Abstract
The existence of a novel double-molybdate phase with a palmierite-type structure, Cs(2)Ba(MoO(4))(2), is revealed in this work, and its structural properties at room temperature have been characterized in detail using X-ray and neutron diffraction measurements. In addition, its thermal stability and thermal expansion are investigated in the temperature range 298-673 K using high-temperature X-ray diffraction, leading to the volumetric thermal expansion coefficient α(V) ≈ 43.0 × 10(-6) K(-1). The compound's standard enthalpy of formation at 298.15 K has been obtained using solution calorimetry, which yielded Δ(f)H(m)°(Cs(2)Ba(MoO(4))(2), cr, 298.15 K) = -3066.6 ± 3.1 kJ· mol(-1), and its standard entropy at 298.15 K has been derived from low-temperature (2.1-294.3 K) thermal-relaxation calorimetry as S(m)°(Cs(2)Ba(MoO(4))(2), cr, 298.15 K) = 381.2 ± 11.8 J K(-1) mol(-1).