  High-pressure techniques open exploration of functional materials in broad
research fields. An established diamond anvil cell with a boron-doped diamond
heater and transport measurement terminals has performed the high-pressure
synthesis of a cubic Sn$_{3}$S$_{4}$ superconductor. X-ray diffraction and
Raman spectroscopy reveal that the Sn$_{3}$S$_{4}$ phase is stable in the
pressure range of P>5 GPa in a decompression process. Transport measurement
terminals in the diamond anvil cell detect a metallic nature and
superconductivity in the synthesized Sn$_{3}$S$_{4}$ with a maximum onset
transition temperature of 13.3 K at 5.6 GPa. The observed pressure-T$_{c}$
relationship is consistent with that from the first-principles calculation. The
observation of superconductivity in Sn$_{3}$S$_{4}$ opens further materials
exploration under high temperature and pressure conditions.
