Characterization and photoluminescent properties of sol–gel-derived Ca2(1−x)La7.6+x(SiO4)6O2:Eu0.4, Lix phosphors

An Apatite-Group Praseodymium Carbonate Fluoroxybritholite: Hydrothermal Synthesis, Crystal Structure, and Implications for Natural and Synthetic Britholites

“…The concern is the unintended incorporation of carbonate. Many synthesis routes include the use of organic materials or carbonates in the starting materials. ,,,,,​− ,​,​,,​,,​, Indeed, carbonate is occasionally observed in synthetic apatites and britholites, even though it is presumably volatile and expected to degas as CO 2 during calcining. ,,,,, Evidently, some carbonate is stabilized and retained in the crystal lattice . As starting materials are usually prepared stoichiometrically, this leads to the problem of excess Si, which could then either precipitate as a silica polymorph (SiO 2 either quartz or tridymite), or bond with other components in the system to form other byproduct phases (e.g., CaSiO 3 wollastonite).…”

“…10 These methods commonly result in crystals only a few micrometres large, nanocrystals, or long but thin needles about 1−2 μm thick. [1][2][3][9][10][11][15][16][17]25,26,35,36 This crystal morphology may not be suitable for all applications. Additionally, these methods result in either endmember britholite�Ca 2 Ln 3 (SiO 4 ) 3 OH�or oxybritholite, with no intermediate compositions that may be useful in certain applications.…”

“…Synthesis methods include hydrothermal growth, ,− solid-state sintering, ,,,​− ,− occasionally with preliminary treatments such as sol–gel synthesis, or microwave radiation . These methods commonly result in crystals only a few micrometres large, nanocrystals, or long but thin needles about 1–2 μm thick. − ,− ,​​− ,,​​,, This crystal morphology may not be suitable for all applications. Additionally, these methods result in either endmember britholiteCa 2 Ln 3 (SiO 4 ) 3 OHor oxybritholite, with no intermediate compositions that may be useful in certain applications.…”

The structure and texture genesis of apatite-type lanthanum silicates during their synthesis by co-precipitation

“…Recently, Peng reported that La 9.33 (SiO 4 ) 6 O 2 : Ln 3+ (Ln = Ce, Eu, Tb) microfibers can provide green and red emission as dependent upon the nature of doping ions, which makes these materials potentially attractive for applications in field emission displays [9]. Li's photoluminescence studies showed that Ca 2(1−x) La 7.6+x (SiO 4 ) 6 O 2 :Eu 0.4 -based phosphors could be readily excited by near-UV (387 nm) irradiation, which makes them promising red-emitting materials for commercial near-UV LED-pumped white light emitting diodes, with Li + doping resulting in remarkably enhanced photoluminescence performance of these solids [11].…”

“…Apatite-type silicates of rare earth elements known for a long time as structural analogs of Ca 10 (PO 4 ) 6 F 2 fluoroapatite [1][2][3][4][5][6][7] are considered as promising materials for such applications as matrix for radioactive waste immobilization, lasers and phosphors [2,[7][8][9][10][11][12][13][14]. Recently, Peng reported that La 9.33 (SiO 4 ) 6 O 2 : Ln 3+ (Ln = Ce, Eu, Tb) microfibers can provide green and red emission as dependent upon the nature of doping ions, which makes these materials potentially attractive for applications in field emission displays [9].…”