Optical and transport properties of LaTi1-xMx(O,N)3±δ (x=0; 0.1, M=Nb5+, W6+) thin films prepared by plasma ammonolysis

Oxynitride thin films of composition LaTi1−xMx(O,N)3±δ with x=0; 0.1 and M=Nb5+, W6+ were prepared by nitridation via microwave-induced plasma (MIP) ammonolysis, which allowed keeping the nitridation time short (16 min). The higher possible oxidation states of the B-site substituents (Nb5+, W6+) with respect to Ti4+ caused higher N content for LaTi0.9Nb0.1(O,N)3±δ and LaTi0.9W0.1(O,N)3±δ compared to LaTiO2N due to charge-compensation. XPS O 1s and N 1s core level and valence band spectra evidenced for increasing N content in the order LaTiO2N<LaTi0.9Nb0.1(O,N)3±δ<LaTi0.9W0.1(O,N)3±δ. All films were N deficient comparing with their stoichiometric formulas and assuming cations in highest oxidation states. Along with increasing N content, the bandgaps decreased from 2.4 to 2.2 and 2.1 eV for LaTiO2N, LaTi0.9Nb0.1(O,N)3±δ, and LaTi0.9W0.1(O,N)3±δ and the electronic conductivities increased along with the decreased bandgaps. The Seebeck coefficients at 860 K indicated the highest charge-carrier density for LaTi0.9W0.1(O,N)3±δ.Fil: Maegli, Alexandra E.. Eidgenössische Materialprüfungs- und Forschungsanstalt; SuizaFil: Sagarna, Leyre. Eidgenössische Materialprüfungs- und Forschungsanstalt; SuizaFil: Populoh, Sascha. Eidgenössische Materialprüfungs- und Forschungsanstalt; SuizaFil: Penkala, Bartosz. Eidgenössische Materialprüfungs- und Forschungsanstalt; SuizaFil: Otal, Eugenio Hernan. Eidgenössische Materialprüfungs- und Forschungsanstalt; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Weidenkaff, Anke. Eidgenössische Materialprüfungs- und Forschungsanstalt; Suiz

EuTiO3TiO_3 magnetic structure studied by neutron powder diffraction and resonant x-ray scattering

We combine neutron powder diffraction and x-ray single-crystal magnetic diffraction at the Eu L2 edge to scrutinize the magnetic motif of the Eu ions in magnetoelectric EuTiO3. Our measurements are consistent with an antiferromagnetic G-type pattern with the Eu magnetic moments ordering along the a,b -plane diagonal. Recent reports of a novel transition at 2.75 K with a flop of magnetic moments upon poling the sample in an electric field cannot be confirmed for a nonpoled sample. Our neutron diffraction data do not show any significant change of the structure below the N\ub4eel temperature. Magnetoelastic coupling, if present, is therefore expected to be negligible

Synthesis, Crystal Structure, Electric and Magnetic Properties of LaVO 2.78 N 0.10

Perovskite-type LaVO2.78N0.10 powder was synthesized by thermal ammonolysis of the oxide precursor LaVO4. By X-ray, neutron, and electron diffraction an orthorhombic crystal structure with space group Pnma was identified. XANES spectra showed that the oxidation state of vanadium changes from 5+ in LaVO4 to approximately 3+ in LaVO2.78N0.10. The temperature dependence of the electrical conductivity revealed an Arrhenius-type behavior with an activation energy of 0.103 eV in the temperature range of 119–302 K indicating that the conduction process is thermally activated band transition. Based on the positive Seebeck coefficient, holes were identified as the dominant charge carriers in the temperature range of 100–302 K. Both the Seebeck coefficient and the thermal conductivity showed an anomaly at 138 K, which is attributed to the Néel temperature for antiferromagnetic ordering according to magnetic susceptibility measurements