This paper reports on the development of a gamma-ray spectroscopic system for the (i) recording and (ii) processing of spectra. The utilized data read-out unit consists of a PCI digital oscilloscope, personal computer and LabVIEW™ programming environment. A pulse-height spectra of various sources were recorded with two NaI(Tl) detectors and analyzed, demonstrating the proper usage of the detectors. A multichannel analyzer implements the Gaussian photopeak fitting. The presented method provides results which are in compliance to the ones taken from commercial spectroscopy systems. Each individual hardware or software unit can be further utilized in different spectrometric user-systems. An application of the developed system for research and teaching purposes regarding the design of digital spectrometric systems has been successfully tested at the laboratories of the Department of Experimental Physics.

Low-alloy 42CrMo4 steels were studied by ⁵⁷Fe Mössbauer spectroscopy (MS), X-ray diffractometry (XRD), and Energy Dispersive X-ray Spectroscopy (EDS) measurements. The investigations were performed on metallographic samples, which were subjected to a series of successive grinding and polishing with a progressively finer grit. Conversion X-ray Mössbauer spectroscopy (CXMS) was used to determine the occurrence of austenite in steel samples. It is a unique method detecting the austenite content very sensitively. Six samples with different surface preparation were investigated, starting with 4.8% of austenite on an as-cut sample, and a large decrease in the retained austenite to 2.6% was observed after the first grinding of a hardened cut sample. Additionally, an unexpectedly large decrease in the austenite content to 2.3% was found due to the final polishing. A second time applied successive grinding and polishing of all samples resulted in identical austenite content determined by CXMS of approx. 5%, which proved the applicability of the CXMS method. Generally, the result calls attention to the importance of preparation of metallurgical samples by grinding and polishing where the results can vary significantly on the level of surface processing.

This research presents an elaborate study on the superspin glass (SSG) state in greenly synthesized interacting assembly of Zn _0.5 Mn _0.5 Fe ₂ O ₄ nanoparticles (ZMF NPs). The superparamagnetic (SPM) character of ZMF NPs at 300 K was well established by comprehensive dc-magnetization, modified Langevin function fitting and ⁵⁷ Fe Mössbauer analysis. Magnetization data exhibited a transformation of ZMF NPs from SPM ( M _s = 23 emu g ⁻¹ , T _B = 118 K) to ferrimagnetic (FiM: M _s = 50 emu g ⁻¹ , H _c = 1056 Oe & M _r = 13 emu g ⁻¹ ) upon cooling down to 5 K. Notably, at the same time, spin dynamics in ZMF NPs suggested SPM-SSG crossover at ∼120 K. Existence of SSG phase in ZMF NPs is proven by the observation of memory effects via Zero-field cooled (ZFC), field cooled (FC) and thermoremanent (TMR) protocols applied in the dc-magnetization measurements. In addition, isothermal remanent magnetization revealed Heisenberg-like spin dimensionality, while relaxation dynamics along with the ageing effect served as concluding evidence of low-temperature SSG phase in ZMF NPs. Low temperature electron spin resonance (ESR) and Henkel plot measurements indicated that demagnetizing factors like dipolar interactions are responsible for the SSG type behavior of ZMF NPs at low temperatures. Overall, greenly synthesized ZMF NPs offer a fertile ground for investigating the complex nano-magnetism at low temperatures in nanoferrites.

⁵⁷Fe transmission and conversion electron Mössbauer spectroscopy as well as XRD were used to study the effect of swift heavy ion irradiation on stress-annealed FINEMET samples with a composition of Fe_73.5Si_13.5Nb₃B₉Cu₁. The XRD of the samples indicated changes neither in the crystal structure nor in the texture of irradiated ribbons as compared to those of non-irradiated ones. However, changes in the magnetic anisotropy both in the bulk as well as at the surface of the FINEMET alloy ribbons irradiated by 160 MeV ¹³²Xe ions with a fluence of 10¹³ ion cm⁻² were revealed via the decrease in relative areas of the second and fifth lines of the magnetic sextets in the corresponding Mössbauer spectra. The irradiation-induced change in the magnetic anisotropy in the bulk was found to be similar or somewhat higher than that at the surface. The results are discussed in terms of the defects produced by irradiation and corresponding changes in the orientation of spins depending on the direction of the stress generated around these defects.

In materials research, especially in the case of nanomaterials, the option of performing the low-temperature Mössbauer spectroscopy measurements is very desirable. For this purpose, a new design of low-temperature Mössbauer spectrometer, working in the transmission mode, is introduced. The main part of the presented device is composed of a cryostat (Dewar flask). The next part of the cryostat includes a vacuum chamber with the sample holder connected to the Dewar flask by a heat conducting rod and Mössbauer spectrometer attached onto cryostat. The measurements are performed at a temperature of liquid nitrogen, i.e., 77 K. The price and maintenance of the cryostat is very low acquired with very easy and useful environment for the operator.