2011, Vol.21, No.2

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

Mong Hsu rubies from Myanmar include typically the dark core and blue patch but most of the previous research has merely focused on the dark core. This work is aimed to understanding clearly the characteristic of the dark core and blue patch of Mong Hsu rubies. It was found from the FTIR analysis that the dark core and blue patch region showed the absorption peaks of boehmite (1986 cm−1), diaspore (2115 cm−1) and water (3400~3900 cm−1) but the absorption peaks of O-H stretching (3309 cm−1and 3078 cm−1) were found only in blue patch region. The UV-VIS-NIR analysis of the dark core region revealed the stronger absorption of Cr 3+at 405 and 554 nm compared to the blue patch region. In range of 600~800 nm, the UV absorption characteristic at 659, 675 and 693 nm assigned to Cr 3+of core group samples is distinct from that of blue patch. The SEM-EDS examinations disclosed the existence of lots of micro-cracks and pores in the core regions compared to blue patch region.

High sensitivity IR image sensors require materials characteristics with temperature coefficient of resistance (TCR)and IR range absorption. In this study, the metal-dielectric thermo sensitive films (MDTF) based on (SiO2)x-(Ti)y composition were deposited on substrates of germanium and glass by thermal evaporator. The SiO2 : Ti mixture was made from the ratio of 9 : 1, 8 : 2, 7 : 3, 6 : 4, respectively. (SiO2)x-(Ti)y mixture powder was loaded on tungsten boat in evaporator and was 15.5 cm from the substrate. Resistance of (SiO2)x-(Ti)y in the range of 273~333 K were measured as a function of temperature. Temperature coefficient of resistance (TCR) was calculated by the resistance variation. Under the various mixture ratios condition, it is possible to obtain SiO2-Ti layers with resistance from units kilo-ohm to hundreds kilo-ohm. Finally, our results showed that Temperature coefficient of resistance (TCR) of these films varies from −1.4 to −2.6 %K−1.

The TiO2 films were prepared on glass, silicon and quartz substrate at different temperature by radio frequency reactive magnetron sputtering under different flow ratios of Ar and O2 gases. The films were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and UV-VIS spectrophotometer. Only the anatase phase was observed in films and their diffaction peaks increased with temprature of substrate. The size of crystallites decreased with higher concentration of oxygen. Refractive index and optical absorption of thin films decreased with higher concentration of oxygen. The thin films which have good transmittance spectra and smooth surface, deposited in the sputtering ambient with 10 % of O2 at the temperature from 300oC to 400oC.