報告書番号

L04006

タイトル（和文）

陽電子消滅法によるセメントとガラスにおける表面劣化の検出

タイトル（英文）

Applicability of the positron annihilation methods to the analysis of mineral dissolution reaction in surface of cemnt and glass

概要 （図表や脚注は「報告書全文」に掲載しております）

陽電子消滅法によるガラスなど非金属鉱物における固液界面反応の分析法の確立を目的として、人為的に固液界面反応を進めたセメントと石英ガラスを試料に、陽電子消滅法によって化学的変化と構造変化を捕捉可能であることを検証した。その結果、（１）塩酸水溶液で劣化させたセメントではCaとSの溶脱が著しく、このとき陽電子寿命が長寿命化して消滅γ線のドップラー拡がりも増大した。（２）水酸化ナトリウム水溶液で劣化させた石英ガラスでは化学的組成変化はないが、セメントとは逆に、陽電子寿命が短寿命化してドップラー拡がりも減少した。（３）これらの陽電子消滅特性の変化は、セメントでは化学的組成の変化を、また石英ガラスでは表面分子の構造変化を捕らえたものと評価された。

概要 （英文）

The analysis of the mineral dissolution reaction anyhow utilizes the analysis technique of both liquid phase and solid phase. The conventional technique such as scanning electron microscopy, X-ray diffraction, some spectroscopic techniques for solid and/or liquid phases is useful for the purpose but sometimes not practical. The apparent reaction rate may be a function of time and gradually decreasing with time in many cases. This is due to some kind of fee-back effect because the chemical species dissolved by the reaction alters the solution chemistry itself and this change may cause the additional effect to the reaction. The flow-through test is sometimes used instead for batch type experiments to maintain the constant or steady solution chemistry. If we need intrinsic reaction rate by the batch experiments, the analysis at the initial stage of reaction is required. This implies more sensitive analysis method is required to avoid the change of solution chemistry. It is thus largely depends on the analytical sensitivity to know the intrinsic reaction rate at the very initial stage of the reaction. We apply the positron annihilation methods for this purpose as the preliminary study of feasibility. The major results obtained were as follows;(1) Cement sample showed longer life-time as the dissolution reaction progressed. The X-ray microscope analysis suggests the leaching of calcium from the sample and this tendency is accordance with the longer life-time.(2) In case of quartz glass, although no observable data were obtained by both X-ray spectroscopy and scanning electron microscopy, the positron life-time spectra showed very distinct differences in the strong base solution. The average life-time seems to be linear function of concentration and quite good accordance with theoretical calculation of the silica dissolution reaction theory.(3) The results indicated the applicability of the positron annihilation to the analysis of the mineral dissolution at the very initial stage of reaction. Even in preliminary investigation with limited number of samples, we believe that the power of the new analysis method can be applicable to the mineral dissolution reaction.

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