This invention deal with a flaky effect pigment comprising as optical active layer a single platelet consisting of a semiconductor material with a band gap in a range of 0.1 to 2.5 eV and having an average atomic composition of: a) Si.sub.(1-x)Ge.sub.x, wherein 0<x<1.00 or b) Si.sub.(1-y)Sn.sub.y, wherein 0<y<0.90 or c) Ge.sub.(1-z)Sn.sub.2, wherein 0<z0.60 or d) Si.sub.(1-m-n)Ge.sub.mSn.sub.n, wherein 0<m<1.00, 0<n<1.00 with the provisos that x<1.00; y<1.00, z<1.00 and m+n<1.00. These effect pigments exhibit attractive optical properties and are radartransparent.

Disclosed herein is an effect pigment having a layer stack which comprises a highly reflective metallic flake having a first major interface and opposed to this first interface a second major interface, and at least one side surface and directly adjacent on one or of both of these major interfaces a layer of a semiconducting material having an average atomic composition of: a) Si.sub.(1-x)Sn.sub.x, wherein 0<x<0.90 or b) Ge.sub.(1-y)Sn.sub.y, wherein 0<y0.80 or c) Si.sub.(1-m-n)Ge.sub.mSn.sub.n, wherein 0<m<1.00, 0<n<1.00 and with the proviso that m+n<1.00.

Weather stable pearlescent pigment having a basic pearlescent with an interference color which comprises a transparent platelet-shaped substrate and at least one metal oxide layer with a refractive index >1.8 and on top of this basic pearlescent pigment a weather stabilizing top coating comprising at least one metal oxide and an organofunctional surface modification, wherein a) for a basic pearlescent pigment with silvery interference color the weather stabilizing top coating consists of a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, or b) for a basic pearlescent pigment with a colored interference color or a silvery interference color the weather stabilizing top coating comprises a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, and a second metal oxide from a second metal M2 from the group consisting of Si, Al, Zn, Mg, Zr, Sn and mixtures or combinations thereof, and in each case a) or b) the organofunctional surface modification comprises organofunctional silanes or water-based pre-condensated organofunctional silanes.

This invention involves a coated flaky metal effect pigment comprising a metal effect flake as substrate coated by the following consecutive coating sequences: a) optionally a discontinuous or a continuous layer of Mo-oxide, b1) an inorganic metal oxide layer comprising mainly SiO.sub.2, c1) a hybrid layer comprising SiO.sub.2 modified by a diphenyl silane, a phenylsilane or mixtures thereof or c2) a hybrid layer comprising SiO.sub.2 modified by a diphenyl silane, a phenylsilane or mixtures thereof, b2) an inorganic metal oxide layer comprising mainly SiO.sub.2, and d) optionally a further top-coat of organofunctional silanes, titanates, aluminates or zirconates.

A pigment, including a flake including a metal core having a first surface and a second surface, a first dielectric layer interfacing with a first surface of the metal core, and a second dielectric layer interfacing with a second surface of the metal core; a first inorganic layer encapsulating the flake; and an organic layer encapsulating the first organic layer is disclosed. A colorant composition including the pigment is also disclosed. A method of making the pigment, and a method of making a colorant composition are also disclosed.

Weather stable pearlescent pigment having a basic pearlescent with an interference color which comprises a transparent platelet-shaped substrate and at least one metal oxide layer with a refractive index >1.8 and on top of this basic pearlescent pigment a weather stabilizing top coating comprising at least one metal oxide and an organofunctional surface modification, wherein a) for a basic pearlescent pigment with silvery interference color the weather stabilizing top coating consists of a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, or b) for a basic pearlescent pigment with a colored interference color or a silvery interference color the weather stabilizing top coating comprises a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, and a second metal oxide from a second metal M2 from the group consisting of Si, Al, Zn, Mg, Zr, Sn and mixtures or combinations thereof, and in each case a) or b) the organofunctional surface modification comprises organofunctional silanes or water-based pre-condensated organofunctional silanes.

There is disclosed a method including chemically converting a first material of a lamellar particle into a compound of the first material. The step of chemical conversion can be performed by a reactant, and the reactant can be in a form of at least one of a solid state, a liquid state, a vapor state, and a plasma state.