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Polycrystal Synthesis, Crystal Growth, Structure, and Optical Properties of AgGaGe <sub/><i> <i>n</i> </i> </sub> S <sub/> 2( <i> <i>n</i> </i> +1) </sub> ( <i>n</i> = 2, 3, 4, and 5) Single Crystals for Mid-IR Laser Applications
摘要： AgGaGenS2(n+1) crystal is a series of quaternary for mid-IR laser applications of nonlinear optical materials converting a 1.064 μm pump signal (Nd:YAG laser) to 4?11 μm laser output, but only AgGaGeS4 has attracted the most attention, remaining the other promising AgGaGenS2(n+1) crystal whose physicochemical properties can be modulated by n value. In this work, AgGaGenS2(n+1) (n = 2, 3, 4, and 5) polycrystals are synthesized by vapor transport and mechanical oscillation method with di?erent cooling processes. High-resolution X-ray di?raction analysis and re?nement have revealed that all the four compounds are crystallized in the noncentrosymmetric orthorhombic space group Fdd2, resulting in the excellent nonlinear optical property, and the distortion of tetrahedron with the variation of n value causes the discrepancy of physicochemical property. Besides, using the modi?ed Bridgman method, AgGaGenS2(n+1) single crystals with 15 mm diameter and 20?40 mm length have been grown. We have discussed the structure and composition of AgGaGenS2(n+1) by XPS spectra and analyzed the three kinds of vibration modes of tetrahedral clusters by the Raman spectra. The Hall measurement indicates that the AgGaGenS2(n+1) single crystals are p-type semiconductor, and the carrier concentration decreases with the increasing n value. All the transmittances of as-grown AgGaGenS2(n+1) samples exceeds 60% in the transparent range, especially the transmittance of AgGaGe2S6, is up to 70% at 1064 nm, and the band gap of as-grown crystal increases from 2.85 eV for AgGaGe2S6 to 2.92 eV for AgGaGe5S12. After a thermal annealing treatment, the absorptions at 2.9, 4, and 10 μm have been eliminated, and the band gap changed into the range of 2.89?2.96 eV.
关键词： Hall measurement,nonlinear optical materials,thermal annealing treatment,vapor transport,AgGaGenS2(n+1),Bridgman method,Raman spectra,mid-IR laser applications,XPS spectra,mechanical oscillation method
更新于2025-11-14 15:27:09
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Temperature dependence of luminescence properties in Li2WO4 single crystal grown by Bridgman method
摘要： Transparent Li2WO4 single crystal was grown by vertical Bridgman method. The phase identification, Fourier transform infrared spectra, thermal behavior, and optical transmission spectra of Li2WO4 crystal had been studied in detail. The luminescence properties as a function of temperature were investigated systematically. The transmissivity of as-polished crystal samples with the thickness of 2.0 mm, 4.0 mm, and 6.0 mm reached 85–89%, 81–85%, and 78–81% in 400–800 nm wavelength range, respectively. Li2WO4 crystal has wide luminescence peaks around 626 nm, 574 nm, and 543 nm at the ambient temperature of 30 K, 50 K, and 75 K, respectively. The luminescence peaks are ascribed to the intrinsic luminescence emission of tetrahedral [WO4]2-. The emission line width presents an obvious broadening with the increasing temperature. The maximal luminescence intensity increases with the ambient temperatures cooling down. The luminescence decay times monotonically decrease with the temperature increasing in temperature range of 30–75 K. The decay times at 30 K, 50 K, and 75 K correspond to 97.92 m s, 30.16 m s, and 1.97 m s, respectively, while maintain a constant around 1.80 m s in 75–300 K.
关键词： Bridgman method,Crystal growth,Li2WO4,Luminescence
更新于2025-09-23 15:23:52
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Growth of Single-Crystal Cd0.9Zn0.1Te Ingots Using Pressure Controlled Bridgman Method
摘要： We report growth of single-crystal Cd0.9Zn0.1Te ingots while using the pressure-controlled Bridgman method. The Cd pressure was controlled during growth to suppress its evaporation from the melt and reduce the size of Te inclusions in the as-grown crystals. The accelerated crucible rotation technique (ACRT) was used to suppress constitutional supercooling. The fast accelerating and slow decelerating rotation speeds were optimized. Two-inch Cd0.9Zn0.1Te single-crystal ingots without grain boundaries or twins were grown reproducibly. Glow discharge mass spectrometry results indicate the e?ective segregation coe?cients of Zn and In dopants are 1.24 and 0.18, respectively. The full width half maximum (FWHM) of X-ray rocking curve was approximately 22.5 ”, and the IR transmittance was approximately 61%, indicating high crystallinity. The mean size of the Te inclusions was approximately 13.4 μm. Single-crystal wafers were cut into 5 × 5 × 2 mm3 slices and then used to fabricate gamma ray detectors. The energy resolution and peak-to-valley ratio maps were constructed while using 59.5 keV gamma ray measurements, which proved the high uniformity of detection performance.
关键词： ACRT,CZT single-crystal ingot,pressure control,Bridgman method
更新于2025-09-23 15:19:57