstract: A member of supporting magnetic disc substrates is provided, comprising a ceramic sinter containing a ceramic component and at least one conductive component selected from a group consisting of iron, niobium, tin zinc, copper, nickel, cobalt, and chromium, wherein the ceramic sinter has conductive aggregates on its peripheral surface. In the member, the ceramic component may be forsterite and the conductive component is iron oxide, wherein the ceramic sinter comprises a main phase of 2MgO.SiO2 and a secondary phase of at least one of MgFe2O4, Fe3O4 and Fe2O3.

Abstract: A member used within a plasma processing apparatus and exposed to a plasma of a halogen gas such as BCl3 or Cl2 is formed from a sintered body of metals of Group IIIa of Periodic Table such as Y, La, Ce, Nd and Dy, and Al and/or Si, for example, 3Y2O3.5Al2O3, 2Y2O3.Al2O3, Y2O3.Al2O3 or disilicate or monosilicate, and in particular, in this sintered body, the content of impurity metals of Group IIa of Periodic Table contained in the sintered body is controlled to be 0.15 wt % or more in total. Specifically, for this member, an yttrium-aluminum-garnet sintered body having a porosity of 3% or less and also having a surface roughness of 1 &mgr;m or less in center line average roughness Ra is utilized.

Abstract: A member used within a plasma processing apparatus and exposed to a plasma of a halogen gas such as BCl3 or Cl2 is formed from a sintered body of metals of Group IIIa of Periodic Table such as Y, La, Ce, Nd and Dy, and Al and/or Si, for example, 3Y2O3·5Al2O3, 2Y2O3·Al2O3, Y2O3·Al2O3 or disilicate or monosilicate, and in particular, in this sintered body, the content of impurity metals of Group IIa of Periodic Table contained in the sintered body is controlled to be 0.15 wt % or more in total. Specifically, for this member, an yttrium-aluminum-garnet sintered body having a porosity of 3% or less and also having a surface roughness of 1 &mgr;m or less in center line average roughness Ra is utilized.