GREEN LUMINOPHORS IN THE FAMILY OF PHOSPHATES WITH WHITLOCKITE STRUCTURE

Journal of Structural Chemistry - Phosphates Ca9Gd1–xTbx(PO4)7 with whitlockite structure are prepared for the first time by the solid-phase method. The obtained compounds are studied by a...     

Structural Features of Phosphates Ca9 – xMxDy(PO4)7 (M = Zn2+ or Mg2+)

Physics of the Solid State - Phosphate solid solutions based on the whitlockite family Ca9 – xMxDy(PO4)7 (M = Zn2+ or Mg2+) have been obtained. The samples have been...     

The first layer potassium–bismuth-nickel oxophosphate KBi<Subscript>4</Subscript>Ni<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>O<Subscript>4</Subscript>: Synthesis,crystal structure,and expected magnetic properties

The new potassium–bismuth–nickel oxophosphate obtained by hydrothermal synthesis in the Bi(OH)₃–NiCO₃–K₂CO₃–K₃PO₄ system is studied by X-ray diffraction, IR spectroscopy, and Raman spectroscopy. Parameters of the orthorhombic cell are as follows: a = 13.632(1) Å, b = 19.610(2) Å, and c = 5.4377(3) Å; V = 1452.64(2) ų; and space group Pnma. The structure is solved and refined to the final discrepancy factor R ₁ = 5.76% in the anisotropic approximation of atomic displacements using 3606 reflections with I > 2σ(I). The crystal-chemical formula (Z = 4) is KBi₄{Ni₂O₄(PO₄)₃}, where the composition of the layer nickel–phosphate polyanion is enclosed in braces. Theoretical calculations show that all exchange spin interactions between Ni²⁺ ions are antiferromagnetic and very weak (J < 0.1 cm^–1) because of the polyatomic character of bridging Ni–O–P–O–Ni and Ni–O–Bi–O–Ni groups. Thus, this compound is expected to be paramagnetic with very weak antiferromagnetic exchange interactions and appreciable energy of zero-field splitting of the spin levels of Ni²⁺ ions.     

Erratum to: CONTENT OF THE ISSUE 2 (2022)

Journal of Structural Chemistry - An Erratum to this paper has been published: https://doi.org/10.1134/S0022476622040205     

Strontium Substituted β-Tricalcium Phosphate Ceramics: Physiochemical Properties and Cytocompatibility

Sr²⁺-substituted β-tricalcium phosphate (β-TCP) powders were synthesized using the mechano-chemical activation method with subsequent pressing and sintering to obtain ceramics. The concentration of Sr²⁺ in the samples was 0 (non-substituted TCP, as a reference), 3.33 (0.1SrTCP), and 16.67 (0.5SrTCP) mol.% with the expected Ca₃(PO₄)₂, Ca_2.9Sr_0.1(PO₄)₂, and Ca_2.5Sr_0.5(PO₄)₂ formulas, respectively. The chemical compositions were confirmed by the energy-dispersive X-ray spectrometry (EDX) and the inductively coupled plasma optical emission spectroscopy (ICP-OES) methods. The study of the phase composition of the synthesized powders and ceramics by the powder X-ray diffraction (PXRD) method revealed that β-TCP is the main phase in all compounds except 0.1SrTCP, in which the apatite (Ap)-type phase was predominant. TCP and 0.5SrTCP ceramics were soaked in the standard saline solution for 21 days, and the phase analysis revealed the partial dissolution of the initial β-TCP phase with the formation of the Ap-type phase and changes in the microstructure of the ceramics. The Sr²⁺ ion release from the ceramic was measured by the ICP-OES. The human osteosarcoma MG-63 cell line was used for viability, adhesion, spreading, and cytocompatibility studies. The results show that the introduction of Sr²⁺ ions into the β-TCP improved cell adhesion, proliferation, and cytocompatibility of the prepared samples. The obtained results provide a base for the application of the Sr²⁺-substituted ceramics in model experiments in vivo.     

New Series of Red-Light Phosphor Ca9−xZnxGd0.9(PO4)7:0.1Eu3+ (x = 0–1)

In this study, a new series of phosphors, Ca_9−xZn_xGd_0.9(PO₄)₇:0.1Eu³⁺ (x = 0.00–1.00, step dx 0.05), was synthesized, consisting of centro- and non-centrosymmetric phases with β-Ca₃(PO₄)₂-type structure. Crystal structures with space groups R3c (0.00 ≤ x < 0.35) and R3¯c (x > 0.8) were determined using X-ray powder diffraction and the method of optical second harmonic generation. In the region 0.35 ≤ x ≤ 0.75, phases R3c and R3¯c were present simultaneously. Refinement of the Ca₈ZnGd(PO₄)₇ crystal structure with the Rietveld method showed that 71% of Gd³⁺ ions are in M3 sites and 29% are in M1 sites. A luminescent spectroscopy study of Ca_9−xZn_xGd_0.9(PO₄)₇:0.1Eu³⁺ indicated the energy transfer from the crystalline host to the Gd³⁺ and Eu³⁺ luminescent centers. The maximum Eu³⁺ luminescence intensity corresponds to the composition with x = 1.     

KTm[B4O6(OH)4] ⋅ 3H2O: A New Member of Borate Family with Mica-like Tetrahedral Layers

Crystallography Reports - Crystals of new borate KTm[B4O6(OH)4] ? 3H2O (sp. gr. Р $$\bar {3}$$ 1m, a = 4.5472(7) Å, c = 12.151(3) Å) have been obtained under hydrothermal...