Three Alkali Metal Lead Orthophosphates – Syntheses, Crystal Structures and Properties of APbPO 4 (A = K, Rb, Cs)

New antimony fluorooxoborates with strong birefringence and unprecedented structural characterisation

Fluorooxoborates constitute a rich source of optical crystals due to their structural diversity and excellent performance. Antimony fluorooxoborates with stereochemically active lone pairs of electrons still have not been found, although the first antimony borate was discovered several years ago. In this study, we have achieved the successful synthesis of the first antimony(III) fluorooxoborate with an unprecedented [B2O4F]∞ chain, namely SbB2O4F. Remarkably, SbB2O4F shows strong birefringence (0.171@1064 nm) and short UV cutoff edges (about 220 nm) according to calculations. The birefringence of SbB2O4F mainly originates from the highly distorted [SbO4] groups.

K2RbB8PO16: A Borophosphate with Moderate Birefringence and Deep-Ultraviolet Transmission

A new borophosphate, K2RbB8PO16 (KRBPO) was synthesized. It exhibits a bilayer structure consisting of two B-O layers with an 18-membered ring (18-MR) joined by [PO4], which is composed of the π-conjugated group [BO3] and non-π-conjugated groups [BO4] and [PO4]. The UV-vis-NIR diffuse reflectance spectroscopy shows that the cutoff edge is less than 200 nm. The calculation indicates that KRBPO exhibits moderate birefringence of 0.057@1064 nm, and the source of birefringence is mainly from the [BO3] groups.

Growth, Structure and Optical Characterization of Rb3Ti3P5O20 Single Crystal

Phosphate crystals attract much attention on account of their rich crystal structures and excellent physical and chemical properties. Herein, Rb3Ti3P5O20 single crystals were grown by the high temperature solution method using Rb2CO3 and NH4H2PO4 as the fluxes. This crystal, with non-centrosymmetric Pca21 space group, presents a three-dimensional framework structure composed of [TiO6] octahedron, [PO4] tetrahedra, and [P2O7] dimers. The electronic structure was measured via X-ray photoelectron spectroscopy. The measurements found that Rb3Ti3P5O20 has stronger Ti–O ionic bonding properties and weaker P–O covalent bonding properties compared to RbTiOPO4. Optical measurements indicated that Rb3Ti3P5O20 has a 3.54 eV band gap and a wide transmission range (0.33–4.5 μm). Theoretical calculations showed that Rb3Ti3P5O20 crystals have a moderate birefringence of 0.079 at 1064 nm. In addition, the relationship of the structure–property was studied using first-principles method. The results demonstrated that TiO6 octahedron played a significant role for the optical properties.

Thermal stability and self-reduction of a new red phosphor NaMg(PO3)3:Mn2+

For Mn-activated phosphors, the luminescent performance is strongly dependent on the oxidation state of Mn. In this paper, a series of red phosphors NaMg(PO3)3:xMn2+ (NMP:xMn2+) were synthesized by high temperature...

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.