Synthesis and crystal structure of langbeinite related mixed‐metal phosphates K_1.822Nd_0.822Zr_1.178(PO₄)₃ and K₂LuZr(PO₄)₃

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.…”

Phase formation in molten system (Na/K)2O‐TiO2‐P2O5. Crystal structures of NASICON and langbeinite‐related phosphates (K/Na)1+xTi2(PO4)3 (x = 0 and 0.357)

“…In the case of phosphate K 0.10 Na 0.90 Ti 2 (PO 4 ) 3 such blocks are connected along axes c that is characteristic for sodium‐containing compounds with NASICON‐type structure (figure a). In the structure of K 0.877 Na 0.48 Ti ІІІ 0.357 Ti ІV 1.643 (PO 4 ) 3 the fragments [Ti 2 (PO 4 ) 3 ] run in four directions parallel to the cube diagonals (figure b) that is characteristic for complex substituted potassium or rubidium‐containing langbeinites .…”

Crystal structure of langbeinite-related Rb0.743K0.845Co0.293Ti1.707(PO4)3

“…They are: metal substitution in octahedra, element substitution in anion tetrahedra, and substitution of ions in cavities. Among these compounds, potassium-containing langbeinites are the most studied (Ogorodnyk et al, 2006(Ogorodnyk et al, , 2007bNorberg, 2002;Orlova et al, 2003). However, several reports concerning phosphate langbeinites with Rb + in the cavities of the framework are known: Rb 2 FeZr(PO 4 ) 3 (Trubach et al, 2004), Rb 2 YbTi(PO 4 ) 3 (Gustafsson et al, 2005) and Rb 2 TiY(PO 4 ) 3 (Gustafsson et al, 2006).…”