Scintillation properties of Cs₄Mg₃F₁₀ crystal grown by micro-pulling-down method

In our search for cross-luminescence (CL) scintillators suitable for fast-timing applications, we have chosen CsMgF3 as one of the perspective candidates. During the attempts to grow CsMgF3 by the micro-pulling-down method, we have revealed the presence of Cs4Mg3F10 which is in contradiction with the published equilibrium phase diagram. The Cs4Mg3F10 has an orthorhombic structure, consisting of face-sharing MgF6 octahedra triplets (4 triplets per unit cell), joined to 4 other triplets by corner sharing. These chain-like structures are separated by Cs+ ions. Moreover, Cs4Mg3F10 is non-hygroscopic despite the hygroscopic nature of CsF. The best crystals were grown from CsF-rich melt to suppress off-stoichiometry due to CsF evaporation during crystal growth. Both radioluminescence spectra and scintillation decay kinetics exhibit complex character and the presence of CL in Cs4Mg3F10 is still under question. However, due to relatively low scintillation efficiency and the presence of slow components in scintillation decay, Cs4Mg3F10 is not suitable for fast-timing applications.