Redetermination of high-temperature heat capacity of Mg2SiO4 ringwoodite: Measurement and lattice vibrational model calculation
Redetermination of high-temperature heat capacity of Mg2SiO4 ringwoodite: Measurement and lattice vibrational model calculation
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DOI：
10.2138/am.2012.4054
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发表时间：
2012-08
影响因子：
3.1
通讯作者：
H. Kojitani;M. Oohata;T. Inoue;M. Akaogi
中科院分区：
文献类型：
--
作者：
H. Kojitani;M. Oohata;T. Inoue;M. Akaogi
摘要用差示扫描量热法测定了镁橄榄石和菱锰矿在306-833 K温度范围内的等压热容。Mg 2SiO 4镁橄榄石的CP测定结果与前人报道的结果一致。另一方面，目前的Mg_2SiO_4林伍德石的碳比约3-5%，比以前的研究人员测量。利用晶格振动模型计算了Mg 2SiO 4 ringwoodite的量热数据，并将其外推至2500 K，与热弛豫法测得的低温CP数据吻合较好.计算的CP显示出良好的协议与目前的量热数据。在250-2500 K范围内，CP可用温度多项式表示：CP = 164.30 + 1.0216 × 10− 2 T + 7.6665 × 103 T −1 - 1.1595 × 107 T −2 + 1.3807 × 109 T −3 [J/（mol·K）]。
Abstract Isobaric heat capacities (CP) of Mg2SiO4 forsterite and ringwoodite were measured by differential scanning calorimetry in the temperature range of 306-833 K. The measured CP of Mg2SiO4 forsterite was consistent with those reported by previous studies. On the other hand, the present CP of Mg2SiO4 ringwoodite was about 3-5% larger than those measured by previous researchers. The calorimetric data of Mg2SiO4 ringwoodite were extrapolated to 2500 K using a lattice vibrational model calculation, which well reproduced the low-temperature CP data measured by thermal relaxation method. The calculated CP shows good agreement with the present calorimetric data. The obtained CP was expressed by the polynomial of temperature: CP = 164.30 + 1.0216 × 10−2T + 7.6665 × 103T−1 - 1.1595 × 107T−2 + 1.3807 × 109T−3 [J/(mol·K)] in the range of 250-2500 K.