This paper presents new developments in inorganic scintillators widely used for radiation detection. It addresses major emerging research topics outlining current needs for applications and material sciences issues with the overall aim to provide an up-to-date picture of the field. While the traditional forms of scintillators have been crystals and ceramics, new research on films, nanoparticles, and microstructured materials is discussed as these material forms can bring new functionality and therefore find applications in radiation detection. The last part of the contribution reports on the very recent evolutions of the most advanced theories, methods, and analyses to describe the scintillation mechanisms.

The physical properties of perovskites of the type AC 3 B 4 O 12 , whose structure derives from simple perovskites ABO 3 , are reviewed. The A position is subject to strong structural distortions and splits into two new positions A and C. In the structure of AC 3 B 4 O 12 vacancies and any cations with a large radius, irrespective of their charge state, can be present in the icosahedral environment of A: Na + , Cd 2+ , Ca 2+ , Sr 2+ , Y 3+ , Ln 3+ , and Nd 4+ . The C position in the square environment of oxygen can be occupied only by the Jahn-Teller cations Cu 2+ and Mn 3+ . Transition and nontransition metal ions-Mn 3+ , Fe 3+ , Al 3+ , Cr 3+ , Ti 4+ , Mn 4+ , Ge 4+ , Ru 4+ , Ir 4+ , Ta 5+ , Nb 5+ , Ta 5+ , Sb 5+ -can occupy the B position in an octahedral environment. Some members of the family of complex perovskites possess properties which are characteristic for systems with heavy fermions; collinear and noncollinear magnetic structures with high ordering temperatures occur in these materials; tunneling magnetoresistance and high permittivity are observed. The diversity and unique properties make these materials attractive for practical applications.

Absorption, reflection as well as luminescence emission, excitation, and decay curves for single crystals of LuAlO 3 :Ce 3+ and LuAlO 3 :Pr 3+ grown by the Bridgman technique have been measured at various temperatures. The fluorescence spectra photo-excited over a wide energy domain ranging from the UV to the x-ray region, and the kinetics are typical of the cerium and praseodymium ions. These experimental results show that the exciton transfer to the dopant occurs at around 8 eV, and the energy transfer via sequential hole and electron trapping is dominant at higher energy. This process must be considered as the main scintillation mechanism in this crystal. The high efficiency of this mechanism is explained by the small energy difference between the 4f level of the dopant and the top of the valence band, estimated from XPS measurements.

Scintillating nanoparticles (NPs) in combination with X-ray or γ-radiation have a great potential for deep-tissue cancer therapy because they can be used to locally activate photosensitizers and generate singlet oxygen in tumours by means of the photodynamic effect. To understand the complex spatial distribution of energy deposition in a macroscopic volume of water loaded with nanoscintillators, we have developed a GEANT4-based Monte Carlo program. We thus obtain estimates of the maximum expected efficiency of singlet oxygen production for various materials coupled to PS, X-ray energies, NP concentrations and NP sizes. A new parameter, ηnano, is introduced to quantify the fraction of energy that is deposited in the NPs themselves, which is crucial for the efficiency of singlet oxygen production but has not been taken into account adequately so far. We furthermore emphasise the substantial contribution of primary interactions taking place in water, particularly under irradiation with high energy photons. The interplay of all these contributions to the photodynamic effect has to be taken into account in order to optimize nanoscintillators for therapeutic applications.