Although the dry ice method used to synthesize exfoliated graphite/graphene is little known and used, it has significant advantages over others: it is low cost, simple, and a large quantity of material can be obtained using some inorganic and highly available acids (which can be reused). Despite the above advantages, the main reason for its incipient development is the resulting presence of magnesium oxide in the final product. In the present work, three different treat-ments were tested to remove this remnant using some acid chemical leaching processes, making use of hydrochloric acid, aqua regia, and piranha solution. Based on the experimental evidence, it was found that using aqua regia and combining the leaching process with mechanical milling was the most efficient way of removing such a remnant, the residue being only 0.9 wt.%. This value is low when compared to that obtained with the other acid leaching solutions and purifi-cation process (2.8 - 29.6 wt.%). A mandatory high-energy mechanical milling stage was neces-sary during this treatment, in order to expose and dissolve the highly insoluble oxide without secondary chemical reactions on the graphenes. High-energy mechanical milling is an effective route to exfoliate graphite/graphene, which allows the magnesium oxide to be more susceptible to acid treatment. The obtained surface area was 504 m2g-1; this high value resulting from the in-tense exfoliation can potentiate the use of this material for a wide variety of applications.

Although the dry ice method used to synthesize turbostratic carbon/graphene is little known and used, it has significant advantages over others, such as the following: it is low cost, simple, and a large quantity of material can be obtained using some inorganic and highly available acids (which can be reused). Despite the above advantages, the main reason for its incipient development is the resulting presence of magnesium oxide in the final product. In the present work, three different treatments were tested to remove this remnant using some acid chemical leaching processes, including hydrochloric acid, aqua regia, and piranha solution. Based on the experimental evidence, it was determined that using aqua regia and combining the leaching process with mechanical milling was the most efficient way of removing such a remnant, the residue being only 0.9 wt.%. This value is low compared to that obtained with the other acid leaching solutions and purification processes (2.8–29.6 wt.%). A mandatory high-energy mechanical milling stage was necessary during this treatment to expose and dissolve the highly insoluble oxide without secondary chemical reactions on the turbostratic carbon. High-energy mechanical milling is an effective route to exfoliate graphite, which allows the magnesium oxide to be more susceptible to acid treatment. A yield of turbostratic carbon/graphene of 1 wt.% was obtained from the metallic Mg. The obtained surface area was 504.8 m2g−1; this high value resulting from the intense exfoliation can potentiate the use of this material for a wide variety of applications.

Polycrystalline‐multiferroic Bi0.85Pr0.15‐xEuxFe0.97Mn0.03O3 (0, 0.01, 0.02, 0.03, 0.4, 0.05) thin films were grown on fluorine‐doped tin oxide (FTO)/glass substrate with radio frequency (RF) magnetron sputtering. Rietveld quantitative analysis reveals that whereas the starting materials (nanoparticles [NPs] and ceramics) are composed of tetragonal P4italicmm symmetry, the thin films can lose 80% of this symmetry to become rhombohedral R3c symmetry. The structure evolution from tetragonal to rhombohedral symmetry indicates that the Eu3+ ion acts positively to reduce the tensile residual stress component from 24 to 1.8 MPa in the thin films. The band gap shifts to 2.17 eV by Eu substitution at the A‐site of the perovskite. Scanning electron microscopy (SEM) results show high‐elongated nanocrystals that share parallel facets without porosity. In that morphology, the Eu has a strong influence on reducing the magnetic coercivity from 10.7 to 6.5 kOe, which has been interpreted in terms of local shape anisotropy. Although the magnetic response increases monotonously, the ferroelectric polarization decreases with doping. These changes are explained through local defects created by the evolution of the VO·· concentration that changes significantly by Eu doping.

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