Exploring the compression behavior of HP-BiNbO₄ under high pressure

In the present work, a third form, the so-called HP-BiNbO₄ synthesized at high pressure and high temperature is investigated with the in-situ angle-dispersive x-ray diffraction (ADXRD) measurements under high pressure. We explore the compression behavior and phase stability of HP-BiNbO₄. The structure of HP-BiNbO₄ is first determined. The x-ray diffraction data reveal that the structure HP-BiNbO₄ is stable under pressures up to 24.1 GPa. The ADXRD data yield a bulk modulus K_o=185 (7) GPa with a pressure derivative K_o'=2.9 (0.8). Furthermore, the data are compared with those of other ABO₄ compounds. The results show that the bulk modulus of HP-BiNbO₄ (about 185 GPa) is slightly higher than that of tetragonal BiVO₄ and significantly greater than those of the tungstates and molybdates.