Abstract
The thermal behavior of two new non-linear optical (NLO) materials, urea-(D) tartaric acid (UDT) and urea-(DL) tartaric acid (UDLT) were studied by using DSC, TG and TMA. The results show that: 1) The two crystals have different melting points but similar decomposition temperatures due to the influences of intermolecular forces, which is attributed to the stereo effects of (D)-tartaric and (DL)-tartaric acid molecules; 2) There was only thermal expansion and no thermal contraction when the UDT and UDLT crystals were heated; 3) There was no phase transition within the measured temperature range; 4) The thermal expansion of the UDT and UDLT crystals shows a small anisotropy; 5) The specific heats of UDT and UDLT change linearly with temperature in the measured temperature range and the value for UDT is 1.321 J g-1 K-1 at 320 K while the specific heat of UDLT is 1.357 J g-1 K-1 at the same temperature.
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F. Q. Meng, M. K. Lu and H. Zeng, Cryst. Res. Technol., 31 (1996) 33.
M. K. Lu, F. W. Meng, H. Zeng and W. T. Yu, Cryst. Res. Technol., 31 (1996) 833.
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Meng, F.Q., Lu, M.K., Yang, Z.H. et al. Thermal Behavior of Urea-(D) Tartaric Acid and Urea-(DL) Tartaric Acid Crystals. Journal of Thermal Analysis and Calorimetry 52, 609–613 (1998). https://doi.org/10.1023/A:1010184009607
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DOI: https://doi.org/10.1023/A:1010184009607