Conggang Li,Zeliang Gao,Xiangxin Tian,Qian Wu,Weiqun Lu,Youxuan Sun,Xutang Tao
Large sized crystals of CdTeMoO6 with dimensions up to 30 × 12 × 9 mm3 were successfully grown using the top-seeded solution growth technique with an optimized flux system. High resolution X-ray diffraction rocking curve measurements revealed that the full-width at half-maximum (FWHM) of the rocking curve was 36 arcsec from the (001) reflection, which indicated high crystal quality. A complete set of room temperature elastic, dielectric, and piezoelectric constants of CdTeMoO6 single crystals was obtained using both resonance techniques and impedance analysis. The results demonstrate that the CdTeMoO6 crystals exhibit intriguing piezoelectric and elastic properties. The piezoelectric coefficients d14 and d36 reached 20.14 pC N−1 and 7.58 pC N−1, respectively, and the corresponding electromechanical coupling coefficients k14 and k36 were up to 22.78% and 19.48%, respectively. Furthermore, the relationship between the crystal structure and piezoelectric properties is also investigated. Our observations indicate that CdTeMoO6 crystals are good potential candidates for piezoelectric applications.
Acentric compounds with a layered structure are of current interest owing to their advanced functional properties for technical applications. However, the growth of bulk single crystals of acentric materials with a quasi-two-dimensional structure is challenging, which severely hinders the intrinsic properties investigation and optoelectronic applications of these materials. Herein, we report the controlled growth of bulk CdTeMoO6 single crystals with a layered structure and the investigation of their linear and nonlinear optical properties. High quality CdTeMoO6 single crystals with dimensions of ∼26 × 10 × 9 mm3 were successfully grown through the modified top-seeded solution growth method using TeO2-MoO3 as a flux. The transparent range of CdTeMoO6 single crystals is in the range of 0.345–5.40 μm, and with large birefringence (Δn = no – ne = 0.2868–0.2219 from 514 nm to 1.5467 μm). In addition, the nonlinear optical (NLO) coefficient d36 of CdTeMoO6 single crystals was measured to be 8.5 pm/V using Maker Fringe techniques. We also found CdTeMoO6 is type-I phase-matchable based on the calculated phase-matching curves. Our results indicated that CdTeMoO6 single crystal is an excellent birefringent material combined with a promising NLO material for optoelectronic applications.
Materials with excellent nonlinear optical properties, especially the second-harmonic-generation (SHG) ability that can double the frequency of a laser ω to 2ω, are greatly important to modern optical technology. Recently, a temperature-induced SHG “on–off” phenomenon has been reported in dozens of metal–organic complexes, which have emerged as candidates in advanced optoelectronic applications. As a counterpart to temperature, pressure is also expected to trigger a SHG “on–off” phenomenon; nevertheless, such material is relatively limited. Herein, we report the observation of a pressure-induced SHG “on–off” phenomenon accompanied by a structural phase transition and piezochromism in CdTeMoO6. Under ∼10 GPa compression, the material exhibits a sharp transition from the “SHG-on” state to the “SHG-off” state. Coupled with the SHG “on–off” phenomenon, a structural transition occurs from two-dimensional to three-dimensional due to the dramatic change in the coordination environments of Te4+ and Mo6+ from [TeO4] and [MoO4] tetrahedra to [TeO6] and [MoO6] octahedra, respectively. The suppression of stereoactive lone-pair electrons on Te4+ is considered to be responsible for the SHG-off state under high pressure. Piezochromism from colorless to black is also observed coupled with the SHG “on–off” phenomenon, which can be attributed to the hybridization between Mo 4d and O 2p orbitals. Moreover, we demonstrate that the “three-in-one” transition (structural transition, SHG on–off, and piezochromism) is irreversible at room temperature but reversible upon annealing at increased temperatures (230–350 °C) with SHG, lattice dimension and color returning to those of the initial state. All of these behaviors make CdTeMoO6 a maneuverable pressure- and temperature-regulated SHG switching material with pragmatic multifunctionality.
危险品化学品经营许可证（带存储）