Comparison of the optical parameters of a CaF 2 single crystal and optical ceramics (original) (raw)

Two types of additional absorption spectra in CaF2 crystals

Soviet Physics Journal, 1969

A study of two types of additional absorption spectra observed in colored CaF 2 crystals is reported. The spectral shape for the additively colored crystal is governed by the experimental conditions; during photochemical coloring, it depends on the thermal prehistory of the sample. In all cases, a spectrum consisting of bands at 370 and 560 nm appears in crystals having a band near 200 nm. An additional band appears at 560 nm in the Smakula spectrum at high-irradiation doses; there are three stages in the increase of this band with increasing dose. A similar dependence on the radiation dose is observed for the 560-nmband in synthesized CaF 2 crystals. It is suggested that this band is due to defects produced in the lattice during the irradiation.

Luminescence properties of CaF2:Mn optically transparent ceramic

Journal of Luminescence, 2015

The optically transparent ceramics (OTC) of CaF 2 :Mn were fabricated by a vacuum hot-press method. Photo-luminescence (PL) and radio-luminescence measurements were carried out on CaF 2 :Mn OTCs to study the effect of processing on the luminescence properties of the material. The temperature dependence of PL and decay kinetics were investigated down to 77 K. The results were compared with the reported luminescence properties of CaF 2 :Mn single crystals. The comparison shows that the luminescence is similar at room temperature, however, the evolution of luminescence with temperature and decay mechanism of Mn 2+ centers in OTC are quite different. A possible explanation for the differences in the luminescence properties of CaF 2 :Mn OTC has been proposed.

4 Growth and Characterization of Doped CaF 2 Crystals

2017

The alkaline-earth fluorides crystallize in the cubic structure and constitute an important class of relatively simple ionic crystals whose optical and lattice-dynamical properties have theoretical and experimental interest. The CaF2 crystals have been used for long time in many optical components due to its exceptional transparency in the UV as well as in the IR spectral domain. CaF2, SrF3 and BaF2 have been among the first solid-state laser hosts and they were lased at the beginning of the 1960s doped with RE3+ ions; these rare-earth doped crystals, however, have been abandoned as laser systems during a long time. The reason resides in the charge compensation which is required to maintain the electrical neutrality of crystals. This process gives rise to a rich multisite structure including so-called isolated centers and more or less complex centers [Petit et al., 2008], which leads to broad absorption and emission bands comparable with those of glasses. Rare earth doped CaF2 recen...

Additive coloring of CaF2 optical ceramic

Optics and Spectroscopy, 2011

The specificity of additive coloring of CaF 2 optical ceramic (formation of color centers in it and photothermochemical transformation of these centers in colored ceramic samples) has been considered. Under the same coloring conditions, this process occurs more slowly in ceramics rather than in crystals; at the same time, the limiting concentration of color centers that can be introduced into ceramics is much higher. The photothermochemical transformations of color centers in crystals and ceramics, which occur under illumination at different wavelengths and upon heating, have been studied. The specific features of introduction of color centers into ceramic and their transformation under illumination and heating are likely to be related to the mass twinning of ceramic grains.

Structural, spectral-luminescent, and lasing properties of nanostructured Tm : CaF 2 ceramics

Quantum Electronics, 2012

The structure and the spectral-luminescent properties of CaF 2 -TmF 3 fluoride ceramics and single crystals are studied. AFM investigations revealed a layered nanostructure of grains, which was not observed in reference samples of single crystals. It is found that the spectral-luminescent properties of CaF 2 -TmF 3 ceramics and single crystals are similar. Lasing at the 3 F 4 ® 3 H 6 transition of Tm 3+ ions in CaF 2 -TmF 3 ceramics (wavelength 1898 nm) under diode pimping is obtained for the first time.

Laser grade CaF2with controllable properties: growing conditions and structural imperfection

Journal of Physics D: Applied Physics, 2007

Optical properties of CaF 2 , grown by a controlled Bridgman-Stockbarger technique, are studied by CuBr and SrBr 2 vapour lasers. Absorption losses are determined as a function of the grown crystal volume, the crystallization front (CF), and the real crystallization rate. It is found that the absorption losses are relatively independent of the transmitted wavelengths in a wide spectral range from the deep ultraviolet (DUV) to the middle infrared (MIR) spectral region and their minimum corresponds to CF positions within the upper half of the adiabatic furnace zone, where the CR reaches a constant value slightly higher than the speed of crucible movement. The crystal quality conforms to laser grade CaF 2 for the DUV, visible and MIR spectral regions and may be controlled efficiently by introducing an appropriate systematic correction in the furnace temperature field, which shifts the CF position.

Thermoluminescence spectra and X-ray luminescence spectra of CaF2-Nd single crystals

Journal of Materials Science, 1987

X-ray luminescence measurements are an important tool in the study of the optical properties of a fluorite system. In the case of CaF2-Nd the major emission under X-ray excitation is in the infrared region, which has been studied extensively. In this paper emission in the ultraviolet and visible range under X-ray excitation is reported. Thermoluminescence (TL) and TL spectra in the same region have also been measured. The similarities in the peak emission wavelengths in the two processes show that the emission centres involved are the same.

Luminescence efficiency of CaF2:Eu single crystals: Temperature dependence

Procedia Structural Integrity, 2020

During the last decades, there is increasing interest in applications of scintillators at harsh environments (i.e., high temperatures or radiation fluxes), such as in geophysical detectors for deep geology boreholes, non-destructive testing (NDT) of pipelines in oil and gas industry, space and marine exploration, nuclear reactor monitoring, radiation chemistry, etc. To this aim, the current study is the first step towards the investigation of the luminescence efficiency dependence of single-crystal scintillators over wide temperature ranges. Calcium fluoride doped with europium (CaF 2 :Eu) was selected due to the fact that it has a high melting point at 1418°C and is also robust to mechanical and thermal shocks. The dimensions of the single-crystal sample were 10x10x10 mm 3 , and it was irradiated using typical X-ray radiographic exposures (90 kVp, 63mAs) in order to measure the light photon intensity dependence with temperature (22 to 128 °C). The luminescence efficiency was found maximum at the lowest examined temperature (22.01 efficiency units-E.U. at 22 °C-environmental). With increasing temperature, the luminescence efficiency decreased almost exponentially due to thermal quenching (4.43 efficiency units-E.U. at 128 °C).