A complete experimental study of the physical properties playing a relevant role in magnetic refrigeration application (structural, magnetic, magnetocaloric and thermal) has been performed over nine selected Fe2P-type R6TX2 (R = Gd, Tb, Dy; T Mn, Fe, Co, Ni; X Sb, Te) intermetallic compounds, to work close room temperature. Two phase transitions are observed for these materials: paramagnetic ferromagnetic transition range 182-282 K spin reorientation 26-76 K. As consequence, two peaks...

Low molecular weight glass formers encapsulated within clathrate structures offer a singular testground to study the intricate interplay of confined motion and ferroelectric properties. Using broadband dielectric spectroscopy (BDS), we investigate dynamic behavior 1-propyl-1H-imidazole supramolecular enclosure formed by duad semicage p-tert-butylcalix[4]arene. Unlike bulk liquid, where spectrum is dominated structural relaxation, clathrates paraelectric phase reveals two distinct relaxation...

The discovery of the novel Gd 3 Co 1+ x Ni 1− compound is reported. It shown that magnetocaloric properties are among best in its working temperature range and Co/Ni substitution tunes without compromising performance.

The critical behavior of the paramagnetic to antiferromagnetic transition in $R$MnO${}_{3}$ ($R$ $=$ Sm, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) has been studied with an ac photopyroelectric calorimeter, which gives simultaneously thermal diffusivity and specific heat as a function temperature high resolution around N\'eel temperature. Dy) orthorhombic perovskite structure, whereas other manganites are hexagonal, thus revealing strong anisotropy. SmMnO${}_{3}$ type-A ordering exhibits 3D-XY behavior,...

The aim of this work is to characterize vertical cracks finite size and arbitrary shape using optically excited lock-in thermography. In the first place, we have solved direct problem, which consists calculating surface temperature distribution when shape, width crack are known. To do developed a new method based on discontinuous elements, allows one deal even with very narrow cracks, for classical element methods fail. steel samples containing semi-infinite illuminated laser beam focused...

An ac photopyroelectric calorimeter has been used to measure the thermal diffusivity of perovskite manganite family ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Mn}{\mathrm{O}}_{3}$ on a set single crystals with doping range $0\ensuremath{\leqslant}x\ensuremath{\leqslant}0.35$. Taking into account that inverse same critical behavior as specific heat, exponent $\ensuremath{\alpha}$ magnetic transitions obtained. The results point short-range interaction models for pure...

An ac photopyroelectric calorimeter has been used to simultaneously measure the specific heat $({c}_{p})$, thermal conductivity $(K)$, and diffusivity $(D)$ around antiferromagnetic paramagnetic phase transition in CoO NiO single crystals. Up now, no agreement on critical behavior of both oxides obtained. The results for seven samples grown different laboratories have compared. We found that, irrespective origin samples, exponent amplitude ratio ${c}_{p}$, $D$, $K$ agree with predictions...

Flying spot thermography is an efficient thermographic non-destructive technique that has been widely applied to detect surface breaking cracks on large parts in a fast way. It consists heating the sample with laser moves at constant speed and recording temperature infrared camera. The presence of crack hinders heat propagation produces discontinuity surface, is, signature crack. In this tutorial, we address two quantitative applications flying thermography: measurement thermal diffusivity...

A family of novel intermetallic R3CoNi with heavy rare earth ions has been synthesized (R = Tb, Dy, Ho, Er, Tm, Lu) and a study the crystal structure these phases performed. All compounds adopt rhombohedral Er3Ni2-type [Pearson's symbol hR45; space group R-3h (N. 148)]. thorough investigation their magnetic magnetocaloric properties undertaken. Magnetization ac-susceptibility measurements as function temperature show that samples Tm present paramagnetic to ferromagnetic (PM-FM) transition at...

The thermal diffusivity of solid samples is systematically underestimated in a photopyroelectric technique used the standard back configuration due to presence coupling fluid between sample and detector. In this work, we propose new method overcome undesired effect fluid. It relies on use transparent pyroelectric sensor fluid, together with self-normalization procedure. way, are able measure accurately (a) opaque samples, (b) optical absorption coefficient semitransparent samples.

Magnetic as well calorimetric measurements have been performed on single crystal samples of $\mathrm{P}{\mathrm{r}}_{0.6}\mathrm{S}{\mathrm{r}}_{0.4}\mathrm{Mn}{\mathrm{O}}_{3}$ and $\mathrm{N}{\mathrm{d}}_{0.6}\mathrm{S}{\mathrm{r}}_{0.4}\mathrm{Mn}{\mathrm{O}}_{3}$ to develop a complete critical behavior study the paramagnetic ferromagnetic transition in both manganites. The exponents...

The structural, magnetic, magnetocaloric (MCE) and thermal properties of seven Fe2P-type Dy6(Fe,Mn)X2 (XSb, Bi, Te) intermetallics (space group P6¯2m, N 189, hP9) have been experimentally studied. They present a paramagnetic to ferromagnetic transition (in the range 129–370 K), followed, as temperature decreases, by spin-reorientation one (from 52 170 K) ground magnetic state at 2 K with antiferromagnetic components. This turns into when field is applied. critical exponents β,γ,δ related...

The thermal diffusivity of the ferroelectric family Sn(2)P(2)(Se(x)S(1 - x))(6) (0 ≤ x 1) has been measured by a high-resolution ac photopyroelectric technique, using single crystals, with aim studying evolution transition Se doping. Its change from second order character to first while passing Lifshitz point (x approximately 0.28) evaluated, as well splitting at high concentrations. critical behavior in terms different universality classes and their underlying physical dominant effects...

An ac photopyroelectric calorimeter has been used to simultaneously measure the specific heat, thermal conductivity, and diffusivity around antiferromagnetic paramagnetic phase transition in $\mathrm{K}\mathrm{Mn}{\mathrm{F}}_{3}$. It found that critical exponent amplitude ratio of are same as those heat. Both values agree with predictions three-dimensional Heisenberg model for isotropic magnets, although this is not only magnetic but also structural well. The conductivity shows a broad peak...