Thermal diffusivity of oxide perovskite compounds at elevated temperature
Thermal diffusivity of oxide perovskite compounds at elevated temperature
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氧化物钙钛矿化合物在高温下的热扩散率
DOI：
10.1063/1.3371815
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发表时间：
2010
影响因子：
3.2
通讯作者：
A. Hofmeister
中科院分区：
文献类型：
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作者：
A. Hofmeister
采用非接触式激光闪光分析法，从室温（T）到2000 K，测量了11种具有不同钙钛矿结构的化合物（合成SrTiO 3，SrTiO 3：Fe 3+，BaTiO 3，KTaO 3，KNbO 3，NdGaO 3，YAlO 3，YAlO 3：Tm，LaAlO 3，La0.29Sr0.66Al0.65Ta0.35O3，和天然Ca 1.01Mn0.001Fe0.007Ti 0.99O3）的热扩散系数（D）的声子分量。结构转型（例如，从正交晶到四方晶）在800 K以下表现为1/D的陡峭台阶。在800 K以上，结构转变发生在大约150 K的间隔。 类似的宽峰伴随着从无色到黑色的变化，这归因于与石墨涂层接触的Ti、Nb或Ta的部分还原。否则，D随着T的增加而减小，并且如果存在替代无序，则接近1600 K附近的常数（Dsat）。我们的数据最好描述为D−1遵循T中的低阶多项式。有序的立方钙钛矿占据D（T）−1的单一趋势，定义t.
The phonon component of thermal diffusivity (D) for eleven compounds (synthetic SrTiO3, SrTiO3:Fe3+, BaTiO3, KTaO3, KNbO3, NdGaO3, YAlO3, YAlO3:Tm, LaAlO3, La0.29Sr0.66Al0.65Ta0.35O3, and natural Ca1.01Mn0.001Fe0.007Ti0.99O3) with various perovskite structures was measured from ambient temperature (T) up to ∼2000 K using contact-free, laser-flash analysis, from which effects of ballistic radiative transfer were removed. Structural transitions (e.g., orthorhombic to tetragonal) below 800 K were manifest as sharp steps in 1/D. Above 800 K, structural transitions occur over intervals of ∼150 K. Similarly broad peaks accompany changes from colorless to black, attributable to partial reduction in Ti, Nb, or Ta from contact with graphite coatings. Otherwise, D decreases with increasing T and, if substitutional disorder exists, approaches a constant (Dsat) near 1600 K. Our data are best described as D−1 following a low order polynomial in T. Ordered, cubic perovskites occupy a single trend for D(T)−1, defining t...