The first-principles calculations of the structural and magnetic properties of kotoite NiCo(BO3)2 have been carried out. The minimization of the lattice parameters shows the values to be in good agreement with the experimental data (the difference is less than 1%). The atomic coor- dinates have been calculated. Cobalt ions tend to occupy position 2a and nickel ions tend to occupy position 4f . The same magnetic cell as in Ni3B2O6 but quadrupled in size (2a × b × 2c) has the minimum exchange energy for Ni2Co(BO3)2. In Ni2Co(BO3)2, the magnetic moments are oriented along the b axis as in Co3B2O6
Sofronova et al. (Thu,) studied this question.