A high pressure X-ray diffraction study of RhOOH was carried out up to 17.44 GPa to investigate the compression behavior of an oxyhydroxide with an InOOH-related structure. A fit to the third-order Birch–Murnaghan equation of state gave K0= 208 ± 6 GPa, and K′ = 9.4 ± 1.3. The temperature derivative of the bulk modulus was found to be ∂K/∂T = −0.06 ± 0.02 GPa K−1. The refined parameters for volume thermal expansion were α0= 2.7 ± 0.3 × 10−5K−1; α1= 1.7 ± 1.1 × 10−8K−2in the polynomial form (α(T) = α0+ α1(T−300)). Our results show that RhOOH is very incompressible, and has a higher bulk modulus than other InOOH-structured oxyhydroxides (e.g. δ-AlOOH, ε-FeOOH, and γ-MnOOH).
- equation of state
- InOOH-type oxyhydroxide