Transition metal iodates. IV. Crystallographic, magnetic and nonlinear optic survey of the copper iodates
1973; Elsevier BV; Volume: 8; Issue: 3 Linguagem: Inglês
10.1016/0022-4596(73)90095-9
ISSN1095-726X
AutoresS. C. Abrahams, R. C. Sherwood, J. Bernstein, K. Nassau,
Tópico(s)Crystal Structures and Properties
ResumoThree anhydrous polymorphs of cupric iodate, two hydrates, and the basic iodate salesite have been investigated. α-Cu(IO3)2 is monoclinic, space group P21, 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 ΘN = 8.5 K, α-Cu(IO3)2 is antiferromagnetic and also pyroelectric. β-Cu(IO3)2 is triclinic, space group P1, 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(IO3)2 is monoclinic, space group P21m, 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(IO3)2 becomes antiferromagnetic below ΘN = 5 K. Cu(IO3)2·2H2O is monoclinic, space group P21c, 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(IO3)2·2H2O is paramagnetic to 1.4 K. Cu(IO3)2·23H2O (mineral bellingerite) is triclinic, space group P1, 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)IO3 (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 Θp = −340 K. The only copper iodate studied that generates second harmonics is α-Cu(IO3)2. Indexed powder patterns are given for all six compounds.
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