Abstract: A method for preparing needle-like, fibrous or porous diamond, or an aggregate thereof, which comprises subjecting diamond synthesized by a chemical vapor deposition method or a plasma-assisted vapor deposition method, or a film of such diamond, to plasma treatment in a gas stream containing oxygen, carbon dioxide, steam, hydrogen, a halogenated hydrocarbon or a halogenated carbon, or to thermal oxidation treatment in a gas stream containing oxygen, carbon dioxide or steam, for etching.

Abstract: The process for producing a glass mold according to the present invention comprises forming, on a glass mold base, a thin film consisting of diamond crystallites, graphite crystallites and amorphous carbon and having a maximum surface roughness of 200 .ANG. or below, by a plasma CVD method or a thermal CVD method using a mixed gas comprising an organic gas and hydrogen gas, the concentration of the organic gas in the mixed gas being at least 3 mole %.The glass mold obtained according to the present process has advantages of having excellent releasability of molded glass article after press molding, excellent durability and a long life.

Abstract: A silicophosphate laser glass having a composition comprising, in % by mole,45 to 70% P.sub.2 O.sub.5 ;5 to 20% SiO.sub.2 ;60 to 95% P.sub.2 O.sub.5 +SiO.sub.2 +Al.sub.2 O.sub.5 ;10%<Al.sub.2 O.sub.3 .ltoreq.20%;20%<(Al.sub.2 O.sub.3 +SiO.sub.2).ltoreq.30%;4 to 30% Li.sub.2 O+Na.sub.2 O+K.sub.2 O;0.01 to 12% Nd.sub.2 O.sub.3 ;0 to 5% La.sub.2 O.sub.3 +Y.sub.2 O.sub.3 +B.sub.2 O.sub.5 ;0 to 10% R'O; and0 to 1% Nb.sub.2 O.sub.5 +CeO.sub.2,wherein R' is Mg, Ca, Sr, Ba, Zn or Pb. The silicophosphate laser glass can construct an excellent laser glass as an amplifying medium.

Abstract: A process of surface-treating a laser glass is disclosed which comprises coating a specific sol solution obtained by hydrolysis and partial polycondensation of a mixture containing a metal alcoholate on the glass surface and heating the coated glass to form a glassy coating, wherein the glass surface may be treated, prior to the coating, with an alkali aqueous solution and with an aqueous solution of phosphoric acid in sequence, or the coating and the heating may repeated to form a double- or multilayer of the same or different kind of glassy coatings. The thus treated laser glass has increased thermal shock resistance and water resistance.