It has already been demonstrated that a large variety of synthetic langbeinites, based on the structure of K₂Mg₂(SO₄)₃, can be stabilized with room temperature non-centrosymmetric structures . Chemically speaking, fully substituting both sulfate SO42- for phosphate PO43- group and diamagnetic Mg2+ ions for paramagnetic Cr3+ cations is possible only if a mixed counter cation (Na+A2+) is introduced on the potassium site. NaBa1-xSrxCr2(PO4)3 solids, ceramics, with x=0 and 1 were recently reported to show intriguing physical properties (hysteric magneto capacitance signal when x=0 and a parallel magnetic long range ordering when x=1). During this internship we aim to grow single crystals NaBa1-xSrxCr2(PO4)3, from high temperature solutions, because obtaining single crystals is mandatory to investigate the physical properties/nuclear structure relationships with respect to an external stimulus. This work is developed in the frame of a collaboration project which main goal is the search of multiferroics solids based on polyanionic framworks.