Recent Advances in Science and Technology of Materials

1. Front Matter

   Pages i-xv

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2. Defects in Solids

   1. Kinetics of Defect Formation in Alkali Halides at Helium Temperatures

      • G. J. Dienes

      Pages 1-14

   2. Relaxation of Impurity-Defect Complexes in Fluorite Crystals

      • J. H. Crawford Jr., E. L. Kitts Jr.

      Pages 15-26

   3. Intrinsic Point Defects in Oxides with the Rutile Structure

      • R. A. Weeks

      Pages 27-38

   4. The Capture of Electrons by Negatively Charged Impurity Atoms in N-Type Germanium

      • E. F. El-Wahidy, A. G. Mironov

      Pages 39-46

   5. Radiation Defects in Heavily Irradiated GaAs

      • E. Yu. Brailovskii, V. N. Broudnyi, I. D. Konozenko, M. A. Krivov

      Pages 47-58

3. Electrical Properties

   1. The Problem of Chemical Inhomogeneities in Electronic Materials

      • Harry C. Gatos, August F. Witt

      Pages 59-75

   2. A Review of the Electrical Properties and Microstructure of Vanadium Phosphate Glasses

      • D. L. Kinser, L. K. Wilson

      Pages 77-90

   3. Electrical Switching in Calcium Phosphate Glasses Containing Iron

      • M. H. Omar, M. N. Morcos

      Pages 91-107

   4. Role of Iron and Electrical Conductivity in Iron Calcium Phosphate Glasses

      • R. S. Motran, A. M. Bishay, D. P. Johnson

      Pages 109-130

   5. Properties of Simultaneously Sputtered Thin Metal Films

      • F. Ismail, L. M. El Nadi

      Pages 131-141

   6. Indirect Exciton with Degenerate Valence Band in the Two-Photon Absorption in Semiconductors

      • A. R. Hassan

      Pages 143-151

   7. Structure of Chalcogenide Glasses

      • Norbert J. Kreidl, Werner Ratzenboeck

      Pages 153-170

   8. Effect of Heat Treatment on Electrical Properties and Structure of As-Te-Ge Chalcogenide Thin Films

      • F. H. Hammad, A. A. Ammar, M. M. Hafiz, A. El-Nadi

      Pages 171-188

   9. Application of Avrami’s Equation to the Conductivity Changes of Amorphous Selenium

      • M. K. El-Mously, F. E. Gani

      Pages 189-196

   10. Electrical Properties of Quenched SnO2 Films on Glass Substrates

       • E. W. Wartenberg, P. W. Ackermann

       Pages 197-204

   11. Physical Properties of Sputtered Amorphous Germanium Thin Films: The Role of Technological Parameters

       • M. Závětová, S. Koc, J. Zemek

       Pages 205-210

4. Magnetic Properties

   1. Some Recent Results on Paramagnetic Spin-Lattice Relaxation in Hydrated Paramagnetic Salts of the Iron Group

      • C. J. Gorter, A. J. van Duyneveldt

      Pages 211-233

   2. ESR and Optical Studies of Induced Centres in Binary Silver and Alkali Borate Glasses

      • F. Assabghy, E. Boulos, S. Calamawy, A. Bishay, N. Kreidl

      Pages 235-246

   3. ESR and Structural Studies on Pseudo-Alexandrite

      • S. Arafa, S. Haraldson, A. Hassib

      Pages 247-258

If an ion in a crystal is replaced by an impurity ion with a different charge, compensation for the charge difference must be accomplished. This is usually done by an intrinsic defect, i. e. a lattice vacancy or interstitial host ion, in such a way to balance the excess or deficit of charge. The introduction of cation vacan­ cies along with divalent cation impurities in alkali halides is a familiar example. If these crystals are carefully annealed, nearly all of the compensating defects migrate to the impurity ions to form impurity-defect complexes. It is the behavior of these complexes that are the principal concern in this paper. Almost invariably such complexes are dipolar in character, and when subjected to an electric or mechanical stress field, they will tend to realign to an orienta­ tion of lower energy provided the thermal activation is sufficiently great. If the complex consists of an impurity-vacancy couple, re­ orientation may occur either by the vacancy moving around the impu­ rity or by an exchange of positions of the partners. In general the activation energy for these two distinct reorientation paths is different. If the complex consists of an impurity-interstitial couple, interchange of positions is unlikely and reorientation is considered to occur exclusively by the motion of the interstitial around the vacancy.

• X-ray
• crystal
• defects
• deformation
• energy
• glass
• iron
• material
• materials
• metals
• semiconductors
• stress

• Solid State and Materials Research Center, American University in Cairo, Cairo, Egypt

  Adli Bishay

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