Synthesis and investigation of the new phosphates K2 LnZr(PO4)3 (Ln = Ce-Yb, Y) with langbeinite Structure

Langbeinite Phosphates KPbM2(PO4)3(M = Cr, Fe): Synthesis, Structure, Thermal Expansion, and Magnetic Properties Investigation

“…In the last two decades, a large number of phosphates and sulfates with langbeinite structure have been developed for electro-optical and ferroelastic activity. Among them, KBaFe 2 (PO 4 ) 3 , KSrFe 2 (PO 4 ) 3 , KBaCr 2 (PO 4 ) 3 , Pb 1.5 V 2 (PO 4 ) 3 , K 2 M 3+ (M 4+ O 4 )­(PO 4 ) 2 (M 3+ = Fe, Sc; M 4+ = Mo, W), and K 2 M 0.5 Ti 1.5 (PO 4 ) 3 (M = Mn, Co) have been proposed as magnetic materials. ,− Rare earth ions doped K 2 GdZr­(PO 4 ) 3 , (Ce 3+ , Eu 2+ , Tb 3+ )/KMSc 2 (PO 4 ) 3 (M = Ba, Sr), (Eu, Cu)/K 2 Ca 2 (SO 4 ) 3 , K 2 Y 1– x Eu x Zr­(PO 4 ) 3 , and Nd 3+ :K 2 Mg 2 (SO 4 ) 3 are reported as luminescent materials. − Recently, Ba 3 In 4 (PO 4 ) 6 and KBaIn 2 (PO 4 ) 3 are identified as excellent host materials for color tunable phosphors. , The physicochemical properties of langbeinites comprised with cesium and/or rubidium ions such as KCsFeZr­(PO 4 ) 3 , Cs 2 Ni 2 (MoO 4 ) 3 , Rb 3 Yb 2 (PO 4 ) 3 , Rb 2 YbTi­(PO 4 ) 3 , Rb 2 Cd 2 (SO 4 ) 3 , Rb 2 Yb 0.32 Ti 1.68 (PO 4 ) 3 , and Cs 1+ x Ln x Zr 2– x (PO 4 ) 3 (Ln = Sm–Lu), have also been investigated. ,− Since langbeinites exhibit different structural arrangements upon ionic substitutions and undergo phase transitions down to the temperature, the crystal chemistry of several langbeinite-type compounds has been extensively studied. − For instance, crystal chemistry of K 2 FeZr­(PO 4 ) 3 , Pb 1.5 V 2 (PO 4 ) 3 , K 2 LnZr­(PO 4 ) 3 (Ln = Ce–Yb, Y), K 1.822 Nd 0.822 Zr 1.178 (PO 4 ) 3 , K 2 LuZr­(PO 4 ) 3 , K 2 MTi­(PO 4 ) 3 (M = Er, Yb or Y), Na 2 MTi­(PO 4 ) 3 (M = Fe, Cr), and titanium/lanthanide-mixed langbeinite phosphates with distinct structural relation between NZP and langbeinite structures have been reported. ,− Although the crystal structure investigation, luminescence, and magnetic properties of the above listed compounds are known, until now there are no reports available on KPbM 2 (PO 4 ) 3 (M = Cr, Fe) to the best of our knowledge. Therefore, in the current work we mainly focused on the structural elucidation of these two compounds, study of their thermal expansion, and magnetic behavior.…”

Equilibrium langbeinite-related phosphates Cs1 + x Ln x Zr2 − x (PO4)3 (Ln = Sm–Lu) in the melted systems Cs2O–P2O5–LnF3–ZrF4

“…A number of large mono-or polyvalent cations have been tested for their ability to serve as cavity cations. For sodium, Na 2 MTi(PO 4 ) 3 (M = Fe, Cr) were obtained and characterized by Isasi & Daidouh (2000), while the group of potassium-containing langbeinites is the largest: KTi 2 (PO 4 ) 3 (Masse et al, 1972), K 2 Ti 2 (PO 4 ) 3 (Leclaire et al, 1989), K 1 + x Ti 2 À y Al y (PO 4 ) 3 (Slobodyanik et al, 1991), K 2 CrTi(PO 4 ) 3 (Boudjada & Perret, 1977;Norberg, 2002), A 2 MTi(PO 4 ) 3 , A = K, Rb, Tl; M = Cr, Fe (Perret & Boudjada, 1979), K 2 VTi (PO 4 ) 3 (Rangan & Gopalakrishnan, 1994), K 2 MTi(PO 4 ) 3 , M = Er, Yb, Y (Norberg, 2002), K 2 M 0.5 Ti 1.5 (PO 4 ) 3 , M = Mn, Co, Ni Ogorodnyk et al, 2007), K 2 MZr(PO 4 ) 3 , M = Y, Gd (Wulff et al, 1992), K 2 FeZr(PO 4 ) 3 (Orlova et al, 2003), K 2 LnZr(PO 4 ) 3 , Ln = Ce-Lu (Trubach et al, 2004b), K 2 BiHf(PO 4 ) 3 (Losilla et al, 1998) (Lajmi et al, 2003). Rubidium-containing langbeinites are much more scarce: Rb 2 FeZr(PO 4 ) 3 (Trubach et al, 2004a), Rb 2 YbTi(PO 4 ) 3 and Rb 2 Yb 0.32 Ti 1.68 (PO 4 ) 3 (Gustafsson et al, 2005), Rb 2 Mg 0.5 Zr 1.5 (PO 4 ) 3 (Orlova et al, 2005), Rb 2 YTi(PO 4 ) 3 (Gustafsson et al, 2006).…”