Poopćenje analitičkih izraza za pseudo -voigtovu funkciju koja se rabi u analizama difrakcijskih vrhova

Nous revisitons ici la théorie, utilisée en analyse des profils de raies de diffraction des rayons X et des neutrons, relative à la fonction de forme du pic dite de pseudo -Voigt (notée pV). Nous présentons une généralisation des expressions de la largeur intégrale et à mi-hauteur de la fonction pV, de la transformée de Fourier de cette fonction ainsi que du seuil du paramètre de mélange h. Nous incorporons nos résultats dans la procédure de fit, ce qui améliore les facteurs de précision.Razmatramo teoriju koja se primjenjuje u analizi linija difraktiranog rentgenskog zračenja i neutrona a odnosi se na tzv. pseudo-Voigtovu (skraćeno pV) funkciju za opis oblika vrha. Dajemo poopćenje analitičkog izraza za ukupnu širinu i širinu na pola visine vrha funkcije pV, Fourierovu transformaciju izraza, kao i prag parametra miješanja η. Primijenjujemo naš postupak za prilagodbu i postižemo poboljšanje točnosti

Relation between interlayer exchange coupling and nonferromagnetic behavior of Fe in Ni/Fe/Co superlattices

International audienceRecent experimental studies, using a photoemission electron microscope on a Ni∕Fe∕Co∕Cu(100) system, found that the Fe layers at both the Fe∕Co and Fe∕Ni interfaces are ferromagnetically ordered, and that there is an oscillatory intercoupling between the Co and Ni layers across the Fe spacer. In the present paper we performed self-consistent ab initio calculations to determine the magnetic profile and the interlayer exchange coupling (IEC) in fcc Ni∕Fen∕Co(100) superlattices, for different thicknesses of the Fe spacer (n=1–7). The compositional ordering at the Fe∕Co and Fe∕Ni interfaces leads to a completely different IEC behavior. Strong Fe-Ni(Co) ferromagnetic coupling with enhanced Fe magnetic moment are always obtained in the intermixed layers

Analytical Modeling of Dual-Junction Tandem Solar Cells Based on an InGaP/GaAs Heterojunction Stacked on a Ge Substrate

An analytical model is used to describe the electrical characteristics of a dual-junction tandem solar cell performing with a conversion efficiency of 32.56% under air mass 1.5 global (AM1.5G) spectrum. The tandem structure consists of a thin heterojunction top cell made of indium gallium phosphide (InGaP) on gallium arsenide (GaAs), mechanically stacked on a relatively thick germanium (Ge) substrate, which acts as bottom cell. In order to obtain the best performance of such a structure, we simulate for both the upper and lower sub-cell the current density–voltage, power density–voltage, and spectral response behaviors, taking into account the doping-dependent transport parameters and a wide range of minority carrier surface recombination velocities. For the proposed tandem cell, our calculations predict optimal photovoltaic parameters, namely the short-circuit current density (J sc ), open-circuit voltage (V oc ), maximum power density (P max ), and fill factor (FF) are J sc = 28.25 mA/cm 2 , V oc = 1.24 V, P max = 31.64 mW/cm 2 , and FF = 89.95%, respectively. The present study could prove useful in supporting the design of high efficiency dual junction structures by investigating the role of different materials and physical parameters