Abstract: The invention relates to a reflective feature, e.g., reflective security feature or reflective decorative feature, comprising a first element at least partially coplanar with a second element. The first element causes incident light to be reflected with a first intensity that varies as the angle of incidence changes relative to a surface of the reflective feature. The invention also relates to a direct write printing process for forming such a reflective feature from an ink comprising metallic nanoparticles.

Abstract: A particulate composition comprises a plurality of particles wherein at least one of the particles comprises at least two different crystalline and/or glass phases, each phase comprising a host lattice and a dopant sensitive to electromagnetic radiation. The different phases simultaneously produce different responses on exposure to photons of the same energy, whereby the output from the particulate composition when exposed to said photons is the sum of the responses from the different phases.

Abstract: A particulate composition comprises a plurality of particles wherein at least one of the particles comprises at least two different crystalline and/or glass phases, each phase comprising a host lattice and a dopant sensitive to electromagnetic radiation. The different phases simultaneously produce different responses on exposure to photons of the same energy, whereby the output from the particulate composition when exposed to said photons is the sum of the responses from the different phases.

Abstract: A particulate composition comprises a plurality of particles wherein at least one of the particles comprises at least two different crystalline and/or glass phases, each phase comprising a host lattice and a dopant sensitive to electromagnetic radiation. The different phases simultaneously produce different responses on exposure to photons of the same energy, whereby the output from the particulate composition when exposed to said photons is the sum of the responses from the different phases.

Abstract: A phosphor composition comprises a host lattice, a dopant and a decay modifying component different from the dopant and the host lattice and effective to alter the rate of decay of the radiation emitted by the phosphor composition in response to excitation by photons of a given energy. The decay modifying component is added to the phosphor composition in a predetermined amount between 1 and 10,000 parts per million of the composition. By varying the amount of the decay modifying component added to the phosphor composition, it is possible to produce a set of phosphor compositions with different, controlled rates of decay of the radiation emitted by the compositions.

Abstract: This invention is directed to security features that are formed, created, printed from inks comprising metallic particles and/or metallic nanoparticles. Preferably, the security feature is a reflective security features that comprises metallic nanoparticles where the reflective security features are formed by a direct-writing process, e.g., an ink jet printing process, using an ink comprising metallic nanoparticles. The invention is also directed to the use of these security features in many applications and to processes for making them.