Ab initio studies of magnetism and topology in solid Pd-rich $${\varvec{a}}$$-PdSi alloys

Abstract

In 1965 Duwez et al. reported having generated an amorphous, stable phase of palladium-silicon in the region 15 to 23 atomic percent, at.%, silicon. These pioneering efforts have led to the development of solid materials that are now known as Bulk Metallic Glasses, BMG. In 2019 Rodríguez et al. discovered, computationally, that bulk amorphous Pd becomes magnetic, and so does porous/amorphous Pd. Puzzled by these results, the study of several solid binary systems in the Pd-rich zone was undertaken; in particular, the study of the glassy metallic alloy a-Pd$$_{100-c}$$ 100 - c Si$$_{c}$$ c , for $$0 \le c \le 22$$ 0 ≤ c ≤ 22 , (c in at.%) to see what their topology is, what their electronic properties are and to inquire about their magnetism. In this work it is shown that this metallic glass is in fact magnetic in the region $$0 \le c < 15$$ 0 ≤ c < 15 . Collaterally $$\alpha$$ α and $$\beta$$ β magnetization curves are shown where the net magnetic moment is presented. The topology and the position of the first few peaks of the pair distribution functions, which agrees well with experiment, are also discussed. The BMGs produced experimentally so far are limited in size, but despite this limitation, recent industrial efforts have developed some useful devices that may revolutionize technology.

Short‐Range Atomic Topology of Ab Initio Generated Amorphous PdSi Alloys

“…The highest temperature depends on the phase diagram of the system and for the case of the PdSi alloys, the highest temperature was 1500 K for concentrations c < 10 at%, and 1000 K for c > 10 at%. [ 1 ] the end of this process, the disorder has been attained and a Geometry Optimization, GO, is carried out to let the disordered structure evolve into the amorphous one at a local energy minimum. It is evident that the amorphous arrangement is not the minimum–minimorum of the energy; such minimum energy structures would be the crystalline ones.…”

“…As part of a study to investigate the possible magnetic properties of the palladium‐rich region of the amorphous palladium‐silicon system, a‐PdSi, [ 1 ] a detailed analysis of the amorphous structures generated in the process was undertaken, structures that were systematically developed to make possible a study of the evolution of their topology using consistent simulational parameters. Evidently, it is necessary to create amorphous structures throughout the whole concentration range to produce a complete characterization of the PdSi system; however, since the predicted magnetism for the solid alloys disappeared for concentrations of the order of 20 atomic percent, at%, silicon, [ 1 ] the study of higher concentrations of silicon were not carried out, but a complementary, more extensive study, is a must.…”

“…Palladium has also manifested magnetic properties of the ferro‐type when expanded, [ 2 ] when amorphized [ 3 ] and when contaminated with hydrogen, deuterium, or tritium, [ 4 ] or with Si. [ 1 ]…”

“…Palladium has also manifested magnetic properties of the ferro-type when expanded, [2] when amorphized [3] and when contaminated with hydrogen, deuterium, or tritium, [4] or with Si. [1] On the other hand, silicon is a semiconductor in the condensed crystalline and amorphous states with an energy gap of the order of 1 eV. Alloying these two elements would certainly generate unexpected properties due to the dissimilar nature of the constituents.…”