High-pressure and high-temperature structure and equation of state of Na<sub>3</sub>Ca<sub>2</sub>La(CO<sub>3</sub>)<sub>5</sub> burbankite

Abstract. In this study we report the synthesis of single crystals burbankite, Na3Ca2La(CO3)5, at 5 GPa and 1073 K. The structural evolution, bulk modulus thermal expansion burbankite were studied determined by two separate high-pressure (0–7.07(5) GPa) high-temperature (298–746 K) in situ single-crystal X-ray diffraction experiments. refined parameters a second-order Birch–Murnaghan equation state (EoS) are V0= 593.22(3) Å3 KT0= 69.8(4) GPa. coefficients Berman-type EoS α0= 6.0(2) ×10-5 K−1, α1= 5.7(7) ×10-8 K−2 591.95(8) Å3. thermoelastic allow us to estimate larger density pressure-temperature range 5.5–6 1173–1273 K, with respect carbonatitic magmas same conditions. For reason, suggest that might fractionate from magma play key role as an upper-mantle reservoir light trivalent rare earth elements (REE3+).