Electrical switching in Sb doped Al 23 Te 77 glasses
| Autor: | K. P. Ramesh, Pumlianmunga |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Materials science Doping Analytical chemistry 02 engineering and technology General Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Threshold voltage law.invention Amorphous solid Protein filament Crystallography symbols.namesake law 0103 physical sciences Magic angle spinning symbols General Materials Science Crystallization 0210 nano-technology Glass transition Raman spectroscopy |
| Zdroj: | Journal of Physics and Chemistry of Solids. 107:68-74 |
| ISSN: | 0022-3697 |
| DOI: | 10.1016/j.jpcs.2017.03.015 |
| Popis: | Bulk glasses (Al 23 Te 77 )Sb x (0≤ x≤10) prepared by melt quenching method show a change in switching type from threshold to memory for x≥5. An increase in threshold current (I th ) and a concomitant decrease in threshold voltage (V th ) and resisitivity(ρ) have been observed with the increase of Sb content. Raman spectra of the switched region in memory switching compositions show a red shift with respect to the as prepared glasses whereas in threshold switching compositions no such shift is observed. The magic angle spinning nuclear magnetic resonance (MAS NMR) of 27 Al atom shows three different environments for Al ( [4] Al, [5] Al and [6] Al). The samples annealed at their respective crystallization temperatures show rapid increase in [4] Al sites by annihilating [5] Al sites. The melts of threshold switching glasses (x≤2.5) quenched in water at room temperature (27 °C) show amorphous structure whereas, the melt of memory switching glasses (x>2.5) solidify into crystalline structure. The higher coordination of Al increases the cross-linking and rigidity. The addition of Sb increases the glass transition(T g ) and decreases the crystallization temperature(T c ). The decrease in the interval between the T g and T c eases the transition between the amorphous and crystalline states and improves the memory properties. The temperature rise at the time of switching can be as high as its melting temperature and the material in between the electrodes may melt to form a filament. The filament may consists of temporary (high resistive amorphous) and permanent (high conducting crystalline) units. The ratio between the temporary and the permanent units may decide the switching type. The filament is dominated by the permanent units in memory switching compositions and by the temporary units in threshold switching compositions. The present study suggests that both the threshold and memory switching can be understood by the thermal model and filament formation. |
| Databáze: | OpenAIRE |
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