Selected synthesis of cubic and hexagonal NaYF4 crystals via a complex-assisted hydrothermal route

Controlled synthesis and luminescence properties from cubic to hexagonal NaYF4:Ln3+ (Ln=Eu and Yb/Tm) microcrystals

“…It is well known that NaYF 4 may be prepared in two polymorphic forms, namely, cubic and hexagonal phases [13,14]. The crystal structure of the hexagonal NaYF 4 was known to have three cation sites, one for Y 3+ ions, one for both Y 3+ and Na + ions, and the third for Na + ions [6].…”

Hydrothermal synthesis of optically active fluoride particles doped with rare earth ions in the presence of ethylenediaminetetra acetic acid (EDTA)

“…Tako na primer, sferične čestice kubne kristalne strukture (prečnika oko 300 nm) su sintetisane hidrotermalnim postupkom iz prekursora koncentracije 0.05 mmol i RE 3+ :EDTA= 1:2 na temperaturama od 160 do 180 ºC, dok je dodavanjem etanola i povećanjem koncentracije fluorida moguće dobiti β NaYF4 mikrokristale [13,14]. Kubne α NaYF4 nanosfere (50-100 mn) kao i heksagonalne β NaYF4 mikročestice (veličine oko 2.5 μm) sintetisane su hidrotermalnim postupkom (180 ºC, 24h) pri većem odnosu F -/RE 3+ i EDTA/RE 3+ , dok smanjenje koncentracije dovodi do formiranja YF3 [15]. Utvrđeno je i da do transformacije kubne u heksagonalnu fazu dolazi i sa porastom temeperature, povećanjem koncentracije reaktanata ali i odnosa F -/RE 3+ , što ujedno često ima za rezultat i promenu morfologije čestica [16].…”

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

“…ratio governing mainly the morphology. In such a synthesis, F -acts both as the reactant and as the mineralizer [117].…”