In this study, pyrolusiteore （MnO2） was subjected to mechanical milling with a high-energy mill with carbonized tea plant wastes and the effect of grinding time on the crystal structure of the material was investiga...In this study, pyrolusiteore （MnO2） was subjected to mechanical milling with a high-energy mill with carbonized tea plant wastes and the effect of grinding time on the crystal structure of the material was investigated. The ratio of Mn/Fe was 8/1, the ratio of C/（MnO2 ＋ Fe3O4） was 2 and the ratio of ball to ore was 10/1. The samples were mechanically ground at 10, 15, 20, 30, 60, 90 and 120 hours. In the processes performed on the attritor, the rotation speed of the mill shaft was determined to be 350 rpm. The results were characterized by TG-DTA, SEM and XRD analyzes. As a result of the experimental studies, it was observed that the samples subjected to mechanical grinding for 120 hours were gradually reduced due to the increasing grinding time at all the diffraction peaks when the XRD peaks were compared with the grinding times. In the thermogravimetric analysis, the sample milled for 120 hours, 50% weight loss was observed at 470 ℃, weight loss of up to 56% was observed at progressive temperatures.展开更多
The coexistence of magnetic ordering and ferroelectricity, ing on the origin of ferroelectricity, multiferroic materials known as multiferroics, has drawn a lot of research effort. Depend can be classified into differ...The coexistence of magnetic ordering and ferroelectricity, ing on the origin of ferroelectricity, multiferroic materials known as multiferroics, has drawn a lot of research effort. Depend can be classified into different groups. In this paper, we review re cent progress in the field of multiferroics induced by different forms of charge ordering. In addition to a general description of charge order and electronic ferroelectricity, we focus on two specific systems： （1） charge order with frustration in RFe2O4 （R=Lu, Yb） system; （2） charge ordered perovskite manganites of the type （R1-xCax）MnO3 （R=La, Pr）. The charge ordering can be tuned by external electric fields, which results in pronounced magnetoelectric effects and strong dielectric tunability. Other materials and possible candidates with charge order induced multiferroics are also briefly summarized.展开更多
文摘In this study, pyrolusiteore （MnO2） was subjected to mechanical milling with a high-energy mill with carbonized tea plant wastes and the effect of grinding time on the crystal structure of the material was investigated. The ratio of Mn/Fe was 8/1, the ratio of C/（MnO2 ＋ Fe3O4） was 2 and the ratio of ball to ore was 10/1. The samples were mechanically ground at 10, 15, 20, 30, 60, 90 and 120 hours. In the processes performed on the attritor, the rotation speed of the mill shaft was determined to be 350 rpm. The results were characterized by TG-DTA, SEM and XRD analyzes. As a result of the experimental studies, it was observed that the samples subjected to mechanical grinding for 120 hours were gradually reduced due to the increasing grinding time at all the diffraction peaks when the XRD peaks were compared with the grinding times. In the thermogravimetric analysis, the sample milled for 120 hours, 50% weight loss was observed at 470 ℃, weight loss of up to 56% was observed at progressive temperatures.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11074293,51021061 and 50831006)
文摘The coexistence of magnetic ordering and ferroelectricity, ing on the origin of ferroelectricity, multiferroic materials known as multiferroics, has drawn a lot of research effort. Depend can be classified into different groups. In this paper, we review re cent progress in the field of multiferroics induced by different forms of charge ordering. In addition to a general description of charge order and electronic ferroelectricity, we focus on two specific systems： （1） charge order with frustration in RFe2O4 （R=Lu, Yb） system; （2） charge ordered perovskite manganites of the type （R1-xCax）MnO3 （R=La, Pr）. The charge ordering can be tuned by external electric fields, which results in pronounced magnetoelectric effects and strong dielectric tunability. Other materials and possible candidates with charge order induced multiferroics are also briefly summarized.
