Influence of structural distortions upon photoluminescence properties of Eu3+ and Tb3+ activated Na3Ln(BO3)2 (Ln=Y, Gd) borates

► Crystal structure of Na3Gd(BO3)2 by X-ray powder diffraction. ► Photoluminescence properties of Eu3+ and Tb3+ doped Na3Ln(BO3)2 (Ln=Y, Gd). ► Higher Eu3+ and Tb3+ emission for Na3Gd(BO3)2 due to an irregular environment of Gd3+. ► Higher Eu3+ and Tb3+ emission for Na3Gd(BO3)2 due to energy transfer from Gd3+. ► Lower Tb3+ critical concentration for Na3Gd(BO3)2 due to short Gd3+-Gd3+ distances.