CẤU TRÚC VÀ TÍNH CHẤT TỪ CỦA HỆ GỐM Pr0,7Ao,3Mn03 (A = Ca, Sr, Ba) CHẾ TẠO BẰNG PHƯƠNG PHÁP NGHIỀN PHẢN ỨNG KẾT HỢP XỬ LÝ NHIỆT

Abstract

Pro,7Ao,ỉMnOĩ (with A = Ca, Sr, Ba) ceramics belonging to an orthorhombic structure were successfully prepared by a combination o f the reactive milling and the heat treatment methods. Based on experimental data o f X-ray diffraction and M (H, T), the effect o f cation replacement at Pr/A-site on the structure and the magnetic properties o f the Pro.yAoỉMnOĩ (A = Ca, Sr, Ba) system has been carefully investigated. The results show a change in the lattice parameters and a significant shift in the ferromagnetic-paramagnetic phase transition temperature (Tc) when a p art o f the Pr3 ion was replaced by a larger ion (Ca2+, Sr2+, and Ba2+). Under an applied magnetic fie ld change o f 10 kOe, Pro ĩSro ĩM nO ĩ sample stands out clearly in a large magnetocaloric effect near room temperature with the characteristic values such as ỊAS^axl and ACpmax about 3.06 and 95.82 J/kgK, respectively.
Keywords: Magnetocaloric, magnetic phase transition, manganites, Pro.7Sro.3MnO3.