Undulated oxo-centered layers in PbLn$_3$O$_4$ (VO$_4$ ) (Ln= La and Nd) and relationship with Nd$_4$O$_4$(GeO$_4$ )

Marie Colmont (1) , Olivier Mentre (2, 1) , Natacha Henry (1) , Alain Pautrat (3) , Bastien Leclercq (1) , Frédéric Capet (1) , Nora Djelal (1) , Pascal Roussel (1, 2)

1 UCCS - Unité de Catalyse et Chimie du Solide - UMR 8181
2 LCPS - Laboratoire de cristallochimie et physicochimie du solide
3 CRISMAT - Laboratoire de cristallographie et sciences des matériaux

Single crystals of PbLa$_3$O$_4$(VO$_4$) have been synthesized using the flux growth technique and characterized by X-ray diffraction. The crystal structure of the tittle phase was solved by charge flipping and refined to R$_1$ = 0.024 (wR$_2$ = 0.031) for 2777 reflections [I>3σ(I)]. The compound is orthorhombic and crystallized in the space group Cmcm: a = 5.8686(6)Å, b = 17.898(2)Å, c = 7.9190(7)Å, V = 831.8(1)Å3, Z = 4. The structure is built on [PbLa$_3$O$_4$]$^{3+}$ layers with zig-zag cross-sections, surrounded by isolated (VO$_4$)$_3$- tetrahedra. Its crystal structure shows direct relationship with the isoformular Nd$_4$O$_4$(GeO$_4$) compound which crystallized in the primitive non centrosymmetric Pb2$_1m$ sub-group. Its stability in temperature and under air was checked as well as optical properties. In a second part, lanthanum was substituted by neodymium giving rise to a paramagnet and f→ f electronic excitations superposed to the broad absorption front below 3.05 eV related to the presence of VO$_4$ groups.

Mots clés: Lanthanum; Lead; Vanadium; Oxo-centered tetrahedra; Flux growth synthesis; Crystal structure; Optical and magnetic properties

Domaines: Matériaux

Marie Colmont, Olivier Mentre, Natacha Henry, Alain Pautrat, Bastien Leclercq, et al.. Undulated oxo-centered layers in PbLn$_3$O$_4$ (VO$_4$ ) (Ln= La and Nd) and relationship with Nd$_4$O$_4$(GeO$_4$ ). Journal of Solid State Chemistry, 2018, 260, pp.101 - 105. ⟨10.1016/j.jssc.2018.01.016⟩. ⟨hal-01779322⟩