The product of hydrothermal synthesis was determined as analogue of lindgrenite. The compound crystallizes in space group P21/n, a = 5.3941(2), b = 14.0249(4), c = 5.6095(2) Å, β = 98.519(3)˚, V = 419.68(2) Å3. The DSC and TGA analyses revealed mass loss for 3.94 % at Ò = 200-400 ˚Ñ that was assigned to the dehydroxylation and for 4.15 % at Ò = 800-850 ˚Ñ that was attributed to the decomposition. High-temperature X-ray diffraction indicated the phase transformation at Ò = 350 ˚Ñ from synthetic lindgrenite Cu3MoO4(OH)2 to analogue of cupromolybdite Cu3MoO9 accompanied by dehydroxylation. The main coefficients of thermal expansion for lindgrenite (×10-6) are: α11 = α22 = 6, α33 = 26. The main coefficients of thermal expansion for cupromolybdite (×10-6) are α11 = 15, α22 = 8, α33 = 5.
Keywords: crystal chemistry, high temperature behaviour, lindgrenite, cupromolybdite