Search

A series of Co/Mn compensated Ca3Co1+xMn1-xO6 compounds were synthesized. The structure and magnetization were characterized, as well as the dielectric properties were studied. In Co/Mn compensated samples, the well-ranked Co/Mn ionic order is destroyed which manifests the suppression of the formation of the short-range magnetic order. As a result, the freezing anomaly around Tf = 150 K diminishes. For the two Co/Mn compensated samples, the critical field HSF that causes magnetic structure change from ↑↑↓↓ state to ↑↑↓↑ state also increases. The appearance of dielectric peak at the antiferromagnetic phase transition temperature clearly indicates the coupling effect between the spin dipole and electric dipole. The temperature corresponding to the dielectric peak increases with the increasing measurement frequency. The frequency dependence of ferroelectric peak identifies relaxor ferroelectric nature. In dielectric measurements associated with magnetic fields, Δε` and Δtanδ have the same sign elucidating intrinsic magnetodielectric effect of Ca3Co1+xMn1-xO6. For the Co/Mn compensated x = ±0.05 two samples, the suppressed magnetic short-range order also leads to a low diffusion exponent γ and the weak relaxor ferroelectric nature. The thermal activation process of the dipole response is characterized by the Vogel–Fulcher equation and the results confirm that the freezing process of Ca3Co1+xMn1-xO6 is mainly dominated by coupling of polar nanodomains. [ABSTRACT FROM AUTHOR]

It remains ambiguous how college students form perceptions of professional development by identifying their emotional reactions and reflecting on their experiences in a situated setting. College students undergo professional development by participating in field experiences and reflecting on their experiential learning. In addition, researchers have increasingly insisted that student emotional reactions to learning should be addressed in higher education. Therefore, this qualitative study explored the emotional reactions of six college juniors and how they made sense of professional development, analyzing the contents of their reflective papers in a field experience course. The findings indicated that 10 types of emotional reactions caused students to form perceptions regarding professional development. The three major themes of these perceptions were acquiring and applying professional knowledge, the importance of self-understanding, and discovering professional attitudes. The study elucidates how college student awareness of emotional reactions could facilitate reflecting on experiential learning.

Field experience makes a strong contribution to the learning of students. However, the procedure for conducting training sessions based on experiential teaching methods is relatively unclear, and the contents and aspects of students' reflections during such training are not well known. This study applied experiential teaching methods in a college field experience course and investigated reflections on the experiences of 13 students. The content of students' thoughts and other relevant data were analysed using Kolb's experiential learning model. The students' concepts formed during reflection might not immediately develop into the active experimentation process, indicating the challenges faced by students with the process of reflection during field experience.

This paper reports the synthesis, microstructure and electrical properties of a new Ba4SrBiTi3Nb7O30 ceramic. X-ray diffraction analysis shows that the sample crystallizes into tungsten bronze structure, and the space group is P4bm. The electrical measurement results show that Ba4SrBiTi3Nb7O30 exhibits good dielectric and ferroelectric properties. The temperature-dependent dielectric permittivity indicates that the transition temperature of the prepared Ba4SrBiTi3Nb7O30 sample is around Tm ≈ 250K. With increasing the frequency, the dielectric peak moves to a lower temperature. Below 250 K, obvious polarization current can be detected, corresponding to the formation of spontaneous ferroelectric polarization. These results indicate the relaxor ferroelectric behavior of Ba4SrBiTi3Nb7O30 ceramic. [ABSTRACT FROM AUTHOR]

The current study explores Taiwanese preschool children's understanding of the value of caring in school. This study offers researchers and practitioners opportunities to study children's perspectives in a particular cultural setting and discuss the connectedness of culture and children's views on caring. Participatory research and qualitative methods were used, encompassing the collecting of children's speech, photography, and drawings. The findings regarding the understanding of caring indicated the following: (1) Children interpret caring among peers and from school surroundings; (2) children perceive teacher care in daily classroom routines; (3) children learn about values when outdoors, in learning areas, and during transition times; and (4) children exhibit the ability to distinguish non-caring behaviour. This study shows that for children caring was most frequently defined as helping others in need and as teacher care in daily routines. The children's views on caring were influenced by culture, and they created meanings for caring. [ABSTRACT FROM AUTHOR]

A rare-earth-like manganite [Y.sub.0.125][Ca.sub.0.875]Mn[O.sub.3] was systemically studied by the structure, electric and magnetic measurement. The results show that there exists a considerable magnetoresistance effect in this system. And two transitions are found on electrical transport corresponding to conventional metal-insulator (M-I) transition and Kondo-like behavior. From the magnetization in the zero-field-cooled (ZFC) and field-cooled (FC), a large irreversibility was observed with a cusp at 108 K about considered as spin-glass freezing temperature. Below 108 K, a coexistence of ferromagnetic spin-glass and ferromagnetic ordering phase appears, which indicates a long-range ferromagnetic behavior in spin-glass state. These suggest an intrinsic ferromagnetic spin-glass state in the [Y.sub.0.125][Ca.sub.0.875]Mn[O.sub.3] system at low temperatures and may be suppressed with applied higher field of about 8.0 Tesla. Index Terms--Electric transport, ferromagnetic spin-glass, magnetic properties, rare-earth-like manganite.

In this paper, the GdCrO3 polycrystalline samples with different particle sizes were prepared by the sol–gel method and the structure, vacancy defects, magnetocaloric property, dielectric property were investigated in detail. The results indicate that the lattice constant and vacancy defects can be affected greatly by the particle size. With the particle sizes increases, the magnetic entropy becomes larger at first, and then it decreases accompanying particle size becomes larger than 395 nm. That is, the d = 395 nm sample presents the best magnetocaloric property and the maximum magnetic entropy (− ΔSM) and the refrigerant capacity (RCP) at T = 3 K and H = 3 T condition is 33.41 J·kg−1 K−1 and 552.4 J kg−1. The temperature and magnetic field dependent permittivity also confirm the magneto-dielectric effect of the prepared GdCrO3. As the particle size increases, the coupling coefficient enhanced continuously. Especially for the d = 485 nm sample, a small field of 1 T could cause the dielectric constant increases by about 10%. This work suggests that increasing the particle size is an effective method for improving the magnetocaloric and magnetoelectric properties of GdCrO3. [ABSTRACT FROM AUTHOR]

Polycrystalline GdCrO3 was synthesized by the solid-state reaction method. The temperature-dependent microstructure and magnetic properties were investigated systematically. Both the Raman and FTIR spectra indicate a microstructure anomaly around 170 K. Magnetic studies demonstrate that the sample experiences two magnetic transitions around TN(Cr) ~ 167 K and TN(Gd) ~ 2.8 K related to the AFM Cr3+–Cr3+ interaction and Gd3+–Gd3+ interaction. Interestingly, the ferrimagnetic interaction between Gd and Cr ions results in the temperature-dependent magnetic reversal (TMR) together with a spin flipping (SF) that occurs at Tmin ~ 25.7 K. Due to the anisotropic exchange interaction of the Gd3+–Cr3+, a spin reorientation (SR) from Г4 (Gx, Ay, Fz) phase to Г2 (Fx, Cy, Gz) phase occurs at TSR ~ 7.8 K. In addition, a giant magnetocaloric effect (MCE) caused by the second-order AFM phase transition of Gd3+ ordering is observed at T = 3 K and H = 3 T with a magnetic entropy of − ΔSM ~ 32.8 J/kg⋅K. The present research suggests that GdCrO3 can be considered as a potential candidate material for applying in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Polycrystalline GdCrO3 was synthesized by the solid-state reaction method. The temperature-dependent microstructure and magnetic properties were investigated systematically. Both the Raman and FTIR spectra indicate a microstructure anomaly around 170 K. Magnetic studies demonstrate that the sample experiences two magnetic transitions around TN(Cr) ~ 167 K and TN(Gd) ~ 2.8 K related to the AFM Cr3+–Cr3+ interaction and Gd3+–Gd3+ interaction. Interestingly, the ferrimagnetic interaction between Gd and Cr ions results in the temperature-dependent magnetic reversal (TMR) together with a spin flipping (SF) that occurs at Tmin ~ 25.7 K. Due to the anisotropic exchange interaction of the Gd3+–Cr3+, a spin reorientation (SR) from Г4 (Gx, Ay, Fz) phase to Г2 (Fx, Cy, Gz) phase occurs at TSR ~ 7.8 K. In addition, a giant magnetocaloric effect (MCE) caused by the second-order AFM phase transition of Gd3+ ordering is observed at T = 3 K and H = 3 T with a magnetic entropy of − ΔSM ~ 32.8 J/kg⋅K. The present research suggests that GdCrO3 can be considered as a potential candidate material for applying in magnetic refrigeration. [ABSTRACT FROM AUTHOR]