Simultaneous Differential Thermal Analysis Research Articles

Enhancing the Analysis of Eu3+ Photoluminescence in Coordination Compounds in the Solid State by Determining their Refractive Index

AbstractThis study is focused on determining the refractive index as a crucial parameter for evaluating the intrinsic quantum yield and the ligand sensitisation efficiency in solid‐state trivalent lanthanide coordination compounds. For this, eight trivalent europium complexes with phenyl‐terpyridine ([EuX3(ptpy)(L)], X=Cl− or NO3−, ptpy=4′‐phenyl‐2,2′ : 6′,2′′‐terpyridine, L=H2O or other molecules) were examined. Their refractive indices were determined using the Becke lines test by immersing transparent material in a series of media with known refractive indices. Using the set of media presented here, determining crystalline materials′ refractive indices from 1.41 to 1.73 with a step of 0.01 is possible. Assessment of the refractive indices of the complexes mentioned above allowed a comprehensive analysis of their photophysical properties in the solid state. Moreover, this method can be extrapolated for other solid‐state materials, offering valuable insights in the broader field of photophysics. In addition to photoluminescence investigations, the compounds presented were characterised by single‐crystal X‐ray diffraction (SCXRD), powder X‐ray diffraction (PXRD), Hirschfeld surface area analysis, UV‐Vis reflectance spectroscopy, hydrolysis sensitivity analysis, and simultaneous thermogravimetry and differential thermal analysis coupled with mass‐spectrometry (STA‐MS).

The Influence of Alkaline Pretreatment of Waste Nutshell for Use in Particulate Biocomposites

The aim of this work was to determine how different types of alkaline pretreatment influence the properties of waste almond and hazelnut nutshell, as well as their compatibility with model inorganic geopolymer matrixes for the formation of biocomposites with potential use in civil engineering. For alkaline pretreatment, 3, 6 and 9% NaOH water solutions and milk of lime were used under different temperature and time conditions. The rise in the crystallinity index was confirmed by X-ray powder diffraction analysis, while the corroboration of the removal of amorphous and undesirable components was demonstrated through Fourier-transform infrared spectroscopy. Furthermore, the effectiveness of the pretreatments was confirmed via simultaneous differential thermal and thermogravimetric analysis, and the positive change in the morphology of the surface of the waste nutshell (WN) and the deposition of the desired phases was established using scanning electron microscopy. Surface free energy and adhesion parameters were calculated using the Owens, Wendt, Rabel and Kaelble method for WN as fillers and geopolymers as model novel inorganic binders. This research indicates that the 6% NaOH treatment is the optimal pretreatment process for preparing WN as the filler in combination with potassium and metakaolin geopolymer that has been cured at room temperature.

Effect of heat treatment temperature on the morphology and upconversion properties of LaF3:Yb,Er nanoparticles

LaF3:5%Yb3+,0.5%Er3+ upconverting nanoparticles were synthesized with co-precipitation method and heat treated at temperatures 300–600 °C. The morphology of the particles was characterized by high-resolution transmission electron microscopy coupled with energy-dispersive spectrometry and dynamic light scattering. Crystal structure was studied by X-ray diffraction (XRD), and thermal behaviour was investigated by simultaneous thermogravimetry and differential thermal analysis (TG/DTA). Upconversion behaviour was studied in detail by fluorescence spectroscopy, with 980 nm excitation. Particle sizes increased with increasing heat treatment temperature, and samples showed significant aggregation above 500 °C. Hexagonal LaF3 crystal structure was identified for all samples, with increased crystallinity after heat treatment at 400 °C, which was corroborated with TG/DTA results. XRD and energy-dispersive spectrometry results revealed that at higher temperatures new crystal phases formed, as some Yb3+ and Er3+ dopant ions segregated into new nanocrystals, made of, for example, YbOF and YbOOH, which caused a significant decrease in the upconversion emission of the samples. The highest upconversion emission was achieved after heat treatment at 400 °C.

Studies on fluorination of Fe3O4 (magnetite) by NH4HF2

Fluorination of magnetite (Fe3O4) by NH4HF2 was investigated using simultaneous thermogravimetry and differential thermal analysis (TG-DTA), and observing the morphology and phase changes using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffractometry (XRD). The results indicate that fluorination with the involvement of oxygen begins at room temperature, peaks at 1784ºC, and is completed at 200ºC with the formation of only (NH4)3FeF6. On heating, (NH4)3FeF6 gradually releases NH4F by the formation of NH4FeF4 at 259ºC, then (NH4)0.l8FeF3 at 327ºC, and finally FeF3 with minor FeF2 at 400ºC due to the partial reduction of Fe (III) to Fe (II). At 550ºC, FeF3 is oxidized to FeOF/Fe2O3.

Thermal and electrical transport property study of direct vapour transport grown Cu2SnS3 single crystals

Copper tin sulphide (Cu2SnS3) (CTS) single crystals are grown by vapour transport technique of direct (DVT) type. The stoichiometric compositional analysis; Cu: 40.78 % (37.21 %), Sn: 31.09 % (34.35 %) and S: 28.13 % (28.15 %); showed the crystals to be slightly copper rich and tin deficient, bracket values are standard data. The X-ray diffraction showed the CTS to possess cubic unit structure having lattice parameter of 5.43 Å. The high resolution transmission electron microscopy substantiated the crystalline character. The thermal analysis are carried out by recording simultaneous thermogravimetric, differential thermogravimetric and differential thermal analysis curves. These analysis are done in inert atmosphere for three heating rates of 10, 15 and 20 K⋅min−1 in the range from ambient to 1023 K. The thermocurves are analyzed by two standard methods of Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters like activation energy, changes of entropy, enthalphy and Gibbs free energy are determined using KAS and FWO methods. These determined thermodynamic parameters of as-grown CTS single crystals matches each other stating the validity of the analysis. Temperature variation of electrical transport properties like dc electrical resistivity (ρ) and Seebeck coefficient (S) are measured in the temperature range of 323 K to 473 K. The values of ‘ρ’ decreases with temperature, stating semiconducting nature of crystals. The observed ‘S’ values are found to be positive in entire temperature range, stating crystals to be of p-type semiconducting nature.

Hydrogen reduction of spent lithium-ion battery cathode material for metal recovery: Mechanism and kinetics.

Hydrogen reduction is becoming a promising method for recycling lithium-ion battery cathode materials. However, the reaction mechanism and kinetics during hydrogen reduction are unclear, requiring further investigation. Therefore, non-isothermal and isothermal reduction experiments were conducted to evaluate the temperature dependence of the hydrogen reduction kinetics using simultaneous thermogravimetric and differential thermal analysis equipped with mass spectrometry. XRD and SEM were used to characterize the reduction products to understand the underlying reduction mechanisms. The hydrogen reduction profile could be divided into three main stages: decomposition of cathode materials, reduction of the resultant nickel and cobalt oxides, and reduction of LiMnO2 and residual nickel and cobalt oxides. The hydrogen reduction rate increased with increasing temperature, and 800°C was the optimum temperature for separating the magnetic Ni-Co alloy from the non-magnetic manganese oxide particles. The apparent activation energy for the isothermal tests in the range of 500–700°C was 84.86 kJ/mol, and the rate-controlling step was the inward diffusion of H2(g) within each particle. There was an downward progression of the reduction through the material bed for the isothermal tests in the range of 700–900°C, with an apparent activation energy of 51.82 kJ/mol.

Thermal, spectroscopic characterization and evaluation of antibacterial and cytotoxicity properties of quercetin-PEG-silica hybrid materials

This study reports the characterization of two series of organic-inorganic silica-based hybrid materials with 15 and 20 wt% of quercetin (Q), respectively, and 6, 12, 24 and 50 wt% of polyethylene glycol (P) (for each of them). After the sol-gel synthesis they have been characterized using different techniques (Fourier-Transform Infrared and Micro-Raman spectroscopies, Thermogravimetry, Differential Thermal Analysis). Two tests were also carried out to evaluate their biomedical properties to estimate their antibacterial activity and their cytotoxicity. FT-IR measurements revealed the interaction between the components of the hybrid materials, while Micro-Raman spectra confirmed the presence of quercetin in an oxidized form. Simultaneous Thermogravimetry and Differential Thermal Analysis coupled with Mass Spectrometry enabled to investigate the thermal behavior of the hybrids (up to 800 °C) and to analyze the gas mixtures evolved upon heating in severe inert argon atmosphere. Antibacterial tests showed that an increase of PEG contents results in a decrease of the bacterial growth. Finally, cytotoxicity assessment highlighted that entrapping quercetin in hybrids at high PEG content leads to the constitution of materials that enjoy PEG biocompatibility, while cytotoxic effects are depleted.

Reticulated porous lanthanum strontium manganite structures for solar thermochemical hydrogen production

Porous ceramic foams are utilized in various fields and applications due to their advantageous properties such as high porosity, high specific surface area, and controlled permeability. Non-stoichiometric oxide foams are of particular interest for the solar thermochemical production of hydrogen in directly irradiated solar receivers due to their enhanced heat transfer capabilities and structural integrity. We report the fabrication of lanthanum strontium manganite replica foams and their solar thermochemical water splitting performance. Highly porous (>80%) foams were produced with controlled structure and tested in a high temperature water splitting furnace to demonstrate stability and overall performance. The temperature profile of the burnout and sintering of the foam structure were altered based on simultaneous differential scanning calorimetry and thermal gravimetry analysis. Two-step sintering was used both to retain micron-sized pores (D50 = 0.4 μm) on the foam's struts and to limit grain growth to a grain size of ∼1 μm. The structural characteristics were confirmed by porosimetry and scanning electron microscopy. The foams were repeatedly cycled, producing approximately 200 μmol/g of H2 per cycle. Water splitting performance was tested for 50 cycles and approximately 35 h at 1400 °C. No statistical difference in the effective hydrogen production per cycle was observed, which is promising for long-term redox cycle stability.

Investigation on crystallization kinetics using thermal analysis and crystalline behavior of yttrium iron garnet (Y3Fe5O12) compounds

The objectives of this work were to investigate the crystallization kinetics of Yttrium Iron Garnet (Y3Fe5O12, YIG) using the thermal analysis. The Differential Scanning Colorimetric (DSC) analysis confirmed that crystallization begins to form the YIG from the nitrates of the YIG gel product at the melting temperature of 337 °C. Two weight losses were discovered from the nitrates of the YIG gel product using simultaneous thermo gravimetric analysis (TGA) and differential thermal analysis (DTA), in the temperature range of 70 to 130 °C and 760 °C, indicating the amorphous state to change the crystalline state formation. A thermo magnetization analysis (TMA) was performed on the synthesized YIG calcined at 850 °C, and the Curie temperature results were thoroughly examined. The Williamson-Hall (W-H) plots and transmission electron microscope (TEM) analysis were used to study the crystalline strain and crystalline formation of the as-prepared YIG particles at 850 °C calcined temperatures.

Mortars from the Palace of Knossos in Crete, Greece: A Multi-Analytical Approach

The study of building materials constituting cultural heritage is fundamental to understand their characteristics and predict their behavior. When considering materials from archaeological sites, their characterization can provide not only relevant information for a broader understanding of the site and its importance and significance but can also increase knowledge about ancient materials and their performance. The Palace of Knossos is a very important archaeological site in the European history context, and its preservation benefits from the characterization of the constituent materials. Samples of mortars from this monument were collected under the scope of the H2020 HERACLES project, where a multi-analytical approach was chosen using established protocols for the different sample typologies. Instrumental techniques such as optical microscopy (OM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and simultaneous thermogravimetry and differential thermal analysis (TG–DTA) were used for the chemical, mineralogical, and morphological characterization of these mortar samples. The results indicate that the majority are lime mortars, both aerial and hydraulic, but gypsum-based mortars were also identified. Differences in the chemical composition of the samples in distinct areas of the monument allowed us to reflect on the variety of materials used in the construction of the Palace of Knossos.

ZnO nanoparticles prepared via a green synthesis approach: Physical properties, photocatalytic and antibacterial activity

The aqueous extract of Phoenix roebelenii palm leaves has been utilized for the first time as an effective chelating/stabilizing agent used to synthesize zinc oxide nanoparticles (ZnO NPs) via a green chemistry approach. The physical properties of the nanoparticles were examined using X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), simultaneous thermogravimetric analysis (TGA) and differential thermal analysis (DTA), photoluminescence (PL) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Our XRD investigations revealed that the ZnO NPs have a single phase wurtzite structure with P63mc space group. The crystallite size and lattice strain were calculated using X-ray peak broadening analysis utilizing the Williamson-Hall (W-H) method and were found to be 15.6 nm and 2.1 × 10−3 respectively. The shape of the ZnO NPs was almost spherical, as revealed by TEM analysis. The DRS spectrum showed a direct band gap energy of 3.24 eV. DTA/TGA indicated that the required calcination temperature was 500°C in order to form stable ZnO NPs. PL spectroscopy revealed the presence of weak UV emission related to the free exciton and wide visible-light emission due to oxygen vacancies and other structural defects. The reaction between P. roebelenii palm leaves extract and the zinc precursor was monitored using FTIR spectroscopy at different reaction times. The potential mechanism for the formation of the ZnO NPs using P. roebelenii leaves extract as a natural chelating and stabilizing agent has been discussed. The bioinspired ZnO NPs achieved an outstanding degradation activity of 98% toward methylene blue (MB) dye after 105 min of UV illumination. In addition, the ZnO NPs exhibit a significant bactericidal effect towards gram-positive (Staphylococcus aureus and Streptococcus pneumoniae) and gram-negative (Escherichia coli and Salmonella typhi) pathogenic bacteria.

The in vitro release features of 5-Fluorouracil from tablets with chitosan, soy protein extract and chitosan-soyprotein extract blend as carriers and their thermal degradation characteristics

Natural polymers are finding widespread applications in drug delivery, scaffold fabrication, bio plastic production, food packaging, wound dressing etc. due to their availability, biodegradability, biocompatibility, renewable nature, ease of modification to achieve the desirable properties etc. In the present study, the commercially available soy protein extract (SPE), chitosan(CSN) and their physical blend(CSN-SPE) have been chosen as drug carrier matrices to campare their in vitro drug release features in simulated intestinal fluid for controlled release applications taking 5-fluorouracil (5-FU) as a typical drug. The percentages of 5-FU released from the SPE, CSN and CSN-SPE tablets as a function of time were quantified by reverse phase High Performance Liquid Chromatography using KH2PO4 solution (pH 6.8) as the mobile phase and C-18 column as the stationery phase. The observed drug release features were found to be different for these polymer carriers. The percentages of drug released during the initial periods upto 60 min were less in the CSN-SPE tablet than those observed for CSN and SPE tablets. This implied that the drug release rate can be modified by the proper choice of natural polymers in the blends as carriers. The thermal degradation characteristics of CSN, SPE and CSN-SPE blend and their 5-FU tablets were also analysed by simultaneous Thermogravimetry (TG) and Differential Thermal Analysis (DTA). Comparative analysis of the TG and DTA traces of these polymers and their 5-FU tablets implied that there may be a drug-matrix interaction. This along with different degrees of swellability and degradability of these polymers might account for the differences in the drug release features. The structures of CSN, SPE and CSN-SPE blend were characterized by FT-IR spectroscopy.

Thermal analysis of cellulosic stalk (stem) fiber from the ornamental Allamanda Blanchetii plant for commercial exploitations

In the wake of economic eco-friendly materials there is increasing demand to substitute synthetic fibers with vegetable fibers of plant origin for various applications. Here a ligno-cellulosic stalk (stem) fiber from the ornamental Allamanda Blanchetii (AMB) plant was extracted by manual scutching and hackling and purified by defatting, scouring and hydrogen peroxide bleaching. The fiber was characterized by FT-IR spectroscopy, and simultaneous thermogravimetry (TG) and differential thermal analysis taking the raw cotton as reference. FT-IR spectrum of crude AMB fiber displayed absorption frequencies common to those of ligno-cellulosic fibers, and that of the treated fiber indicated the removal of hemicellulose and lignin. Onset temperatures for the major degradation steps of the raw AMB and cotton fibers revealed nearly equal thermal stability for them, and both of them degraded exothermically under N2. The silky white flexible treated AMB fiber (density < 1 g/cc) degraded endothermically under N2 and was thermally more stable than the crude AMB fiber. The observed thermal characteristics of the treated AMB fiber implied that it can be exploited for the production of textiles, composites and activated/conductive carbon.

Complex evolution of phase during the thermal investigation of Brushite-type calcium phosphate CaHPO4•2H2O

This study focused on a detailed examination of the thermal behavior of Brushite-based calcium phosphate (CaHPO4•2H2O, DCPD) to identify and characterize the intermediate phases which have been the subject of previous several controversies. For that, in situ high-temperature X-ray diffraction (HT-XRD) supported by Fourier transform infrared spectroscopy (FTIR), simultaneous thermal gravimetry and differential thermal analysis (TG/DTA), and scanning electron microscopy (SEM) analysis were used and the combination of results showed that the progressive thermal stress of DCPD in air resulted in a complex heterogeneous formulation consisting of dibasic calcium phosphate anhydrous (CaHPO4, DCPA) and an amorphous calcium phosphate, which appears at low temperatures (~160 °C) and persists up to 375 °C. This amorphous phase was identified as a disordered calcium pyrophosphate (Ca2P2O7, CPP) by the appearance in FTIR spectra of a characteristic band δ(P—O—P) of pyrophosphate groups, located at 740 cm−1. This band is shifted to low frequencies (725 cm−1) as the temperature is increased, indicating the crystallization of the amorphous CPP material into γ-CPP. The high temperature treatment (≥ 375 °C) leads to β−CPP polymorph. The quantification of the amorphous CPP phase by HT-XRD analysis depends on the heating rate of the decomposition of DCPD and presents a maximum at 300 °C for 10 °C min−1. According to the present characterization results, obtaining pure DCPA from the thermal dehydration of DCPD is not effective and leads to biphasic materials including a disordered calcium pyrophosphate phase.

Simultaneous Differential Thermal Analysis and Thermogravimetric Analysis of Si-30B Alloy

This article focuses on the experimental determination of the transformation temperature of Si-30B alloy in the temperature range of 25-1820 °C in a flowing gas atmosphere (He, 99.9992%) carried out by simultaneous differential thermal analysis and thermogravimetric analysis (DTA–TG) using a graphite container. The DTA curve during heating showed the presence of two critical temperatures, i.e., T = 1380.7 °C and T = 1532.0 °C. The first one corresponds to the melting point of a eutectic system (Si + SiB6). The high-temperature interaction and reactivity between the alloy and the container during DTA–TG test were evaluated by scanning electron microscopy coupled with energy-dispersive x-ray analysis. The results have demonstrated that the graphite container reacts with both liquid silicon and boron dissolved in liquid constituent of the alloy to form SiC and B4C, respectively.

Simultaneous thermogravimetric and differential thermal analysis determination of products formed during hydration of blended Portland cement doped with zinc

With the increasing use of secondary raw materials and alternative fuels in the cement production industry, the amount of present trash elements rapidly increases. Most of these problematic elements affect the quality of produced clinker or blended cement. This study focuses on zinc and his influence on the hydration process and the formation of new hydration products. Zinc in percentage by mass of OPC 1% and 5% was added in the form of Zn(NO3)2, ZnCl2 and ZnO for modelling of the formation or modification of newly formed products. These new phases are present in mostly trace quantities, and quantification of even well-known phases such as Ca(OH)2 via X-ray diffraction method (XRD) is not suitable due to poor crystallinity and stoichiometry of some zinc compounds related phases. On the other hand, even smaller quantities of known phases could be precisely characterized via simultaneous thermogravimetric (TG) and differential thermal analysis (DTA). Special emphasis was given to mentioned Ca(OH)2 as one of the hydration degree indicators. With a very high content of chloride and nitrate anoint, the hydration, process was not only retarded by zinc but significantly altered causing creation of new phases mainly ettringite analogues with these anoints. In samples with a high dosage of Zn(NO3)2, ZnCl2 even Ca(OH)2 as hydration product cannot be identified by TG–dTG nor XRD. On the other hand with ZnO as zinc source, significant influence on hydration was proven. Initially as retarding agent for early stages of hydration, but also as the agent that increased final degree of hydration relatively to reference OPC.

Thermal decomposition of Yttrium 2-methylbutyrate in argon

The thermal decomposition of yttrium 2-methylbutyrate (Y(C4H9CO2)3) under argon gas flow has been investigated by means of simultaneous thermogravimetry and differential thermal analysis, FTIR-spectroscopy (solid residue and evolved gas analysis), mass spectrometry, hot-stage optical microscopy and X-ray diffraction with a standard laboratory Cu-tube source as well as with a high-energy synchrotron radiation source. At least one structural transition occurs in the solid state between 100 °C and 160 °C. The decomposition of the Y 2-methylbutyrate salt takes place above 400 °C. A first stage results in the formation of Y2O2CO3 between 400 °C and 490 °C. This decomposition step is accompanied by the release of CO2, a symmetrical ketone (3,5-dimethyl-4-heptanone), as well as probably a terminal alkyne, which could not be unambiguously identified. At higher temperature, Y2O2CO3 is slowly converted to Y2O3 with release of CO2, while some carbonaceous residue is eliminated via combustion. The TG trace reaches the final plateau at about 1200 °C.

Carbonation of heat-activated serpentine driven by Microcystis aeruginosa PCC7806

The capture and storage of CO2 has been a critical strategy towards coping with global warming in recent years. Mineral carbonation is gaining much attention as a novel method of CO2 storage owing to its stability and safety. In this study, the mechanism and effect of carbonation of heat-activated serpentine [Mg3Si2O5(OH)4] driven by cyanobacteria were explored, taking Microcystis aeruginosa PCC7806 as an example. The serpentine was heated at different temperatures, and thermal decomposition of serpentine was characterized by simultaneous thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD) and scanning electron microscope (SEM). The pH, ion concentrations, mineral composition and surface morphology in the process of interactions between the algae cells and heat-activated serpentine were analyzed. The results show that the serpentine can be transformed to forsterite after heat treatment at over 614 °C, and the medium for the addition of heat-activated serpentine at over 614 °C did not allow algae growth. The algae grew well in BG11 liquid medium with 400 °C heat-activated serpentine, and the pH of the culture liquid reached 10.2–10.3, which is in favor of the carbonation of serpentine. The analysis results show the carbonation of trace serpentine. Moreover, the carbonation effect of 400 °C heat-activated serpentine driven by the algae in a solid medium was the most significant, and the carbonate content of serpentine increased by 75.21% as detected by chemical analysis. XRD, SEM, and energy dispersive spectrometer (EDS) results indicate that amorphous CaMg(CO3)2 and MgCO3 were formed on the surface of serpentine driven by the algae. This study advances our understanding of the biological mechanism of serpentine carbonation, and provides a new way to fully exploit serpentine resources in carbon sequestration.

Corn starch incorporated with freeze-concentrated Ilex paraguariensis extracts: a potential nutraceutical product

Yerba mate (Ilex paraguariensis) traditionally grown in South America. Its extract contains bioactive compounds which are associated with pharmacological activities. Freeze-concentration (cryoconcentration) process allows the removal of water preserving the bioactive compounds in extracts. Furthermore, yerba mate extract incorporation into starches is promising for food and pharmaceutical uses. This process can be evaluated using simultaneous Thermogravimetry and differential thermal analysis (TG–DTA). The aim of this study was to obtain corn starch incorporated with freeze-concentrated yerba mate extract. The evaluation of freeze-concentration was carried by extracts analyses of density, total dry matter and ash. The evaluation of yerba mate extract incorporation into corn starch was performed using simultaneous TG–DTA system. Density results revealed extracts different composition and dry matter indicated that compounds were concentrated at 0.576% ratio after freeze-concentration stage. Nevertheless, incorporated starches showed exothermic peaks in DTA curves at temperatures between 287 and 514 °C, which increased in intensity in agreement with freeze-concentration stages advance. Thus, yerba mate oxygenated compounds were incorporated into starches. Nutraceutical products can be obtained using the incorporation of yerba mate extract into starches; however, further studies are necessary to extend these applications.

Thermal and structural analysis of the reaction pathways of α-spodumene with NH4HF2

In this work, the thermal and microstructural analysis of the reaction pathways of α-spodumene with NH4HF2 at low temperatures is presented. The thermal behavior of NH4HF2, mixtures α-LiAlSi2O6/NH4HF2 and by-products (NH4)3SiF6·F/(NH4)2SiF6, are analyzed by simultaneous thermogravimetry and differential thermal analysis (TG-DTA). The study of the crystallite size and lattice strain in the solids is carried out using X-ray diffraction (XRD). The obtained results indicate that the heating rate has a remarkable influence on the processes. At low heating rates, 1 K/min, the reaction between the mineral and NH4HF2 begins at about 351 K and is completed around 426 K, approximately. The obtained products are LiF, (NH4)3SiF6·F, (NH4)3AlF6, NH3 and H2O. In the 368–429 K temperature range, the unreacted NH4HF2 is removed and (NH4)3SiF6·F starts to decompose to generate (NH4)2SiF6. Finally, (NH4)2SiF6 and (NH4)3AlF6 sublimate and decompose at 433 and 493 K, respectively. The main final product is a LiF/AlF3 mixture at 533 K.