KTb 3F 10 (KTF) has been developed in recent years as a candidate Faraday rotator material because of its cubic symmetry, high figures of merit, and low absorption coefficient. While considerable efforts have focused on crystal growth and optical properties, investigations of fundamental thermodynamic behavior of KTF have been limited. Here, we report elastic moduli C 11, C 12, and C 44 of single crystalline KTF measured by resonant ultrasound spectroscopy from 280 K up to 300 K and the obtained temperature derivatives of each modulus. We additionally report the single crystal elastic moduli of the rare-earth garnet Y 3Al 5O 12 (YAG), yielding results that agree well with the prior literature. We found C 11 = 135.62 GPa, C 12 = 58.11 GPa, and C 44 = 44.81 GPa for KTF and C 11 = 332.43 GPa, C 12 = 109.58 GPa, and C 44 = 114.81 GPa for YAG at room temperature. The present results have been compared with previous experimental and theoretical results and with common oxide and fluoride optical materials, revealing the relative softness of KTF. The low elastic moduli of KTF are, in turn, responsible for its low thermal conductivity and low Debye frequency compared to other laser host materials.

中文翻译：

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超声共振光谱法测定KTb3F10单晶弹性模量

KTb 3F 10 (KTF) 由于其立方对称性、高品质因数和低吸收系数，近年来被开发为候选法拉第转子材料。虽然相当多的努力集中在晶体生长和光学特性上，但对 KTF 基本热力学行为的研究却很有限。在这里，我们报告了单晶 KTF 的弹性模量 C 11、C 12 和 C 44，通过共振超声光谱从 280 K 到 300 K 以及获得的每个模量的温度导数。我们还报告了稀土石榴石 Y 3Al 5O 12 (YAG) 的单晶弹性模量，得出的结果与先前文献非常吻合。我们发现 KTF 的 C 11 = 135.62 GPa、C 12 = 58.11 GPa 和 C 44 = 44.81 GPa，C 11 = 332.43 GPa、C 12 = 109.58 GPa 和 C 44 = 114。YAG 在室温下为 81 GPa。目前的结果已与先前的实验和理论结果以及常见的氧化物和氟化物光学材料进行了比较，揭示了 KTF 的相对柔软性。与其他激光主体材料相比，KTF 的低弹性模量反过来又是导致其低热导率和低德拜频率的原因。