Room-temperature angle-dispersive x-ray diffraction measurements on spinel ${\text{ZnGa}}_2{\text{O}}_4$ up to 56 GPa show evidence of two structural phase transformations. At 31.2 GPa, ${\text{ZnGa}}_2{\text{O}}_4$ undergoes a transition from the cubic spinel structure to a tetragonal spinel structure similar to that of ${\text{ZnMn}}_2{\text{O}}_4$. At 55 GPa, a second transition to the orthorhombic marokite structure (${\text{CaMn}}_2{\text{O}}_4$-type) takes place. The equation of state of cubic spinel ${\text{ZnGa}}_2{\text{O}}_4$ is determined: $V_0=580.1\left(9\right){\text{Å}}^3$, $B_0=233\left(8\right)\text{GPa}$, $B_0^{\prime }=8.3\left(4\right)$, and $B_0^{″}=-0.1145{\text{GPa}}^{-1}$ (implied value); showing that ${\text{ZnGa}}_2{\text{O}}_4$ is one of the less compressible spinels studied to date. For the tetragonal structure an equation of state is also determined: $V_0=287.8\left(9\right){\text{Å}}^3$, $B_0=257\left(11\right)\text{GPa}$, $B_0^{\prime }=7.5\left(6\right)$, and $B_0^{″}=-0.0764{\text{GPa}}^{-1}$ (implied value). The reported structural sequence coincides with that found in ${\text{NiMn}}_2{\text{O}}_4$ and ${\text{MgMn}}_2{\text{O}}_4$.

• Received 14 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.024103