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KTaO3 (KT) is an important material for optoelectronic and tunable microwave applications. However, growing large size and uniform crystals still remain a challenge. In this paper, a promising approach for growing relatively large size and high-quality KT single crystal was explored, and a transparent KT single crystal with dimension of Ф 30 × 80 mm, weighing as much as 406 g, was grown by Czochralski method successfully. The full width at half maximums (FWHMs) of X-ray rocking curves (XRCs) are 0.016°, 0.011°, and 0.016°, respectively, implying that the KT crystal possesses high crystalline quality. A comprehensive investigation of its mechanical, thermal, and optical properties was carried out. The Mohr's hardness is obtained to be 6.0, indicating that the KT is more conducive to being processed compared with diamond. The Sellmeier equation is fitted and the refractive index curve in the range of 400–3000 nm is displayed based on the measured refractive index. All results are of great significance for the further research and application of KT crystal. [ABSTRACT FROM AUTHOR]

Structure, defects, and spectroscopic properties of a Yb,Ho,Pr:YAlO 3 (Yb,Ho,Pr:YAP) single crystal grown by the Czochralski method were investigated. The effective segregation coefficients of the Yb 3+ , Ho 3+ , and Pr 3+ ions are 1.06, 1.32, and 0.90 in YAP host, respectively. The structural parameters are obtained by the X-ray Rietveld refinement method. A high crystalline quality of the Yb,Ho,Pr:YAP is determined by the X-ray rocking curve. The dislocations of (100), (010), and (001) faces are studied using the chemical etching with the phosphoric acid etchant. The absorption spectra show that there exists strong absorption in the wavelength range of 900–1000 nm, and the fluorescence spectrum excited by 970 nm LD presents that the strongest emission is located at 2853 nm, indicating the Yb 3+ ions can be acted as the sensitizer for the Ho 3+ ions. The level lifetimes indicate that the Pr 3+ ions can play a deactivator role for the Ho 3+ ions. All these results imply that the Yb,Ho,Pr:YAP crystal can be regarded as a promising candidate for realizing 2.8–3.1 μm laser output. [ABSTRACT FROM AUTHOR]

A novel Yb,Ho,Pr:LuYAG laser crystal was successfully grown and investigated in detail, which belongs to the cubic system with a space group of I a-3d. The X-ray rocking curve of the as-grown crystal implied high crystalline quality. The dislocation defects were revealed by the chemical method. Moreover, the density, thermal expansion coefficient and thermal conductivity were determined. The absorption coefficient at 935 nm and the emission cross-section at 2.911 μm were obtained to be about 15.18 cm−1 and 2.23 × 10−21 cm2, respectively. The lifetime of the lower laser level 5I 7 was shown to decrease from 7.58 to 5.88 ms, while that of the upper laser level 5I 6 basically remained unchanged, suggesting that the co-doped Pr3+ possessed an efficient deactivation effect and was beneficial in attaining population inversions of Ho3+. The corresponding findings illustrate that the Yb,Ho,Pr:LuYAG crystal can serve as a novel promising gain medium for realizing the 2.911 μm laser pumped by ~ 940 nm high-power InGaAs laser diode. • A novel Yb,Ho,Pr:LuYAG laser crystal was successfully grown by Czochralski method. • The crystal possesses a high thermal conductivity, which is helpful in dissipating heat during laser action. • Yb3+ makes the crystal suitable for 935 nm LD pumping and Pr3+ can inhibit self-termination phenomenon. • High absorption coefficient at 935 nm and large emission cross-section at 2911 nm are beneficial in realizing ∼2.9 μm laser. • The Yb,Ho,Pr:LuYAG crystal is a new promising gain medium for realizing 2.911 μm laser. [ABSTRACT FROM AUTHOR]

A Nd3+-doped Y 2.8 ScAl 4.2 O 12 (Nd:YSAG) single crystal was grown successfully via the Czochralski technology. The crystal structure and crystalline quality of the as-grown Nd:YSAG crystal were determined by the X-ray powder diffraction and X-ray rocking curve, respectively. By X-ray fluorescence analysis, the effective segregation coefficient of Nd3+ is calculated to be 0.33 in the YSAG crystal. Using the chemical etching method, the dislocation density on the (111)-crystalline face is obtained to be about 3.45 × 102 cm−2. The large absorption cross-section (2.95 × 10−20 cm2) and wide FWHM (9.8 nm) around 808.8 nm imply a high LD pumping efficiency. The high emission cross-section (3.53 × 10−20 cm2) at 1336.3 nm and long fluorescence lifetime of Nd3+ ions (286.20 μs) are beneficial to realize laser output. Thereby, all the results indicate that the Nd:YSAG crystal is a potentially new gain material pumped by a LD for near-infrared laser at 1336.3 nm. • A Nd3+:Y 2.8 ScAl 4.2 O 12 crystal was grown successfully by the Czochralski method. • Dislocation density on the (111)-crystalline face is obtained to be 3.45 × 102 cm−2. • A large absorption cross-section (2.95 × 10−20 cm2) implies high pumping efficiency. • High emission cross-section (3.53 × 10−20 cm2) is beneficial to realize 1336.3 nm laser. • All results indicate this crystal is a potential gain material for 1336.3 nm laser. [ABSTRACT FROM AUTHOR]

Yb3+ and Ho3+ co-doped Lu2.55Y0.45Al5O12 (Yb,Ho:LuYAG) crystal with a size of Φ 28 mm × 120 mm was successfully grown by the Czochralski method. The lattice parameters of the as-grown Yb,Ho:LuYAG crystal were obtained by Rietveld refinement with the XRD data. The result of X-ray rocking curve indicated that the grown crystal has a high crystalline quality. From strong absorption band near 935 nm and emission bands within 2700–3000 nm, we found that the Yb3+ ions can be acted as the sensitizer for the activator ions Ho3+. Furthermore, the lifetimes of the 5I6 and 5I7 levels of the Ho3+ ions were 68.25 μs and 7.58 ms, respectively. These results indicated that the Yb,Ho:LuYAG crystal is a promising gain material for 2.91 μm laser pumped by a 940 nm LD. [ABSTRACT FROM AUTHOR]

Large lattice constant Y3Al5O12, Gd3Ga5O12 (GGG), Y3Sc2Ga3O12 (YSGG), Gd3Sc2Ga3O12, Ca0.4Mg0.25Zr0.65Gd2.6Ga4.1O12 (CaMgZr:GGG), and Gd1.17Y1.83Sc2Ga3O12 (GYSGG) substrate crystals with 2 in. in diameter are grown by the Czochralski (Cz) method, their physical, chemical, and optical properties are analyzed and compared in details. The X‐ray rocking curves (XRCs) illustrate that the as‐grown crystals possess high crystalline quality. The lattice constants of six crystals are calculated and that of GYSGG can be easily adjusted in the range of 1.2450–1.2565 nm by changing the Gd/Y proportion. The dislocation densities on the (111)‐crystalline face are about 102 cm−2 order of magnitude. The thermal conductivities of six crystals are measured to be 11.72, 8.98, 6.83, 5.45, 4.67, and 4.66 W m−1 K−1, respectively. It is found that the thermal expansion coefficients of six crystals can be reduced by annealing at 1273 K for 60 h. In addition, the transmission spectra show that the six crystals have excellent transparency and the coefficients of the Sellmeier equation are fitted by the calculated refractive indices. These results of the six crystals can provide the necessary parameters and references for the selection of suitable substrate materials or laser host crystals. [ABSTRACT FROM AUTHOR]

Five substituted gadolinium gallium garnet crystals with different Ca2+/Mg2+/Zr4+ stoichiometric ratio concentrations (Zr4+: 13.0, 15.0, 15.3, 16.3, 19.5 at.%, as well as increasing Ca2+ and Mg2+ concentrations in proportion) were grown by Czochralski technique. Their structure, defect, thermal and optical properties were comparatively studied and analyzed. The lattice parameters are achieved to be 12.47–12.54 Å which are 0.7–1.2 % larger than that of Gd 3 Ga 5 O 12. A linear equation with Zr4+ concentration is fitted to adjust the lattice parameter for demand. X-ray rocking curves with narrow FWHMs of 1.67′, 1.97′, 1.75′, 2.12′, 2.99′, respectively, indicating high crystalline quality when the Zr4+ concentration is below 16.3 at.%. The dislocation densities are 62, 47, 63, 315 and 3184 cm−2, suggesting the value increases rapidly when the Zr4+ concentration exceeds 16.3 at.% due to large lattice distortion. The thermal expansion coefficients are about 8.55 × 10−6 to 8.72 × 10−6 K−1, respectively. All the transmittances are above 80 % from visible to infrared wavelengths, and Sellmeier coefficients of refraction index equation were fitted, which is benefit for CaMgZr:GGG as substrate and optics application. The above results suggest that a more suitable substrate can be obtained for the series YIG magnetic-optic thin films by optimizing the Ca2+/Mg2+/Zr4+ concentrations. ● Five SGGG single crystals with different Ca2+/Mg2+/Zr4+ concentrations were successfully grown by Cz method. ● Relationship of concentrations and lattice constants can be described by fitting equation to adjust lattice parameter better. ● The Ca2+/Mg2+/Zr4+ concentrations have significative effect on crystalline quality, dislocation density and thermal expansion. ● Experimental refractive index and energy gaps data for different SGGG single crystals are provided. ● Potential and economic application value of SGGG in laser gain medium or substrate for series YIG magneto-optical thin films. [ABSTRACT FROM AUTHOR]

• A LuYSGG single crystal was grown by the Czochralski method. • Mohs hardness and surface roughness were obtained to be 6.86 and 0.23 nm. • Thermal expansion coefficient and thermal conductivity were 8.5 × 10−6 K−1 and 4.79 W m−1 K−1. • Sellmeier equation was fitted and the refractive index curve was displayed. • Results can provide useful parameters for LuYSGG crystal as substrate and laser host. We investigate the physical and chemical properties of a Lu 1 Y 2 Sc 2 Ga 3 O 12 (LuYSGG) single crystal with high quality grown by the Czochralski (Cz) method. The XRC result shows the crystal has high crystalline quality and the lattice constant is calculated to be 12.4253 Å, and the lattice constant value could be adjusted by changing the ratio of Lu and Y. The dislocation density on the (1 1 1)-crystalline face is achieved to be about 200 cm−2. The Mohs hardness is obtained to be 6.86. The surface roughness (R a) of the polished LuYSGG wafer is only 0.23 nm. The thermal expansion coefficient and the thermal conductivity are measured to be 8.5 × 10−6 K−1 and 4.79 W m−1 K−1, respectively, indicating the LuYSGG has better thermal properties. In addition, the Sellmeier equation is fitted by the measured refractive indices at a few distinct wavelengths using the method of minimum deviation angle, and the refractive index curve in the range of 400–3000 nm is displayed. The maximum phonon energy of LuYSGG crystal is determined to be 880.7 cm−1. All the obtained results can provide useful reference parameters for the further investigation of LuYSGG crystal as epitaxial magneto-optical thin film substrate and laser host. [ABSTRACT FROM AUTHOR]

Recently, we proposed GdTaO 4 as a promising high-density scintillator but the scintillation mechanism was still unknown. In this paper, we investigated the temperature-dependent luminescent properties of GdTaO 4 crystal. The emission spectra are characterized by a broad band composed of two Gaussian components located at ~2.2 eV and ~2.7 eV of 8–300 K, which are both thermally quenched with the activation energy of 156 meV and 175 meV, respectively. These two bands are believed to be from different luminescent centers, judging from the excitation spectra, thermal activation energy and decay curves. Additionally, it was also found that the annealing atmosphere exerts little influence on the luminescence intensity. Based on the results, we tentatively assigned the high-energy band to self-trapped excitons (STE) localized in TaO 4 3 − groups and the low-energy band to relaxed excitons related to lattice imperfections. [ABSTRACT FROM AUTHOR]