SmCa4O(BO3)3 (SCOB) crystallizes in the noncentrosymmetric monoclinic space group Cm with cell parameters a = 0.8129(5), b = 1.6076(1), c = 0.3584(1) nm, β = 101.36(2)°, and Z = 2. Raman results showed that the characteristic spectra of SCOB are mainly contributed by the B-O triangles and partly by the Ca(1)-O octahedra. The structural rigidity of SCOB is mainly ascribed to the B-O bond stretching and bending modes and partly by the Ca(1)-O bonds. The rigid structure of the B-O triangles and the quasi-rigid structure of the Ca(1)-O octahedra are necessary to the SCOB crystal as a laser host. The large distortions of the Sm-O and Ca(2)-O octahedra intensify the polar forces and anisotropic lattice forces, which generally imply the best nonlinear properties possible for SCOB as a nonlinear optical material and piezocrystal. Thermal measurements show a larger value of the specific heat and three small expansion coefficients, which show that SCOB can allow a large temperature gradient, especially in the Y direction. Displacement parameters indicated that the thermal ellipsoids of the Sm and Ca(2) atoms had significantly large components along the b direction. Synthetical study indicated that the SCOB crystal should be outstanding as an efficient self-frequency doubled material. © 2002 Materials Research Society.