Abstract: Novel stable forms of technetium and methods for their production are provided. These methods have particular application for the removal of technetium from industrial waste compositions.

Abstract: Anions of the formula (I):[DA.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.m- (I)in which D is Na.sup.+, Ca.sup.2+ ; A is P, As, Sb, Si, Ge, or combinations thereof, M is W.sup.5+, W.sup.6+, or mixtures thereof; M' is a metallic element from groups 2 to 15 of the periodic table; other than W; L is O.sup.2-, OH.sup.-, H.sub.2 O; x is 0-10; and m is 10-20; selectively react with cations Z.sup.n+ to afford anions of the formula (II):[ZA.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.(m+1-n)-(II)wherein n is 3 or 4; Z=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, or Bi, when n=3, and Z=Ce, U, Np, Pu, or Am, when n =4. This reaction may be used for the selective encapsulation of lanthanide or actinide cations, and salts containing anions of formula (II) may be vitrified to form glasses or reduced to form tungsten "bronze" materials suitable for the long-term storage of radioactive lanthanides or actinides.

Abstract: Anions of the formula (I):[DA.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.m- (I)in which D is Na.sup.+, Ca.sup.2+; A is P, As, Sb, Si, Ge, or combinations thereof M is W.sup.5+, W.sup.6.alpha., or mixtures thereof; M' is a metallic element from groups 2 to 15 of the periodic table; other than W; L is O.sup.2-, OH.sup.-, H.sub.2 O; x is 0-10; and m is 10-20; selectively react with cations Z.sup.n+ to afford anions of the formula (II):[ZA.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.(m+1-n)- (II)wherein n is 3 or 4; Z=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, or Bi, when n=3, and Z=Ce, U, Np, Pu, or Am, when n=4. This reaction may be used for the selective encapsultion of lanthanide or actinide cations, and salts containing anions of formula (II) may be vitrified to form glasses or reduced to form tungsten "bronze" materials suitable for the long-germ storage of radioactive lanthanides or actinides.