Formation of fresnoite-type Ba2TiGe2O8 crystallites in BaO-TiO2-GeO2 glass thin film and its optical nonlinearity

Abstract

We report on fabrication of the BaO-TiO2-GeO2 glass thin films on a fused silica substrate by RF sputtering, and investigation of the crystallization behavior, surface texture and the optical non-linearity in the glass thin film by means of AFM, XRD, Raman and Maker fringe techniques. Although the Ba2TiGe2O8, hereafter abbreviated to BTG, phase with second-order optical nonlinearity was mainly crystallized, the precipitation of the sub-phase of BaGe4O9 was also confirmed in the heat-treated glass thin films. In the glass thin film heat-treated at heat-treatment temperature (THT) = 730-750°C, the (211) preferential orientation of BTG phase and an upheaval about 300-400 nm were confirmed at the surface. These transparent crystallized glass thin films indicated a clearly Maker fringe patterns, demonstrating a second-order optical nonlinearity, and the effective second-order nonlinear optical constant, deff, was estimated to be ~0.8 pm/V.

Fresnoite thin films grown by pulsed laser deposition: photoluminescence and laser crystallization

“…27 Optically non-linear BTG thin films were grown by RF magnetron sputtering and the second harmonic generation was investigated. 28,29 In this paper, we report for the first time, to the best of our knowledge, pulsed laser deposited fresnoite thin films on singlecrystalline Si (100), MgO (100) and a-plane sapphire substrates. The c-axis texture of the different BTS films is visualized by XRD patterns and TEM cross-sections along with selected-area electron diffraction (SAD) patterns.…”

Structural, thermal and microwave dielectric properties of the novel microwave material Ba 2 TiGe 2 O 8

“…Ba2TiGe2O8 could be the Ge-O-Ge bond[22][23][24]. The five-fold coordinated titanium is the majority species present in the Ba2TiGe2O8 as revealed by the strongest band at 843 cm −1 in the spectrum.…”