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

Abstract

New langbeinite-type phosphates KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 are synthesized by solution method and characterized by powder X-ray diffraction, infrared spectra, thermogravimetric and differential thermal analysis, scanning electron microscope, and energy dispersive X-ray analysis. Rietveld refinement reveals that both of the compounds crystallize in the cubic system with P2 1 3 space group, and the calculated lattice parameters for Cr and Fe phases are 9.7332(2) and 9.8325(7) Å, respectively. The electron micrographs confirm the crystalline nature of the samples from their surface morphologies. Infrared spectra display the characteristic features of P−O and M−O vibrational bands for both of the phases. Thermal analysis of KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 indicates that they are thermally stable up to 1273 K. The axial thermal expansion is studied by high-temperature X-ray diffraction between 298 and 1073 K. The average thermal expansion coefficients of KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 are identified as 8.9 × 10 −6 and 10.8 × 10 −6 K −1 , respectively. Magnetic study reveals both of the compounds follow Curie−Weiss behavior in the higher-temperature region, and antiferromagnetic interactions are dominant.

The electronic and magnetic properties of KPbM2(PO4)3 (M = Cr and Fe) by first-principles calculations

“…198) and the experimental lattice constants are 9.7332 and 9.8325 Å for KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 , respectively. 21) Our optimized lattice constants are in good agreement with the experimental ones, which are 9.7945 and 9.8407 Å for KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 respectively.…”

“…These results are consistent with the experimental effective spin moments. 21) It is also found that different magnetic configurations have almost the same spin moments, which means that the magnetism in both phosphates is quite localized. Therefore, the differences in the total energies between different magnetic configurations are mainly contributed by the interatomic exchange interaction.…”

“…[16][17][18][19][20] Recently, two new langbeinite phosphates KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 were synthesized by the solution method. 21) Thermal analysis shows that both compounds are thermally stable at temperatures as high as 1273 K and the average thermal expansion coefficients of KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 are 8.9 × 10 -6 and 10.8 × 10 -6 K −1 , respectively. The magnetic measurements indicate that both KPbCr 2 (PO 4 ) 3 and KPbFe 2 (PO 4 ) 3 are antiferromagnetic (AFM) and follow Curie-Weiss behavior in the temperature range of 8−300 and 34−300 K, respectively.…”

Li3[Al(PO4)2(H2O)1.5] and Na[AlP2O7]: from 2D layered polar to 3D centrosymmetric framework structures

“…19,20 Although, in general, the phosphorus atoms are only fourfold coordinated with oxygen atoms to form the PO 4 tetrahedra, the PO 4 tetrahedra can be further interconnected by sharing oxygen atoms to create a diversity of structure units, such as isolated [P n O 3n+1 ] (n+2)− (n ≥ 1) groups, [PO 3 ] ∞ chains, and [P n O 3n ] n− (n ≥ 3) rings. [21][22][23][24] Their rich structural diversity has resulted in the discovery of thousands of inorganic phosphates. [25][26][27] For example recently it has been noticed that mixed oxo-anionic phosphates with different degrees of phosphate group polymerization can also be synthesized, such as Na 4 Mg 3 ij(PO 4 ) 2 IJP 2 O 7 )], Rb 6 Bi 4 ij(PO 4 ) 2 IJP 2 -O 7 ) 3 ], Na 4 Ni 5 ij(PO 4 ) 2 IJP 2 O 7 ) 2 ], Na 7 Y 2 ij(P 2 O 7 ) 2 IJP 3 O 10 )], KMg 6 ij(P 2 -O 7 ) 2 IJP 3 O 10 )], Pb 2 Cd 3 ij(PO 4 ) 2 IJP 2 O 7 )], and TI 3 Ti 3 Oij(PO 4 ) 3 IJP 2 -O 7 )], [28][29][30][31][32][33][34] which even violate Pauling's fifth rule.…”

Structure and optical property evolution in PbM(PO4)X (M = Zn, Sn; X = halogen): SHG effect and birefringence

“…† The P-O stretching vibrations fall in the regions of 1086-921, 1074-937 and 1080-964 cm −1 , while the bending vibrations fall essentially in the region of 600-400 cm −1 . 51,52 The UV-vis-NIR diffuse reflectance spectra of compounds 1, 3 and 4 revealed that they exhibited wide transparency ranges from 500 to 2000 nm (Fig. S4 †).…”