Affiliation:
1. Institute of Solid State Chemistry UB RAS Pervomaiskaya str. 91 Ekaterinburg 620990 Russia
2. Max Planck Institute of Colloids and Interfaces Am Mühlenberg 1 14476 Potsdam Germany
3. ISIS Facility Rutherford Appleton Laboratory Harwell Science & Innovation Campus Chilton Oxfordshire OX11 0QX UK
4. Ural Federal University Mira str. 19 Ekaterinburg 620062 Russia
Abstract
AbstractOxyapatites A10(GeO4)6O2 (A – alkaline, rare‐earth elements) are considered promising materials for applications in solid‐state lighting and non‐contact thermometry. The temperature dynamics of the oxygen sublattice have a crucial influence on the luminescent properties of these optical hosts. Here, the structural evolution with temperature of germanates with the general formula ALa9(GeO4)6O2 (A – Li, Na, K, Rb) is investigated, using X‐ray and neutron powder diffraction methods. These compounds crystallize in space‐group P63/m. NPD experiments helped to determine the oxygen and alkaline metal positions. Thermally‐induced reentrant structural transitions relating to the oxygen in the apatite channel are discovered for the first time. In the example of Eu‐doped RbLa9(GeO4)6O2 and KLa9(GeO4)6O2, it is demonstrated that the luminescence of the Eu3+ ion is influenced by small changes in the crystal structure.
Funder
Russian Academy of Sciences