To use a crystal unit as an oscillator, its oscillated frequency is required to be stable against temperature variations .A quartz crystal has crystallographic axes, and crystal cut is defined according to the cutting angle against a crystallographic axis and its associated mode of vibration. Typical types of crystal cut and frequency-temperature characteristics are shown in Fig.2.

石英晶体作为谐振器在使用时，要求其谐振频率在温度发生变化时保持稳定。温频特性与切割角有关，每个石英晶体具有结晶轴，晶体切割是按其振动模式沿垂直于结晶轴的角度切割的。典型的晶体切割和温频特性。