An experimental apparatus was assembled based on a four-wire 3o method to determine the thermal conductivity of bulk and thin film materials. By driving a current of angular frequency o through a thin heating wire deposited on a specimen surface, a localized thermal wave with a frequency 2o is created. Due to the change of the metal line's resistance with increasing temperature the imposed temperature oscillation can be estimated by measuring the voltage drop at a frequency 3o. The 3o measurements were performed in a frequency range covering five orders of magnitude (1 Hz--300 kHz).; Bulk materials with a low thermal conductivity (soda lime with 1.15 W/(m·K) and Pyrex with 1.33 W/(m·K)) as well as silicon that possesses a much higher thermal conductivity (130 W/(m·K)) were measured by the 3o method. In addition, the thermal conductivities of silica films of thicknesses between 0.3 mum to 3.2 mum were measured. The determined thermal conductivity of those silica films (1.55 W/(m·K)) was independent of film thickness. Finally, the possibility of measuring the thermal conductivity of thin diamond films is discussed.
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机译：根据四线3o方法组装了一个实验设备，以确定块状和薄膜材料的热导率。通过沉积在样品表面的细加热丝驱动角频率为o的电流，会产生频率为2o的局部热波。由于金属线的电阻随温度升高而变化，因此可以通过测量频率为3o的电压降来估算施加的温度振荡。 3o测量在覆盖五个数量级（1 Hz--300 kHz）的频率范围内进行。导热系数低的块状材料（苏打石灰为1.15 W /（m·K），派热克斯纤维为1.33 W /（m·K））以及具有更高导热系数（130 W /（m·K）的硅））用3o方法测量。另外，测量了厚度在0.3μm至3.2μm之间的二氧化硅膜的热导率。那些二氧化硅膜的确定的热导率（1.55 W /（m·K））与膜厚度无关。最后，讨论了测量金刚石薄膜导热系数的可能性。
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