English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

During the systematic investigation of the ternary system Ca(CH 3 COO) 2 -Ca(HCOO) 2 -H 2 O at room temperature, the congruent crystallisation of two solid calcium acetate formates was observed: the hitherto unknown Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O and the poorly characterised Ca(CH 3 COO)(HCOO)·H 2 O. The latter is a frequently observed efflorescence phase found on calcareous objects and it could be also identified as a corrosion phase in a natural history collection of birds' eggs. Elemental and thermal analyses were employed to determine the phase compositions and by Raman and IR spectroscopy the presence of acetate and formate anions in both solids was confirmed. Laboratory X-ray powder diffraction data were used to solve the crystal structures. Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O crystallises in a primitive tetragonal unit cell with space group P4 1 2 1 2 and lattice parameters of a = 6.8655(1) Å and c = 45.5454(6) Å, while Ca(CH 3 COO)(HCOO)·H 2 O crystallises in a primitive monoclinic unit cell with space group P2 1 /c and lattice parameters of a = 9.2729(1) Å, b = 6.8002(1) Å, c = 11.2219(2) Å and β = 121.232(1)°. Calcium carboxylate zig-zag chains [Ca(μ 2 -RCOO) + ] n (R = CH 3 or H) are the main motif of both crystal structures. In Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O these chains are exclusively composed of acetate anions, whereas in Ca(CH 3 COO)(HCOO)·H 2 O only formate anions are situated in the chains. The remaining places in the 7-8 fold coordination sphere of the calcium cations are filled by water molecules and additional carboxylate anions that interconnect neighbouring chains, which eventually leads to layered motifs in both structures.

Efflorescence on calcareous objects in museums: crystallisation, phase characterisation and crystal structures of calcium acetate formate phases