There is provided a paint including a pigment, a carrier liquid, a binder, one or more additives, and a taggant corresponding to the one or more additives. The taggant is provided in an amount up to substantially 0.1% by weight of the paint. The taggant is excitable by infra-red or UV light at one wavelength to emit light at one or more other wavelengths, the emission wavelength or spectrum of the taggant being indicative of the additive(s) in the paint. A method of authenticating the paint on a substrate is also provided.

A phosphor is represented by the general formula
aM.sup.IX.Math.M.sup.II.sub.1-xM.sup.IM.sup.VO.sub.4:(Re).sub.x
where M.sup.I is at least one atomic element selected from the group consisting of K, Li, Na, Rb, Cs, Fr, Cu, and Ag, with K being essential; M.sup.II is at least one atomic element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Mn, Zn, Cd, and Sn; M.sup.V is at least one atomic element selected from the group consisting of P, V, Nb, Ta, As, Sb, and Bi; X is at least one halogen element, with F being essential; Re is at least one atomic element selected from the group consisting of rare earth elements, with Eu being essential; and a is in the range 0.6a1.4.

The present invention generally relates to a process for fabricating Chloro Alkali Phosphate Doped/Codoped by rare earth ions for optical laser amplifiers. The process includes mixing 38-42 wt. % of Phosphorus pentoxide (P.sub.2O.sub.5), 28-32 wt. % of Zinc oxide (ZnO), 9-11 wt. % of Barium fluoride (BaF.sub.2), 17-19 wt. % of Lithium chloride (LiCl), and 1-3 wt. % of Lead(II) fluoride (PbF.sub.2); filling a silica, platinum, and alumina crucible to the mixture; heating the mixture upon increasing a furnace temperature to 1000-1050 C. at a rate of 10 C. per minute and maintaining it for two hours to melt the glass; and pouring the glass melt into a preheated stainless steel mold at 350 C. and transferring the mold to a holding furnace heated to 350-370 C. and annealing for two hours thereby cooling to room temperature to obtain Chloro Alkali Phosphate matrix glass that is undoped, doped, or codoped with high thermal stability.

A phosphor is represented by the general formula

aM.sup.IX.M.sup.II.sub.1-xM.sup.IM.sup.VO.sub.4:(Re).sub.x

where M.sup.I is at least one atomic element selected from the group consisting of K, Li, Na, Rb, Cs, Fr, Cu, and Ag, with K being essential; M.sup.II is at least one atomic element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Mn, Zn, Cd, and Sn; M.sup.V is at least one atomic element selected from the group consisting of P, V, Nb, Ta, As, Sb, and Bi; X is at least one halogen element, with F being essential; Re is at least one atomic element selected from the group consisting of rare earth elements, with Eu being essential; and a is in the range 0.6a1.4.

A wavelength converting material comprising a phosphate compound have a chemical formula of AB.sub.1-m-nPO.sub.4:M.sub.m, N.sub.n, wherein A comprises an alkali metal element, B comprises an alkaline earth metal element, M is a sensitizer comprising a rare-earth element, and N is an acceptor comprising a rare-earth element, wherein 0<m0.3 and 0<n0.3.

A uranium-based phosphor selected from (i) phosphors having formula I or II:

##STR00001##

where the phosphor having formula I or II is doped with an activator ion including Pr.sup.3+, Sm.sup.3+, or mixtures thereof, where 0a1, 0b1, 0.75x1.25, 0.75y1.25, 0.75z1.25, 2.5p3.5, 1.75q2.25, and 3.5r4.5; (ii) a phosphor having formula I or II, where the phosphor having formula I or II is doped with an activator ion selected from Eu.sup.3+, Pr.sup.3+, Sm.sup.3+, and mixtures thereof; and a counter ion comprising one or more alkali metal ions; and (iii) phosphors having formula III

##STR00002##

where the phosphors having formula III are doped with an activator ion selected from: Eu.sup.3+, Pr.sup.3+, Sm.sup.3+, and mixtures thereof, where A is Li, Na, K, Rb, Cs, or a combination thereof.