The dielectric relaxation behavior of a bent-core liquid-crystalline (BC) material showing B2 phase and its 17% mixture with another rod-like material (R-BC) has been investigated. The appearance of a newly induced B1 phase has been detected in the R-BC system. We found comparatively lower value of dielectric permittivity of the R-BC system than that of BC material. Moreover, a lower value of relaxation frequency of the long axis rotation mode in BC material compared to that of the R-BC material has been observed. These results have been discussed on the basis of molecular origin for the formation of B phases in the materials.