国产X射线衍射仪低温测试的温度准确性验证

Confirmation of Temperature Accuracy of Low-temperature Measurements on Domestic X-ray Diffractometer

采用冷压陶瓷技术开发具有一级相变、居里温度（TC）低于室温的（Ba0.91La0.09）Ti1-0.09/4O3（BL9T）单相陶瓷。该陶瓷用于国产X射线衍射仪低温粉末XRD测量时的温度准确性验证。考虑晶体结构随温度的弛豫后，由介电温谱和变温拉曼光谱技术综合确定的砭最高为-62℃，以确保BL9T在％以上始终处于立方结构。以BL9T的单胞体积（圪）与温度的线性膨胀关系为依据，验证了在低于室温进行粉末×RD测量时变温样品室具有较高的温度准确性。在-30℃到-60℃温度范围内，变温样品室内热电偶的监控温度（瓦）与陶瓷粉末样品表面的实际温度（t）的偏差非常小（〈2℃）。

The cold-pressing ceramic technique was adopted to develop a single-phase （Ba0.91La0.09）Ti1-0.09/4O3 （BL9T） ceramic with first-order phase transition and with the Curie temperature （Tc） lower than room temperature. This ceramic was used for the confirmation of temperature accuracy of low-temperature powder XRD measurements on domestic X-ray diffractometer. After the relaxation of crystal structure with temperature was considered, the maximum value of Tc was determined as -62 ℃ by dielectric-temperature and temperature-dependent Raman spectroscopy techniques.For this result,BL9T was maintained as cubic above Tc.On the basis of the linear expansion of unit cell volume （V0） versus temperature,it was confirmed that the temperature camera exhibited a higher temperature accuracy when powder XRD measurements at temperatures lower than room temperature were carried out.In a temperature range of-30 to -60℃ ,the difference between the monitoring temperature detected by a thermal couple in the temperature camera （To） and the actual temperature of ceramic powders surface （Ta） was very small （〈 2℃ ）