Whether ice in cold cosmic environments is physically separated from the silicate dust or mixed with individual silicate moieties is not known. However, different grain models give very different compositions and temperatures of grains. The aim of the present study is to compare the mid-infrared spectra of laboratory silicate grain/water ice mixtures with astronomical observations to evaluate the presence of dust/ice mixtures in interstellar and circumstellar environments. The laboratory data can explain the observations, assuming reasonable mass-averaged temperatures for the protostellar envelopes and protoplanetary disks, demonstrating that a substantial fraction of water ice may be mixed with silicate grains. On the basis of the combination of laboratory data and infrared observations, we provide evidence of the presence of solid-state water in the diffuse interstellar medium. Our results have implications for future laboratory studies investigating cosmic dust grain analogues and for future observations trying to identify the structure, composition and temperature of grains in different astrophysical environments.

尚不清楚在寒冷的宇宙环境中将冰与硅酸盐粉尘物理隔离还是与各个硅酸盐部分混合。但是，不同的晶粒模型会给出非常不同的晶粒组成和温度。本研究的目的是将实验室硅酸盐颗粒/水冰混合物的中红外光谱与天文观测值进行比较，以评估星际和星际环境中粉尘/冰混合物的存在。实验室数据可以解释这些观测结果，假设原恒星外壳和原行星盘的质量平均温度合理，这表明大部分水冰可能与硅酸盐颗粒混合。在实验室数据和红外观测相结合的基础上，我们提供了弥漫星际介质中固态水存在的证据。我们的研究结果对未来研究宇宙尘埃颗粒类似物的实验室研究以及试图确定不同天体环境中颗粒的结构，组成和温度的未来观察具有重要意义。