Morphological micro-patterning of tubular-windows on crystalline K2V3O8 sheets

Improved Synthesis of Alkali Metal Vanadates Using a Hydrothermal Method

“…The acidic aqueous solvent gives plate morphology, compared to the nanorods obtained under solvothermal reaction conditions employing ethanol as solvent and reducing agent [13]. While the organic reactants and solvent are crucial factors, vanadium oxide sources seem to have no effect on the size and morphology of the product (including acidity with V2O5 observed herein and previously [13] and basicity with KVO3 [14]). Zinc acetate acts as a good catalyst in the formation of K2V3O8 with relatively higher yield than previously obtained, but with the yield limited due to Zn 2+ competing with VO 2+ ions forming K2ZnV2O7 with increasing amounts of Zn(OAc)22H2O.…”

“…Previous work had found that both reaction pH and temperature play crucial roles in determining the isolated solid product [18], and that the nature of organic sources and solvent could lead to reduction of oxidation state of the transition metal and/or control of size and morphology of the crystal products [13,14]. With x = 1 and M = K + , Rb + , Cs + , orange plates were formed in neutral media at 110 C without an organic source, whereas for x = 2 and M = K + , phase-pure black plates, similar to those of [14], were isolated from basic media at 140 C, using an organic base (enMe) to adjust pH and act as a reducing agent. Acetic acid/acetate in this work may be similar to apidic acid/apidate in [14] which is suggested to act as a buffer.…”

“…With x = 1 and M = K + , Rb + , Cs + , orange plates were formed in neutral media at 110 C without an organic source, whereas for x = 2 and M = K + , phase-pure black plates, similar to those of [14], were isolated from basic media at 140 C, using an organic base (enMe) to adjust pH and act as a reducing agent. Acetic acid/acetate in this work may be similar to apidic acid/apidate in [14] which is suggested to act as a buffer. The acidic aqueous solvent gives plate morphology, compared to the nanorods obtained under solvothermal reaction conditions employing ethanol as solvent and reducing agent [13].…”

“…Most trivanadates have been prepared at high temperature by ceramic synthesis routes [3][4][7][8][9][12][13][14] with difficulty in controlling the composition of the mixed-valence vanadium compounds as in the synthesis of K2(V 4+ O)V 5+ 2O7. Galy and Carpy [4] obtained the single crystal product from solid state reaction of the K2O-V2O5-VO2 system.…”

“…KV3O8 was synthesized by acidification of the corresponding metavanadate solution at near ambient temperatures of about 60-80 C, but the quality of the single crystals was not good enough [7]. Good single crystals of KV3O8 were synthesized in low yield by hydrothermal reaction at 250 C of V2O5 powder with alkali metal nitrate, chloride, and sulfate solution [8], later K2V3O8 nanorods were prepared in low yield under solvothermal conditions at 200 C employing a reducing agent and ethanol as a solvent [13], and still later tubular-windows on sheet-like K2V3O8 single crystals were prepared in pure phase under hydrothermal conditions from KVO3-KOH-apidic acid as a mild reducing agent, buffer, and a potentially morphological directing agent at 180 C for 2 days [14].…”