Growth And Properties Of Na₂Ce₄?MoO₄?₇ And CaDyAlO₄ Magneto-optical Crystals

In this paper,the optimization of polycrystalline material synthesis and crystal growth of scheelite-type Na2Ce4(MoO4)7(NCM)and perovskite-like CaDyAlO4(CDA)magneto-optical crystals were investigated,and the crystal defects,crystal structure,basic physical properties,optical and magneto-optical properties were systematically studied.NCM and CDA polycrystalline materials were synthesized by high temperature solid phase method.The synthesized polycrystalline materials were characterized by XRD and IR,and the polycrystalline materials synthesis process with good crystallinity and high purity was found.NCM crystal has been grown by the Czochralski method.Structure refinement of XRD data confirms that the compound crystallizes in the tetragonal system I41/a.Scanning electron microscopy(SEM)was used to analyze the defects of cracks,streaks,pores and scattering centers in NCM crystals.The physical properties of NCM crystals such as density,Vickers hardness and thermal expansion coefficient were measured.After the NCM crystals were strictly oriented,cut and polished,the transmission spectra of the wafers in the 400-1600 nm regions were measured,and the crystal exhibits a high transmittance in the 600-1600nm regions,approximately 77%-79%.The XPS test found that Ce3+ and Mob+ ions can stably exist in the scheelite structure before and after the crystal annealing,and the valences did not change.The measurement of magnetic susceptibility in different directions shows that the NCM crystal is paramagnetic and has obvious magnetic anisotropy,its easy magnetization direction is consistent with the optical path.The Faraday rotation angle of the crystal at 635 nm and 1064 nm were measured by extinction method,the calculated Verdet constants are-194.5 rad/m T and-58.5 rad/m·T,respectively,about 1.5 times the TGG crystals.CDA crystal has been grown by the Czochralski method.Structure refinement of XRD data confirms that the compound crystallizes in the ABCO4 type perovskite-like structure,space group I4/mmm.The reasons for the different colors of CDA crystals under different growth atmospheres were analyzed.The physical properties of CDA crystals such as density,Vickers hardness and thermal expansion coefficient were measured.After the CDA crystals were strictly oriented,cut and polished,the transmission spectra of the wafers in the 400-1600 nm regions were measured,it was found that the crystal grown under the 5%H2+95%Ar atmosphere exhibited a higher transmittance in the 490-750 nm regions than the crystal grown under the N2 atmosphere,approximately 80%.The fluorescence spectrum of CDA crystal was measured and it was found that the crystal can be excited at a wide range of wavelengths.The emission peaks are mainly concentrated in the blue wavelength regions of 450-500 nm and the yellow wavelength regions of 550-600 nm,and the intensity of yellow light is greater than the intensity of blue light.The measurement of magnetic susceptibility in different directions shows that the CDA crystal is paramagnetic and has obvious magnetic anisotropy,its easy magnetization direction is consistent with the optical path.The Faraday rotation angle of the crystal at 635 nm and 1064 nm were measured by extinction method,the calculated Verdet constants are-297.2 rad/m.T and-211.7 rad/m·Tmrespectively,about 1.6 times the TGG crystals.