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Ferroelectric films of BaSrTiO3 (BST) are identified as a potential alternative to silicon dioxide in the silicon-based microelectronics industry owing to their very high dielectric constant. The distribution of space charge and polarization in BST ceramics is studied at room temperature with the laser induced pressure pulse method.

We describe the space charge dynamics in MgO single crystals under high voltage at room temperature. The space charge profiles are measured in a nondestructive way using light induced pressure pulses. The build up of a positive space charge near the anode and of a negative space charge near the cathode are observed. The amplitude and extension of these charges depend on the electrode materials. Hole and electron injections at the interfaces can explain the charge distributions observed. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Electrical breakdown in insulators very often initiate near high field regions of the structure, as found near small-radius impurities or at electrode defects. This is attributed to the development of localized space charges. For this reason many efforts have been made to determine such charge. Various techniques are now available, but they are not directly applicable to complex geometries where it is difficult to determine analytically the field configuration and thus the relation between the measured variables and the space charge distribution. To solve this problem, we propose to use a numerical simulation using a finite element method (FEM). In this paper we describe how it can be implemented in the case of the pressure wave propagation (PWP) method. It is shown that measured signals in insulating samples with divergent electric field regions are well fitted by simulations. We show that this allows for the determination of space charge distribution in such samples.

Summary: Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a progressive and painful disease syndrome that affects aged horses. It affects incisor, canine and infrequently cheek teeth, and is characterised by gingival inflammation, oedema and recession, calculus deposition, feed accumulation, subgingival swellings with or without associated draining tracts, bulbous enlargement of teeth, tooth mobility, associated periodontal disease, tooth fracture and/or tooth loss. The aetiology of EOTRH is likely to be multi‐factorial. However, histopathological findings consistently suggest an aetiological contribution of initial biomechanical stresses and strains, followed by secondary involvement of micro‐organisms. Diagnosis is based on clinical presentation, age and radiographic changes including lytic changes, widening or loss of the periodontal ligament, hypercementosis, tooth fracture and alveolar bone loss. Treatment of EOTRH is not currently possible, but the condition can be managed to some degree, quite successfully for many years in some cases. However, the disease is progressive and invariably results in extraction of the tooth or teeth involved. The prognosis is most probably guarded at best and poor in most cases; however, complete removal of affected teeth carries a good prognosis for an improved quality of life in the short to medium term. [ABSTRACT FROM AUTHOR]

Describes high resolution photothermal imaging of high frequency phenomena using a visible charge coupled device camera associated with a multichannel lock-in scheme. Creation of an electronic 'stroboscope'; Heterodyne method; Joule effect; Peltier effect.