Lanthanide-based luminescent hybrid materials.

Recent research in the field of phosphor and scintillator materials and related detectors is reviewed. After a historical introduction the fundamental issues are explained regarding the interaction of x-ray radiation with a solid state. Crucial parameters and characteristics important for the performance of these materials in applications, including the employed measurement methods, are described. Extended description of the materials currently in use or under intense study is given. Scintillation detector configurations are further briefly overviewed and selected applications are mentioned in more detail to provide an illustration.

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Scintillation detectors for x-rays

https://www.lehigh.edu/operando/Publications/1999%20Titania-silica%20molec%20struc%20physico-chemical.pdf

Titania-silica as catalysts : molecular structural characteristics and physico-chemical properties

A review of medical diagnostic imaging methods utilizing x-rays or gamma rays and the application and development of inorganic scintillators is presented.

https://iopscience.iop.org/article/10.1088/0031-9155/47/8/201/pdf

Inorganic scintillators in medical imaging.

Chemical stability of metallic nanoparticles: a parameter controlling their potential cellular toxicity in vitro.

To examine the polishing mechanism in chemical mechanical polishing of a thermally grown SiO 2 film by CeO 2 particles, the surface structure of the film and the polishing waste were investigated by various analytical means. Fourier-transformed-infrared-attenuated-total-reflection (FT-IR-ATR) spectra indicated that the film surface structure was strained as a result of a reaction with CeO 2 . A small amount of Si was found by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) in the waste supernatant and it was detected as particles by optical interference measurement. The scanning electronic microscopy (SEM) image of the particles showed a not-well-defined shape like cotton scraps, but their IR transmission spectrum resembled that of the SiO 2 film. From these results we concluded that the SiO 2 film surface is first reacted with CeO 2 particles and a multiple number of chemical bondings of Si–O–Ce are formed on the surface. Then mechanical tearing of Si–O–Si bonds leads to the SiO 2 removal as a lump instead of Si(OH) 4 monomer, and the lump is released from the CeO 2 particles downstream.

Mechanism of polishing of SiO2 films by CeO2 particles

The dependence of the light output and the decay times of Ce-doped Gd/sub 2/SiO/sub 5/ on Ce concentration was measured. It is shown that the light output is almost constant and the decay time can be easily changed by changing Ce concentration. It is concluded that these properties make it possible to use GSO(Ce) scintillators as position-sensitive detectors. >

Cerium doped GSO scintillators and its application to position sensitive detectors

A new method for optical fibre fabrication has been found. The method is based on the so-called `sol-gel process′, which enables one to produce a core rod for optical fibre. Pure silica core fibre fabricated using this method exhibits an optical attenuation characteristic as low as 6 dB/km at a wavelength of 0.85 μm.

New optical fibre fabrication method

Growth of cerium-doped gadolinium pyrosilicate (Gd2Si2O7:Ce) single crystals, which show 2.5 times greater light output for gamma-rays and five times greater light output for alpha particles than GSO single crystals, is accomplished using floating zone growth method (FZ method). Although growth of Gd2Si2O7 (GPS) single crystal is considered to be difficult because it melts incongruently according to the phase diagram in a Gd2O3-SiO2 system, we attempted crystal growth of Ce:GPS because the possibility exists that heavy Ce doping changes the phase diagram. Transparent single crystals were obtained, but cracks were observed in the crystals. The crystal structure was triclinic with space group P/1 and density of 5.5 g/cm3. Two peaks were observed by photoluminescence spectrum measurement at 374 nm and 394 nm caused by 5d-4f transition in Ce3+ ion. Decay times of Ce:GPS were 46 ns for gamma-ray and 39 ns for alpha particles; its density was 5.5 g/cm3. We consider that the energy resolution of 23% will be improved by fabrication of large crystals and improvement of crystal perfectability.

Floating zone growth and scintillation characteristics of cerium-doped gadolinium pyrosilicate single crystals

Single crystal Ce-doped Gd/sub 2/SiO/sub 5/ (GSO) has a good balance of scintillation properties such as high density, intense light output, and short decay time, and also has an excellent temperature response and excellent radiation hardness. We studied causes for cracks in single-crystal GSO which have been a major problem in GSO growth, and tried to optimize the growth conditions by using a two-zone furnace which reduced thermal gradient. We were thus able to grow a crack-free single-crystal of GSO that was 80 mm in diameter and 280 mm long. Specimens with 20/spl times/20/spl times/200 mm/sup 3/ sampled from the large GSO boules with 0.5 and 1.5 mol% Ce have been evaluated for high energy physics application.

Kenzo Susa

Papers

Mechanism of polishing of SiO2 films by CeO2 particles

Cerium doped GSO scintillators and its application to position sensitive detectors

New optical fibre fabrication method

Floating zone growth and scintillation characteristics of cerium-doped gadolinium pyrosilicate single crystals

Scintillation performance of large Ce-doped Gd/sub 2/SiO/sub 5/ (GSO) single crystal