The melting behavior of CsPbBr3 perovskite was studied by differential thermal analysis (DTA). It was found that melting of CsPbBr3 occurs non-isothermally in the temperature range of 561 to 570 °C. From the temperature dependence of the solid-phase melting rate, it was established that at 567±1 °C the change in the mechanism of the solid-phase melting goes from fragmentation to dissolution at the surface. The obtained values of the activation energy of the melting of the solid phase in CsPbBr3 show that the activation energy of the dissolution of the solid-phase fragments is 4 times greater than the energy of the fragmentation of the solid phase.
We investigated melting and crystallization processes of Cd0.50Mn0.50Te. Using differential thermal analysis (DTA) we studied the solid-liquid equilibrium temperature range, the temperature dependence of the volume fraction of the solid phase in the melt, and crystallization peculiarities. We observed that changing a dwell temperature from 1346 to 1354 K results in an increase of the crystallization temperature of the Cd0.50Mn0.50Te melt. Since the melt is in a semiliquid state, its crystallization occurs over a solid-phase domain. It was found that a slightly overheated Cd0.50Mn0.50Te melt (up to 10 K) crystallizes more slowly than more overheated melts, and that the Cd0.50Mn0.50Te solid solutions are in a semi-liquid state in the temperature range of 1338-1354 K.
In this work the structural, optical and electrical properties of Cd1-x-yMnxZnyTe single crystals (x=0.10, 0.20, y=0.15) grown by the vertical Bridgman method were investigated. Based on differential thermal analysis results, it was found that the crystallization rate increases as the crystallization temperature (Ts) decreases. It is determined that the volume fraction of solid phase in Cd0.75Mn0.10Zn0.15Te and Cd0.65Mn0.20Zn0.15Te alloys decrease to a minimum in the temperature ranges 1366–1389 K and 1363-1388 K, respectively. The activation energies of melting and crystallization processes for these alloys under different conditions are established. The linear character of the dependence between the preexponential factor (lnφsol.phase,0 and lnVmelt., sol. phase,0) and the activation energy of these processes is determined, which is evidence of a compensation effect. The band-gap value was estimated to be ~ 1.73 eV for Cd0.75Mn0.10Zn0.15Te and ~1.84 eV for Cd0.65Mn0.20Zn0.15Te at 300 K. Typical transmission images showed the presence of small Te inclusions (5- 10 μm) in the crystals. The electrical resistivity, obtained from the I-V curves, was ~104 Ω·cm for both crystals and decreased slightly toward the end of the ingots.
High temperature Hall-effect investigations were used to study the change of the concentration and mobility of charge-carriers in Cd0.85Mn0.10Zn0.05Te and Cd0.85Mn0.10Zn0.05Te: In crystals grown by the vertical Bridgman technique. The Cd0.85Mn0.10Zn0.05Te and Cd0.85Mn0.10Zn0.05Te: In samples are characterized by optical and electrical measurements, and by IR-microscopy. We determined that the value of band gap increase with the Mn and Zn amount increasing in the Cd1-x-yMnxZnyTe crystals. We also show that after the high-temperature Hall-effect measurements performed under Cd overpressure the both crystals resistivity increase from 104 Ohm×cm to 106 Ohm×cm, and amount and size of Te inclusions decrease. According to the results of the high temperature Hall-effect investigations the temperatures and Cd vapor pressures intervals were established in which Indium plays major role and controls the concentration of charge carriers.
In this paper, correlation between CMZT melt state and structure properties of crystals, grown by vertical Bridgman method, was investigated. The Cd0.9-xMnxZn0.1Te crystals with various Mn composition (x = 0.1; 0.2) were grown by two-step preparation method from high purity elemental components. We have conducted series of crystal growth runs with different melt superheating degree over the alloys melting temperature. As a result, we have got the ingots with various crystalline structures and properties. It was concluded that worth crystalline structure had the bulks which were grown from the melt with lowest superheating degree. We have determined also that band gap rose (from 1.67 at x=0.1 to 1.79 eV at x=0.2) with Mn content increasing.
Solid-liquid phase transitions in Cd0.95-xMnxZn0.05Te alloys with x = 0.20 and 0.30 were investigated by differential thermal analysis (DTA). The heating/cooling rates were 5 and 10 K/min with a melt dwell time of 10, 30 and 60 minutes. Cd0.95-xMnxZn0.05Te (x=0.20, 0.30) single-crystal ingots were grown by the vertical Bridgman method guided by the DTA results.
Te inclusions (1-20 micron diameter), typical of melt-grown CdTe and Cd(Zn)Te crystals, were observed in the ingots by infrared transmission microscopy. The measured X-ray diffraction patterns showed that all compositions are found to be in a single phase. Using current-voltage (I-V) measurements, the resistivity of the samples from each ingot was estimated to be about 105 Ohm·cm. The optical transmission analysis demonstrated that the band-gap of the investigated ingots increased from 1.77 to 1.88 eV with an increase of the MnTe content from 20 to 30 mol. %.
In this paper, we have investigated some structural properties, Raman spectra of Zn1-xMnxTe films deposited by the closed space vacuum sublimation under different growth conditions. The obtained results of the Raman spectroscopy and XRD analysis show single phase composition of the samples. The presence of phonon replicas in the Raman spectra of the films indicates their high structural quality. The manganese content (about 7 %) in the layers was determined
according to shifting the relative peaks positions.
Peculiarities of Cd0.95-xMnxZn0.05Te (x=0.05-0.25) alloys melting and crystallization kinetics were investigated by the differential thermal analysis at various heating/cooling rates. We synthesized Cd0.95-xMnxZn0.05Te alloys from elemental materials in a double-zone furnace. Their melting-crystallization rate was 5- and 10-K/min with a melt-dwell time of 1-, 10-, 20-, and 30-minutes. We found that the melting temperature, Tm, declined with increasing “x”, while the crystallization temperature, Ts, rose with increasing “x”. We detailed the dependencies of the crystallization rate versus the melt’s crystallization temperature. In most cases, the dependencies dropped with the rise of the crystallization temperature, while the crystallization temperature fell with decreasing melt-dwell time.
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