A large frequency dependence of the maximum dielectric constant temperature was observed for LiTaO3 nanocrystals (the diameter ≈20 Å) dispersed in mesoporous silicate. At the applied field frequency of 100 kHz, the maximum temperatures in the real and imaginary parts were 365 and 345 °C, respectively. The maximum temperature in the real part is apparently lower than the paraelectric–ferroelectric transition temperature (645 °C) of bulk LiTaO3. The maximum temperature in the imaginary part rose from 285 to 420 °C with increasing frequency from 10 to 1000 kHz. Since the bulk LiTaO3 shows no relaxor behavior, such superparaelectric behavior is obviously a consequence of nanominiaturization of LiTaO3 crystal and insignificant cooperative interactions between the nanoparticles.

SUMMARY A new fluorescence method for histochemical demonstration of phosphatase is presented by use of riboflavin‐5‐phosphoric ester as substrate. Consideration of mechanism of the yellow coloring in situ of the enzyme activity is described. Distribution of riboflavin‐nucleotidase in rabbit tissues is compared with nonspecific phosphatase and 5‐nucleotidase.

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Splitting between the field-cooled dielectric constant and the zero-field-cooled dielectric constant was observed for a diluted system of LiTaO 3 nanoparticles ͑diameter Ϸ30 Å͒ embedded in amorphous SiO 2 . At the applied field frequency of 100 kHz, the real part of the field-cooled dielectric constant diverged from that of the zero-field-cooled one at Ϸ380°C. The bifurcation point of the history-dependent dielectric constant rose from Ϸ310 to Ϸ540°C upon increasing the field frequency from 10 to 1000 kHz. Bulk LiTaO 3 powders showed no splitting in the history-dependent dielectric constant and the maximum at 645°C in the real part of the dielectric constant, despite the variation of frequency. Both the splitting of the history-dependent dielectric constant and the frequency dependence of the bifurcation point suggest that the LiTaO 3 nanoparticles with a single-domain structure were in the superparaelectric state as a consequence of insignificant cooperative interactions among the nanoparticles in the diluted system. The energy barrier of Ϸ0.9 eV separating two (ϩp and Ϫp) polarization states corroborated the potential of the LiTaO 3 nanoparticle for ultrahigh-density recording media applications.