Disks recorded in a same format are normally read at a same speed, even during playback of an audio video or the like, and during copying on a hard disk drive or the like. Suggested is a method for producing lithium sulfide for a solid electrolyte material for lithium ion batteries that is used as a solid electrolyte material for lithium ion batteries, the method including bringing lithium carbonate powder into contact with a gas containing sulfur in a dry state, simultaneously heating the lithium carbonate, and thereby obtaining lithium sulfide powder. Corresponding user interfaces, systems, and methods are also disclosed. The initiator system and the hardening composition can be used in various fields, including the dental and orthodontic area. For oxygen-sensitive applications, an inert gas, such as nitrogen gas, can be employed as the pressurized gas.