Über Das kristallinische Tonerdehydrat v. Bonsdorff's

Abstract

Das aus Alkalialuminatlösungen durch Hydrolyse oder langsame Einwirkung von CO2 ausfallende kristallinische Tonerdehydrat v. Bonsdorffs ist nur dann Hydrargillit, wenn die Ausscheidung sehr langsam erfolgt. Andernfalls handelt es sich ebenfalls um eine kristallinische Tonerde von der Zusammensetzung Al2O3 · 3H2O, doch besitzt diese eine andere Struktur. Ihr Röntgenogramm wurde zuerst von J. Böhm an einem auf anderem Wege gewonnenen Präparate erhalten.

Chemical Solution Deposition of Al(OH)3‐AlOOH Films: Application for Surface Sensitizing of Rigid and Flexible Substrates to Improve the Adhesion in Coating Technology Areas

“…In particular, unlike others metal oxides in which we have experience in their synthesis as thin film, in aqueous solutions aluminum salts can form aluminum oxyhydroxide (AlOOH), in addition to Al(OH) 3 and Al 2 O 3 species. Furthermore, each of these three compounds can adopt different structural phases, which further complicates the XPS interpretation; there are at least four well-known phases for Al(OH) 3 : gibbsite [40] or hydrargillite [41] (α-Al(OH) 3 ), bayerite [42] (β-Al(OH) 3 ), nordstrandite [43] ([γ-]Al(OH) 3 ), and doyleite [44] ([δ-] Al(OH) 3 ); there are at least three well-known phases for AlOOH: diaspore [45] (α-AlOOH), böhmite or boehmite [46] (γ-AlOOH), and pseudoboehmite [47] (highly hydrated γ-AlOOH); and, besides the "transition" aluminas (χ-, k-, θ-, δ-, η-, and 1-Al 2 O 3 ), there are two well-known phases for Al 2 O 3 : corundum [48] (α-Al 2 O 3 ) and the unnamed gamma-alumina [49] (γ-Al 2 O 3 , often considered a transition alumina). Although each of these phases surely has associated particular binding energy positions, a proper identification of each of them by XPS is a very complicated task; for example, even when Rotole & Sherwood addressed in an interesting series of papers [50][51][52][53][54][55][56][57] the different phases of Al(OH) 3 , AlOOH, and Al 2 O 3 , their results difficultly permit to discriminate between the different phases by XPS analysis (particularly because they used the center of the peaks as the true positions instead of employing deconvolutions).…”

Böhmite and Bayerite

“…Provided the temperature is the same, a slow precipitation is tthen favorable for the formation of gibbsite, and rapid precipitation for bayerite (9). More accurate details for the production of the two alumina hydrates in this manner, which is important from a technical point of view, may be found in other articles (11,13,17).…”

“…3H20), to the properties of which we shall refer later, also belongs to the y-series of Haber, since it produces cubic y-oxide on complete extraction of water. It is metastable a t room temperature in contrast to gibbsite (hydrargillite) (9,10,11,17), but stable in comparison with bohmite (3, 20, 24). It is probably identical with the substance designated as p-Al203.3H~O by Edwards and Tosterud. It is quite evident from the photographs of Weiser and Milligan that their preparations, made "according to Huttig," cannot be mixtures of bohmite and gibbsite; this may also be seen from a comparison of the positions of the lines of the alleged "6-AlzOa.xHzO" (bohmite) and of gibbsite with the positions of the lines of the preparations according to Huttig.…”

“…), causes bayerite to change into gibbsite (hydrargillite) (9). The series order of stability is therefore bohmite > bayerite > gibbsite.…”

“…The aluminate solution may also be more concentrated, for example, with a specific gravity of 1.15 (17). If the carbon dioxide be allowed to act very slowly at ordinary temperature, as, for instance, by allowing the container to stand exposed to the air, then gibbsite is obtained (9). Gibbsite of larger crystalline structure may be obtained more rapidly by allowing carbon dioxide to pass slowly over a solution of aluminate heated to 96-1OO0C.…”