Structure cristalline de NaBaPO4

Structure of the low-temperature variety of calcium sodium orthophosphate, NaCaPO4

“…They are in good agreement with those found for NaCda(PO4) 3 (Ben Amara, Olazcuaga, Le Flem & Vlasse, 1979), NaMg 4-(PO4) 3 (Ben Amara, Vlasse, Olazcuaga, Le Flem & HagenmuUer, 1983), NaBaPO 4 (Kolsi et al, 1981), which range from 1.522 to 1.549/~. The average tetrahedral angles are in the range 109.4 to 109.5 ° The structural determination of NaCaPO4 provides one more link in the chain of structures derived from the fl-K2SO 4 or the glaserite type and having the general formula hxBy(XO4)(x+y)/2.…”

“…The study of the low-temperature phase of NaBaPO4 does not reveal a surperstructure, but confirms a very close relationship to the ct-K2SO4-type structure, although its symmetry seems to be monoclinic (Kolsi et al, 1981).…”

“…Let us quote: NaMPO 4 (M= Ca, St, Ba) and N%Ln(PO4)2 (Ln = rare earth) (Klement & Kresse, 1961, Vlasse, Parent, Salmon, Le Flem & Hagenmuller, 1980Kolsi, Quarton & Freundlich, 1981). For the NaaLn(PO4) 2 compounds the hightemperature form transforms into a low-temperature variety by cationic ordering in the strings containing the Na ÷ and rare-earth ions, accompanied by a rotation of the [PO 4] tetrahedra to accommodate the new coordination requirements.…”

Photoluminescent Properties of ABaPO4:Eu (A=Na, K) Phosphors Prepared by the Combustion‐Assisted Synthesis Method

“…There are no observed differences for the emission band shape and position under different excitation wavelengths (l ex 5 263, 318 nm), except for luminescent intensity. As reported by Kolsi,12 the network of NaBaPO 4 is built up with PO 4 tetrahedra, NaO 6 octahedra, and BaO 12 and MO 10 polyhedra (M 5 Na or Ba). There are two different crystallographic sites for Ba 21 ions in the NaBaPO 4 structure.…”

Correlation between structure and photoluminescence of the europium doped glaserite-type phosphate Na2SrMg(PO4)2

“…Na 4 Ca 13 Mg 5 (PO 4 ) 18 [19] and Na 4 Ca 21 Mg 4 (PO 4 ) 18 [16] crystallize in the trigonal system with space groups R3 and R3 m, respectively. NaBaPO 4 has two polymorphs crystallizing in the space groups P3 m1 and C2/m, respectively [15,20]. Na 2 CaMg(PO 4 ) 2 exhibits a reversible phase transition at (1078 AE 5)K from the monoclinic space group P2 1 /c to the trigonal one P3 m1 [16].…”