Zinc Borate Chemical Garden and Zinc Borate Powders from Tincal Mineral and Zinc Sulfate Heptahydrate

Abstract

The formation of the first membrane, the swelling of the crystal by incoming water from the semipermeable membrane and the formation of irregular shaped branches were observed by optical microscopy, when zinc sulfate heptahydrate crystals were immersed in saturated borax solution. The powders obtained by mixing dilute aqueous borax and zinc sulfate solutions had B, O, Na, S and Zn elements. Presence of Na Zn 1/2 B 4 O 7 .xH 2 O was indicated by EDX analysis. The molar ratio of B 2 O 3 /ZnO in powders was around 2. FTIR analysis indicated the ratio of absorbance values of asymmetric stretching vibrations of B (3) -O at 1351 cm -1 to that of B (4) -O at 1026 cm -1 increased with their heating time at 90ºC during their preparation. X-ray diffraction patterns indicated the presence of Zn(OH) 2 and Zn 4 (OH) 6 (SO 4 )•4H 2 O. The zinc borate compounds in the powders were not crystalline since no sharp peaks related to zinc borates were present in x-ray diffraction diagram. There were two mass loss steps in TG curves of the powders. The first step at 150-350ºC and the second step at 700-950ºC were due to elimination of water and due to decomposition of sulfate ions respectively. The submicron powders were a mixture of zinc borate, Zn(OH) 2 , Zn 4 (OH) 6 (SO 4 )•4H 2 O and Na Zn 1/2 B 4 O 7 .xH 2 O and they could be used as lubricant additive due to their small particle size of 600 nm.

Light-modulated colour transformation in highly intertwined vertically growing silver tungstate tubes

“…33 There have been several reports on the formation of chemobrionic architectures via the utilization of several anions such as silicates and hydroxides among others. [34][35][36][37][38][39] Metal tungstates are an important class of inorganic materials with broad applications in photoluminescence, optics, humidity sensors, magnetics, and catalysis and a report exists on the cobalt tungstate chemical garden. 40 Chemical gardens have potential applications in biochemistry, 41 astrochemistry, 42 cement hydrations, 43 hydrothermal vent analogues, 44 and other technological fields.…”