Qian Zhengnan

Effect of Fe doping in La1−xSrxMnO3

The effects of Fe doping on the magnetic, transport, and magnetoresistance properties are studied for La0.7Sr0.3Mn1−yFeyO3 (y=0–0.18) and La1−xSrxMn0.88Fe0.12O3 (x=0.1–0.50). For increasing y, a peak in the thermal dependence of the resistivity appears and develops at the temperature TPl lower than TC, while the another peak near TC becomes smaller and then disappears. At 78 K the La1−xSrxMn0.88Fe0.12O3 oxides are insulators for x 0.5 and only the lower-temperature metal–insulator transition peak appears for 0.25<x<0.45. With increase of x from 0.25, TPl increases, becomes maximum at x=0.4 and then decreases. The temperature dependence of resistivity for the doped samples is quite different from that of the undoped La1−xSrxMnO3 series.

AN INVESTIGATION USING HIGH-PRESSURE SYNTHESIS OF DOUBLE-RARE-EARTH OXIDES OF ABO3-COMPOSITION

Abstract The synthesis of the double-rare-earth oxides PrTmO3, PrYbO3, NdYbO3, NdLuO3, LaGdO3 and LaDyO3 is investigated by using high pressure and high temperature methods (4.0 GPa, 1200–1350°C) for the first time. The analyses by X-ray diffraction show that all products (except PrYbO3) are single-phase materials: NdLuO3 belongs to the P-type structure, PrYbO3 is mainly P-type, and the others belong to B-type. The PrTmO3 is a new material which has not yet been reported in the literature.

An investigation of the effect of high pressure on the synthesis of LaLnO3 compounds

Abstract In the present paper, by using the high pressure method for the first time, the complex oxides of rare earth LaLnO3 (Ln  Ho, Er, Yb, Lu, Y) have been successfully synthesized at 29 kb. Compared with the synthesis at atmospheric pressure it can be seen that, for the most part, the high pressure is able to decrease the temperature of synthesis, accelerate the reaction rate, increase the transformation rate of products, greatly shorten the synthetic time and, at the same time, increase the dissociation temperature.

High pressure synthesis of new jadeites with fluorescent emission

Abstract Some new kinds of jadeite gems having a visible emission have been synthesized by doping Eu2O3, Dy2O3, CeO2 of 0.01–0.1 mol. under high pressure and high temperature. The effect of the non-symmetry crystal field in the jadeite on the fluorescent emission has been discussed.