Three novel Pb oxyhalides, Pb3[O10Pb20](GeO4)4Cl10 (1), [O16Pb22][OPb](OH)I10(I,Br)(H2O) (2), and Pb5.5Si0.5O6Cl (3), have been prepared by high-temperature solid-state reactions (1 and 3) and hydrothermal method (2). The structure of 1 is based upon novel [O10Pb20](20+) layers of edge- and corner-sharing oxocentered OPb4 tetrahedra with cavities occupied by the GeO4 tetrahedral anions. The interlayer space contains low-occupied Pb sites and Cl(-) anions. The structure of 2 contains unique [O16Pb22][12+] layers of edge-sharing OPb4 tetrahedra with X(-) ions (X = I, Br) in and in between the layers. The structure of 3 is the first example of the Pb oxyhalide with the 3:1 ratio between the O-Pb and X sheets (X = halide). The unprecedented structure topologies and architectures observed in the title compounds are closely related to those observed in rare natural Pb oxyhalides that have no synthetic analogues to date.

In this paper, lanthanum molybdenum oxides (La2MoO6 and La2Mo2O9) and their Bi-doped derivatives were investigated as potential rare-earth-free phosphors. An X-Ray diffraction analysis coupled with an EDX study confirmed the purity of the samples and the insertion of bismuth in 1 molar % amount. Kubelka-Munk transformed reflectance spectra clearly indicated that the insertion of Bi induces a shortening of the optical gap in La2MoO6 but has no impact on the one of La2Mo2O9. Moreover, excitation and emission spectra evidenced a strong temperature quenching effect in all materials. Also the CIEx,y parameters at 77K are almost identical with or without Bi-doping for the two host lattices. Clearly, it was shown, combining experimental data, abinitio calculations and empirical positioning of absorption bands that luminescence of Bi-doped La2MoO6 sample is mainly related to the host lattice itself and distortions induced by La/Bi substitution. The role of the Bi 3+ dopant is indirect and the luminescence is mainly due to a MoO charge transfer rather than an on-site Bi 3+ 3 P1,0  1 S0 transition. Concerning La2Mo2O9, there is no effect following the insertion of Bi implying that the role of Bi is insignificant.  ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website xxxx at DOI: xxxx. Materials preparation, characterization methods, computational details, Rietveld refinements and EDS analysis.

This relatively low-temperature process involves complete rearrangement of the crystal structure-from a 2D architecture featuring slabs [Pb 2 F 2 ] 2+ formed by fluorine-centered tetrahedra into a structure characterized by 1D motifs based on [OPb 2 ] 2+ chains of oxocentered tetrahedra. The comparative crystal chemistry of the obtained anion-centered structural architectures is discussed. (Siidra et al. 2013c(Siidra et al. , 2015. Most of these structures can be notionally decomposed into tetragonal subcells with an a parameter similar to that of litharge (commonly 3.75-4.35 Å, depending on the layer composition), while c can vary over a wide range (from 5 to more than 75 Å) as might be expected for layered structures (Charkin 2008). Within these "archetypic" subcells, the 2 ∞ [XM] (X = anion, M = cation) slabs contain two X and two M atoms; they are positively charged and interleave with various anionic species. The OM 4 oxocentered tetrahedra, with M = Pb 2+ , Bi 3+ or rare-earth elements, are the most common contributors to these slabs. Second rank the FM 4 fluoride-centered tetrahedra with M being rare-earth or alkaline-earth elements, but most commonly Pb 2+ . [Pb 2 F 2 ] 2+ slabs have been found in the structures of the minerals matlockite [Pb 2 F 2 ](Cl) 2 (c = 9 Å) (Pasero and Perchiazzi 1996), grandreefite [Pb 2 F 2 ](SO 4 ) (c = 14 Å)

Two new bismuth compounds, oxovanadate Bi 3 (VO 4 )O 3 and oxoarsenate Bi 3.5 (AsO 4 )(OH) 0.5 O 3.5 , were prepared using supercritical hydrothermal pressure. Dealing with the anionic sublattice, both crystal structures are built on anti-oxo-OBi 4 / OBi 3 or -OBi 4 /OBi 5 units connected together in infinite corrugated 2D layers surrounded by isolated XO 4 (X = V or As) tetrahedra. These edifices complete a series initiated by the recent Bi 3 (PO 4 )O 3 prepared under similar conditions. With the latter being assigned to the "simplest" bioxophosphate in terms of structural complexity, this aspect was investigated among the other compounds in their chemical ternaries. These phases are suggested to be high-pressure polymorphs, not possible to tackle when working at ambient pressure and temperature conditions.