Barium Titanium Oxynitride from Ammonia-Free Nitridation of Reduced BaTiO3

We investigated the nitridation of reduced BaTiO3, BaTiO2.60H0.08, corresponding to an oxyhydride with a large concentration of O defects (>10%). The material is readily nitrided under flowing N2 gas at temperatures between 400 and 450 °C to yield oxynitrides BaTiO2.6Nx (x = 0.2−0.22) with a slightly tetragonally distorted perovskite structure, a ≈ 4.01 and c ≈ 4.02 Å, and Ti partially remaining in the oxidation state III. The tetragonal structure was confirmed from Raman spectroscopy. 14N MAS NMR spectroscopy shows a single resonance at 270 ppm, which is typical for perovskite transition metal oxynitrides. However, largely different signal intensity for materials with very similar N content suggests N/O/vacancy ordering when prolonging nitridation times to hours. Diffuse reflectance UV-VIS spectroscopy shows a reduction of the intrinsic band gap to 2.4–2.45 eV compared to BaTiO3 (~3.2 eV). Mott-Schottky measurements confirm n-type conductivity and reveal a slight negative shift of the conduction band edge from –0.59 V (BaTiO3) to ~–0.65 eV.

Enhancement of Optical Activity and Properties of Barium Titanium Oxides to Be Active in Sunlight through Using Hollandite Phase Instead of Perovskite Phase

The present study aims to enhance the optical properties of barium titanate through narrowing its band gap energy to be effective for photocatalytic reactions in sunlight and be useful for solar cells. This target was achieved through growth of the hollandite phase instead of the perovskite phase inside the barium titanate crystals. By using solvent thermal reactions and thermal treatment at different temperatures (250 °C, 600 °C, and 900 °C), the hollandite phase of barium titanate was successfully obtained and confirmed through X-ray diffraction (XRD), Raman spectra and scanning electron microscopy techniques. XRD patterns showed a clear hollandite phase of barium titanium oxides for the sample calcined at 900 °C (BT1-900); however, the samples at 600 °C showed the presence of mixed phases. The mean crystallite size of the BT1-900 sample was found to be 38 nm. Morphological images revealed that the hollandite phase of barium titanate consisted of a mixed morphology of spheres and sheet-like features. The optical properties of barium titanate showed that its absorption edge shifted to the visible region and indicated band gap energy tuning ranging from 1.75 eV to 2.3 eV. Photocatalytic studies showed the complete and fast decolorization and mineralization of green pollutants (naphthol green B; NGB) in the prepared barium titanate with hollandite phase after illumination in sunlight for ten minutes. Finally, it can be concluded that the low band gap energy of barium titanate having the hollandite phase introduces beneficial structures for optical applications in sunlight.

Energy Storage Capacity and Electrocaloric Effect on Sn Modified Barium Titanium Oxide (BaTi0.8Sn0.2O3)

Modified Barium Titanium Oxide ( BaTi 0.8 Sn 0.2 O 3 ) was prepared by using the solid-state reaction method. The crystal structure, energy storage behavior, and electrocaloric properties were studied. The phase purity and structural analysis were investigated using the X-ray diffraction technique and the Rietveld refinement of XRD pattern. The microstructure of the sample was recorded by using the Field Emission Scanning Electron Microscopy (FESEM). The temperature variation dielectric property shows that the ceramic exhibits diffuse phase transition behaviour. The ferroelectric nature in BaTi 0.8 Sn 0.2 O 3 has been depicted from P-E loops analysis. The energy storage behaviour and electrocaloric properties were estimated from the temperature variation P-E loops at 40kV/cm. The electrocaloric effect was studied by an indirect method using Maxwell relation, and the electrocaloric value has been estimated to with 94% of energy storage efficiency.

Direct synthesis of barium titanium oxyhydride for use as a hydrogen-permeable electrode

Barium titanium oxyhydride BaTiO3–xHx is a promising functional material that exhibits H–/e– mixed conduction. Here we firstly report a direct synthesis of BaTiO3–xHx by mechanochemical method. The prepared polycrystalline sample...

Sifat Termal dan Analisis Komposisi Material Barium Zirkonium Titanat (BZT) dengan Doping Lantanum dan Indium

Material Barium Zirkonium Titantat (BZT) dibuat menggunakan metode sol gel yang dilanjutkan dengan Spin Coating pada substrat Silikon. Untuk mendapatkan material Barium Zirkonium Titantat (BZT)dalam bentuk serbuk dilakukan pemanasan menggunakan hotplate pada suhu 90oC hingga larutan BZT berubah menjadi serbuk. Selanjutnya untuk menumbuhkan lapisan BZT pada substrat, dilakukan metode spin coating yang dilanjutkan proses pyrolisi. Selanjutnya substrat yang telah dilapisi larutan BZT dipanaskan pada suhu 800oC selama 3 jam. Untuk mengetahui sifat termal dan kristalisasi pada BZT dilakukan Uji DTA/TGA. Pengujian EDAX dilakukan untuk mengetahui komposisi lapisan BZT yang telah terdeposisi pada substrat. Dari hasil uji DTA/TGA terlihat bahwa proses kristalisasi BZT mulai terjadi pada suhu 400oC dan proses endotermik dari BZT terjadi pada suhu 463oC. Hasil uji EDAX komposisi unsur Barium, Titanium, serta doping Lantanum dan Indium telah terdeposisi pada subtrat silikon, serta dari hasil tersebut dapat disumpulkan kristal BZT dengan doping La dan In telah berhasil di deposisi dan ditumbuhkan pada substrat Si.