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石英晶体的非线性特性几乎是使谐振器和振荡器产生频率不稳定的总根源。虽然固有的和感应的非线性具有相同的量级,但还是有可能将两者加以区别。非线性引起两种不同的现象:一个有限幅度的波在非线性介质中的传播,或一个小幅度的波在非线性应变介质中的传播。谐波产生、幅频效应、相互调制是与第一类型有关的现象。它们取决于晶体的各向异性和几何形状,也取决于波的结构。对外部或内部扰动的灵敏性,是高频波和由扰动感应产生的准静态变形之间非线性耦合的结果。对温度、力、压力、加速度和电场的灵敏性都在进行研究,以便能应用于高稳定振荡器和传感器。描述晶体振荡的另一种方法是应用点阵波和声子的概念。这样一个微观模型,使我们能够借助于晶体非谐性引起的声子相互作用(有限的导热性、热膨胀、声衰减、速度变化等)进行单一的描述。
The non-linear nature of quartz crystals is almost always the source of the instability of the resonators and oscillators. Although inherent and induced nonlinearities have the same order of magnitude, it is still possible to distinguish the two. Nonlinearities cause two different phenomena: the propagation of a finite amplitude wave in a nonlinear medium, or the propagation of a small amplitude wave in a nonlinear strain medium. Harmonic generation, amplitude-frequency effect, mutual modulation is the first type of phenomenon. They depend on the anisotropy and geometry of the crystal and on the structure of the wave. The sensitivity to external or internal disturbances is the result of a non-linear coupling between high-frequency waves and quasi-static deformation caused by disturbance induction. Research on temperature, force, pressure, acceleration, and electric field sensitivity is being conducted to apply to high-stability oscillators and sensors. Another way to describe crystal oscillation is to apply the notion of lattice waves and phonons. Such a microscopic model enables us to make a single description by means of the phonon interaction (limited thermal conductivity, thermal expansion, acoustic attenuation, velocity variation, etc.) caused by the non-resonance of the crystal.