Synthesis and Formation Mechanism of La₂O₂S via a Novel Solvothermal Pressure-Relief Process

Abstract

A new solvothermal pressure-relief (SPR) process was successfully developed for synthesis of La2O2S at relatively low temperature (300 °C) by using La(NO3)3·nH2O and NH2CSNH2 as reactants in organic media. In contrast, the normal solvothermal and hydrothermal process can only produce La(OH)CO3 and La(OH)SO4, respectively. The present SPR process provides a favorable low-temperature reaction pathway for synthesis of lanthanide oxysulfides. The mechanism and solvent effects on the formation of lanthanum oxysulfide were investigated.

Controlled synthesis of Eu3+-doped La2O2S nanophosphors by refluxing method

“…However, under the same conditions, the pure La 2 O 2 S could not be obtained. Previous studies show that it is necessary for the reaction temperature to be above 300 � C in order to obtain pure La 2 O 2 S [14,23]. However, in our refluxing system, the reaction temperature is not more than 260 � C. We believe that the decomposition of La(HCOO) 3 plays important roles in the formation process of La 2 O 2 S at such relatively lower reaction temperature.…”

“…There have been some successful methodologies for the synthesis of Ln 2 O 2 S host such as direct high-temperature solid-state reaction route [12], sulphuration method of rare earth oxides [13] and solvothermal method [14]. However, until now, there are only a few reports on the preparation of Eu 3þ -doped Ln 2 O 2 S nanophosphors.…”

Lanthanide‐Containing Photoluminescent Materials: From Hybrid Hydrogel to Inorganic Nanotubes

“…3 + -cholate supramolecular system: It is worth noting that lanthanide oxysulfide nanotubes, which are rarely prepared through a solution route, [16] are conveniently obtained by means of a self-templating approach in the Ln 3 + -cholate hybrid hydrogel. In this strategy, metal ions serve as both the inorganic precursor and a constituent of the soft template, which is further deposited from supramolecular selfassemblies to generate inorganic nanomaterials with corresponding shape.…”

“…The quantum efficiency value is lower than that of bulk lanthanide oxysulfide phosphors, probably because of the drastically enlarged surface-to-volume ratio favoring recombination, which does not engender visible emission. [16] Preparation (Figure 7 a and c), which can be used as a soft template to synthesize lanthanide oxysulfide nanotubes. As indicated in TEM images ( Figure Figure S5f and S5f in the Supporting Information).…”

Solvothermal and hydrothermal processes: the main physico-chemical factors involved and new trends

“…(i) the solvothermal pressure-relief process during which the produced gas into the high-pressure vessel is controlled [120]; (ii) the solvothermal scission-template-transportation route with the formation of an intermediate compound acting as the template [121]; (iii) the extraction solvothermal method [122]; (iv) and the phase-transfer catalysis [123].…”