The electrical and structural properties of poly (3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin films deposited from aqueous dispersion using different concentrations of selected secondary dopants are studied in detail. An improvement of the electrical conductivity by three orders of magnitude is achieved for dimethyl sulfoxide, sorbitol, ethylene glycol, and N,N-dimethylformamide, and the secondary dopant concentration dependence of the conductivity exhibits almost identical behavior for all investigated secondary dopants. Detailed analysis of the surface morphology and Raman spectra reveals no presence of the secondary dopant in fabricated films, and thus the dopants are truly causing the secondary doping effect. Although the ratio of benzenoid and quinoid vibrations in Raman spectra is unaffected by doping, the phase transition in PEDOT:PSS films owing to doping is confirmed. Further analysis of temperature-dependent conductivity reveals 1D variable range hopping (VRH) charge transport for undoped PEDOT:PSS, whereas highly conductive doped PEDOT:PSS films exhibit 3D VRH charge transport. We demonstrate that the charge-hopping dimensionality change should be a fundamental reason for the conductivity enhancement.

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In this paper, the effect of heat treatment on the development of nanocrystallites in rapidly quenched Fe79Mo8Cu1B12 alloy is investigated. The surface morphology is examined using non-contact mode atomic force microscopy (AFM). The results are compared with those obtained by transmission Mössbauer spectroscopy (TMS), conversion electron Mössbauer spectrometry (CEMS) and x-ray diffraction (XRD). It was found that the sample is not fully amorphous even in the as-quenched state. Minor amounts of bcc-Fe grains were detected on the wheel side of the ribbon-shaped samples while no indications of the crystalline phase were observed in the bulk. The crystallization onset is observed after annealing at 410 °C, when bcc-Fe nanograins are quite well developed. More intense crystallization is evidenced after annealing at higher temperatures, when the content of the crystalline phase increases progressively. The second crystallization, not discussed in the present paper, is characterized by the occurrence of additional crystalline phases, and appears after annealing at 650 °C. We suggest a crystallization model assuming no drastic change in the size of the primarily formed bcc-Fe nanograins with temperature as proved by XRD. The increase in annealing temperature induces the formation of a higher number of crystalline particles, which form large irregular agglomerates (80–130 nm in height), in accordance with the AFM data.

Herein, several ways to evaluate Mössbauer spectra of model binary Fe100−xCrx alloys with chromium content varying in the range from 1 to 50 at% (x = 0.94, 2.2, 4.9, 10.4, 15.4, 22.1, and 52.9) are discussed. For low chromium concentrations (up to 15 at%), the method of binomial distribution of individual sextets is suitable. Depending upon the Cr content, the number of sextets used can be, however, as high as 20. The specific number of sextets is determined according to probabilities of individual atomic sites calculated from binomial distribution. Mössbauer spectra of samples with Cr concentrations higher than 20 at% are evaluated by distributions of hyperfine magnetic fields. The composition of model alloys is verified using X‐ray fluorescence. Their surface is analyzed by two different surface‐sensitive methods: scanning electron microscopy and atomic force microscopy. The main technique used to analyze the materials’ subsurface layers is conversion electron Mössbauer spectroscopy. The applied fitting models and results are useful in studies of the microstructure of real types of construction and stainless steels.

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