Thermal expansion properties of Ag₂O crystal structure by powder neutron diffraction

Thermal expansion property of Silver(I)-Oxide (Ag₂O) was structurally investigated by neutron powder diffraction from 3 K to 400 K, and measured by X-ray powder diffraction from 20 K to 498 K. Temperature dependency of lattice parameter by neutron diffraction indicates the negative thermal expansion (NTE) below room temperature, and it changes to positive thermal expansion (PTE) from 300 K to 400 K. And this result is consistent with X-ray diffraction and TMA measurement. Moreover, the result by X-ray diffraction shows that lattice parameter significantly decreases above 400 K. Since the result by TG measurement shows the mass loss remarkably in this temperature region, it is considered that decreasing lattice parameter above 400 K is caused from thermal decomposition. (author)