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  • 1 Dalian Institute of Chemical Physics, Chinese Academy of Sciences Thermochemistry Laboratory Dalian 116023 China
  • | 2 Graduate University of the Chinese Academy of Sciences Beijing 100049 China
  • | 3 Hunan University of Arts and Science Department of Chemistry Changde 415000 China
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Abstract  

A fully automated adiabatic calorimeter controlled on line by a computer used for heat capacity measurements in the temperature range from 80 to 400 K was constructed. The hardware of the calorimetric system consisted of a Data Acquisition/Switch Unit, 34970A Agilent, a 7 1/2 Digit Nano Volt /Micro Ohm Meter, 34420A Agilent, and a P4 computer. The software was developed according to modern controlling theory. The adiabatic calorimeter consisted mainly of a sample cell equipped with a miniature platinum resistance thermometer and an electric heater, two (inner and outer) adiabatic shields, two sets of six junction differential thermocouple piles and a high vacuum can. A Lake Shore 340 Temperature Controller and the two sets of differential thermocouples were used to control the adiabatic conditions between the cell and its surroundings. The reliability of the calorimeter was verified by measuring the heat capacities of synthetic sapphire (α-Al2O3), Standard Reference Material 720. The deviation of the data obtained by this calorimeter from those published by NIST was within ±0.1% in the temperature range from 80 to 400 K.