Magnetic properties and magnetocaloric effects in (Ho_1−xY_x)₅Pd₂ compounds*

Abstract

The crystal structure, magnetic and magnetocaloric properties of (Ho1−x Y x )5Pd2 (x = 0, 0.25, and 0.5) compounds are investigated. All the compounds crystallize in a cubic Dy5Pd2-type structure with the space group Fd3m and undergo a second order transition from spin glass (SG) state to paramagnetic (PM) state. The spin glass transition temperatures T g decrease from 26 K for x = 0 to 13 K for x = 0.5. In the PM region, the reciprocal susceptibilities for all the compounds obey the Curie–Weiss law. The paramagnetic Curie temperatures ( θ p ) for Ho5Pd2, (Ho0.75Y0.25)5Pd2, and (Ho0.5Y0.5)5Pd2 are determined to be 32 K, 30 K, and 22 K, respectively, and the corresponding effective magnetic moments ( μ eff ) are 10.8 μ B /Ho, 10.3 μ B /RE, and 7.5 μ B /RE, respectively. Magnetocaloric effect (MCE) is anticipated according to the Maxwell relation, based on the isothermal magnetization curves. For a magnetic field change of 0–5 T, the maximum values of the isothermal magnetic entropy change − Δ S M of the (Ho1−x Y x )5Pd2 (x = 0, 0.25, and 0.5) compounds are determined to be 11.5 J · kg − 1 · K − 1 , 11.1 J · kg − 1 · K − 1 , and 8.9 K J · kg − 1 · K − 1 , with corresponding refrigerant capacity values of 382.3 J · kg − 1 , 336.2 J · kg − 1 , and 242.5 J · kg − 1 , respectively.

Nanolasers Enabled by Metallic Nanoparticles: From Spasers to Random Lasers

“…A number of reports suggested that metallic nanostructures with a specific morphology are of preference as spasing resonators with a low threshold gain. [37,[57][58][59][60][61][62][63][64][65] These studies generally determined the threshold gain by using the finite-element method or discrete dipole approximation to calculate absorption and scattering cross sections (referred to as σ abs and σ sca hereafter) of the core-shell spasing nanoparticle. The magnitudes of σ abs and σ sca will increase rapidly when the amount of gain is increased to a critical value and then decline with a further increase in the amount of gain.…”

Tunable preparation of highly dispersed NixMn-LDO catalysts derived from NixMn-LDHs precursors and application in low-temperature NH3-SCR reactions

“…Comparatively, the pore size distribution range of Ni x Mn-LDO (x ¼ 4, 5, 6) was greatly reduced and more concentrated around 5-20 nm, which implies that the latter had a more uniform pore size structure. 43 Moreover, the surface area was obtained in Table 2 by calculating with BET method. Obviously, the surface area value of samples was sensitive to the proportion of Ni/Mn and displayed an upward trend from 41 to 83 m 2 g À1 with enhancement of Ni/Mn molar ratios.…”

“…44 The Ni 5 Mn-LDO catalyst presented a large specic surface area (70 m 2 g À1 ), suitable average pore diameter (9.35 nm) and pore volume (0.17 cm g À1 ), resulting in the desirable SCR activity. 43,45 3.2.5 NH 3 -TPD analysis. In NH 3 -SCR reaction, the adsorption and activation of NH 3 by catalyst is an important factor affecting the DeNO x action.…”

An Amended Chemical Mass Balance Model for Source Apportionment of PM2.5 in Typical Chinese Eastern Coastal Cities

“…[14] The source profiles of vehicle and sea salt particles were also added. [20][21][22] The principle of CMB can be described by Equation (1), which assumes that each receptor concentration of a chemical species is composed of the linear sum of the products of the source profile species and source contributions. The effective variance solution was applied to calculate S j in Equation (1) by minimizing the weighted sums of the squares of the differences between the measured and calculated values of C i and F ij .…”