Swapna Mohanachandran Nair Sindhu, Tripon Carmen, Gutt Robert, Farcas Alexandra, Bojan Marcel, Korte Dorota, Kacso Irina, Franko Mladen, Dadarlat Dorin
Laboratory for Environmental and Life Sciences, University of Nova Gorica, Vipavska 13, SI-5000 Nova Gorica, Slovenia.
National R&D Institute for Isotopic and Molecular Technologies, Donat 67-103, 400293 Cluj-Napoca, Romania.
Materials (Basel). 2023 Jul 26;16(15):5242. doi: 10.3390/ma16155242.
A general theory of a photopyroelectric (PPE) configuration, based on an opaque sample and transparent pyroelectric sensor, backing and coupling fluids is developed. A combined back-front detection investigation, based on a frequency scan of the phase of the PPE signals, followed by a self-normalization of the phases' behavior, leads to the possibility of simultaneously measuring both thermal effusivity and diffusivity of a solid sample. A particular case of this configuration, with no coupling fluid at the sample/backing interface and air instead of coupling fluid at the sample/sensor interface (non-contact method) is suitable for simultaneous measurement ofboth thermal diffusivity and effusivity (in fact complete thermal characterization) of porous solids. Compared with the already proposed configurations for investigations of porous materials, this novel configuration makes use of a fitting procedure with only one fitting parameter, in order to guarantee the uniqueness of the solution. The porous solids belong to a class of materials which are by far not easy to be investigated using PPE. To the best of our knowledge, porous materials represent the only type of compounds, belonging to condensed matter, which were not taken into consideration (until recently) as potential samples for PPE calorimetric investigations. Consequently, the method proposed in this paper complete the area of applications of the PPE method. Applications on some porous building materials and cellulose-based samples validate the theory.
基于不透明样品、透明热释电传感器、背衬和耦合流体，建立了光热释电（PPE）配置的通用理论。基于PPE信号相位的频率扫描进行前后联合检测研究，随后对相位行为进行自归一化，从而有可能同时测量固体样品的热扩散率和热导率。这种配置的一个特殊情况是，样品/背衬界面处没有耦合流体，样品/传感器界面处用空气代替耦合流体（非接触法），适用于同时测量多孔固体的热扩散率和热导率（实际上是完整的热特性）。与已提出的用于多孔材料研究的配置相比，这种新颖的配置采用了仅具有一个拟合参数的拟合程序，以确保解的唯一性。多孔固体属于一类迄今为止使用PPE不易研究的材料。据我们所知，多孔材料是凝聚态物质中唯一一类（直到最近）未被视为PPE量热研究潜在样品的化合物类型。因此，本文提出的方法完善了PPE方法的应用领域。对一些多孔建筑材料和纤维素基样品的应用验证了该理论。
