Patent GB-961937-A (GB)
Title: Improvements in or relating to luminescent materials and their manufacture
Inventor: BROWN CYRIL SIMON
IPC: C09K11/63
Filed: 1960-07-26
Abstract: A luminescent material excitable by cathode rays consists of calcium borate of the composition CaO.B2O3 and having a crystal structure defined by specified X-ray diffraction line spacings, activated by manganese.  The material can be prepared by heating a mixture of either CaO or Ca(OH)2 and H3BO3 in relative proportions such that the molecular ratio of CaO : B2O3 derived therefrom is within the range of 3 : 2 to 1 : 2, preferably 1 : 1, or heating a fired and powdered reaction product of such a mixture, together with a small proportion of an oxide or hydroxide of Mn, in contact with water in a sealed vessel, for a period of at least two days at a temperature of at least 350 DEG  C. The starting mixture can contain a compound or compounds of Ca, and/or a compound or compounds of Mn, which dissolves or dissolve to an appreciable extent in water at the operating temperature and readily decompose on heating to give the oxides or hydroxides, e.g. oxalates or carbonates.  The proportion of the Mn compound can be such as to give a Mn content of 0.1 to 1.0 mol. per cent in the final product.  The heating can be carried out in an autoclave, the initial mixture of powdered material being placed, with the water, in a container formed of an inert material, e.g. of gold or platinum, which container is then sealed and placed in the autoclave chamber into which is introduced sufficient water to control the pressure developed in the chamber at a value substantially equal to or slightly greater than that capable of being developed within the container. Alternatively, the heating is carried out in an autoclave provided with a liner of inert material, the initial mixture of powdered material being placed directly within the autoclave together with the requisite volume of water for developing a pressure of at least 85 atmospheres at the operating temperature. In both cases the autoclave can be heated to a temperature in the range of 400 DEG  to 500 DEG  C. and the pressure developed can be controlled at about 500 atmospheres.  It is stated that a calcium borate, omitting the manganese, prepared by the above methods, has substantially the same X-ray diffraction pattern as the calcium borate with the manganese.ALSO:A luminescent material excitable by cathoderays consists of calcium borate of the composition CaO.B2O3 and having a crystal structure defined by specified X-ray diffraction line spacings, activated by Mn.  The material can be prepared by heating a mixture of either CaO or Ca(OH)2 and H3BO3 in relative proportions such that the molecular ratio of CaO: B2O3 derived therefrom is within the range of 3: 2 to 1: 2, preferably 1: 1, or heating a fired and powdered reaction product of such a mixture, together with a small proportion of an oxide or hydroxide of Mn, in contact with water in a sealed vessel, for a period of at least 2 days at a temperature of at least 350 DEG  C.  The starting mixture can contain a compound or compounds of Ca, and/or a compound or compounds of Mn, which dissolves or dissolve to an appreciable extent in water at the operating temperature and readily decompose on heating to give the oxides or hydroxides, e.g. oxalates or carbonates. The proportion of the Mn compound can be such as to give a Mn content of 0.1 to 1.0 mol. per cent in the final product.  The heating can be carried out in an autoclave, the initial mixture of powdered material being placed, with the water, in a container formed of an inert material, e.g. of gold or platinum, which container is then sealed and placed in the autoclave chamber into which is introduced sufficient water to control the pressure developed in the chamber at a value substantially equal to or slightly greater than that capable of being developed within the container. Alternatively, the heating is carried out in an autoclave provided with a liner of inert material, the initial mixture of powdered material being placed directly within the autoclave together with the requisite volume of water for developing a pressure of at least 85 atmospheres at the operating temperature. In both cases the autoclave can be heated to a temperature in the range of 400 DEG  to 500 DEG  C. and the pressure developed can be controlled at about 500 atmospheres.