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The formation of ErNbO4 powder, prepared by calcining an Er2O3 (50 mol%) and Nb2O5 (50 mol%) powder mixture at 1100 and 1600 °C for different durations, was investigated by using X-ray diffraction. The experimental results have displayed that although the solid-state reaction had started to some extent when the mixture was pre-calcined at 1100 °C for a duration of 13 h, the two original phases Er2O3 and Nb2O5 still dominated the mixture. When the duration of the calcination reaction was increased to 120 h at the same temperature, the resultant mixture experienced a nearly complete phase transformation. Accordingly, the ErNbO4 phase was dominant phase in the mixture. Nevertheless, a small portion of the raw powder still existed in the mixture. When the calcining temperature was elevated to 1600 °C, ErNbO4 powder with higher purity could be obtained for a relatively much shorter duration (only up to several tens of hours). A simple formation mechanism of ErNbO4, an elevated-temperature-assisted solid-state chemical reaction: Er2O3+Nb2O5⇌2ErNbO4, is suggested. In addition, the present experimental results offer important evidence for the formation of the additional phase ErNbO4 induced in Er:LiNbO3 crystals by vapour transport equilibration (VTE) treatment. [Copyright &y& Elsevier]

Ti-diffused LiTaO 3 strip waveguide was fabricated by in-diffusion of 8-μm-wide, 100-nm-thick Ti-strip at 1300 °C for 6 h in wet O 2 atmosphere. Its composition, surface morphology, lattice parameter, optical properties and Ti profile characteristics were fully characterized. It is shown that the waveguide is in the congruent composition environment. The waveguide surface caves in ∼70 nm below the crystal surface due to Ti-induced lattice contraction, which is verified by X-ray single-crystal diffraction. Optical characterizations show that the waveguide well supports both TE and TM single-mode propagation at the 1.5 μm wavelength, is polarization-insensitive, and has a loss of 0.4 (0.3) dB/cm for the TM (TE) mode. Secondary ion mass spectrometry analysis shows that the Ti profile follows a sum of two error functions in the width direction and a Gaussian function in the depth direction of the waveguide. [ABSTRACT FROM AUTHOR]