Studies on Aging of Fresh Precipitates. XIX. Aging of Freshly Precipitated Barium Sulfate in Dilute Barium and Sulfate Solutions¹

Controlled Synthesis and Self-Assembly of Single-Crystalline CuO Nanorods and Nanoribbons

“…The short nanorods are attached to one another using their low Miller-indexed crystal planes, {001}, {100}, and {110} surfaces, respectively. This type of crystallite growth has been well-known in recent years, and can be described to a cementing process or an “oriented attachment” in nanoscale regime in which a larger crystal structure is formed from smaller ones by direct joining of suitable crystal planes. − The examples observed in the recent years include TiO 2 nanocrystallites, β-Co(OH) 2 nanoplatelets, ZnO nanorods, and α-MoO 3 nanoforks. − ,− In the netted structures of Figure (iii and iv), attachment with two {110} crystal planes results in a turning of nanorod alignment and an angle of 107.8° departing two different sets of nanorods in the planar networks (Figure d). The required crystal facets of {110} in this self-attachment are indeed present in the short nanorods [Figure (ii), Figure ] due to the slower growth.…”

“…This type of crystallite growth has been wellknown in recent years, and can be described to a cementing process or an "oriented attachment" in nanoscale regime in which a larger crystal structure is formed from smaller ones by direct joining of suitable crystal planes. [44][45][46][47] The examples observed in the recent years include TiO 2 nanocrystallites, β-Co(OH) 2 nanoplatelets, ZnO nanorods, and R-MoO 3 nanoforks. [17][18][19][47][48][49] In the netted structures of Figure 5 (iii and iv), attachment with two {110} crystal planes results in a turning of nanorod alignment and an angle of 107.8°departing two different sets of nanorods in the planar networks (Figure 6d).…”

ZnO/CoO and ZnCo2O4 Hierarchical Bipyramid Nanoframes: Morphology Control, Formation Mechanism, and Their Lithium Storage Properties

“…With respect to the generation of architectures, the process usually involves postarrangement of prefabricated building blocks; this postarrangement is induced by numerous driving forces, including capillary effects, surface tension, electric and magnetic forces. − Here, architectures are constructed from building units formed in situ . In this regard, freshly generated nanofibers cement together side-by-side along the longitudinal direction, undergoing oriented attachment to develop into larger crystals . Simultaneously, nanoflakes self-assemble into framelike hierarchical structures.…”

“…37 In this regard, freshly generated nanofibers cement together side-by-side along the longitudinal direction, undergoing oriented attachment to develop into larger crystals. 38 Simultaneously, nanoflakes self-assemble into framelike hierarchical structures. Notably, in our system, no capping agent was used to protect the nanoflakes.…”

Precipitation of Barium Sulfate: Investigation by Electron Microscopy

“…The aging of barium sulfate crystals in contact with mother liquid does not result in any significant change in crystal size nor in apparent degree of perfection unless the particle size at the start of the aging period is well under 1 micron, in which case THE precipitation of barium sulfate has been studied widely because of the continuing practical importance of the gravimetric method for determining sulfate and because many factors regarding purification and perfection of precipitates are encountered. Kolthoff and Noponen (5,6) have studied in detail the aging of precipitated barium sulfate in contact with mother liquids of varied compositions. They have presented evidence that the freshly precipitated material is highly imperfect, and that the gradual perfection which follows is not predominantly due to Ostwald ripening.…”