Study of acoustic parameters of lanthanum-gallium tantalate single crystals subjected to cyclic deformation and thermal shock
Study of acoustic parameters of lanthanum-gallium tantalate single crystals subjected to cyclic deformation and thermal shock
复制标题
钽酸镧镓单晶循环变形和热冲击声学参数研究
DOI：
10.26896/1028-6861-2018-84-11-28-35
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
V. S. Petrakov
中科院分区：
文献类型：
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作者：
E. K. Naimil;S. Bazalevskaya;O. M. Kugaenko;V. S. Petrakov
采用内摩擦（IF）法和频率为105 Hz的多个压电振子，研究了钽酸镧镓（LGT、La3Ta0,5Ga5,5O14）各向异性压电单晶中晶体各向异性和机械循环变形和热冲击时形成的结构缺陷对相速度、衰减系数、体声波（BAW）Q因子等声学参数的影响。在各向异性 LGT 单晶中观察到有效弹性模量 (E)、BAW 相速度 (Vp)、衰减系数和 Q 因子的各向异性。结果表明，LGT 样品在 2.5 kN 载荷下、载荷循环次数高达 5 x 105、循环频率为 100 MHz 和热冲击 (100 - 120°C) 下的循环变形对纵向体声波的有效弹性模量和相速度值没有影响，分别为：对于 X 切割 — E = 111 GPa，Vp = 4250 m/sec；对于 Z 形切割 — E = 181 GPa，Vp = 5430 m/sec。 X 向和 Z 向切割循环变形后，纵向 BAW 的衰减系数增加了 1.5 - 2 倍，导致品质因数降低了两倍。热冲击对 X 切割样品的衰减系数和 Q 因子几乎没有影响。对于 Z 切样品，热冲击会导致衰减系数增加三倍并降低 Q 因子。基于齿状酸盐的压电压力传感器的敏感元件应防止温度高于 150°C 时的热冲击，并且材料的机械压缩循环总数在频率 100 - 150 Hz 且负载不超过 2.5 kN 时不应超过 5 x 105 个循环。
The effect of crystal anisotropy and defects of the structure formed upon mechanical cyclic deformation and thermal shock on acoustic parameters such as phase velocity, attenuation coefficient, Q-factor of bulk acoustic wave (BAW) has been studied in lanthanum-gallium tantalate (LGT, La3Ta0,5Ga5,5O14) anisotropic piezoelectric single crystals using inner friction (IF) method with multiple piezoelectric vibrator at a frequency of 105 Hz. The anisotropy of the effective elasticity modulus (E), BAW phase velocity (Vp), attenuation coefficient and Q-factor was observed in anisotropic LGT single crystals. It is shown that cyclic deformation of LGT samples under a load of 2.5 kN with the number of load cycles up to 5 x 105 with a cycling frequency of 100 MHz and thermal shock (100 - 120°C) have no effect on the values of the effective elasticity modulus and phase velocity of the longitudinal BAW, respectively: for X-cut — E =111 GPa, Vp = 4250 m/sec; for Z-cut — E = 181 GPa, Vp = 5430 m/sec. The attenuation coefficient of the longitudinal BAW increased by 1.5 - 2 times after cyclic deformation for both X-and Z-cuts, which resulted in a two-fold decrease of the quality factor. Thermal shock has almost no effect on the attenuation coefficient and Q-factor for X-cut samples. For Z-cut samples thermal shock leads to a three-fold increase of the attenuation coefficient and decrease of the Q-factor. Sensitive elements of piezopressure sensors based on langatate should be protected from thermal shock at a temperature above 150°C, and the total number of the mechanical compression cycles of the material should not exceed 5 x 105 cycles at a frequency of 100 - 150 Hz with the loads not exceeding 2.5 kN.