Relationship between anion and cation nonstoichiometries and valence state of titanium in perovskite-type oxynitrides LaTiO2N

Abstract

Three series of (La,Sr)TiO2N compounds, with either anion nonstoichiometry LaTiO2+xN1-x, cation nonstoichiometry La1-x Ti1+xO2N or an La1-xSrxTiO2N series, have been prepared in order to clarify, by XPS spectroscopy, the influence of composition on the valence state of titanium. Though the substitution of lanthanum by strontium was effective in the enhancement of reflectivity in the longer wavelength region above the absorption edge, the valence state of titanium did not change in either the La1-xTi1+xO2N or the La1-xSrxTiO2N series. However, it was found that the increase of oxygen content in the LaTiO2+xN1-x series causes oxidation of the titanium.

Enhanced Fenton degradation of Rhodamine B over nanoscaled Cu-doped LaTiO3 perovskite

“…As shown in Fig. 2, the strong peak at 458.0 eV could be assigned to Ti 4+ [22,23] for the sample X Cu = 0.0, while the Ti 2p 3/2 peak of the sample X Cu = 0.6 was well fit into the peaks of Ti 3+ (∼457.5 eV) and Ti 4+ (∼458.5 eV) [24] and the surface concentration ratio of Ti 3+ to Ti 4+ was about 4.6:1. Therefore, it was confirmed that the insertion of Cu into the La/Ti system led to the conversion of the crystalline phase from La 2 Ti 2 O 7 to LaTiO 3 , thus produced the existence environment of the Ti 3+ ion which could exhibit higher Fenton catalytic activity.…”

Structural and optical properties of perovskite-type LaTiO2N synthesized using urea or thiourea as co-nitriding agents

“…Nitrogen is less electronegative than oxygen and incorporation of N 3− into metal oxides results in a considerable reduction in the band gap since the 2p orbitals of nitrogen have a higher energy than the 2p orbitals of oxygen [2][3][4][5][6]. On nitriding La 2 Ti 2 O 7 to LaTiO 2 N, the absorption edge red shifts from 3.2 eV to 2.2 eV [2][3][4][5][6][7][8][9][10][11]. By precise control of the nitridation conditions, LaTiO 2+x N 1−x pigments with orange, yellow, green and blue colours have been synthesized [8,10].…”

“…On nitriding La 2 Ti 2 O 7 to LaTiO 2 N, the absorption edge red shifts from 3.2 eV to 2.2 eV [2][3][4][5][6][7][8][9][10][11]. By precise control of the nitridation conditions, LaTiO 2+x N 1−x pigments with orange, yellow, green and blue colours have been synthesized [8,10]. Further colour manipulation can be achieved through lanthanum substitution with Ca 2+ , Sr 2+ or Ba 2+ , or titanium substitution with Nb 5+ or W 6+ [8][9][10][11][12][13][14][15][16].…”

Synthesis and adsorption ability of nanoparticles of perovskite oxynitride LaTiO2N

“…12), 13) Masuda et al mentioned that the substitution of La by Sr is effective in the enhancement of reflectivity in the longer wavelength region. 13) Photocatalysts that function under visible light irradiation are desirable for solar energy utilization. The perovskitetype oxynitride, LaTiO2N is one such candidate for use as a photocatalysts.…”