A luminescent particle including a surface comprising glass that surrounds one or more particles of one or more light emissive materials is disclosed. Preferably the surface comprises a vitrified glass. Methods form making a luminescent particle including a surface comprising glass that surrounds one or more particles of one or more light emissive materials is also disclosed. Compositions and products including a luminescent particle are further disclosed.

A method for manufacturing a silica glass body includes preheating a porous silica glass body, and placing the preheated porous silica glass body in a resonator that resonates a microwave having a frequency band of 1 GHz to 30 GHz to heat the porous silica glass body with the microwave. At least a part of the porous silica glass body contains an additive other than silicon and oxygen. The porous silica glass body is preheated to a temperature equal to or higher than a glass transition temperature of the additive-added portion of the porous silica glass body in the preheating. The porous silica glass with the additive is heated with the microwave in the heating with the microwave.

The porous glass base material manufacturing apparatus releases gas of organic siloxane raw materials into the flame of a group of burners that moves relative to a starting base material along the longitudinal direction of the starting base material rotating around a rotation axis along the longitudinal direction to form soot of porous glass particles on the surface of the starting base material. The porous glass base material manufacturing apparatus is equipped with a vaporizer that vaporizes liquid raw materials containing organic siloxane in a liquid state supplied from a raw material tank to make a raw material mixed gas mixed with raw material gas and carrier gas and a raw material gas pipe that supplies the raw material mixed gas to the burner. The raw material gas pipe is insulated and kept warm by double insulation.

A method for manufacturing porous glass base material includes supplying a liquid raw material containing an organic siloxane raw material in a liquid state supplied from a raw material tank to a vaporizer, mixing the liquid raw material of the organic siloxane with a carrier gas in a vaporizer and vaporizing the liquid raw material to make the raw material mixed gas in which the raw material gas and carrier gas are mixed, supplying the raw material mixed gas to a burner via a raw material gas pipe, and forming soot of porous glass particles on the surface of a starting base material by releasing the raw material mixed gas into the flame of the burner that moves relative to the starting base material along the longitudinal direction of the starting base material rotating around a rotation axis along the longitudinal direction.