Dependence Of Transition Temperature Research Articles

Analytical description of domain morphology and phase diagrams of ferroelectric nanoparticles

Analytical description of domain structure morphology and phase diagrams of ferroelectric nanoparticles is developed in the framework of Landau-Ginzburg-Devonshire approach. To model realistic conditions of incomplete screening of spontaneous polarization at the particle surface, it was considered covered by an ultra-thin layer of screening charge with effective screening length. The phase diagrams, calculated for spherical Sn2P2S6 nanoparticles in coordinates "temperature" and "effective screening length" by finite element modelling, demonstrate the emergence of poly-domain region at the tricritical point and its broadening with increasing the screening length for the particle radius over a critical value. Metastable and stable labyrinthine domain structures exist in Sn2P2S6 nanoparticles with radius (8–10) nm and more. We derived simple analytical expressions for the boundaries between paraelectric, single-domain and poly-domain ferroelectric phases, tricritical point and the necessary condition for the appearance of labyrinthine domains, and demonstrated their high accuracy in comparison with finite element modelling results.Analytical expressions for the dependence of the ferroelectric-paraelectric transition temperature on the particle radius in the single-domain and poly-domain states of the particle were compared with analogous dependences experimentally measured for SrBi2Ta2O9 nanoparticles and simulated for Sn2P2S6 nanocrystals by Monte Carlo method within the framework of axial next-nearest-neighbours Ising model. The analytical expression for the ferroelectric-paraelectric transition temperature in the poly-domain state quantitatively agrees with experimental and simulated results, and it accurately reproduces empirical Ishikawa equation at all temperatures, justifying it theoretically. Analytical description shows that phase diagrams and domain morphologies, which are qualitatively similar to the ones calculated in this work, can be expected in other ferroelectric nanoparticles covered by the screening charges, being rather different for the ferroelectrics with the first and second order ferroelectric-paraelectric transitions respectively.

Thermal analysis of structural phase transition behavior of Ln2Ni1−xCuxO4+δ (Ln = Nd, Pr) under various oxygen partial pressures

Structural phase transition behavior between orthorhombic and tetragonal in Ln2Ni1−xCuxO4+δ (Ln = Nd, Pr), which attracts interest as new cathode material for solid oxide fuel cells, has been investigated with thermal analysis under controlled oxygen partial pressures (P(O2)). For Nd2Ni1−xCuxO4+δ with 0.0 ≤ x ≤ 0.1, temperature, enthalpy change (ΔH) and change in excess oxygen content (Δδ) at the phase transition decreased with increasing Cu content. The phase transition temperature decreased with decreasing P(O2), whereas little variation was observed in ΔH and Δδ. For Nd2Ni1−xCuxO4+δ with x ≥ 0.15, crystal structure was tetragonal and no phase transition was detected below 750 °C. For Pr2Ni1−xCuxO4+δ with x = 0.0 and 0.1, phase transition was observed by DSC, showing similar dependence of phase transition temperature and ΔH on Cu content and P(O2) with that of Nd2Ni1−xCuxO4+δ. Δδ was not detected in TG curve of Pr2Ni0.9Cu0.1O4+δ, which could be attributed to too small Δδ. From Ellingham diagram prepared using temperature and P(O2) at the phase transition, variation of standard enthalpy (ΔH°) and standard entropy (ΔS°) was evaluated. It was revealed that variation of phase transition temperature by Cu content and difference of the phase transition temperature between Nd2Ni1−xCuxO4+δ and Pr2Ni1−xCuxO4+δ showed correspondence with variation of ΔH°. Excess oxygen content, δ, in Nd2Ni1−xCuxO4+δ, evaluated with reduction in TG apparatus, decreased with increasing Cu content. It was suggested that some amount of δ was required for stabilization of orthorhombic phase and that low δ by Cu substitution stabilized the tetragonal structure of the specimens with x ≥ 0.15.

MADS-Box Transcription Factor MadsA Regulates Dimorphic Transition, Conidiation, and Germination of Talaromyces marneffei.

The opportunistic human pathogen Talaromyces marneffei exhibits a temperature-dependent dimorphic transition, which is closely related with its pathogenicity. This species grows as multinucleate mycelia that produce infectious conidia at 25°C, while undergoes a dimorphic transition to generate uninucleate yeast form cells at 37°C. The mechanisms of phenotype switching are not fully understood. The transcription factor madsA gene is a member of the MADS-box gene family. Previously, it was found that overexpression of madsA gene resulted in mycelial growth instead of yeast form at 37°C. In the current study, the madsA deletion mutant (ΔmadsA) and complemented strain (CMA) were constructed by genetic manipulation. We compared the phenotypes, growth, conidiation, conidial germination and susceptibility to stresses (including osmotic and oxidative) of the ΔmadsA with the wild-type (WT) and CMA strains. The results showed that the ΔmadsA displayed a faster process of the yeast-to-mycelium transition than the WT and CMA. In addition, the deletion of madsA led to a delay in conidia production and conidial germination. The tolerance of ΔmadsA conidia to hydrogen peroxide was better than that of the WT and CMA strains. Then, RNA-seq was performed to identify differences in gene expression between the ΔmadsA mutant and WT strain during the yeast phase, mycelium phase, yeast-to-mycelium transition and mycelium-to-yeast transition, respectively. Gene ontology functional enrichment analyses indicated that some important processes such as transmembrane transport, oxidation-reduction process, protein catabolic process and response to oxidative stress were affected by the madsA deletion. Together, our results suggest that madsA functions as a global regulator involved in the conidiation and germination, especially in the dimorphic transition of T. marneffei. Its roles in the survival, pathogenicity and transmission of T. marneffei require further investigation.

The spin-reorientation magnetic transitions in Ga-doped SmCrO3

Orthochromite SmCrO3 is known to show spin reorientation around 34 K and which was assigned as transition from Γ4 to Γ2. Our work reports the spin reorientation transitions in a series of Ga-doped SmCrO3: the spin reorientation transition from Γ4 to Γ2 at TSR2 = 88 K and another spin reorientation transition of Γ2 to Γ1 at TSR1 = 15 K were observed simultaneously when the content of Ga is 30%. Importantly, the evolution of spin reorientation transitions from the single spin reorientation of Γ4 → Γ2 to double ones of Γ4 → Γ2 → Γ1, and then to the single one of Γ2 → Γ1 is caused by the increase of Ga doping concentration. The M-T and M-H measurements have been made to study the temperature and magnetic field dependence of these spin reorientation transitions. These temperatures and doping dependence of spin reorientation transitions in RCrO3 (R = rare earth or yttrium) can appeal to the magnetic switching devices design based on these findings.

CuAgSe nanocrystals: colloidal synthesis, characterization and their thermoelectric performance

CuAgSe is a promising thermoelectric (TE) material for its superior carrier mobility and ultralow lattice thermal conductivity. Herein, we present a scalable colloidal method to prepare monodisperse CuAgSe nanocrystals with high yield. The collected powder sample was washed by a sulfur-free reagent of NaNH2 to remove the surface organic ligands (CuAgSe-W) and then annealed (CuAgSe-W-A). Both kinds of ligand-free samples were then hot pressed into dense pellets to measure the TE property. The results revealed that the crystal structure of both samples changed from low-temperature β-phase to high-temperature α-phase at around 465 K. Sample CuAgSe-W shows interesting temperature-dependent transition from N-type to P-type, which could be potentially used as thermal control transistor. Sample CuAgSe-W-A does not display this transition state but it exhibits potential for intermediate temperature TE applications with a figure-of-merit zT reaching 0.68 at 566 K.

Mössbauer Studies of Z-Type Sr3Co2Fe24O41 Strontium Ferrite

Sr3Co2Fe24O41 plocrystalline sample was synthesized by using a polymerizable complex method. We investigated the crystallographic and the magnetic properties of sample by using X-ray diffractometer, vibrating sample magnetometer, and Mossbauer spectrometer. Based on the Rietveld refinement, the crystal structure of the sample was found to be single-phased and to be hexagonal with space group of P63/mmc. The hysteresis curves of sample were measured under 15 kOe at various temperatures ranging from 4.2 and 295 K. From the temperature dependence of the magnetization curves under 100 Oe at temperatures between 4.2 and 740 K, three temperature-dependent magnetic transitions were found to have occurred in the Sr3Co2Fe24O41 sample. The Mossbauer spectra of the samples were obtained at various temperatures ranging from 4.2 and 295 K.

Composition dependence of transition temperatures on quaternary Co-Fe-Ni-Ga melt-spun alloys

The composition dependence of transition temperatures on quaternary Co-Fe-Ni-Ga melt-spun alloys with constant Ga content are examined. A few at.% of Fe replacement for Co in Co50Ni22Ga28 drastically reduce martensitic transformation temperature (TM) whereas ferromagnetic transition temperature (Tc) remains above 400 K. Increasing Ni instead of Co in Fe doped specimen can raise TM around room temperature again. Further increase of Fe content with this manner, the alloys finally connected to ternary Ni-Fe-Ga of ferromagnetic shape memory region. The martensitic transition start temperature (MS) of Co-Fe-Ni-Ga28 alloys show good correlation with the valence electron ratio (e/a). The MS vs e/a plot clearly shows that trend lines are separated for each Fe content, and intervals of trend lines seem to be proportional to Fe content at lower Fe region. The Tc and saturation magnetization of Co-Fe-Ni-Ga28 alloys show almost linear relation with magnetic valence Zm.

Bipolar Conduction as the Possible Origin of the Electronic Transition in Pentatellurides: Metallic vs Semiconducting Behavior

The pentatellurides, ZrTe5 and HfTe5 are layered compounds with one dimensional transition-metal chains that show a never understood temperature dependent transition in transport properties as well as recently discovered properties suggesting topological semimetallic behavior. Here we show that these materials are semiconductors and that the electronic transition is due to a combination of bipolar effects and different anisotropies for electrons and holes. We report magneto-transport properties for two kinds of ZrTe5 single crystals grown with the chemical vapor transport (S1) and the flux method (S2), respectively. These have distinct transport properties at zero field: the S1 displays a metallic behavior with a pronounced resistance peak and a sudden sign reversal in thermopower at approximately 130 K, consistent with previous observations of the electronic transition; in strikingly contrast, the S2 exhibits a semiconducting-like behavior at low temperatures and a positive thermopower over the whole temperature range. Refinements on the single-crystal X-ray diffraction and the energy dispersive spectroscopy analysis revealed the presence of noticeable Te-vacancies in the sample S1, confirming that the widely observed anomalous transport behaviors in pentatellurides actually take place in the Te-deficient samples. Electronic structure calculations show narrow gap semiconducting behavior, with different transport anisotropies for holes and electrons. For the degenerately doped n-type samples, our transport calculations can result in a resistivity peak and crossover in thermopower from negative to positive at temperatures close to that observed experimentally. Our present work resolves the longstanding puzzle regarding the anomalous transport behaviors of pentatellurides, and also resolves the electronic structure in favor of a semiconducting state.

Temperature dependence of excitonic transitions in Al0.60Ga0.40N/Al0.70Ga0.30N multiple quantum wells from 4 to 750 K

The excitonic optical properties of an Al0.60Ga0.40N/Al0.70Ga0.30N multiple quantum well structure were studied by photoluminescence (PL) spectroscopy at various temperatures. An analysis of the temperature dependence of PL peak energy revealed the stronger localization of excitons than biexcitons, consistent with the trend predicted from the difference between the spatial extents of excitons and biexcitons. The PL linewidth of the excitons increased linearly with increasing temperature up to 300 K and then more rapidly above 300 K. This result indicated that the exciton-longitudinal optical phonon interaction became prominent as the broadening mechanism of the exciton linewidth above 300 K. The luminescence of both excitons and biexcitons exhibited low thermal quenching, with their intensities at 300 K remaining at 37% and 47%, respectively, of their intensities at 4 K. These observations reflected the high thermal stability of the excitons and biexcitons in this multiple quantum well structure. In addition, the ratio of the PL intensity of the exciton-biexciton scattering to the product of the exciton and biexciton luminescence intensities was independent of temperature up to 200 K and increased rapidly with increasing temperature above 250 K. The temperature-independent behavior of this ratio up to 200 K originated from the localization of excitons and biexcitons, and the rapid increase in this ratio with temperature above 250 K reflected an increase in the frequency of interactions between the excitons and biexcitons due to the gradual delocalization of the excitons and biexcitons with increasing temperature.

Microscopic Description of the Thermodynamics of a Lipid Membrane at a Liquid–Gel Phase Transition

A microscopic model of the lipid membrane is constructed that provides analytically tractable description of the physical mechanism of the first order liquid-gel phase transition. We demonstrate that liquid-gel phase transition is cooperative effect of the three major interactions: inter-lipid van der Waals attraction, steric repulsion and hydrophobic tension. The model explicitly shows that temperature-dependent inter-lipid steric repulsion switches the system from liquid to gel phase when the temperature decreases. The switching manifests itself in the increase of lateral compressibility of the lipids as the temperature decreases, making phase with smaller area more preferable below the transition temperature. The model gives qualitatively correct picture of abrupt change at transition temperature of the area per lipid, membrane thickness and volume per hydrocarbon group in the lipid chains. The calculated dependence of phase transition temperature on lipid chain length is in quantitative agreement with experimental data. Steric repulsion between the lipid molecules is shown to be the only driver of the phase transition, as van der Waals attraction and hydrophobic tension are weakly temperature dependent.

Understanding the magnetism in noncentrosymmetric CeIrGe3 : Muon spin relaxation and neutron scattering studies

The magnetic properties of a pressure induced noncentrosymmetric heavy-fermion superconductor CeIrGe$_3$ have been investigated by muon spin relaxation ($\mu$SR), powder neutron diffraction (ND) and inelastic neutron scattering (INS) techniques at ambient pressure. For completeness we have also measured the ac magnetic susceptibility $\chi_{\rm ac}(T)$, dc magnetic susceptibility $\chi(T)$, dc isothermal magnetization $M(H)$ and heat capacity $C_{\rm p}(T,H)$ down to 2 K. CeIrGe$_{3}$ is known to exhibit pressure induced superconductivity ($T_{\rm c}\approx 1.5$ K) at a pressure of 20 GPa and antiferromagnetic ordering at 8.7 K, 4.7 K and 0.7 K at ambient pressure. Our $\chi_{\rm ac}(T)$ and $\chi(T)$ data show an additional anomaly near 6.2 K which is also captured in $C_{\rm p}(T)$ data. From $\chi_{\rm ac}(T)$, $\chi(T)$ and $C_{\rm p}(T)$ measurements we infer three antiferromagnetic transitions above 2 K at $T_{\rm N1}= 8.5$ K, $T_{\rm N2}= 6.0$ K and $T_{\rm N3}= 4.6$ K. Our $\mu$SR study also confirms the presence of three transitions through the observation of one frequency for $T_{\rm N2} < T\leq T_{\rm N1}$, two frequencies for $T_{\rm N3} < T\leq T_{\rm N2}$ and three frequencies for $T\leq T_{\rm N3}$ in the oscillatory asymmetry. The ND data reveal an incommensurate nature of the magnetic ordering at $T=7$ K with the propagation vector k = (0,0,0.688(3)), and a commensurate magnetic structure at $T=1.5$ K with the propagation vector locked to the value k = (0,0,2/3) and magnetic moments oriented along the $c$ axis. The commensurate structure couples a macroscopic ferromagnetic component, resulting in a strong dependence of the lock-in transition temperature on external magnetic field. The INS data show two well defined crystal electric field (CEF) excitations arising from the CEF-split Kramers doublet ground state of Ce$^{3+}$.

Structural impact of nitrogen incorporation on properties of alkali germanophosphate glasses

AbstractThe structure, atomic packing density, calorimetric glass transition, and hardness of mixed sodium–lithium germanophosphate oxynitride glasses with varying Ge/P and N/P ratios were investigated. The combined influences of nitridation and mixed network former effect (MNFE) on the glass structure were analyzed using Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and 31P nuclear magnetic resonance (NMR) spectroscopy. Evidence for the existence of germanium in a higher coordination state, i.e., five‐ or sixfold coordination, was obtained by performing XPS analysis of the oxide glasses, with indication of conversion to tetrahedral coordination upon nitridation. Raman spectroscopy measurements implied that the germanate network was modified upon nitridation, including the removal of ring‐like germanate structures and P–O–Ge mixed linkages. The partial anionic N‐for‐O substitution gave rise to the linear dependence of the glass transition temperature (Tg) and hardness (HV) on nitrogen content (expressed as N/P ratio), especially for lower Ge/P ratio. However, nitridation also caused an unexpected increase in liquid fragility and decrease in density. This suggests that the governing structural parameter for property evolution in such LiNaGePON glasses is not only the increased degree of cross‐linking of the phosphate chains, but rather the short‐ and intermediate‐range structural modifications within the germanate component of the oxynitride glasses.

Temperature-dependent structural transition, electronic properties and impedance spectroscopy analysis of Tl2InGaS4 crystals grown by the Bridgman method

In this work, we report the temporary structural modifications associated with the in situ heating of the Tl2InGaS4 crystals in the temperature range of 300–420 K. The analysis of the X-ray diffraction patterns revealed the temperature-independent possible phase transformations between the monoclinic and triclinic phases. The temperature analysis of the lattice parameters, crystallite size, strain, dislocation density and stacking faults has shown a temporary enhancement in the crystallinity of this compound above 375 K. Significant increase in the grain size accompanied to decrease in the strain, defect density and stacking faults was observed above this temperature. The scanning electron microscopy imaging has shown that the crystals are layer structured with high quality layers of thicknesses of ~ 12 nm. In addition the energy dispersive X-ray analysis has shown that the crystal comprise no detectable impurity. Moreover, the room temperature optical characterizations has shown that the Tl2InGaS4 exhibit an energy band gap of 2.5 eV. The temperature dependent electrical resistivity measurements indicated highly resistive crystal with activation energy values of 0.84 and 0.19 eV above and below 375 K, respectively. On the other hand, room temperature impedance spectroscopy analysis in the frequency domain of 10–1800 MHz has shown that the crystal exhibits negative resistance and negative capacitance effects below and above 1580 MHz. The crystals are observed also to behave as band stop filter with notch frequency of 1711 MHz.

Combined Effect of Phosphorus Grain Boundary Segregation, Yield Strength, and Grain Size on Embrittlement of a Cr–Mo Low‐Alloy Steel

The dependence of fracture appearance transition temperature (FATT) on phosphorus grain boundary segregation, yield strength, and grain size is experimentally evaluated for a 2.25Cr–1Mo low‐alloy steel. Both the phosphorus boundary segregation and yield strength are directly correlated to the FATT of the steel. However, the prior austenite grain size is not directly linked to the FATT although it influences phosphorus boundary segregation and yield strength. The FATT exhibits linear relations to phosphorus segregation concentration and yield strength, but there is no synergistic effect between these two entities. Based on the measurements, an embrittlement equation is established, which is expressed as FATT(°C) = 0.25σs + 2.64CP–270, where σs is the yield strength in MPa and CP is the phosphorus boundary concentration in at%. The calculated FATTs have a good agreement with the measured ones.

Effect of antimony on glass transition and thermal stability of Se78−xTe18Sn2Sbx (x = 0, 2, 4 and 6 at.%) multicomponent glassy alloys

Multicomponent glassy alloys Se78−xTe18Sn2Sbx (x = 0, 2, 4 and 6) have been synthesized using melt quench technique. The prepared samples have been characterized by X-ray diffraction technique and differential scanning calorimetry (DSC). Glass transition kinetics of Se78−xTe18Sn2Sbx (x = 0, 2, 4 and 6 at.%) glassy alloys has been examined using DSC. DSC runs have been recorded at different heating rates (5, 10, 15 and 20 K min−1) for each sample under investigation. Heating rate dependence of glass transition temperature (Tg) has been studied using Lasocka empirical relation. The activation energy of glass transition has been evaluated using Kissinger and Moynihan’s relation. The effect of antimony concentration on glass transition temperature and activation energy has been investigated in the prepared samples. Glass-forming ability and thermal stability of Se78−xTe18Sn2Sbx (x = 0, 2, 4 and 6) glassy alloys have been monitored through the evaluation of thermal stability using Dietzal relation, Hurby parameter, and Saad and Poulin parameter. The above-mentioned parameters are found to be compositionally dependent, which indicates that among the studied glass samples the stability is maximum for Sb at 2% content.

Accurate quantification of hydration number for polyethylene glycol molecules**Project supported by the National Natural Science Foundation of China (Grant Nos. 11474325 and 11290161) and the Knowledge Innovation Project of Chinese Academy of Sciences on Water Science Research (Grant No. KJZD-EW-M03).

Hydration water can even decide the physicochemical properties of hydrated organic molecules. However, by far the most important hydration number for organic molecules, in particular polyethylene glycol which we are concerned with here, usually suffers from a large discrepancy. Here, we provide a scheme for accurate and unambiguous quantification of the hydration number based on the universal water-content dependence of glass transition temperature for aqueous solutions, testified by experimental results for polyethylene glycol molecules of a molar weight ranging from 200 to 20000. Moreover, we also clarify the fundamental misunderstanding lying in the definition and quantification of hydration water for PEG molecules in the literature, therein the hydration number for PEG in water-rich solutions has been determined at a critical concentration, across which the properties of the solution display obviously distinct water-content dependence.

Clarifying the gel-to-glass transformation in Al2O3-SiO2 systems

In this paper, we clarify the gel-to-glass (G-G) transformation behavior of the sol-gel derived xAl2O3-(100 − x)SiO2 (x = 0, 10, 20 and 30 mol) systems by differential scanning calorimetry, X-ray diffraction, infrared (IR) spectroscopy and transmission electron microscopy. The SiO2-Al2O3 gels exhibit lower G-G transition temperature than the pure SiO2 reference gel. Adding Al2O3 to the SiO2 gel can suppress the dependence of glass transition temperature (Tg) on hydroxyl concentration, and this effect is attributed to the highly cross-linked structure in alumina-silica gels. In addition, the Al-rich phase separates from the Si-rich matrix phase, and such immiscibility increases with increasing Al2O3 content. This behavior is similar to that of the melt-quenched alumina-silica glasses.

Effect of lithium isotopes on the phase transition in NASICON-type lithium-ion conductor LiZr2(PO4)3

Polycrystalline NASICON-type Li-ion conductor LiZr2(PO4)3 (LZPO) with different ratios of Li isotopes, namely 6LiZr2(PO4)3 (6-LZPO), 7LiZr2(PO4)3 (7-LZPO), and LZPO with the natural Li isotope ratio (n-LZPO), has been synthesized by a conventional solid state reaction. The phase transformation as a function of temperature between the low-temperature triclinic phase, which exhibits lower Li-ion conductivity, and high-temperature rhombohedral phase, which exhibits higher Li-ion conductivity, has been evaluated by powder X-ray diffraction (XRD), electron diffraction, and differential scanning calorimetry (DSC) measurements. According to XRD and DSC measurements, the phase transition temperature decreases in the order 6-LZPO > n-LZPO ≈ 7-LZPO. The dependence of phase transition temperature on the Li isotope implies that Li ions have a strong effect on phase stability. The phase transition is primarily related to the change in configuration entropy of Li ions in LZPO.

Exciton-phonon coupling channels in a ‘strain-free’ GaAs droplet epitaxy single quantum dot

We examine the temperature-dependent excitonic transition energy shift of strain-free GaAs droplet epitaxy (DE) quantum dots (QDs). Interestingly the statistical investigation of QD optical properties enables us to observe three distinct temperature dispersions for four series of DE QDs. We present comparative analyses of the exciton-phonon coupling mechanisms employing various empirical to multi-oscillator models associated with each QD-specific phonon dispersion spectrum. The systematic investigation of such QD exciton-phonon coupling is crucial for fine control of local defects in engineered quantum dot single-photon sources.

Temperature dependent optical properties of ZnO thin film using ellipsometry and photoluminescence

We report the temperature dependence of the dielectric function, the exciton binding energy and the electronic transitions of crystallized ZnO thin film using spectroscopic ellipsometry (SE) and photoluminescence (PL). ZnO layers were prepared by sol-gel method and deposited on crystalline silicon (Si) by spin coating technique. The ZnO optical properties were determined between 300 K and 620 K. Rigorous study of optical responses was achieved in order to demonstrate the quenching exciton of ZnO as a function of temperature. Numerical technique named constrained cubic splines approximation (CCS), Tauc-Lorentz (TL) and Tanguy dispersion models were selected for the ellipsometry data modeling in order to obtain the dielectric function of ZnO. The results reveals that the exciton bound becomes widely flattening at 470 K on the one hand, and on the other that the Tanguy dispersion law is more appropriate for determining the optical responses of ZnO thin film in the temperature range of 300 K–420 K. The Tauc-Lorentz, for its part, reproduces correctly the ZnO dielectric function in 470 K–620 K temperature range. The temperature dependence of the electronic transition given by SE and PL shows that the exciton quenching was observed in 420 K–∼520 K temperature range. This quenching effect can be explained by the equilibrium between the Coulomb force of exciton and its kinetic energy in the film. The kinetic energy was found to induce three degrees of freedom of the exciton.