Transition metal iodates. IV. Crystallographic, magnetic and nonlinear optic survey of the copper iodates

• Published in: Journal of solid state chemistry 1973-11, Vol.8 (3), p.274-279
• Main Authors: Abrahams, S.C., Sherwood, R.C., Bernstein, J.L., Nassau, K.
• Format: Article
• Language: English
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/0022-4596(73)90095-9

Three anhydrous polymorphs of cupric iodate, two hydrates, and the basic iodate salesite have been investigated. α-Cu(IO 3) 2 is monoclinic, space group P2 1, with a = 5.551 ± 0.008, b = 5.101 ± 0.004, c = 9.226 ± 0.010 Å and β = 95°4′ ± 11′, with two formulas in the unit cell. Below Θ N = 8.5 K, α-Cu(IO 3) 2 is antiferromagnetic and also pyroelectric. β-Cu(IO 3) 2 is triclinic, space group P 1 , with a = 11.230 ± 0.006, b = 11.368 ± 0.009, c = 10.630 ± 0.009 Å, α = 99°18.3′ ± 0.3′, β = 107°0.4′ ± 0.2′ and γ = 114°23.8′ ± 0.2′ and eight formulas per unit cell: the crystal is paramagnetic to 1.4K. γ-Cu(IO 3) 2 is monoclinic, space group P2 1 m , with a = 4.977 ± 0.004, b = 6.350 ± 0.004, c = 8.160 ± 0.004 Å and β = 92°20′ ± 4′, with two formulas per unit cell; γ-Cu(IO 3) 2 becomes antiferromagnetic below Θ N = 5 K. Cu(IO 3) 2·2H 2O is monoclinic, space group P2 1c , with a = 6.725 ± 0.005, b = 4.770 ± 0.007, c = 11.131 ± 0.013 Å and β = 103°1′ ± 4′, with two formulas per unit cell; Cu(IO 3) 2·2H 2O is paramagnetic to 1.4 K. Cu(IO 3) 2 · 2 3 H 2O (mineral bellingerite) is triclinic, space group P 1 , with a = 7.197 ± 0.005, b = 7.824 ± 0.004, c = 7.904 ± 0.004 Å, α = 105°2′ ± 2′, β = 97°7′ ± 2′ and γ = 92°54′ ± 2′ with three formulas per unit cell; this crystal is paramagnetic to 1.4 K, with a moderate antiferromagnetic Cu-Cu interaction. Cu(OH)IO 3 (mineral salesite) is orthorhombic, with a = 10.772 ± 0.004, b = 6.702 ± 0.002 and c = 4.769 ± 0.002 Å and four formulas per unit cell. The magnetic susceptibility indicates the possibility of antiferromagnetic ordering at 162 K; strong antiferromagnetic interactions give Θ p = −340 K. The only copper iodate studied that generates second harmonics is α-Cu(IO 3) 2. Indexed powder patterns are given for all six compounds.