The LaF₃ film formed by c-axis oriented uniform-size nanocrystals with diameter of about 400 nm was obtained on the surface of La(NO₃)₃ solution in 1 M HNO₃ by interfacial reaction with HF in the gas medium. The effect of solution acidity on the layer morphology is reported. The film formed by LaF₃:Eu³⁺ oriented nanocrystals with radial compositional gradient has been prepared in a similar way. The synthesized crystals were characterized by SEM, TEM, HRTEM, EPMA, TEM-EDX mapping, XRD analysis, Raman and luminescent spectroscopy. The LaF₃:Eu³⁺ doped nanocrystals can potentially be used as luminescent material.