Crystal data for two new lanthanide acid iodates: Pr(IO₃)₃.HIO₃ and 3La(IO₃)₃.JIO₃.7H₂O

Method of growth and chemical characterization of single crystals of Pr(IO₃)₃. HIO₃ and 3La(IO₃)₃. HIO₃.7H₂O are given together with the powder data. Pr(IO₃)₃.HIO₃ is monoclinic, a = 14.237±0.006, b = 7.578± 0.003, c = 10.616±0.005 Å, β = 110.48±0.04° at 298 K with space group P2₁/a and four formulas perunit cell. 3La(IO₃)₃.HIO₃.7H₂O is orthorhombic, a = 13.18008±0.00010, b = 21.72076±0.00010, c = 12.15514±0.00018 Å at 298 K with space group Aba2 and four formulas per unit cell. The hydrated La acid salt generates second harmonics: the pyroelectric coefficient p₃ = 2.1 x 10⁻⁵ Cm⁻² deg⁻¹. Mo K radiation produces a bright orange coloration.