TSSG Method Research Articles

First principles calculations of structure, vacancy defects, thermodynamic and mechanical properties and near-infrared luminescence properties of Li2CaGeO4 and Er3+: Li2CaGeO4 crystals

Li2CaGeO4 and Er3+: Li2CaGeO4 crystals were successfully grown by TSSG method. The electronic structure, vacancy defects, near-infrared luminescence, thermodynamic stability, and mechanical properties of the crystals were characterized and analyzed by first principles calculation and experimental tests. The results show that Li2CaGeO4 and Er3+: Li2CaGeO4 crystals are typical wide-gap direct bandgap crystals (3.64 and 3.96 eV). The effect of two cationic vacancy defects on crystal properties was studied. The results show that the defects of O2− or Li+ vacancy leads to the change of band structure, and the coupling degree between conduction band and valence band is reduced, and the degree of hybridization is reduced. The probability of non-radiative transition increases greatly and the luminescence intensity decreases. Spectral tests show that the Er3+: Li2CaGeO4 crystal is an excellent laser crystal with a high near-infrared optical output at 1550 nm (4I13/2 → 4I15/2) and long fluorescence decay lifetime (5.804 ms). The thermal vibration and elastic constants of Er3+: Li2CaGeO4 crystal are calculated by simulation. The results show that Er3+: Li2CaGeO4 crystal is a kind of crystal material with easy processing, good brittleness, good thermal stability, and excellent thermal conductivity. Therefore, it has a very high application prospect in the field of laser or thermoelectric.

Studies on a novel Ho3+:KBGM crystal toward the ∼2 μm laser applications

A Ho3+:KBGM crystal with good quality and large size was successfully grown via TSSG method. The crystal’s structure, ambient-temperature polarized absorption and emission spectra and fluorescence lifetime were studied. The J-O theory was adopted to analyze the absorption spectra and results show that crystal exhibits relatively large intensity parameters Ω2 and spectroscopic quality factor which is up to 3.12. At 453 nm, the absorption band is the strongest, and the corresponding cross-sections are 21.94 × 10–20 cm2, 26.66 × 10–20 cm2 and 18.56 × 10–20 cm2 for the -X, -Y and -Z polarizations, respectively. The emission spectra also demonstrate the broad and strong emission band at 2030 nm. The FWHMs and cross-sections are 74 nm, 0.37 × 10−20 cm2, 50 nm, 0.68 × 10−20 cm2, and 49 nm 0.52 × 10−20 cm2 for the three polarizations, respectively. In addition, the crystal has a superior quantum efficiency which is as high as 97.1%. Taking all the analyses into account, it is reasonable to assert that the Ho3+:KBGM crystal an ideal candidate for ∼2 µm laser applications in many areas.

The YMgB5O10 crystal preparation and attractive multi-wavelength emission characteristics of doping Nd3+ ions

YMB and Nd:YMB crystals with excellent physicochemical properties have been grown by TSSG method. The intense multi-wavelength emissions reveal the potential of THz technology.

Large-sized crystal growth and piezoelectric properties of the single crystals of LiNa5Mo9O30

Single crystals of LiNa5Mo9O30 with seeds in the a-, b- and c-directions were successfully grown using the TSSG method. Full sets of dielectric, elastic and piezoelectric matrices of the crystal were determined first time. The octahedral distortion and dipole moment are calculated to explain the piezoelectric properties.

Optimization of fluxes for Yb3+:YMgB5O10 crystal growth and intense multi-wavelength emission characteristics in spectra and laser performances

Yb:YMB crystals were grown using the optimized Li2O–B2O3–LiF flux instead of the traditional K2O3–MoO3 flux by the TSSG method. The demonstration of dual-wavelength laser operation reveals the potential in THz generation.

Crystal growth, structure and laser performance of a new Yb3+:KBaY(MoO4)3 crystal

A Yb3+:KBaY(MoO4)3 (Yb3+:KBYM) crystal with dimensions of 51 mm × 27 mm × 10 mm was successfully grown by the TSSG method. The characteristics of the crystal structure and probability of good optical properties were analyzed. The absorption and emission spectra of Yb3+:KBYM crystal exhibit broadened bands, with the maximum absorption cross-sections of 1.17 × 10-20, 1.44 ×10-20 and 1.37 × 10−20 cm2 at 976 nm for X-, Y- and Z-polarizations, respectively. The corresponding absorption FWHMs are as wide as 77, 46 and 55 nm. The well-known re-absorption effect of Yb3+ in the crystal is discussed. Two methods, the Füchtbauer-Ladenburg method (FL) and reciprocity method (RM) were adopted to compute the emission cross-sections and results show a certain discrepancy but the errors are allowable. The laser potentiality of the Yb3+:KBYM crystal was also evaluated by calculations of minimum inversion fraction βmin, saturation pump intensity Isat, the minimum pump intensity Imin and gain cross-sections spectra. Laser experiment was carried out and Watt-level continuous wave laser has been realized. Results indicate that the Yb3+:KBYM crystal with a disordered structure may be a potential laser media that can be used to generate tunable and ultrashort pulse laser emissions with high quality beam.

Growth of large aperture LBO crystal applied in high power OPCPA schemes

LBO crystal up to 192 × 130 × 89 mm3 in size and 2327 g in weight has been grown by TSSG method and cut into an optical element with a size of 100 mm × 100 mm × 17 mm for critically phase-matched type I (θ = 90°, Ø = 13.85°). Near phase-matching direction growth was introduced to promote yield of the final large aperture LBO elements greatly from the limited mass of crystal. Take into consideration of crystallographic symmetry, the linear thermal expansion coefficients and crystal growth habit, LBO grown along [1 0 0] direction was proved to be the best choice to produce large element which meet the demands of high power OPCPA schemes. The grown LBO crystal possesses high optical quality, and shows no evidence that crystal growth modifications have detrimental influence on the crystal property. The laser-induced damage threshold (LIDT) at λ = 1064 nm and τ = 5 ns is 42 J/cm2 for 1-on-1 type tests. Absorption at 1064 nm has been found to be 10–20 ppm/cm at 1064 nm). Especially, the optical homogeneity reached 1.9 × 10−7 cm−1 in full aperture for the optical elements mentioned above, to the best of our knowledge, the highest optical homogeneity in borate crystals. This extremely high optical homogeneity, large aperture optical element of LBO is more favorable in the high power laser schemes.

High peak-power near-MW laser pulses by third harmonic generation at 355 nm in Ca5(BO3)3F nonlinear single crystals.

In this work, the performance of Ca5(BO3)3F (CBF) single crystals was investigated for the third harmonic generation at 355 nm. A high energy conversion efficiency of 16.9% at 355 nm was reached using a two-conversion-stage setup. First, using a high peak power, passively Q-switched Nd3+:YAG/Cr4+:YAG microlaser based gain aperture in micro-MOPA, the second harmonic at 532 nm was achieved with lithium triborate (LBO) crystal, reaching 1.35 MW peak power. On a second step, laser pulses at 355 nm were generated using a 5 mm-long CBF crystal growth by TSSG method with energy, pulse duration and peak power of 479 µJ, 568 ps and 0.843 MW, respectively. These results are currently the highest reported for CBF material.

New scandium borates RxLayScz(BO3)4 (x+y+z=4, R=Sm, Tb): Synthesis, growth, structure and optical properties

Herein we report the growth of new RxLayScz(BO3)4 (x + y+z = 4, R = Sm, Tb) crystals with large second-harmonic generation (SHG) responses. The obtained compounds, grown from eutectic LiBO2-LiF flux by the TSSG method, crystallize in the space group P321 with the cell parameters a = 9.800(15) Å and c = 7.9565(7) Å for Sm0.34La0.68Sc2.98(BO3)4 and a = 9.7976(7) Å and c = 7.9567(12) Å for Tb0.23La0.77Sc3(BO3)4. These crystalline materials also exhibit luminescent properties related to the optical transitions of Tb3+ and Sm3+; specifically, Tb0.23La0.77Sc3(BO3)4 shows a strong green emission that is dominated by the 5D4 to 7F5 transition. The studied crystals’ SHG intensities were higher than those of KDP crystals, revealing their potential uses in various nonlinear optics applications.

Anisotropic properties and Raman spectra of a LiNa5Mo9O30 single crystal grown by the TSSG method

Single crystal LiNa5Mo9O30 with 52 × 44 × 8 mm3 was successfully grown using the TSSG method. The transmission spectrum, thermal diffusion, thermal conductivity, and polarized Raman spectrum of a-cut configurations were systematically investigated.

Nd3+ and Pr3+ doped anti-zeolite matrix-LiBa12(BO3)7F4: Crystal structures, luminescence properties

The LiBa12(BO3)7F4 crystals doped Nd3+ and Pr3+ were grown from high-temperature solution melts, using the TSSG method. All the samples have the wide absorption band in the visible range of 350–650 nm related to the dichroism, which is typical for other colored “antizeolites”. Strong radiation bands are associated with well known electronic transitions of Pr3+ (3P0 → 3H6 at 630 nm, 3P0 → 2F2 at 670 nm) and Nd3+ (4F3/2 → 4I9/2 at 875 nm, 4F3/2 → 4I11/2 at 1054 nm). In addition crystals of Nd-doped barium fluoride borate solid solutions NdxBa12(BO3)8-xF6x were grown from high temperature solution. Using X-ray single-crystal diffraction, the structure was solved and refined in I4/mcm space group that are similar to other colored “antizeolites” built with the positively charged framework of [Ba12(BO3)6]6+ cation pattern which contains channels built of alternating barium cubes and anticubes. According to the structure refinement of NdxBa12(BO3)8−xF6x, cube channel segments are populated mainly by [F4]4– and [NdF4]– clusters, whereas anticube ones – by (BO3)3– anions.

Bulk crystal growth and characterization of the bismuth ferrite-based material Bi3FeO4(MoO4)2

The large, high-quality Bi3FeO4(MoO4)2single crystals of size up to 28 × 20 × 12 mm3were grown successfully by the TSSG method. The thermal, optical, magnetization, and polarized Raman properties are investigated in detail.

Investigation into the optimized growth, anisotropic properties and theoretical calculations of the polar material Cs2TeW3O12

Bulk single crystals of Cs2TeW3O12were grown successfully by a modified TSSG method and physical properties were systematically investigated.

Dislocation Behavior in Bulk Crystals Grown by TSSG Method

The dislocation behavior during bulk crystal growth on the 4H-SiC (000-1) C-face using the solution method was investigated. A 2 inch wafer with a 4° off angle was fabricated from a bulk crystal grown by the TSSG method, and the dislocations in the crystal were evaluated using synchrotron X-ray topography and TEM observation. From the topograph images, it was found that the TSD density remarkably decreased as the growth progressed. Furthermore, the TEM observation suggested that TSD decreases as the threading dislocations convert to in-plane defects toward the center of the crystal. Conventionally, it was considered that conversion of threading dislocations hardly occurs in solution growth on the C-face. However, it is thought that this phenomenon was not observable because the conversion efficiency is remarkably low. We speculate that dislocations may be transformed by suddenly making macrosteps during bulk growth.

MoSe2 nanoflower as the saturable absorber for 1 μm and 2 μm passively Q-switched bulk state laser

Using the MoSe2 nanoflower prepared via a facile hydrothermal reaction, we firstly realized the 1μm and 2μm passively Q-switched bulk state pulse laser, as far as we know. Using the Yb:GdMgB5O10 crystal grown by TSSG method as the gain medium, the 446ns pulses are yielded at 1062.8nm with 91.8mW of output power and 1.222μJ of pulse energy. Besides, based on Tm:YAP crystal, the 360ns pulses are yielded at around 1936nm with 466.3mW of output power and 3.615μJ of pulse energy. Our results exhibit this MoSe2 nanoflower could be a promising broadband saturable absorber for bulk state laser.

TSSG法によるorthoenstatite単結晶の育成 : バルク成長 I フラックス法

TSSG法によるorthoenstatite単結晶の育成 : バルク成長 I フラックス法

Growth of the complex borates YxRySc2+z(BO3)4 (R = Nd, Pr, x + y + z = 2) with huntite structure

Bulk crystals of new huntite type borates were grown by TSSG method using eutectic LiBO2–LiF as a flux. Chemical composition, X‐ray diffraction, optical absorption and fluorescence spectra of the grown samples were studied.

Crystal growth and optical properties of a UV nonlinear optical material KSrCO3F

Large UV NLO KSrCO3F crystals were grown by a TSSG method, and their linear and nonlinear optical properties were investigated.

Linear and nonlinear optical characterization of methyl-p-hydroxybenzoate (p-MHB) single crystal grown by TSSG method

The nonlinear optical single crystal methyl-p-hydroxybenzoate (p-MHB) was grown by employing top seeded solution growth method (TSSG) for the first time. A good quality small size crystal grown from methanol solution was inserted into the melt as a seed for growth after seasoning it around the melt temperature. Highly transparent optical quality p-MHB single crystal with regular faceting was harvested after the successful growth run. The unit cell parameter of the grown crystal was determined by powder X-ray diffraction (PXRD) and the crystal structure was confirmed by single crystal X-ray diffraction (SCXRD) methods. The UV–Vis–NIR absorption spectrum has been recorded in the range 200–2700nm and it shows that the lower cutoff wavelength exits at 307nm. The study indicates that the grown crystal has good optical transparency window in the visible and near IR region in the range 307–2136nm. Second harmonic generation (SHG) efficiency of the grown crystal was studied by Kurtz-Perry powder method with 1064nm Nd: YAG laser beam as a fundamental source and it was about twice that the standard KDP.

Dielectric and piezoelectric properties of lead-free (K0.44Na0.46)NbO3-0.5%MnO2 single crystals grown by the TSSG method

Lead-free (K0.44Na0.46)NbO3-0.5%MnO2 (KNN-0.5%MnO2) single crystals with dimensions of Ф30×10mm were successfully grown by a top seeded solution growth technique (TSSG). The X-ray diffraction pattern has shown that the as-grown crystals have an orthorhombic perovskite structure. The orthorhombic-tetragonal (TO-T) and tetragonal-cubic phase transition temperature (the Curie temperature TC) of the single crystal were found at 184°C and 412°C, respectively. The KNN-0.5%MnO2 single crystals exhibited high piezoelectric constants d33 and dielectric permittivity εr, being 261pC/N and 275. Well saturated P-E hysteresis loop with remnant polarization Pr=22.06µC/cm2 and coercive field Ec=17.93kV/cm was obtained at a maximum electric field of 3kV/mm. A high strain (0.24%) and electromechanical coupling coefficient Kt (65.9%) were obtained along the (001) orientation. These excellent results indicated that the KNN-0.5%MnO2 single crystals could be used as high quality lead-free material.