Low-temperature Thermal Decomposition Research Articles

Formation of volatile chlorinated and brominated products during low temperature thermal decomposition of the representative PFAS perfluorohexane sulfonate (PFHxS) in the presence of NaCl and NaBr

Per- and polyfluoroalkyl substances (PFAS) are synthetic organofluorine compounds known for their chemical and physical stability as well as their wide range of uses. Some PFAS are widely distributed in the environment, leading to concerns related to both environmental and human health. High temperature thermal treatment (i.e., incineration) has been utilized for PFAS treatment, but this requires significant infrastructure and energy, prompting interest in lower temperature approaches that may still lead to efficient destruction. Lower treatment temperatures, however, increase the potential for incomplete PFAS mineralization and formation of volatile organofluorine (VOF) products. Herein, we report the formation of novel VOF products that include chlorinated and brominated compounds during the thermal treatment of potassium perfluorohexane sulfonate (PFHxS), a representative perfluoroalkyl acid (PFAA). By comparing the gas chromatography-mass spectrometry (GC-MS) results of known VOF stocks to evolved VOF during thermal treatment of PFAS, the formation of perfluorohexyl chloride and perfluorohexyl bromide was observed when PFHxS was heated at temperatures between 275 and 475 °C in the presence of NaCl and NaBr, respectively. To our knowledge, this is the first report of chlorinated or brominated VOF products during thermal treatment of a PFAA. These findings suggest that a range of mixed halogenated VOF may form during thermal treatment of PFAS at relatively low temperature (e.g., 500 °C) and that these can be a function of salts present in the matrix.

Experimental characterization of the low-temperature thermal decomposition of diisopropyl methylphosphonate (DIMP)

Diisopropyl methylphosphonate (DIMP) is a chemical weapon agent surrogate. Quantifying the rates of thermal decomposition of such compounds is important to enable predictions of spread of respective toxic vapors in different scenarios. An experimental setup is designed and built to quantify the rate of decomposition of DIMP at temperatures of 200–350 °C. Liquid DIMP is fed from a brass evaporator heated to 140 °C and vented with argon. It is mixed with a pre-heated carrier gas (air or nitrogen) in a steel flow reactor. The gas is sampled from the reactor after a certain residence time and sent to a Fourier transform infrared (FTIR) analyzer. Under 350 °C, the thermal decomposition of DIMP in air occurs much faster than in nitrogen. In air, the decomposition of DIMP can be described as the first order reaction with the rate constant kTs-1=107.4±2.5·exp-21.4±6.6kcal/molRT. Despite measuring substantial reduction in the DIMP concentration due to its thermal decomposition, present measurements could not detect the presence of propene and other decomposition products.

High-specific capacity thermal battery cathode Fe and Ni doped CoS2 by enhanced thermal stability and conductivity

CoS2 can meet the strict requirements of high probability output capacity and high energy output capacity of thermal batteries in modern weaponry thanks to its advantages of low resistivity and high thermal decomposition temperature combined with a full Li+ conductive electrolyte. Nevertheless, CoS2 has the limitations of a low voltage platform and theorical capacity. In this case, Fe and Ni are doped into the CoS2 lattice through low-temperature solid-phase sintering to synthesize Fe0.1Co0.8Ni0.1S2 with a single-phase structure. Fe0.1Co0.8Ni0.1S2 generated by the solid phase method has higher thermal stability, which can reduce the high temperature thermal shock at the immediate start of the thermal battery and assure the safety of the thermal battery in operation. Meanwhile, the mass loss of Fe0.1Co0.8Ni0.1S2 at 615 °C is only 5 %, allowing it to discharge at the maximum effective mass at the normal operating temperature(∼500 °C). Because of the synergistic action of Fe2+, Ni2+, and Co2+ in the discharge process, the discharge voltage of CoS2 increases significantly, giving CoS2 higher specific energy. The simultaneous boost in specific energy and specific capacity indicates that doping has been highly successful in modifying CoS2, making CoS2 more appropriate for the use of high current and long-life thermal cell systems.

Recycling lead from copper plant residue (CPR) using brine leaching – Precipitation - Calcination process

Copper plant residue (CPR) is a hazardous industrial by-product possessing both high toxicity and valuable metal content, necessitating its high value-added utilization. Traditional practices in smelters involve stockpiling and landfilling of CPR, leading to substantial land occupation and water contamination. This study focused on the preparation of PbO and Pb3O4 using the HCl–NaCl leaching–conversion–thermal decomposition process, employing CPR as the primary raw material. The effect of various leaching process conditions on the metal leaching rate was explored. A maximum lead leaching rate of 87.65% was achieved under optimal conditions including leaching temperature, liquid–solid ratio, leaching time, HCl molar concentration, NaCl mass concentration, and particle size. The lead content in the leachate was 15.85 g/L. Experimental data indicated that ash diffusion control served as the rate-limiting step in the HCl–NaCl leaching process. The apparent activation energy was determined to be 18.374 kJ mol−1, with a reaction order of 0.8986 concerning the HCl concentration and an L/S ratio of 0.8124. Additionally, response surface methodology enabled the determination of technological parameters for refining PbCl2 into PbCO3 precursors, yielding a conversion rate exceeding 96.50%. Moreover, the technical indicators of PbO and Pb3O4 obtained through low-temperature thermal decomposition of PbCO3 were investigated. The fabricated PbO and Pb3O4 exhibited purities of 99.65% and 99.26%, respectively, effectively transforming CPR from hazardous waste residue into valuable products. The process ensures the efficient recovery of lead to its maximum extent and promotes residue recycling.

Ammonia Cracking Catalyzed by Ni Nanoparticles Confined in the Framework of CeO2 Support.

For the extraction of hydrogen from ammonia at low temperatures, we investigated Ni-based catalysts fabricated by the thermal decomposition of RNi5 intermetallics (R = Ce or Y). The interconnected microstructure formed via phase separation between the Ni catalyst and the resulting oxide support was observed to evolve via low-temperature thermal decomposition of RNi5. The resulting Ni/CeO2 nanocomposite exhibited superior catalytic activity of ∼25% at 400 °C for NH3 cracking. The high catalytic activity was attributed to the interlocking of Ni nanoparticles with the CeO2 framework. The growth of Ni nanoparticles was prevented by this interconnected microstructure, in which the Ni nanoparticles incorporated nitrogen owing to the size effect, whereas Ni does not commonly form nitrides. To the best of our knowledge, this is a unique example of a microstructure that enhances catalytic NH3 cracking.

Preparation and performance of degradable slow-release fertilizer coating material by a new ionic crosslinked hydrogel material

We report a hydrogel with 25 % polyacrylic acid by grafting and mixing starch with polyacrylic acid and urea. The novel ionic crosslinking strategy through iron ions enabled the high biodegradability of a novel slow-release fertilizer coating material. The ionic cross-linking improved the degree of polymerization of the material and formed a compact structured membrane material, which extended the period of nitrogen release to a sufficient extent. The membrane material obtained through ionic cross-linking exhibited a low thermal decomposition temperature and high thermal weight loss. Material displayed significant degradation with a weight loss of 71.11 % in a 60-day degradation experiment conducted in soil. This cross-linking approach provides a novel route for developing encapsulated slow-release fertilizers. It expands the application of natural polymers in the field of slow-release fertilizers.

Effect of Sericin Content on the Structural Characteristics and Properties of New Silk Nonwoven Fabrics.

Recently, natural silk nonwoven fabrics have attracted attention in biomedical and cosmetic applications because of their excellent biocompatibility, mechanical properties, and easy preparation. Herein, silk nonwoven fabrics were prepared by carding silk filaments to improve their productivity, and the effect of sericin content on the structure and properties of silk nonwoven fabrics was investigated. Owing to the binding effect of sericin in silk, a natural silk nonwoven fabric was successfully prepared through carding, wetting, and hot press treatments. Sericin content affected the structural characteristics and properties of the silk nonwoven fabrics. As the sericin content increased, the silk nonwoven fabrics became more compact with reduced porosity and thickness. Further, with increasing sericin content, the crystallinity and elongation of the silk nonwoven fabrics decreased while the moisture regain and the maximum stress increased. The thermal stability of most silk nonwoven fabrics was not affected by the sericin content. However, silk nonwoven fabrics without sericin had a lower thermal decomposition temperature than other nonwoven fabrics. Regardless of the sericin content, all silk nonwoven fabrics exhibited optimal cell viability and are promising candidates for cosmetic and biomedical applications.

Construction of Hydrophobic Ammonium Perchlorate with Synergistic Catalytic Effect Based on Supramolecular Self-Assembly for Synchronously Catalyzing the Thermal Decomposition of Ammonium Perchlorate and the Combustion of Aluminum.

Ammonium perchlorate (AP), as an important additive component of composite propellants, is critical to the combustion performance of propellants. Herein, AP@1H,1H,2H,2H-perfluorodecyltrichlorosilane (AP@PF) was prepared by establishing a tannic acid-iron ion (TA-Fe) supramolecular self-assembly layer on the AP surface and connecting the 1H,1H,2H,2H-perfluorodecyltrichlorosilane interfacial layer. Results demonstrate that TA-Fe and 1H,1H,2H,2H-perfluorodecyltrichlorosilane are uniformly bound to the surface layer of AP. AP@PF has a lower high-temperature thermal decomposition peak compared to AP. Meanwhile, the exothermic values of low-temperature thermal decomposition (338 J/g) and high-temperature thermal decomposition (597 J/g) of AP@PF are significantly higher than those of AP. In addition, AP@PF exhibits different surface interfacial properties, such as floating on the water surface and exhibiting a static contact angle of 105° on water. AP@PF shows almost no moisture absorption after aging in humid air for 30 days. The exothermic value of the mixture of AP@PF and aluminum powder (156 J/g) is significantly higher than that of the mixture of AP and aluminum (54 J/g), and the mixture of AP@PF and aluminum powder exhibits a higher calorific value and a stronger emission spectrum. Finally, the synergistic catalytic mechanism of AP@PF on the thermal decomposition of AP and the combustion of aluminum powder is also discussed.

Development of low-temperature thermal decomposition recycling technology from photovoltaic modules to flat glass applications

The recycling method for thermal decomposition of photovoltaic modules is a recycling method that can completely remove EVA, which is a sealing material, and can neatly separate the cells and glass. However, most back sheets are made of PET, and if they are simply thermally decomposed, a large amount of complex bonded carbides (“soot”) is generated. We succeeded in suppressing the generation of soot by heating resin components such as PET and EVA, melting and dropping them into a ceramic filter supported by a catalyst, promoting the oxidation reaction, and separating the glass and the cells cleanly. It was confirmed that the thermal decomposed PV glass can be recycled into flat glass by a float glass manufacturing company.

Effects of self‐assembled nucleating agent on the crystallization behavior, thermal properties, and mechanical properties of polylactic acid

AbstractPolylactic acid (PLA) is a biodegradable polyester, but its low crystallization rate and excessive embrittlement limit its application. Decanedioic acid 1,10‐bis (2‐benzoylhydrazide) (TMC‐300) as an effective nucleating agent of PLA will induce PLA epitaxial crystallization and improve the crystallization rate of PLA. This article studied the promoting behavior of TMC‐300 with different contents in composite systems on PLA crystallization. The results showed that with the increase of TMC‐300 content, the crystallinity can be significantly increased, up to 22 times, and t1/2 significantly decreases. Meanwhile, with the addition of TMC‐300, the typical spherical crystal morphology of PLA gradually became attached to TMC‐300 fibrous crystal morphology. In terms of mechanical properties, the tensile strength reached its maximum at 0.5 wt% of TMC‐300 content, increasing from 60.60 MPa (PLA) to 74.59 MPa (0.5‐TMC‐300), an increase of 23.09%. At this time, due to the reduction in spherical crystal size, the elongation at break also increased significantly. However, the thermal stability of PLA composites deteriorated with the increase of nucleating agent content due to the low thermal decomposition temperature of TMC‐300 itself, and the Tmax decreased from 372°C (PLA) to 353°C (5‐TMC‐300), a decrease of 19°C.

3D Electron-Rich ZIF-67 Coordination Compounds Based on 2-Methylimidazole: Synthesis, Characterization and Effect on Thermal Decomposition of RDX, HMX, CL-20, DAP-4 and AP

ZIF-67 is a three-dimensional zeolite imidazole ester framework material with a porous rhombic dodecahedral structure, a large specific surface area and excellent thermal stability. In this paper, the catalytic effect of ZIF-67 on five kinds of energetic materials, including RDX, HMX, CL-20, AP and the new heat-resistant energetic compound DAP-4, was investigated. It was found that when the mass fraction of ZIF-67 was 2%, it showed excellent performance in catalyzing the said compounds. Specifically, ZIF-67 reduced the thermal decomposition peak temperatures of RDX, HMX, CL-20 and DAP-4 by 22.3 °C, 18.8 °C, 4.7 °C and 10.5 °C, respectively. In addition, ZIF-67 lowered the low-temperature and high-temperature thermal decomposition peak temperatures of AP by 27.1 °C and 82.3 °C, respectively. Excitingly, after the addition of ZIF-67, the thermal decomposition temperature of the new heat-resistant high explosive DAP-4 declined by approximately 10.5 °C. In addition, the kinetic parameters of the RDX+ZIF-67, HMX+ZIF-67, CL-20+ZIF-67 and DAP-4+ZIF-67 compounds were analyzed. After the addition of the ZIF-67 catalyst, the activation energy of the four energetic materials decreased, especially HMX+ZIF-67, whose activation energy was approximately 190 kJ·mol-1 lower than that reported previously for HMX. Finally, the catalytic mechanism of ZIF-67 was summarized. ZIF-67 is a potential lead-free, green, insensitive and universal EMOFs-based energetic burning rate catalyst with a bright prospect for application in solid propellants in the future.

Simple direct fabrication of manganese oxide 3-D electrodes on Ni foam via thermal decomposition of manganese Formate-Amine ink for supercapacitors

A simple direct fabrication of 3-D electrodes on Ni foam was accomplished via low-temperature thermal decomposition of inks composed of manganese formate, triethylenetetramine and hexanol. Ni foams dipped in the ink were calcined at various temperatures to fabricate thin films. Calcination at 200 °C resulted in a thin film with small pores on the wire frame of Ni foam. Calcination at 300 °C produced thin films with bump pores on the wire frame and occlusion film between the frame wires. Both thin films showed high per volume capacitance of 6.7 and 7.1F cm−3 for the thin film synthesized at 200 and 300 °C, respectively. The high capacitance was due to the high specific capacitance (SC) of the thin films calcined at 200–220 °C and to the large loading mass on Ni foam of the films calcined at 270–300 °C.

One-Pot Preparation of HTPB/nNi and Its Catalyst for AP.

The liquid phase reduction method is a common method used for preparing nano-nickel powder (nNi). However, the nNi surface is easily oxidized to form nickel oxide film, which affects its performance. In this work, nNi was prepared using anhydrous ethanol as a solvent and hydrazine hydrate as a reducing agent. Furthermore, HTPB/nNi composites were prepared using hydroxyl-terminated polybutadiene (HTPB) as a coating agent. The structure and morphology of the samples are characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The catalytic behavior of HTPB/nNi on the thermal decomposition of ammonium perchlorate (AP) is studied by differential scanning calorimetry (DSC) and thermogravimetric analyzer (TG). The results show that HTPB/nNi has little effect on the low temperature thermal decomposition of AP, but the peak of high temperature thermal decomposition advances from 456 °C to 332 °C.

Evolved Gases and Unified Kinetic Model for Low-temperature Thermal Decomposition of Rice Straw Hydrolysis Residue for Possible Value Addition

Low-temperature thermal decomposition (LTTD) of Rice straw hydrolysis residue (RSHR) was studied using thermogravimetric analysis and Fourier Transform Infrared spectroscopy (TGA-FTIR) at different heating rates. During thermogravimetry, the maximum rate of mass loss of 135% per min was observed at 339 °C ( Tmax ) for heating rate of 50 °C per min. Tmax decreased to 323, 315, and 299 °C with decrease in heating rate to 40, 30, and 20 °C min−1, respectively. LTTD of RSHR yields volatile oxygenated organics – acids, esters, aldehydes, ketones, alcohols and phenols – as revealed by the FTIR spectra of evolved gases. At increased decomposition temperature, carbonyl moieties were less conjugated. The main gaseous products of LTTD were carbon dioxide, carbon monoxide, and methane. Kinetics of LTTD of RSHR was analysed using thermogravimetry results. Activation energy of LTTD followed a Lorentzian distribution with respect to residual mass fraction (RMF). Dependence of LTTD rate on RMF was found to adhere to the truncated Sestak and Berggren model.

Effect of the microporous structure of ammonium perchlorate on thermal behaviour and combustion characteristics

Ammonium perchlorate (AP) is the component with the highest content in composite propellants, and it plays a crucial role in propellant performance. In view of the effects of low-temperature AP thermal decomposition on thermal safety and combustion characteristics, porous ammonium perchlorate (PAP) samples with different mass losses were first prepared by thermal convection heating, and the structures were characterized and analysed. Second, the effects of decomposition degree on the thermal decomposition characteristics of PAP were studied by DSC-TG. Finally, the combustion characteristics of AP/Al binary mixtures were tested with high-speed photography and in a sealed bomb. The results showed that low-temperature decomposition of AP resulted in formation of porous structures for AP particles. The pores first appeared near the surfaces of the particles and began from multiple points at the same time. The pores increased in size to approximately 5 μm and then expanded, and finally, the AP particles were full of pores. After partial decomposition, the crystal structure of AP remained unchanged, but the low and high decomposition temperatures decreased obviously. The decomposition rate accelerated. Due to the porous structure of PAP, the combustion rate of the AP/Al system increased obviously with increasing decomposition of AP. The relationship between the combustion rate and the mass loss was approximately linear under open conditions, and it was exponential for a high-pressure environment. A computational model of the combustion process for the AP/Al binary system was established to explain the effects of pore structure and pressure on the combustion process.

Green and efficient in-situ biosynthesis of antioxidant and antibacterial bacterial cellulose using wine pomace

Biologically active bacterial cellulose (BC) was efficiently synthesized in situ using wine pomace and its hydrolysate. The structural and biomechanical properties together with the biological functions of the BC were investigated. Functional BC from wine pomace and its enzymatic hydrolysate were of high purity and had higher crystallinity indexes (90.61% and 89.88%, respectively) than that from HS medium (82.26%). FTIR results proved the in-situ bindings of polyphenols to the functionalized BC. Compared to BC from HS medium, wine pomace-based BC had more densely packed ultrafine fibrils, higher diameter range distributions of fiber ribbon, but lower thermal decomposition temperatures, as revealed by the SEM micrographs and DSC data. Meanwhile, wine pomace-based BC exhibited higher loads in tensile strength and higher hardness (4.95 ± 0.31 N and 5.13 ± 0.63 N, respectively) than BC in HS medium (3.43 ± 0.14 N). Furthermore, BC synthesized from wine pomace hydrolysate exhibited a slower release rate of phenolic compounds, and possessed more antioxidant activities and better bacteriostatic effects than BC from wine pomace. These results demonstrate that BC synthesized in situ from wine pomace (especially from enzymatic hydrolysate) is a promising biomolecule with a potential application in wound dressing, tissue engineering, and other biomedical fields.

When Copper Oxide meets graphene oxide: A core-shell structure via an intermittent spray coating route for a highly efficient ammonium perchlorate thermal decomposition

Ammonium perchlorate (AP) is the primary oxygen source for solid propellants; its thermal decomposition behavior is determinant for the overall performance of the ensuing propellant. In this perspective, a novel Intermittent, Spray Coating, Draying, and Mixing (ISCDM) method is introduced herein to prepare AP@CuO, PA@GO, and AP@CuO@GO core-shell composites. The as-synthesized materials morphological information, crystalline structure, and elemental composition are probed by powder X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The as-prepared CuO nanospheres were effectively embedded into the AP microparticles surface. AP@CuO microparticles were continuously coated with graphene oxide (GO) nanosheets. Particle size analyzer was used to probe the particle size distribution of core-shell composites. Results show that the application of ISCDM method results in a typical narrow gaussian size distribution with an average diameter of hundred microns ranking from 158.56 µm to 166.22 µm. The thermal decomposition and the catalytic performances were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). AP@CuO@GO core-shell composite exhibits an excellent thermal decomposition behavior: a low thermal decomposition temperature (LTD) of 337 °C, reduced values of the High thermal decomposition temperature HTD to be overlapped with the LTD step, and a significant energy release of 1543 J g−1 are registered.

Evolution of the Micropore Structure of Ammonium Perchlorate during Low-Temperature Decomposition and Its Combustion Characteristics

Ammonium perchlorate (AP) is a common oxidant in solid propellants, and its thermal decomposition characteristics at low temperatures (less than 240 °C) are key to the study of the thermal safety of propellants. Here, the low-temperature thermal decomposition characteristics of AP were investigated at 230 °C. The micromorphology of the low-temperature decomposition residues was characterized by scanning electron microscopy and 3D nano-computed tomography in order to analyse the evolution of microscopic pore structures, and the effect of the AP pore structure on combustion performance was then tested and analysed with a homemade closed bomb. The results demonstrate that the low-temperature decomposition of AP first occurs near the surface of the particles, simultaneously starting at multiple points and forming pores, and then gradually expands towards the interior until almost all of the pores connect with one other. Compared with ordinary AP, porous AP has a significantly improved combustion rate. When the ratio of porous AP to Al was 80:20, the peak pressure in the closed bomb was increased by 2.7 times; the rate of change in peak pressure increased 34 times, leading to a higher reaction speed and higher reaction intensity, and a typical explosion reaction occurred.

Preparation of Y3+ and transition metal ions codoped-BiFeO3 with enhanced magnetism and photocatalytic properties

Nanosized particles of Bi 0.95 Y 0.05 Fe 0.97 M 0.03 O 3 (M ​= ​Mn,Co,Ni,Cu,Zn) were successfully synthesized through thermal decomposition coordination precursors with diethylenetriaminepentaacetic acid (H 5 dtpa) as ligand. All prepared samples were characterized by XRD, Uv–vis DRS, SEM, PL, EIS, VSM and so on. From XRD results, the main phase of the samples was rhombohedral R3c (161) BiFeO 3 , and contained a small amount of soft iron ore Bi 25 FeO 40 . The phase and morphology of prepared samples were affected by doping ions. The average grain size of the samples was about 20 ​nm.T.The Uv–vis demonstrated the band gap of all samples was less than 2 ​eV and the response to light of all samples extended from ultraviolet region to visible region (~650 ​nm).The BFO–Y–Mn exhibited the minimum band gap of 1.77 ​eV. At the same time, photocatalytic activities of all samples prepared were evaluated through the photocatalytic degradation of methyl orange (MO). BiFeO 3 co-doping with 5%Y 3+ and 3%Mn 2+ exhibited excellent photocatalytic activity for MO solution. In the present of BFO–Y–Mn, the degradation rate of MO under light irradiation of 3 ​h was about 98%. Y 3+ ion and transition metal ions co-doped bismuth ferrite were successfully prepared by low-temperature thermal decomposition of coordination precursor method. The effects of different transition metal ions on the phase, magnetism, band structure, and photocatalytic properties of BiFeO 3 have been investigated. According to the energy band potential, it can be inferred that •OH − is the main active species in the photodegradation reaction of MO. • Y 3+ and M 2+ co-doped BiFeO 3 photocatalysts were successfully synthesized by a facile method. • Y 3+ and M 2+ co-doped BiFeO 3 photocatalysts demonstrated residual magnetism at room temperature. • The phase, band structure, and photocatalytic properties of co-doped BiFeO 3 ​have been investigated.

Formation Mechanism of β-Li3PS4 through Decomposition of Complexes.

β-Li3PS4 is a solid electrolyte with high Li+ conductivity, applicable to sulfide-based all-solid-state batteries. While a β-Li3PS4-synthesized by solid-state reaction forms only in a narrow 300-450 °C temperature range upon heating, β-Li3PS4 is readily available by liquid-phase synthesis through low-temperature thermal decomposition of complexes composed of PS43- and various organic solvents. However, the conversion mechanism of β-Li3PS4 from these complexes is not yet understood. Herein, we proposed the synthesis mechanism of β-Li3PS4 from Li3PS4·acetonitrile (Li3PS4·ACN) and Li3PS4·1,2-dimethoxyethane (Li3PS4·DME), whose structural similarity with β-Li3PS4 would reduce the nucleation barrier for the formation of β-Li3PS4. Synchrotron X-ray diffraction clarified that both complexes possess similar layered structures consisting of alternating Li2PS4- and Li+-ACN/DME layers. ACN/DME was removed from these complexes upon heating, and rotation of the PS4 tetrahedra induced a uniaxial compression to form the β-Li3PS4 framework.