D. G. Ran

Thermal and mechanical properties of BaWO4 crystal

A large single crystal of barium tungstate (BaWO4) with dimensions of 22-mmdiameter×80-mm length was grown by the Czochralski method using an iridium crucible. The melting point, molar enthalpy of fusion, and molar entropy of fusion of the crystal were determined to be 1775.10 K, 96913.80Jmol−1, and 54.60JK−1mol−1, respectively. The average linear thermal-expansion coefficients are αa=10.9526×10−6∕K, αb=10.8069×10−6∕K, and αc=35.1063×10−6∕K in the temperature range from 303.15 to 1423.15 K along the three respective crystallographic axes. The density of the crystal follows an almost linear decrease from 6.393×103 to 6.000×103kgm−3 when the temperature is increased from 303.15 to 1423.15 K. The measured specific heat are 115.56–130.96JK−1mol−1 in the temperature range of 323.15–1173.15 K. The thermal diffusion coefficient of the crystal was measured in the temperature range of 297.15–563.15 K. The calculated thermal conductivity is 2.256Wm−1K−1 along the [001] direction and 2.324Wm−1K−1 along the [100] dir...

Anisotropic thermal properties of monoclinic Yb:KLu(WO4)2 crystals

Yb:KLu(WO4)2 (KLuW) crystals with large size and good optical quality have been grown by the top-seeded solution growth (TSSG) method. The melting point and specific heat, anisotropic thermal expansion and thermal conductivity have been measured. The Jackson factor α of a series of observed faces (hkl) on Yb:KLuW crystals have been calculated. In addition, the microhardness has also been measured. We find that the thermal expansion anisotropy of Yb:KLuW is weaker than KGd(WO4)2 (KGW) and KYb(WO4)2 (KYbW) and the thermal conductivity is up to 4.4Wm−1k−1 along [205] directions at 25°C, which is the greatest in their family.

Growth and thermal properties of SrWO4 single crystal

A strontium tungstate (SrWO4) single crystal with dimensions of Φ 25×40mm2 has been grown by the Czochralski method using an iridium crucible. X-ray powder diffraction results show that as grown the SrWO4 crystal belongs to the tetragonal system in the scheelite structure. The effective segregation coefficients of elemental W and Sr in the crystal growth are measured by x-ray fluorescence, and the respective values are close to 1. The thermal properties of the SrWO4 crystal were systemically studied by measuring the thermal expansion, specific heat, and thermal diffusion coefficient. These results show that the crystal possesses a large anisotropic thermal expansion with thermal-expansion coefficients αa=8.61×10−6∕K, αb=8.74×10−6∕K, αc=18.78×10−6∕K over the temperature range of 303.15–773.15K. The measured value of the specific heat is 0.30–0.34Jg−1K−1 when the temperature is increased from 323.15to1073.15K. The thermal diffusion coefficient was measured over the temperature range of 303.15–543.15K. The t...

Thermal properties of monoclinic crystal Er3+:Yb3+:Ca4YO(BO3)3

A large Er3+–Yb3+ co-doped yttrium calcium oxoborate [Er3+:Yb3+:Ca4YO(BO3)3, abbreviated as Er:Yb:YCOB] single crystal, with dimensions of 2.5 cm in diameter and 9.0 cm in length, has been grown along the crystallographic b axis by the Czochralski method. X-ray powder diffraction results show that the as-grown Er:Yb:YCOB crystal belongs to the monoclinic system with space group Cm; the unit-cell constants are a = 8.085, b = 16.048, c = 3.528 A and β = 101.11°. The high crystalline quality of the as-grown single crystal was confirmed by high-resolution X-ray diffraction, which showed the full width at half-maximum of the rocking curves to be less than 20 arcseconds on the (060) and (\overline 201) diffraction planes. The measurement and calculation of the symmetrical second-rank tensor for the monoclinic crystal are described in detail in this paper. The principal coefficients of thermal expansion of the as-grown Er:Yb:YCOB crystal are αI = 11.95 × 10−6 K−1, αII = 9.20 × 10−6 K−1 and αIII = 18.93 × 10−6 K−1 over the temperature range 303.15–873.15 K. The specific heat of the crystal is 725.6 J kg−1 K−1 at 328.15 K. The principal thermal conductivity parameters are KI = 2.882 W m−1 K−1, KII = 2.687 W m−1 K−1 and KIII = 2.692 W m−1 K−1 at 328.15 K.

Diode-pumped Q-switched intracavity frequency-doubled Nd:LuVO4/KTP green laser

A simple and compact diode-pumped acousto-optically Q-switched intracavity frequency-doubled Nd:LuVO4/KTP green laser were demonstrated successfully for the first time. At an incident pump power of 6.5 W, an average output power of 663 mW, a pulse width of 26 ns were obtained with a PRF of 10 kHz. The pulse energy and peak power of the green light were determined to be 66.3 μJ and 2.55 kW, respectively.

Lattice vibration and thermal diffusion of Yb doped KLu(WO4)2 single crystal

Yb doped KLu(WO4)2 (Yb:KLuW) single crystal was grown by the method of top-seeded-solution growth slow-cooling method. Its lattice vibrational modes were calculated by using space group theory, and polarized Raman spectra were measured at room temperature with different scattering geometry projections. The powder transmission of Fourier-transform infrared spectra was also performed as a supplement for Raman spectra to study the lattice vibration of the laser crystal. The main Raman peaks and infrared transmission bands were attributed to the internal mode WO6 octahedrons in the crystals. Two kinds of link ways of WO6 octahedrons implying large distortion had led the Raman peaks to shift to different positions. Large distortions of the WO6 octahedrons in the crystal had led to the splitting of some Raman peaks and even the activation of ν6 mode, which is originally a silent mode by the selection rule. As a self-Raman crystal, the linewidth of the Raman peaks ν1 and ν2 reached 12.5 and 16.6cm−1, with relaxa...