V. Marinova

Refractive index measurements and transmission spectra of Bi2(MoO4)3 single crystals

Abstract Large, optical-quality bismuth molybdate Bi 2 (MoO 4 ) 3 single crystals are grown by the Czochralski method from a stoichiometric melts. The principal refractive indices n x , n y and n z are measured using the classic method of minimum angle of deviation in the visible region of the spectrum. The crossing angle of the optical axes is calculated. It is obtained that bismuth molybdate single crystals possess a wide transmission window between 0.415 and 5.2 μm. The absorption coefficient dependence of the photon energy is presented and the edge of absorption gap is determined.

Optical properties of Bi12TiO20 doped with Al, P, Ag, Cu, Co and co-doped with Al+P single crystals

Large optically homogeneous photorefractive Bi12TiO20 (BTO) single crystals doped with Al, P, Ag, Cu, Co and Ala P-co-doping were obtained by the Top Seeded Solution Growth Method (TSSG) in a Bi2O3 solution. A strong bleaching eAect was observed for the Al, P, Ag and Ala P-doped crystals, whereas doping with Cu and Co induced a strong photochromic eAect and increased the absorption coeAcients in the red spectral region. Al, P, Ala P-doped crystals increased the values of optical rotator power, while Cu and Ag-doped crystals exhibited a strong decrease in optical activity in comparison with non-doped BTO. The influences of doping elements on the optical rotation power are discussed on the basis of two structural elementary cell units ‐ MO4 tetrahedra and BiOn polyhedra. ” 2000 Published by Elsevier Science B.V. All rights reserved.

Optical properties of single Pb(Sc12Ta12)O3 crystals

Single ferroelectric Pb(Sc12Ta12)O3 crystals of perovskite structural type were obtained by the high temperature solution growth (HTSG) method. The refractive index was measured by the prism method at 10 selected wavelengths and the dispersion in the visible spectral range was calculated by Sellmeiers formula. Optical transmission and reflection spectra were measured and the absorption coefficient α was determined in the visible range. Using the calculated α(hν) dependence, the α12(hν) function was plotted and it was used to determine the bandgap width and characterize the fundamental absorption edge.

The growth and optical properties of doped bismuth titanate

Abstract The growth conditions for producing Al, Mn, Cr and Al+Cr doped Bi 12 TiO 20 crystals have been studied. Transmission spectra of various crystals have been measured and the absorption has been determined in the range 0.4 – 0.85 μm. A blue shift in the spectral absorption of Al doped Bi 12 TiO 20 and a red shift in Mn, Cr and Al+Cr doped Bi 12 TiO 20 has been observed as compared to undoped material. In Al+Cr doped crystals the absorption is blue-shifted as compared to Cr-only doping.

Refractive index measurements of mixed HgBrxI2−x single crystals

Abstract Large, optical quality mixed HgBr x I 2− x single crystals were grown by the Bridgman–Stockbarger method. Their principal refractive indices n g , n m and n p were measured at room temperature for the first time, using the classic method of minimum angle of deviation in the visible region of the spectrum. The crossing angles of the optical axes were calculated and the parameters of Sellmaiers dispersion equation were determined.

Growth and characterization of (SnS2)x–(SnSe2)1−x mixed crystals

Abstract (SnS 2 ) x –(SnSe 2 ) 1− x layered crystals were grown using the vertical Bridgman technique for x =0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.9, 1.0. IR-spectra of these compounds were obtained using a Bruker-spectrometer. The structural properties were studied using transmission electron microscopy (TEM). The variation of the structural and optical properties was studied as a function of the composition x .

Electron- and hole-mobility of Hg(BrxI1−x)2 crystals (x = 0.25, 0.50, 0.75)

Abstract The electron- and hole-mobility of Hg(BrxI1−x)2 crystals with compositions x=0.25, 0.50, 0.75 and 1.00 were measured using the time-of-flight method. The samples, in the form of thin layered plates, were irradiated with an 241 Am source; a memory oscilloscope monitored the corresponding current pulses created by the nuclear source. So the flight time and consequently the mobilities of the free electrons and holes were determined, and compared to results obtained on HgI2.

Optical absorption properties of PB5GEO4(VO4)2 single crystals

Abstract Thermal and pulling conditions have been optimized in a laboratory Czochralski apparatus to yield optically homogeneous crystals of hexagonal Pb 5 GeO 4 (VO 4 ) 2 . The wavelength dependence of absorption coefficient was calculated from transmission and reflection measurements in the visible region. A hypothesis regarding the zone structure in connection to the fundamental absorption edge was raised and the bandgap width corresponding to indirect transition at room temperature was determined from the α 1 2 -hv curve.