Beasley M S, Kasting B J, Tracy M E, Guiseppi-Elie A, Richert R, Ediger M D
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, USA.
J Chem Phys. 2020 Sep 28;153(12):124511. doi: 10.1063/5.0019872.
In situ AC nanocalorimetry and dielectric spectroscopy were used to analyze films of vapor-deposited triphenyl phosphite. The goal of this work was to investigate the properties of vapor-deposited glasses of this known polyamorphic system and to determine which liquid is formed when the glass is heated. We find that triphenyl phosphite forms a kinetically stable glass when prepared at substrate temperatures of 0.75-0.95T, where T is the glass transition temperature. Regardless of the substrate temperature utilized during deposition of triphenyl phosphite, heating a vapor-deposited glass always forms the ordinary supercooled liquid (liquid 1). The identity of liquid 1 was confirmed by both the calorimetric signal and the shape and position of the dielectric spectra. For the purposes of comparison, the glacial phase of triphenyl phosphite (liquid 2) was prepared by the conventional method of annealing liquid 1. We speculate that these new results and previous work on vapor deposition of other polyamorphic systems can be explained by the free surface structure being similar to one polyamorph even in a temperature regime where the other polyamorph is more thermodynamically stable in the bulk.
采用原位交流纳米量热法和介电谱法对气相沉积亚磷酸三苯酯薄膜进行了分析。这项工作的目的是研究这种已知的多晶型体系的气相沉积玻璃的性质，并确定玻璃加热时形成哪种液体。我们发现，当在0.75 - 0.95T的衬底温度下制备时（其中T是玻璃化转变温度），亚磷酸三苯酯形成动力学稳定的玻璃。无论在亚磷酸三苯酯沉积过程中使用何种衬底温度，加热气相沉积玻璃总是形成普通的过冷液体（液体1）。通过量热信号以及介电谱的形状和位置证实了液体1的特性。为了进行比较，通过对液体1进行常规退火方法制备了亚磷酸三苯酯的冰相（液体2）。我们推测，这些新结果以及之前关于其他多晶型体系气相沉积的工作可以通过自由表面结构类似于一种多晶型来解释，即使在另一种多晶型在本体中热力学上更稳定的温度范围内也是如此。
