Spin-Flop Transition in Co2B2O5 Pyroborate

Cobalt pyroborate Co2B2O5 single crystals have been obtained by spontaneous crystallization from solution–melt. Powder X-ray diffraction measurements have revealed the triclinic symmetry $$P\overline 1 $$ with the lattice parameters $$a = 3.1666(7)$$ Å, $$b = 6.1543(6)$$ Å, $$c = 9.2785(12)$$ Å, $$\alpha = 104.240(5)^\circ $$ , $$\beta = 90.841(14)^\circ $$ , $$\gamma = 92.064(16)^\circ $$ , and $$V = 175.10(5)$$ Å3. Magnetic properties have been studied in the temperature range of 4.2–300 K and in magnetic fields up to 90 kOe by measuring the static magnetization and molar heat capacity. A transition to an antiferromagnetic state has been detected at TN = 45 K. A spin-flop transition occurs in the sample in strong magnetic fields.