Creation and Accumulation of Radiation Defects in Single Crystals of Magnesium Oxide : Research Aims and Methodology

The range of problems that can be solved with the use of powerful radiation installations is determined: generation of nanosecond ultrahigh-frequency (microwave) pulses, collective acceleration of charged particles, the implementation of a controlled fusion reaction, and the creation of high-power lasers. In this edition, the questions posed for the SCM were solved using the example of single crystals of magnesium oxide. By the beginning of the authors' work, the structure of the color centers induced by radiation in magnesium oxide, the positions of the maxima of the optical absorption and luminescence bands, as well as the values of their half-widths and the temperature range of stability, were sufficiently established. There is practically no information about the location of internode ions in magnesium oxide crystals, and methods for their registration have not been worked out. These data are particularly important since the efficiency of the accumulation of radiation defects depends to a certain extent on the efficiency of fixing displaced of in the crystal lattice. However, all studies confirming this point of view were carried out using low and medium levels of arousal. The effect of high absorbed radiation energy capacities on the formation and accumulation of radiation defects in magnesium oxide crystals has not been practically studied. Preface Introduction Contents 1 Structure, Properties, Point Defects and Radiation Defect Formation in Magnesium Oxide Crystals 1.1 Structure and Properties of MgO Crystals 1.1.1 Crystal Physical Properties 1.1.2 Energy Electronic Structure of MgO 1.1.3 Thermodynamic Equilibrium Defects 1.2 Color Centers of MgO Crystals 1.2.1 Electronic Color Centers 1.2.2 Hole Color Centers 1.2.3 Impurity Color Centers 1.2.4 Interstitial Defects 1.3 Radiation Defect Formation in Magnesium Oxide Crystals 1.3.1 Creation of Radiation Defects in the Anionic Sublattice of Magnesium Oxide Single Crystals 1.3.2 Creation of Radiation Defects in the Cationic Sublattice of Magnesium Oxide Single Crystals 2 Objects and Methods of Research Used in the Study 2.1 Installation of Pulsed Optical Spectroscopy 2.2 Installation for Studying the Angular Distributions of Annihilation Gamma Quanta 2.2.1 Radiation Detectors 2.2.2 Collimator System 2.2.3 Isotope and Sample Attachment Unit 2.2.4 Source of Positrons 2.2.5 The “Cedar” Electrode Device 2.2.6 Measurement Error 2.2.7 Calculation of Positron Absorption in Single Crystals of Magnesium Oxide 2.3 Dosimetry of the Radiation 2.3.1 High-Current Electron Beam 2.3.2 High-Energy Protons 2.3.3 Absorbed X-ray Radiation Energy 2.4 Additional Optical Absorption of Irradiated MgO (I) Crystals 3 Formation of Radiation Defects in MgO Crystals Under High-Temperature Proton Irradiation 3.1 Kinetics of the Change in the Intensity of the Absorption Band with a Maximum at 4.92 eV 3.2 Photo Luminescence of Irradiated MgO (I) Crystals 3.3 Proton Energy Losses in MgO (I) Crystals 3.3.1 Calculation of Proton Energy Losses Due to Ionization and Elastic Collisions 3.3.2 Proton Energy Distribution Over the Depth of Irradiated MgO (I) Crystals 3.4 Distribution of F+-centers by Depth of MgO (I) Crystals Irradiated with Protons 3.5 Summary 4 Stabilization of Frenkel Defects in Crystals of Magnesium Oxide at Impact Displacement of Ions 4.1 Optical Absorption of MgO (II) Crystals 4.2 The Role of Trivalent Cations of Substitutive Impurities in the Phenomena of Stabilization of Radiation Defects in Magnesium Oxide 4.2.1 Kinetics of Accumulation of F+-Centers in Pure and Doped MgO (II) Crystals 4.2.2 Kinetics of Band Intensity Change with hvm = 5.6 eV 4.2.3 Annealing of F+-bands in Irradiated MgO (II) Crystals 4.3 Calculation of the Kinetics of Accumulation of Anionic Frenkel Defects in MgO Crystals Under Elastic Proton Scattering 4.4 Models of Interstitial Defects in Magnesium Oxide Crystals Irradiated with Protons at Room Temperature 4.4.1 Formation of Interstitial Defects Involving Pre-Radiation Imperfections of the Crystal 4.4.2 Interstitial Defects in Defect-Free Areas of MgO Crystals 4.5 Summary 5 Creation of F+-Centers in Proton Tracks at Low Irradiation Temperatures 5.1 Effect of Temperature on the Efficiency of Accumulation of F+-Centers in MgO During Proton Irradiation 5.1.1 Optical Absorption of MgO (I) Crystals Irradiated at Low Temperatures 5.1.2 Accumulation of Radiation Defects at Low Irradiation Temperatures 5.1.3 Effect of Temperature on Accumulation and Annealing of Centers in MgO (I) Crystals 5.2 Thermally Stimulated Conductivity of Irradiated MgO(I) Crystals 5.3 Nature of Low-Temperature Efficiency Change Accumulations of F+-centers 5.4 Summary 6 Accumulation of F-Type Color Centers in Crystals of Magnesium Oxide at High Excitation Densities Accelerated Electrons of Subthreshold Energy 6.1 Accumulation of F+-Centers in Magnesium Oxide Crystals at High Excitation Densities by Accelerated Electrons 6.2 Effect of the Current Density of the Accelerated Electron Beam on the Accumulation of F+-Centers in Magnesium Oxide Crystals 6.3 Summary 7 Stabilization of Interstitial Oxygen Ions Formed Under the Action of a High-Current Electron Beam in the Crystal Lattice of Magnesium Oxide 7.1 About Possible Locations of Interstitial Oxygen Ions in the Crystal Lattice of Magnesium Oxide 7.2 Investigation of the Generation of F+-Color Centers in Single Crystals of Magnesium Oxide Under the Action of a High-Current Beam of Accelerated Electrons of Nanosecond Duration 7.3 Correlation in the Accumulation of F+-Color Centers and Changes in the Charge State of Impurity Iron Ions in Single Crystals of Magnesium Oxide under Irradiation with a High-Current Electron Beam 7.4 Influence of the Calcination Temperature of Magnesium Oxide Crystals on the Accumulation of Radiation Defects of Them 7.5 Summary 8 Experimental Study of Interstitial Oxygen Ions in Magnesium Oxide Crystals 8.1 Investigation of Photoluminescence in Magnesium Oxide Crystals Irradiated by a High-Current Electron Beam 8.2 Study of Positron Annihilation in Single Crystals of Magnesium Oxide 8.3 Summary Appendix References