Direct precipitation of spinel type oxide ZnGa2O4 from aqueous solutions at low temperature below 90°C

Direct Precipitation of Spinel-Type Zn(Fe, Ga)2O4 Solid Solutions from Aqueous Solutions at 90°C: Influence of Iron Valence of Starting Salt on Their Crystallite Growth

“…Hydrothermal synthesis below 2401C could offer direct route to single phase of ZnGa 2 O 4 spinel with high crystallinity (6)(7)(8). Three precipitation methods for direct synthesis of nanosized ZnGa 2 O 4 spinel at 25 -901C have been also presented (9). When aqueous ammonia was added into trivalent gallium and divalent zinc sulfate solution separately, gallium hydroxide (GaO(OH)) and zinc oxide were precipitated as main product, respectively (18).…”

“…From divalent iron salt solution, Fe(OH) 2 Reaction temperature and time are important factors influencing the composition and structure of the precipitates obtained through the soft solution routes. ZnGa 2 O 4 particles have been reported to be successfully precipitated under normal pressure either by dropping a mixed solution of zinc sulfate and gallium sulfate into aqueous NH 3 at a temperature of 25 -901C with stirring or by aging the mixed solution in the presence of urea or HMT at 901C (9). It was shown that aging at a temperature above 301C for more than 2 h was required in order to obtain spinel-type crystalline ZnFe 2 O from the mixed solution of ZnCl 2 and FeCl 2 via addition of aq.…”

“…Synthesis of reactive fine powders of ZnGa 2 O 4 spinel through chemical solution routes, i.e., glycothermal synthesis at 3001C (5) and hydrothermal synthesis below 2401C (6)(7)(8) have been reported. In our previous paper (9), ultrafine ZnGa 2 O 4 particles have been successfully precipitated under normal pressure either by dropping a mixed solution of zinc sulfate and gallium sulfate into aqueous NH 3 at a temperature of 25 -901C with stirring or by aging the mixed solution in the presence of urea or hexamethylenetetramine (HMT) at 901C. For zinc ferrite ZnFe 2 O 4 , successful synthesis has been reported from the aqueous solution of respective metal chlorides at a temperature between 301C and 601C through hydrolysis by either ammonia or hydrazine under normal pressure (10,11).…”

Direct formation of spinel-structured γ-Ga2O3-Al2O3 nanoparticles by a mild hydrothermal method

“…The investigations on the formation and characteristics of nanocrystalline phases and solid solutions focused on the spinel-structured complex oxide similar to γ-Ga 2 O 3 have been performed [22][23][24][25]. As one of oxide systems related to the spinel-type oxide solid solutions in the γ-Al 2 O 3 -γ-Ga 2 O 3 system, similar spinel-structured solid solutions in the ZnAl 2 O 4 -ZnGa 2 O 4 system have also been directly formed as nanocrystals via mild hydrothermal method using tetramethylammonium hydroxide, and the compositional dependence of their structure and optical and luminescence properties has been investigated [26,27] Compared with many literatures on the β-type Ga 2 O 3 , there are not so many reports relating to the γ-type Ga 2 O 3 due to the difficulty in synthesis of metastable γ-type crystalline phase at low temperatures.…”

Synthesis of gallium bearing magnetic particles from aqueous solution: influence of mixing procedure of initial solution and the ratio of Ga/Fe

“…Hirano et al [4,5] precipitated directly spinel-type Zn(Fe,Ga) 2 O 4 and ZnGa 2 O 4 solid solutions from aqueous solution, and investigated the influence of iron valence of starting salt and precipitator on their crystalline growth. But their studies did not give the information about cation distribution in the spinel lattice.…”