PROPERTIES OF TEMPERATURE DEPENDENCE OF THRESHOLD IN PURE AND IMPUHITY-DOPED BLUE BRONZES

Temperature dependence of the threshold of pure and impurity-doped blue bronzes has been studied. It is found that for pare blue bronzes the threshold field near 100K has an anomalous peak, but for impurity-doped samples no anomaly is observed in the range of liquid nitrogen temperature, and the value of the threshold field gradu-ally increases with the decrease of temperature. The results show that in the high-quality pure blue bronzes, there may exist an incommensurate to quasi-commensurate transition near 100K. But for the impurity-doped or "dirty" pure samples, such an incommensurate to quasi-commensurate transition near 100K can be extensively re-strained by impurities or defects, which leads to a pure incommensurate CDW in a wide temperature range.     

影响概括数学关系的因素

虽然人们对于解决数学问题的过程和机制的认识有所不同,但是,概括数学关系在这一过程中的重要作用,是大家所公认的。本文试图从数学教学的角度,来讨论影响概括数学关系的某些因素。     

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