Dipole - dipole and dipole - quadrupole interactions between Sm3+ ions in K4BaSi3O9

K4BaSi3O9 (KBSO) doped with Sm3+ was synthesized for the first time by conventional solid-state method. Results of XRD measurements confirm that the obtained powder is K4BaSi3O9 single phase. The new material exhibits red luminescence with maximum at 641 nm under 407 nm excitation. At 300 K the luminescence intensity is quenched for Sm3+ concentration above 0.5%. The decay profiles revealed the non-radiative energy transfer between the Sm3+ ions. The interaction has dipole - dipole character for low Sm3+ concentrations (up to 1%) then dipole - quadrupole for higher dopant concentration (over 1%). The critical distances are 8.8 Å and 9.5 Å for dipole - dipole and the latter interactions, respectively. This phenomenon is explained by analyzing the probability of occupation of all possible sites available for Sm3+ in KBSO taking into account local charge compensation. The site occupation preference by Sm3+ ions depends on the distances between available cation sites.