Crystal Structure and Magnetic Properties of the New Zn1.5Co1.5B7O13Br   Boracite
  New Zn1.5Co1.5B7O13Br boracite crystals were grown by chemical transport reactions in quartz ampoules, at a temperature of 1173 K. The crystal structure was characterized by X-ray diffraction. The crystals present an orthorhombic structure with space group Pca21, (No. 29). The determined cell parameters were: a = 8.5705(3){\AA}, b = 8.5629(3) {\AA}, and c = 12.1198(4){\AA}, and cell volume, V = 889.45(5) {\AA}3 with Z = 4. Magnetic properties in single crystals of the new boracite, were determined. The Susceptibility-Temperature (X -T) behavior at different magnetic intensities was studied. The inverse of the magnetic susceptibility X-1(T) shows a Curie-Weiss characteristic with spin s = 3/2 and a small orbital contribution, l. At low temperatures, below 10 K, X(T) shows irreversibility that is strongly dependent on the applied magnetic field. This boracite is ferrimagnetic up to a maximum temperature of about 16 K, as shows the coercive field. The reduction of the irreversibility by the influence of the magnetic field, may be related to a metamagnetic phase transition. 
Roberto Escudero, Francisco Morales, Marco A Leyva Ramirez, Jorge   Campa-Molina, and S. Ulloa-Godinez
cond-mat.mtrl-sci