δ‐KNO₃: Synthesis and Structure of a New Modification of Potassium Nitrate

Abstract

Abstract.A novel modification of potassium nitrate is obtained subsequent to solvothermal reaction and crystallization at reduced temperature from diethylformamid (DEF) as solvent. δ-KNO 3 crystallizes with the monoclinic space group P2 1 /c. Most intriguing is the coordination number of potassium and oxygen as expressed by the Niggli notation δ-K 8/8 [NO 4/4 O 4/2 ] that differs from the known modifications of potassium nitrate (α-K 9/9 [NO 9/3 ], β-K 9/9 [NO 9/3 ], γ-K 9/9 [NO 9/3 ]). Moreover,

New High-Pressure and High-Temperature CaCO3 Polymorph

“…The reasonable result corresponded to a monoclinic P 2/ m lattice with the approximate parameters of a ≈ 6.326 Å, b ≈ 4.872 Å, c ≈ 3.994 Å, and β ≈ 108.97° (M20 = 25.12). A search in the Inorganic Crystal Structure Database for AB O 3 compounds with a monoclinic lattice, close cell parameters, and likely Z suggested KClO 3 ( a = 4.630(2) Å, b = 5.568(3) Å, c = 7.047(3) Å, β = 110.21(3)°), KNO 3 ( a = 3.6820(7) Å, b = 5.5830(11) Å, c = 15.065(3) Å, β = 103.91(3)°), and borates of La ( a = 6.348(1) Å, b = 5.084(1) Å, c = 4.186(1) Å, β = 107.89(1)°) and Ce ( a = 6.3022(7) Å, b = 5.0593(6), c = 4.1311(4), β = 107.528(8)°). Of particular interest, they also have modifications that are isostructural with aragonite and calcite-V. − Naturally occurring lead sulfite such as scotlandite PbSO 3 and selenite–molybdomenite PbSeO 3 are also analogues.…”

A transferable force-field for alkali metal nitrates

“…On cooling phase III to 383 K it is possible to recover phase II. There is a metastable monoclinic phase (d-KNO 3 [21]) and a high-pressure orthorhombic phase (IV) [22]. Below 305 K KNO 3 mostly has the growth forms { } 110 , { } 111 , { } 010 and { } 021 [4].…”