Crystal structures of lanthanide and zirconium phosphates with general formula Ln0.33Zr2(PO4)3, where Ln=Ce, Eu, Yb

Synthesis and investigation of neptunium zirconium phosphate, a member of the NZP family: crystal structure, thermal behaviour and Mössbauer spectroscopy studies

“…The reduction of symmetry in phosphates Ln 0.33 Zr 2 (PO 4 ) 3 with the appearance of additional lines in the IR spectra was explained by the ordering of Ln atoms at the M1 positions of the structure. 16 It should be also noted that the IR spectra of phosphates M 0.25 Zr 2 (PO 4 ) 3 (M = Th, U), which were described in the same paper of Kurazhkovskaya et al, 27 resembled much more the spectrum of the parent compound NaZr 2 (PO 4 ) 3 , which led to the conclusion that the actinide atoms were distributed over M1 sites statistically and the symmetry R3c remained.…”

“…Phase analysis of the sample revealed the presence of four crystalline phases: a major component with the structure of NZP and admixtures of ZrP 2 O 7 , NpO 2 and ZrO 2 . The presence of several additional reflections, also observed for the double lanthanide zirconium phosphates, 16 but not for the sodium zirconium phosphate, clearly indicates the reduction of symmetry compared to the prototype compound NaZr 2 (PO 4 ) 3 (from the space group R3c to the space group P3c). Taking this into account and also the fact that neptunium was found to be mainly trivalent, we used the structure of Eu 0.33 Zr 2 (PO 4 ) 3 16 as the starting model for crystal structure refinement, suggesting the chemical formula Np 0.33 Zr 2 (PO 4 ) 3 for the studied phosphate.…”

“…Consequently, the NZP class of materials includes several space groups of related symmetry: R3c, R3, R3, R32, P3c, P3. 1,16,17 In a number of cases monoclinic distortion of the lattice can lead to the appearance of a superstructure with space groups C2/c or Cc. 1 The inclusion of tri-and tetravalent cations of lanthanides and some of the actinides into the structure of NZP phosphates was reported in a number of papers.…”

Combustion synthesis and luminescence investigation of Na3Al2(PO4)3:RE (RE = Ce3+, Eu3+ and Mn2+) phosphor

“…[29]. Based upon ionic radii, Ce 3+ /Eu 3+ [30] and Mn 2+ are expected to substitute Al 3+ in the lattice resulting in six and four coordination sites, respectively to bind up with PO 4 . Similar framework structures were reported in Refs.…”

“…Similar framework structures were reported in Refs. [30,31]. XRD crystallography data of Na 3 Al 2 (PO 4 ) 3 lattices are listed in Table 1.…”