Application of the Dimensional Reduction Formalism to Pb12[Li2(P2O7)2(P4O13)2](P4O13): a Phosphate Containing Three Types of Isolated P–O Groups

Phosphates with Two Types of Isolated P-O Groups: Noncentrosymmetric Na6Sr2Bi3(PO4)(P2O7)4 and Centrosymmetric Cs2CaBi2(PO4)2(P2O7)

Inorganic phosphates are of great interest, because of their rich structural chemistry and multiple functional properties. Compared with the phosphates that only contain the solely condensed P-O groups, the phosphates with various condensed P-O groups are less reported, especially for the noncentrosymmetric (NCS) ones. Here, two new bismuth phosphates, Na₆Sr₂Bi₃(PO₄)(P₂O₇)₄ and Cs₂CaBi₂(PO₄)₂(P₂O₇), were synthesized by the solid-state reaction and both structures contain two types of isolated P-O groups. Remarkably, Na₆Sr₂Bi₃(PO₄)(P₂O₇)₄ crystallizes in the tetragonal space group P4̅2₁c, which represents the first NCS bismuth phosphate with PO₄ and P₂O₇ groups. Detailed structural comparisons among Bi³⁺-containing alkali/alkaline-earth metal phosphates show that the ratios of cations/phosphorus profoundly influence the condensed degree of P-O groups. Ultraviolet-visible-near-infrared (UV-vis-NIR) diffusion spectra show that both compounds have the relatively short UV cutoff edges. And Na₆Sr₂Bi₃(PO₄)(P₂O₇)₄ has a second-harmonic generation response of 1.1 × KDP. The first-principles calculations are carried out to understand the structure-performance relationship.

Cadmium phosphates with two types of fundamental building units and a wide ultraviolet transparency window

Owing to diverse crystal structures and intriguing properties, metal phosphates have attracted much attention in recent studies. In this work, two cadmium phosphates, KCd₆P₇O₂₄ and KCd₃P₃O₁₁, were obtained by the high-temperature solution method. In the crystal structure, both the title compounds contain two types of P-O fundamental building units. Thermal and spectral analyses were carried out on the title compounds, indicating that both of them have good thermal stability and short UV cut-off edges. In addition, the relationship between the electronic structures and optical properties was studied by theoretical calculations.

ACs5Bi4(PO4)2(P2O7)3 (A = K, Rb and Cs) with two kinds of isolated P–O groups designed by dimensional reduction theory

ACs5Bi4(PO4)2(P2O7)3 (A = K, Rb and Cs) were successfully designed and synthesized by dimensional reduction theory with a system of A2O–Bi2O3–P2O5.

Synthesis, structure and characterization of three new Mg-containing phosphates with deep-UV cut-off edges

Three new Mg-containing phosphates, AMg₂P₃O₁₀ (A = Li, Cs) and Rb₂MgP₂O₇, have been successfully synthesized using a high-temperature solution method.

A new disordered langbeinite-type compound, K2Tb1.5Ta0.5P3O12, and Eu3+-doped multicolour light-emitting properties

For the first time, a new langbeinite-type phosphate, namely potassium terbium tantalum tris(phosphate), K₂Tb_1.5Ta_0.5(PO₄)₃, has been prepared successfully using a high-temperature flux method and has been structurally characterized by single-crystal X-ray diffraction. The results show that its structure can be described as a three-dimensional open framework of [Tb_1.5Ta_0.5(PO₄)₃]_∞ interconnected by K⁺ ions. The Tb^III and Ta^V cations in the structure are disordered and occupy the same crystallographic sites. The IR spectrum, the UV-Vis spectrum, the morphology and the Eu³⁺-activated photoluminescence spectroscopic properties were studied. A series of Eu³⁺-doped phosphors, i.e. K₂Tb_1.5-xTa_0.5(PO₄)₃:xEu³⁺ (x = 0.01, 0.03, 0.05, 0.07, 0.10), were prepared via a solid-state reaction and the photoluminescence properties were studied. The results show that under near-UV excitation, the luminescence colour can be tuned from green through yellow to red by simply adjusting the Eu³⁺ concentration from 0 to 0.1, because of the efficient Tb³⁺→Eu³⁺ energy-transfer mechanism.

Unique 3D framework formed by adding MIIO4 groups into high Sb/P ratio phosphatoantimonates

Explorations on a mixed metal phosphatoantimonate system led to the discovery of two new anhydrous phosphatoantimonates, namely, Cs4MSb6P4O28 (M=Mg, Zn), which represent the first examples of quinary AI – MII –SbV – PV– O systems. Single-crystal structure analysis reveals that the two title compounds crystallize in the tetragonal space group I41/a (No. 88). Their structures feature complicated 3D frameworks with interesting tunnel structures comprised of corner sharing MO4 tetrahedra, SbO6 octahedra and PO4 tetrahedra, with the Cs+ cations sitting in the tunnels to balance the valence. Optical reflectance spectrum measurements show that these two compounds are insulators with band gaps of about 4.5 eV.

Syntheses, structures and properties of metal phosphates Pb2Mg(PO4)2, Pb4Zn8(PO4)8 and α-BaZn2(PO4)2

Pb₂Mg(PO₄)₂, Pb₄Zn₈(PO₄)₈ and α-BaZn₂(PO₄)₂ have been synthesized by the standard solid-state reaction and their structures were determined by single crystal X-ray diffraction for the first time. Pb₂Mg(PO₄)₂, Pb₄Zn₈(PO₄)₈ and α-BaZn₂(PO₄)₂ crystallize in the monoclinic crystal system, P2₁/c, C2/c and the trigonal crystal system, P3[combining macron]m1, respectively. The structure of Pb₂Mg(PO₄)₂ possesses a three-dimensional framework consisting of MgO₆ octahedra and PO₄ tetrahedra and the Pb²⁺ cations reside in the [Mg₆P₆O₁₂] tunnels. Pb₄Zn₈(PO₄)₈ and α-BaZn₂(PO₄)₂ are two-dimensional layered structures with [Zn₄P₄O₁₆]_∞ layers for Pb₄Zn₈(PO₄)₈ and [Zn₃P₃O₁₂]_∞ honeycomb double layers for α-BaZn₂(PO₄)₂. And in the structure of Pb₄Zn₈(PO₄)₈, there are four different Zn-P-O layers, which is reported for the first time in zinc phosphates. In addition, thermal property analysis, and UV-Vis-NIR diffuse reflectance and infrared spectroscopy were also performed. First-principles theoretical studies were also conducted to aid the understanding of their band structures and densities of states.

Structure comparison and optical properties of Na7Mg4.5(P2O7)4: a sodium magnesium phosphate with isolated P2O7 units

The crystal structure of Na₇Mg_4.5(P₂O₇)₄ comprises a parallelogram channel composed of corner/edge-sharing isolated [P₂O₇] dimers and a Na(2)O₅ polyhedra to form a 3D framework and has an ultraviolet (UV) cut-off edge of about 210 nm.

Two deep-ultraviolet nonlinear optical alkaline-earth metal borates based on different types of oxoboron clusters

Two non-centrosymmetric alkaline-earth metal borates were synthesized, showing the layered structures constructed from different oxoboron clusters and potentially new candidates for deep-UV NLO materials.

Application of the dimensional reduction formalism to Pb9−xBax[Li2(P2O7)2(P4O13)2] (x = 0, 2, 6, 7): a series of phosphates with two types of isolated polyphosphate groups

Dimensional reduction is used to design and synthesise Pb₉[Li₂(P₂O₇)₂(P₄O₁₃)₂] by using Li₂O to dismantle Pb₃P₄O₁₃.