Size effect of DyF₃ nanoparticles on Curie temperature

Abstract

The series of DyF3 nanoparticles samples are synthesized by the hydrothermal treatment in autoclave at 140°C, 160°C, 200°C and 230°C for 24 h. The samples are characterized by X-ray powder...

A study of the size and clustering effects of DyF3 samples

“…Due to the colossal anisotropy of the magnetic moments along the crystal axes, the concentrated DyF 3 compound can be considered a quasi-Ising ferromagnet with the main dipole–dipole interaction. 10 The susceptibility ratio corresponds to χ b : χ a : χ c = 43 : 4 : 1 in a field of 100 Oe at a temperature of 5 K.…”

“…DyF 3 samples were synthesized using the chloride reaction by precipitation from colloidal solutions. 10 The crystalline hydrate of dysprosium chloride, DyCl 3 ·6H 2 O, was dissolved in deionized water. The acidity of the resulting solution was adjusted with nitric acid, HNO 3 , to pH = 2.…”

“…Sample #1 was obtained by crushing a single crystal and subsequently sieving it through a sieve. 10 The particle size of sample #1 was determined using scanning electron microscopy and those of samples #2-5 were determined using transmission electron microscopy. 10 The particles have an ellipsoidal shape.…”

“…7 The value of the critical exponent of the correlation length of a DyF 3 dipole ferromagnet (υ = 1.51 ± 0.25) was experimentally determined using the finite-size-scaling theory and it is greater than those of exchange ferromagnets. 10 Thus, the fact that the DyF 3 compound is a dipole ferromagnet makes it unique and more interesting for research, since there are much fewer studies on dipole ferromagnets than on exchange ferromagnets.…”

“…It was known that for a single crystal DyF 3 the temperature of ferromagnetic ordering is 2.55 K, 7 for a microsized powder DyF 3 it is 2.54 K, 11 and for the particle size of 16-18 nm and 5 nm, the ferromagnetic phase transition was not observed down to a temperature of 1.8 K. 11,12 Recent studies have shown that with a decrease in the average particle size from 225 nm to 28 nm, the T C shifts from 2.45 K to 2.12 K according to a power law. 10 From the finite-size-scaling theory the diameter of nanoparticles d 0 = 1.2 nm was determined, at which the transition to the ferromagnetic state becomes impossible.…”