Nuclear spin coherence properties of 151 Eu 3+ and 153 Eu 3+ in a Y 2 O 3 transparent ceramic J Karlsson 1 , N Kunkel 1 , A Ikesue 2 , A Ferrier 1,3 and P Goldner 1 1 PSL Research University, Chimie ParisTech, CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France 2 World Laboratory, Mutsuno, Atsuta-ku, Nagoya 456-0023, Japan 3 Sorbonne Universit´ es, UPMC Universit´ e Paris 06, 75005, Paris, France E-mail: jenny.karlsson@chimie-paristech.fr Abstract. We have measured inhomogeneous linewidths and coherence times (T 2 ) of nuclear spin transitions in a Eu 3+ :Y 2 O 3 transparent ceramic by an all-optical spin echo technique. The nuclear spin echo decay curves showed a strong modulation which was attributed to interaction with Y nuclei in the host. The coherence time of the 29 MHz spin transition in 151 Eu 3+ was 16 ms in a small applied magnetic field. Temperature dependent measurements showed that the coherence time was constant up to 18 K and was limited by spin-lattice relaxation for higher temperatures. Nuclear spin echoes in 153 Eu 3+ gave much weaker signals than for the case of 151 Eu 3+ . The spin coherence time for the 73 MHz spin transition in 153 Eu 3+ was estimated to 14 ms in a small magnetic field. The study shows that the spin transitions of ceramic Eu 3+ :Y 2 O 3 have coherence properties comparable to the best rare-earth-doped materials available. PACS numbers: 76.60.Lz, 76.60.Gv, 76.70.Hb, 75.30.Hx Keywords: ODMR, Spin echoes, Rare-earth ions, Ceramics Submitted to: J. Phys.: Condens. Matter