Abstract: The invention relates to a persistent phosphorescent ceramic composite material which is a sintered dense body comprising two or more phases, a first phase consisting of at least one metal oxide and a second phase consisting of a metal oxide containing at least one activating element in a reduced oxidation state. The invention furthermore relates to a method for the preparation of a phosphorescent ceramic composite material as defined in any of the previous claims, the method comprising the following steps: preparing a mixture of a metal oxide and a phosphor; fabricating a green body from the mixture; and heat treating the green body in a reducing atmosphere.

Abstract: Watch component made of a persistent phosphorescent ceramic composite material which is a sintered dense body comprising two or more phases, a first phase consisting of at least one metal oxide and a second phase consisting of a metal oxide containing at least one activating element in a reduced oxidation state, the watch component having a surface which comprises an area which shows phosphorescent emission and an area which does not show phosphorescent emission or which shows phosphorescent emission with an intensity which is lower than that of the emission of the other area.

Abstract: The present invention relates to long decay phosphors comprising rare earth activated strontium aluminates and methods for producing them. The phosphors comprise a matrix of the formula Sr4Al14O25 comprising europium as an activator and a further rare earth element as a co-activator, wherein the molar ratio of Al/Sr in the starting materials is in the range of 3.1 to less than 3.5 and the ratio of Eu/Sr is in the range of 0.0015 to 0.01. The process for the preparation of a phosphor comprises the steps of milling the starting materials for the synthesis of the phosphor, the starting materials comprising a boron compound selected from boric acid, boric oxide or a borate salt in an amount such that the B/Sr molar ratio is between 0.1 and to 0.3, treating the milled composition with heat, grinding the block material which is obtained through the heat treatment, ball-milling the crushed material, sieving the material, and washing the material with an aqueous solution.

Abstract: The invention relates to a persistent phosphorescent ceramic composite material which is a sintered dense body comprising two or more phases, a first phase consisting of at least one metal oxide and a second phase consisting of a metal oxide containing at least one activating element in a reduced oxidation state. The invention furthermore relates to a method for the preparation of a phosphorescent ceramic composite material as defined in any of the previous claims, the method comprising the following steps: preparing a mixture of a metal oxide and a phosphor; fabricating a green body from the mixture; and heat treating the green body in a reducing atmosphere.

Abstract: The invention relates to a persistent phosphorescent ceramic composite material which is a sintered dense body comprising two or more phases, a first phase consisting of at least one metal oxide and a second phase consisting of a metal oxide containing at least one activating element in a reduced oxidation state. The invention furthermore relates to a method for the preparation of a phosphorescent ceramic composite material as defined in any of the previous claims, the method comprising the following steps: preparing a mixture of a metal oxide and a phosphor; fabricating a green body from the mixture; and heat treating the green body in a reducing atmosphere.

Abstract: Watch component made of a persistent phosphorescent ceramic composite material which is a sintered dense body comprising two or more phases, a first phase consisting of at least one metal oxide and a second phase consisting of a metal oxide containing at least one activating element in a reduced oxidation state, the watch component having a surface which comprises an area which shows phosphorescent emission and an area which does not show phosphorescent emission or which shows phosphorescent emission with an intensity which is lower than that of the emission of the other area.

Abstract: The invention relates to an alumina-based opaque ceramic, similar to ruby and having a high toughness. This ceramic comprises, by weight: 0.4% to 5% of at least from one oxide of a metal chosen from chromium, cobalt, nickel, manganese, vanadium, titanium and iron; 0.00080 to 0.5% of magnesium oxide; and 0.05 to 6% of at least one oxide of an element of the group of rare earths. The ceramic is applicable in particular in jewelry, fine jewelry and watch making. The invention also relates to methods of preparing such a ceramic.

Abstract: The invention relates to a persistent phosphorescent ceramic composite material which is a sintered dense body comprising two or more phases, a first phase consisting of at least one metal oxide and a second phase consisting of a metal oxide containing at least one activating element in a reduced oxidation state. The invention furthermore relates to a method for the preparation of a phosphorescent ceramic composite material as defined in any of the previous claims, the method comprising the following steps: preparing a mixture of a metal oxide and a phosphor; fabricating a green body from the mixture; and heat treating the green body in a reducing atmosphere.

Abstract: The invention relates to an alumina-based opaque ceramic, similar to ruby and having a high toughness. This ceramic comprises, by weight: 0.4% to 5% of at least from one oxide of a metal chosen from chromium, cobalt, nickel, manganese, vanadium, titanium and iron; 0.00080 to 0.5% of magnesium oxide; and 0.05 to 6% of at least one oxide of an element of the group of rare earths. The ceramic is applicable in particular in jewellery, fine jewellery and watch making. The invention also relates to methods of preparing such a ceramic.