Pis’ma v ZhETF, vol. 105, iss. 1, pp. 28 – 29 2017 January 10 c Magnetic phase separation and strong enhancement of the Neel temperature at high pressures in a new multiferroic Ba3TaFe3Si2O14 I. S.Lyubutina1), S. S. Starchikova,b, A.G.Gavriliuka,b,c, I.A.Troyana,b,c, Yu. <...> A.Nikiforovaa,b, A.G. Ivanovaa,b, A. I.Chumakovd,e, R.R¨ ufferd aFSRC “Crystallography and Photonics” of Russian Academy of Sciences, 119333 Moscow, Russia bInstitute for Nuclear Research, Russian Academy of Sciences, 142190 Moscow, Troitsk, Russia cREC “Functional Nanomaterials”, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia dEuropean Synchrotron Radiation Facility, CS40220, F-38043, Grenoble, France eNational Research Center “Kurchatov Institute”, 123182 Moscow, Russia Submitted 18 November 2016 DOI: 10.7868/S0370274X17010064 Langasites (La3Ga5SiO14) crystals are famous due to their unique piezoelectric, laser and nonlinear optical properties [1, 2]. <...> It has a layered structure where iron Fe3+ and silicon Si4+ ions occupy the 3f and 2d tetrahedral sites in the ab plane, respectively. <...> The Fe3+ ions form a net of triangle clusters on a hexagonal lattice in the ab planes creating the triangle magnetic structure with frustrated interactions [3, 6] The neutron diffraction studies of the similar crystal Ba3NbFe3Si2O14 [3, 5] revealed the 120◦ – ordering of Fe magnetic moments in the ab plane at low temperatures. <...> In addition, the magnetic vector rotates from layer to layer (in the ab plains), when alternating along the c axis, thus forming a helical magnetic structure [3]. <...> TransmissionMossbauer spectroscopy revealed splitting of crystallographic iron sites into two sublattices at ambient pressures [4, 6] which was associated with the structural phase transition induced by the magnetic ordering below Neel temperature TN = 27.2K. <...> At high pressures P > 20GPa the giant increasing of the Neel temperature up to 120K was found by Nuclear Forward Scattering (NFS) [11, 12]. <...> However the information about non-equivalent iron sites and magnetic structure at high pressures is not obtained <...>