PROBLEM TO BE SOLVED: To provide an inorganic composition having a high mean linear expansion coefficient, a reduced change in an expansion curve, and suitable for compounding with metals and organic materials.SOLUTION: The inorganic composition has a composition comprising an Al2O3 component and an R2O component wherein, R denotes at least one or more kinds selected from Li, Na and K, and is characterized in that a molar ratio expressed by Al2O3/R2O is &le1, and, provided that the length of a sample at 25°C is L0, and the length of the sample at T°C is L, regarding the temperature T, the value of d&alpha(T)/dT represented by d&alpha(T)/dT=(1/L0)×(d2L/dT2) is always &ge0 in the temperature range of -30 to 70°C.COPYRIGHT: (C)2007,JPO&INPIT【課題】 平均線膨張係数が大きく、膨張曲線の変化が少ない、金属、有機材料との複合化に好適な無機組成物の提供。【解決手段】 Al2O3成分と、R2O成分と、ここでRはLi、Na、Kから選ばれる少なくとも一種以上を示す、を含有し、Al2O3/R2Oで表わされるモル比率が1以下であって、25℃における試料の長さをL0、T℃における試料の長さをLとした時、温度Tについてdα(T)/dT=(1/L0)×(d2L/dT2)で表わされるdα(T)/dTの値が、-30℃~70℃の温度範囲において常に0以上である事を特徴とする無機組成物。
