Selection between LTA or FAU phases by manipulating the synthesis gel composition, crystallization time and temperature

LTA and FAU zeolites were synthesized with the addition of cetyltrimethylammonium bromide (CTAB) to assess the effects of Si/Al, Na/Al and H2O/Al ratios, time and temperature on the yield of each structure. The significance of each variable was determined by means of experimental designs, whose response variables were the areas of specific XRD peaks. CTAB did not act as a structure-directing agent, but rather as a growth modifier, increasing the growth rate of LTA and FAU crystals. At low temperature, LTA was afforded at low Si/Al ratio, while FAU crystallized at higher ratios, indicating a competition between the phases. Increasing temperature accelerated the kinetics of recrystallization of the less dense and metastable LTA and FAU phases in denser and more stable phases, such as sodalite and cancrinite. Decreasing the concentration of Na+ and water reduced the crystallinity of both structures, while increasing the concentration of Na+ favored LTA over FAU.

Controlling the shape of wedge-like α-GaOOH particles formed by a hydrolysis process using sodium acetate as a growth modifier

Sodium acetate preferentially suppresses the growth along thec-axis during the hydrolysis formation of α-GaOOH particles.

Thermosensitive polymer controlled morphogenesis and phase discrimination of calcium carbonate

Homogeneous aragonite flowers with controlled surface structures can be synthesized by using a thermosensitive polymer, i.e. poly(ethylene glycol)–poly(N-isopropyl acrylamide)–poly(acrylamido methyl propane sulfonate) (PEG–PNIPAM–PAMPS), as a crystal growth modifier in the mineralization of calcium carbonate.

Rational selection of halide ions for synthesizing highly active Au@Pd nanobipyramids

Highly active Au@Pd nanobipyramids were synthesized using Br− ions as an appropriate growth modifier.

An azobenzene-based photoswitchable crystal growth modifier

An azobenzene derivative reversibly switches to a less effective crystal growth modifier of calcite when irradiated by UV light.

Evolution from small sized Au nanoparticles to hollow Pt/Au nanostructures with Pt nanorods and a mechanistic study

A facile method for synthesizing hollow Au/Pt nanostructures is reported; this strategy involves using small sized Au nanoparticles (NPs) as seeds and KI as growth modifier.