Growth aspects of barium oxalate monohydrate single crystals in gel medium

Abstract

Single crystals of barium oxalate monohydrate (BaC 2 O 4 .H 2 O, BOM) were grown in pure form by controlled diffusion of Ba 2+ using the gel technique at different temperatures. Starting from aqueous Ba 2+ chloride (BaCl 2 ) and acetic acid (C 2 H 2 O 4 ) in gel, this method offers a low-cost and an easiest alternative to other preparation methods for the production of barium oxalate bulky single crystals. The optimal conditions for the growth of BOM crystals in silica gel were found by investigating different growth parameters such as gel pH, gel aging and crystallization temperature. Irrespective of all such crystallization environments, growth rate of the crystals were initially less and then exhibited supersaturation effect leading to non-linearity. Gel aging and temperature has profound effect on nucleation density that resulted less number of crystals of maximum size in the gel matrix. Perfect single crystals were grown on gels of higher pH. The macropore morphology and porosity was controlled by changing age of the gel. It has been found that temperature has a fabulous effect in controlling the nucleation density by altering the supersaturation conditions for the formation of critical nuclei. The entire growth kinetics informed that the grown crystals were derived by the one dimensional diffusion controlled process.

Surface-modified substrates for the Langmuir-Blodgett deposition of patterned ultra-thin and highly oriented collagen coatings

“…The optical micrographs (Figure 7) show that in cases of low which causes a higher nucleation rate, formed small irregular shaped crystals (diameter ~1-15 µm) and aggregates in large quantities at the hydrophilic surface, in a smaller number on collagen coatings and again fewer of those crystals at the hydrophobic surfaces. These results are in excellent agreement with previous studies on BaC 2 O 4 using individual 'substrates' and varying reaction conditions (Raj et al, 2008;Ding et al, 2013). In addition, comparing these outcomes with the contact angles of the respective surfaces (see Table 1) shows an excellent agreement of high precipitation rates with high hydrophilicities.…”

Surface-modified substrates for the Langmuir-Blodgett deposition of patterned ultra-thin and highly oriented collagen coatings

“…The high supersaturation ([Ba 2+ ] = [C2O4 2-] = 10 mM), which causes a higher nucleation rate, formed small irregular shaped crystals (diameter ~1 -15 µm) and aggregates in large quantities at the hydrophilic surface, in a smaller number on collagen coatings and again fewer of those crystals at the hydrophobic surfaces. These results are in excellent agreement with previous studies on BaC2O4 using individual 'substrates' and varying reaction conditions (Raj et al, 2008;Ding et al, 2013). In addition, comparing these outcomes with the contact angles of the respective surfaces (see Table 1) shows an excellent agreement of high precipitation rates with high hydrophilicities.…”

Crystallization in Gels

“…Sr-oxalate X [187,188] Cd-oxalate X Diamagnetic [189][190][191] CdMgHPO 4 X [192] Ndhepthamolybdate X [193] Lahepthamolybdate X X [194] Cu-succinate X [195] Cu-tartrate Diamagnetic [195] …”